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HomeMy WebLinkAbout11-00400034- 00075278 y14 FOR OFFICE USE ONLY CASE NO.: .` - *-ff DATE SUBMITTED: Icy' TIME: CrrY OF COI d.FGE SI v1 ION Home of Tra u University% STAFF: FINAL PLAT APPLICATION (Check one) ❑ Minor ❑ Amending ❑ Final ❑ Vacating © Replat ($700) ($700) ($932) ($932) ($932) Is this plat in the ETJ? ❑ Yes © No Is this plat Commercial ❑ or Residential IN MINIMUM SUBMITTAL REQUIREMENTS: • $700 -$932 Final Plat Application Fee (see above). ❑ $233 Variance Request to Subdivision Regulations Fee (if applicable). $600 (minimum) Development Permit Application / Public Infrastructure Review and Inspection Fee. Fee is 1% of acceptable Engineer's Estimate for public infrastructure, $600 minimum (if fee is > $600, the balance is due prior to the issuance of any plans or development permit). © Application completed in full. .This application form provided by the City of College Station must be used and may not be adjusted or altered. Please attach pages if additional information is provided. Fourteen (14) folded copies of plat. (A signed mylar original must be submitted after approval.) © Two (2) copies of the grading, drainage, and erosion control plans with supporting drainage report. © Two (2) copies of the Public infrastructure plans and supporting documents (if applicable). El Copy of original deed restrictions /covenants for replats (if applicable). © Title report for property current within ninety (90) days or accompanied by a Nothing Further Certificate current within ninety (90) days. The report must include applicable information such as ownership, liens, encumbrances, etc. © Paid tax certificates from City of College Station, Brazos County and College Station I.S.D. • The attached Final Plat checklist with all items checked off or a brief explanation as to why they are not. NOTE: A mylar of the approved preliminary plat must be on file before a final plat application will be considered complete. If the mylar is submitted with the final plat application, it shall be considered a submittal for the preliminary plat project and processed and reviewed as such. Until the mylar has been confirmed by staff to be correct, the final plat application will be considered incomplete. Date of Optional Preapplication or Stormwater Management Conference November 17, 2010 NAME OF PROJECT Randall's University Park - Replat of Lot 3R -2 ADDRESS Chimney Hill Drive SPECIFIED LOCATION OF PROPOSED PLAT: Randall's University Park, Lot 3R -2 of College Station, Brazos County, Texas APPLICANT /PROJECT MANAGER'S INFORMATION (Primary contact for the project): Name RME Consulting Engineers (c% Rabon Metcalf) E -mail rabon @rmengineer.com Street Address P.O. Box 9253 City College Station State 7X Zip Code 77842 Phone Number (979) 764 -0704 Fax Number (979) 764 -0704 10/10 Page 1 of 9 Requested Oversize Participation Total Linear Footage of Parkland [dedication due prior to filing the Final Plat: Proposed Public: ACREAGE: Streets Sidewalks No. of acres to be dedicated + $ development fee Sanitary Sewer Lines No. of acres in floodplain 108 Water Lines No. of acres in detention Channels No. of acres in greenways 45 Storm Sewers OR FEE IN LIEU OF LAND: Bike Lanes / Paths No. of SF Dwelling Units X $ _ $ (date) Approved by Parks & Recreation Advisory Board NOTE: DIGITAL COPY OF PLAT MUST BE SUBMITTED PRIOR TO FILING. The applicant has prepared this application and certifies that the facts stated herein and exhibits attached hereto are true, correct, and complete. IF THIS APPLICATION IS FILED BY ANYONE OTHER THAN THE OWNER OF THE PROPERTY, this application must be accompanied by a power of attorney statement from the owner. If there is more than one owner, all owners must sign the application or the power of attorney. If the owner is a company, the application must be accompanied by proof of authority for the company's representative to sign the application on its behalf LIEN HOLDERS identified in the title report are also considered owners and the appropriate signatures must be provided as described above. •r l I ( Signature an. title Date Page 4 of 9 CERTIFICATIONS REQUIRED FOR ALL DEVELOPMENT Owner Certification: 1. No work of any kind may start until a permit is issued. 2. The permit may be revoked if any false statements are made herein. 3. If revoked, all work must cease until permit is re- issued. 4. Development shall not be used or occupied until a Certificate of Occupancy is issued. 5. The permit will expire if no significant work is progressing within 24 months of issuance. 6. Other permits may be required to fulfill local, state, and federal requirements. Owner will obtain or show compliance with all necessary State and Federal Permits prior to construction including NOI and SWPPP. 7. If required, Elevation Certificates will be provided with elevations certified during construction (forms at slab pre - pour) and post construction. 8. Owner hereby gives consent to City representatives to make reasonable inspections required to verify compliance. 9. If, stormwater mitigation is required, including detention ponds proposed as part of this project, it shall be designed and constructed first in the construction sequence of the project. 10. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that all debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities. All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer for the above named project. All of the applicable codes and ordinances of the City of College Station shall apply. 11. The information and conclusions contained in the attached plans and supporting documents will comply with the current requirements of the City of College Station, Texas Gity Code, Chapter 13 and associated BCS Unified Design Guidelines Technical Specifications, and Standard Details. All development has been designed in accordance with all applicable codes and ordinances of the City of College Station and State and Federal Regulations. , 77 u '.� _, 12. Release of plans to . arc) ,E'..H 'O,' -! r`?�'� c :� t (name or firm) is authorized for bidding purposes only. I understand that final approval and release of plans and development for construction is contingent on contractor signature on approved Development Permit. 13. I, THE OWNER, AGREE TO AND CERTIFY THAT ALL STATEMENTS HEREIN, AND IN ATTACHMENTS FOR THE DEVELOPMENT PERMIT APPLICATION, ARE, TO THE BEST OF MY KNOWLEDGE, TRUE, AND _ACCURATE. i it,f Ax 11t it; +F = r te Property Owner(s) Date Engineer Certification: 1_ The project has been designed to ensure that stormwater mitigation, including detention ponds, proposed as part of the project will be constructed first in the construction sequence. 2. I will obtain or can show compliance with all necessary Local, State and Federal Permits prior to construction including NOI and SWPPP. Design will not prelude compliance with TPDES: I.e., projects over 10 acres may require a sedimentation basin. 3. The information and conclusions contained in the attached plans and supporting documents comply with the current requirements of the City of College Station, Texas City Code, Chapter 13 and associated BCS Unified Design Guidelines. All development has been designed in accordance with all applicable codes and ordinances of the City of College Station and State and Federal Regulations. 4. I, THE ENGINEER, AGREE TO AND CERTIFY THAT ALL STATEMENTS HEREIN, AND IN ATTACHMENTS FOR THE DEVELOPMENT PERMIT APPLICATION, ARE, TO THE BEST OF MY KNOWLEDGE, TRUE, AND ACCURATE. Engineer Date 1ano Page 5 of 9 CERTIFICATIONS REQUIRED FOR ALL DEVELOPMENT Owner Certification: 1. No work of any kind may start until a permit is issued. 2. The permit may be revoked if any false statements are made herein. 3. If revoked, all work must cease until permit is re- issued. 4. Development shall not be used or occupied until a Certificate of Occupancy is issued. 5. The permit will expire if no significant work is progressing within 24 months of issuance. 6. Other permits may be required to fulfill local, state, and federal requirements. Owner will obtain or show compliance with all necessary State and Federal Permits prior to construction including NOI and SWPPP. 7. If required, Elevation Certificates will be provided with elevations certified during construction (forms at slab pre - pour) and post construction. 8. Owner hereby gives consent to City representatives to make reasonable inspections required to verify compliance. -9. If, stormwater mitigation is required, including detention ponds proposed as part of this project, it shall be designed and constructed first in the construction sequence of the project. 10. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that all debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities. All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer for the above named project. All of the applicable codes and ordinances of the City of College Station shall apply. 11. The information and conclusions contained in the attached plans and supporting documents will comply with the current requirements of the City of College Station, Texas City Code, Chapter 13 and associated BCS Unified Design Guidelines Technical Specifications, and Standard Details. All development has been designed in accordance with all applicable codes and ordinances of the City of College Station and State and Federal Regulations. 12. Release of plans to (name or firm) is authorized for bidding purposes only. I understand that final approval and release of plans and development for construction is contingent on contractor signature on approved Development Permit. 13. I, THE OWNER, AGREE TO AND CERTIFY THAT ALL STATEMENTS HEREIN, AND IN ATTACHMENTS FOR THE DEVELOPMENT PERMIT APPLICATION, ARE, TO THE BEST OF MY KNOWLEDGE, TRUE, AND ACCURATE. Property Owner(s) Date Engineer Certification: 1. The project has been designed to ensure that stormwater mitigation, including detention ponds, proposed as part of the project will be constructed first in the construction sequence. 2. I will obtain or can show compliance with all necessary Local, State and Federal Permits prior to construction including NOI and SWPPP. Design will not preclude compliance with TPDES: i.e., projects over 10 acres may require a sedimentation basin. 3. The information and conclusions contained in the attached plans and supporting documents comply with the current requirements of the City of College Station, Texas City Code, Chapter 13 and associated BCS Unified Design Guidelines. All development has been designed in accordance with all applicable codes and ordinances of the City of College Station and State and Federal Regulations. 4. I, THE ENGINEER, AGREE TI AND CERTIFY THAT ALL STATEMENTS HEREIN, AND IN ATTACHMENTS FOR THE DEVELOPMENT P: *MIT APPLICATION, ARE, TO THE BEST OF MY KNOWLEDGE, TRUE, AND ACCURATE. �� �. - LI ( ( Engineer, Date 10/10 Page 5 of 9 The following CERTIFICATIONS apply to development in Special Flood Hazard Areas. Required for Site Plans, Final Plats, Construction Plans, Fill / Grading Permits, and Clearing Only Permits:* A. I, Rabon A. Metcalf, P.E. certify, as demonstrated in the attached drainage study, that the alterations or development covered by this permit, shall not: (i) increase the Base Flood elevation; (ii) create additional areas of Special Flood Hazard Area; (iii) decrease the conveyance capacity to that part of the Special Flood Hazard Area that is not in the floodway and where the velocity of flow in the Base Flood event is greater than one foot per second. This area can also be approximated to be either areas within 100 feet of the boundary of the regulatory floodway or areas where the depth of from the BFE to natural ground is 18 inches or greater; (iv) reduce the Base Flood water storage volume to the part of the Special Flood Hazard Area that is beyond the floodway and conveyance area where the velocity of flow in the Base Flood is equal to and less than one foot per second without acceptable compensation as set forth in the City of College Station Code of Ordinances, Chapter 13 concerning encroachment into the Special Flood Hazard Area; nor (v) increase Base Flood velocities. beyond those areas exem•ted by ord nance in Section 5.11.3a of Chapter 13 Code of Ordinances. 411101 44 l ( o i_ t t o Engineer \ Date Initial * If a platting - status exemption to this requirement is asserted, provide written justification under separate letter in lieu of certification. Required for Site Plans, Final Plats, Construction Plans, and Fill / Grading Permits: B. I, Rabon A. Metcalf, P.E. , certify to the following: (i) that any nonresidential or m Iti- family structure on or proposed to be on this site as part of this application is designed to prevent damago,to the structure or its contents as a result of flooding from the 100 -year storm. ��► — co Engineer \ Date Additional certification for Floodway Encroachments: C. I, Not Applicable , certify that the construction, improvement, or fill covered by this permit shall not increase the base flood elevation. I will apply for a variance to the Zoning Board of Adjustments. Engineer Date 10/10 Paae 6 of 9 Required for all projects proposing structures in Special Flood Hazard Area (Elevation Certificate required). Residential Structures: D. I, Rabon A. Metcalf, P.E. . , certify that all new construction or any substantial improvement of any residential structure shall have the lowest floor, including all utilities, ductwork and any basement, at an elevation at least one foot above the Base Flood Elevation. Required Elevation Certificates will be provided with elevations certified during construct' n (forms at slab pre -pour) and post construction. Engineer / Surveyor Date Commercial Structures: E. I, , certify that all new construction or any substantial improvement of any commercial, industrial, or other non - residential structure are designed to have the lowest floor, including all utilities, ductwork and basements, elevated at least one foot above the Base Flood Elevation Engineer / Surveyor Date OR , certify that the structure with its attendant utility, ductwork, basement and sanitary facilities is designed to be flood - proofed so that the structure and utilities, ductwork, basement and sanitary facilities are designed to be watertight and impermeable to the intrusion of water in all areas below the Base Flood Elevation, and shall resist the structural Toads and buoyancy effects from the hydrostatic and hydrodynamic conditions. Required Elevation Certificates will be provided with elevations certified during construction (forms at slab pre - pour) and post construction. Engineer / Surveyor Date Conditions or comments as part of approval: 10110 Page 7 of 9 o firtiff .s•N i CITY Of COI A 1..G1:JTATw[.' Xoc: o�laa AcA!L'vm'ur' FINAL PLAT MINIMUM REQUIREMENTS (ALL CITY ORDINANCES MUST BE MET) INCLUDING BUT NOT LIMITED TO THE FOLLOWING: (Requirements based on field survey and marked by monuments and markers.) © Drawn on 24" x 36" sheet to scale of 100' per inch. © Vicinity map which includes enough of surrounding area to show general location of subject property in relationship to College Station and its City Limits. No scale required but include north arrow. Q Title Block with the following information: © Name and address of subdivider, recorded owner, planner, engineer and surveyor. • 0 Proposed name of subdivision. (Subdivision name & street names will be approved through Brazos County 911.) Date of preparation. © Engineer's scale in feet. © Total area intended to be developed. North Arrow. • © Subdivision boundary indicated by heavy lines. If more than 1 sheet, an index sheet showing entire subdivision at a scale of 500 feet per inch or larger. [ All applicable certifications based on the type of final plat. © Ownership and Dedication © Surveyor and /or Engineer © City Engineer (and City Planner, if a minor plat) © Planning and Zoning Commission (delete if minor plat) • Brazos County Clerk ❑ Brazos County Commissioners Court Approval (ETJ Plats only) © If submitting a replat where there are existing improvements, submit a survey of the subject property showing the improvements to ensure that no encroachments will be created. ❑ If using private septic systems, add a general note on the plat that no private sewage facility may be installed on any lot in this subdivision without the issuance of a license by the Brazos County Health Unit under the provisions of the private facility regulations adopted by the Commissioner's Court of Brazos County, pursuant to the provisions of Section 21.084 of the Texas Water Code. [ Location of the 100 -Year Floodplain and floodway, if applicable, according to the most recent available data. © Lot corner markers and survey monuments (by symbol) and clearly tied to basic survey data. © Matches the approved preliminary plat. © The location and description with accurate dimensions, bearings or deflection angles and radii, area, center angle, degree of curvature, tangent distance and length of all curves for all of the following: (Show existing items that are intersecting or contiguous with the boundary of or forming a boundary with the subdivision, as well as, those within the subdivision). Existing Proposed © ❑ Streets. Continuous or end in a cul -de -sac, stubbed out streets must end into a temp tum around unless they are shorter than 100 feet © ❑ Public and private R.O.W. locations and widths. (All existing and proposed R.O.W.'s sufficient to meet Thoroughfare Plan_) © ❑ Street offsets and/or intersection angles meet ordinance. 10110 Page8of9 Existing Proposed ❑ Alleys. © © Easements. © © A number or letter to identify each lot or site and each block (numbered sequentially). ❑ 111 Parkland dedication/greenbelt area/park linkages. All proposed dedications must be reviewed by the Parks and Recreation Board and documentation of their recommendation provided prior to being scheduled for P & Z Commission consideration. It is the responsibility of the applicant to provide documentation from the Parks Department of the Board's recommendation. Construction documents for all public infrastructure drawn on 24" x 36" sheets and properly sealed by a Licensed Texas Professional Engineer that include the following: ❑ Street, alley and sidewalk plans, profiles and sections. One sheet must show the overall street, alley and /or sidewalk layout of the subdivision. (may be combined with other utilities). is Sewer Design Report. ❑ Sanitary sewer plan and profile showing depth and grades. One sheet must show the overall sewer layout of the subdivision. (Utilities of sufficient size /depth to meet the utility master plan and any future growth areas.) © Water Design Report and /or Fire Flow Report. © Water line plan showing fire hydrants, valves, etc. with plan and profile lines showing depth and grades. One sheet must show the overall water layout of the subdivision. (Utilities of sufficient size /depth to meet the utility master plan and any future growth areas.) © Storm drainage system plan with contours, street profile, inlets, storm sewer and drainage channels, with profiles and sections. Drainage and runoff areas, and runoff based on 5, 10, 25, 50 and 100 year rain intensity. Detailed drainage structure design, channel lining design & detention if used. One sheet must show the overall drainage layout of the subdivision. © Detailed cost estimates for all public infrastructure listed above sealed by Texas P.E. © Drainage Report with a Technical Design Summary. © Erosion Control Plan (must be included in construction plans). ❑ All off -site easements necessary for infrastructure construction must be shown on the final plat witha volume and page listed to indicate where the separate instrument easements were filed. Separate instrument easements must be executed prior to being scheduled for P &Z Commission consideration. © Are there impact fees associated with this development? ❑ Yes © No Impact fees must be paid prior to building permit. © Will any construction occur in TxDOT rights -of -way? ❑ Yes © No If yes, TxDOT permit must be submitted along with the construction documents. NOTE: 1. We will be requesting the corrected Final Plat to be submitted in digital form if available prior to filing the plat at the Courthouse. 2. If the construction area is greater than 5 acres, EPA Notice of Intent (NOI) must be submitted prior to issuance of a development permit. I Print Form 10/10 Page 9 or 9 TCEQ Office Use Only msmazfoamomagai Notice of Intent (NOI) for Storm Water PennitNo.: TXR15 Discharges Associated with Construction RN: Activity under TPDES General Permit CN: T C E Q (TXR 150000) Ref No: Sign up now for e er'mi s NOI at [Taus :ll - vv \1V eo ,t`1 e xdislcteers/ Get Instant Permit C� v et e. and on{y pay a ' 2!5 applicatIon r ', If f, Nnr you ca^. the application fee on line? s ' - � � s . t o0 fls eo f �11rrg a paper . . J � pay .he app.........,....,.. �:� l•:*re. Go to imps: i,;ti � -, ; e teeq._f r.e.i�:.us 't ;= / Select Fee. Tyne: GENERAT, PERMIT CONSTRUCTION STORM WATER DISCHARGE NOT APPLICATION IMPORTANT: Use the INSTRUCTIONS to fill out each question in this form. •Use the attached CUSTOMER CHECKLIST to make certain all you filled out all required information. -Incomplete applications WILL delay approval or result in automatic Denial. Renewal of General Permit Is this NOI to renew an ACTIVE permit? IYes - What is your permit number? Permit No. 1 ✓ INo - a permit number will be issued. Application Fee if mailing a paper NOI: You must pay the S325 Application Fee to TCEQ for the application to be considered complete. Payment and NOI must be mailed to separate addresses. See instructions for correct mailing addresses. Provide your payment information below, for us to verify payment of the application fee: n Mailed: Check/Money Order No.: Company Name on checking account: I IEPAY: VoucherNo.: Is the Payment Voucher copy attached? n Yes A. OPERATOR (applicant) 1. If the applicant is currently a customer with TCEQ, what is the Customer Number (CN) issued to this entity? CN (Search Centrat Reristrc) 2. Wliat is the Legal Name of the entity (applicant) applying for this permit? Ali Jaffer (The legal name must be spelled exactly as filed with the Texas Secretary of State, County, or in the legal document forming the entity.) 3. What is the name and title of the person signing the application? (The person must be an official meeting signatory requirements in TAC 305.43(a).) Name: Ali Jaffer Job Title: Owner 4. What is the Operator's (applicant) mailing address as recognized by the US Postal Service? (verify at USPS.cacr) Address: 5727 Richmond Avenue, Apt 202 Suite No. /Bldg. No. /Mail Code: City: Dallas State:TX ZIPCode: Country Mailing Information (if outside USA). Country Code: Postal Code: 5. Phone No.: (979 ) 202 -1933 ' Extension: 6. Fax No.: ( ) E -mail Address: aliinksa @yahoo.com 7. Indicate the type of Customer: ® Individual ❑Sole Proprietorship- D.B.A. El Limited Partnershi El Corporation OFederal Govermnent DGeneral Partnership ❑ State Government OCounty Government - not, Government Other Government ❑Other (describe): TCEQ -20022 (03/05/2008) Page 1 8. Independent Operator: IN Yes ❑No (If governmental entity, subsidiary, or part of a larger corporation, check `No ".) 9. Number of Employees: p 0 -20; 021 -100; 0101 -250; 0251 -500; or 0501 or higher 10. Customer Business Tax and Filing Numbers (This item is not applicable to Individuals, Government, GP or Sole Proprietor.) REQUIRED for Corporations and Limited Partnerships ( verify the enntit,,-'s st:nt?_s and i'iirg no. with TN SOS at sit; -: _, ) State Franchise Tax ID Number: Federal Tax ID: TX SOS Charter (filing) Number: DUNS Number (if known): R. APPLICATION CONTACT If TCEQ needs additional information regarding this application, who should be contacted? 1. Name: Rabon A. Metcalf, P.E. Title: Owner Company: RME Consulting Engineers 2. Phone No.: ( 979 ) 764_0704 Extension: 3. Fax No.: 979 764 -0704 E -mail Address: rabon©rmengineer.com C. REGULATED ENTITY (RE) INFORMATION ON PROJECT OR SITE 1. TCEQ Issued RE Reference Number (RN): RN (search Central Reais(-ry ) 2. Name of Project or Site (the name as known by the community where this facility /project is located): Randall's University Park, Lot 3R -2 - College Station, TX (example: phase and name of subdivision or name of project that's unique to the site) 3. Does the site have a physical address? If Yes, complete SectionA for a physical address. If No complete Section B for site location information. Section A: Enter the physical address for the site. (verify it trirlt USPS.co n or other deiiv - v r;n;rce) Street Number: Street Name: Chimney Hill Drive ci College Station, TX ZIP Code: 77840 Section B: Enter the site location information. If no physical address (Street Number & Street Name), provide a written location access description to the site: (Ex.: phase 1 of Woodland subdivision located 2 miles west from intersection of Hwy 290 & IH35 accessible on Hwy 290 South) City \\'here the site is located or nearest city to site: ZIP Code where site is located: 4. Identify the county where the site is located: Brazos 5. Latitude: N 30.63514 Longitude: W 96.33216 6. What is the primary business of this entity? In your own words, briefly describe the primary business of the Regulated Entity: (Do not repeat the SIC and NAICS code) Residential Development 7. What is the mailing address for the regulated entity? Is the RE mailing address the same as the Operator? [ i lYes, address is the same as Operator ❑No, provide the address Street Number: Street Name: City: State: ZIP Code: D. GENERAL CHARACTERISTICS • 1. Is the site located on Indian Cotuitry Lands? la No ❑ Yes — If Yes, do not submit this NOI: Contact EPA, Region VI If the site is on Indian country lands, you must obtain authorization through EPA, Region VI. 2. What is the Standard Industrial Classification (SIC) code (see instructions for common codes): (Se Osha.aov) Primary: 1521 Secondary: TCEQ -20022 (03/05/2008) Page 2 3(a) What is the total number of acres disturbed? 4 acres 3(b) Is the project site part of a larger common plan of development or sale? { wes ® No If Yes, the total number of acres disturbed can be less than 5 acres. lfNo, the total number of acres disturbed must be 5 or snore. If the total number of acres disturbed is less than 5 then the project site does not qualify for coverage through this Notice of Intent. Coverage will be denied. See the requirements in the general permit for small construction sites. 4. Discharge Information ( ,itfOr lififi.; r ) u\ vi _ ,_._; be is r p • 4(a) What is the name of the water body(s) to receive the storm water runoff or potential runoff from the site? Burton Creek 4(b) What is the segment number(s) of the classified water body(s) that the discharge or potential discharge will eventually reach? 1209L 4(c) Are any of the surface water bodies receiving discharges from the construction site on the latest EPA - approved CWA 303(d) list of impaired waters? ( Yes I f Yes, provide the name of the impaired water body(s). _. 4(d) Is the discharge into an MS4? II Yes ❑No I f Yes, what is the name of the MS4 Operator? CitV of College Station Note: 'llte general permit requires you to send a copy of the NOI to the MS4 Operator. 4(e) Is the discharge or potential discharge within the Recharge Zone, Contributing Zone, or Contributing Zone within the Transition Zone of the Edwards Aquifer? . 1 Yes I ' (No If the answer is Yes, please note that a copy of the agency approved Plan required by the Edwards Aquifer .Rule (30 TAC Chapter 213) must be included or referenced in the Storm Water Pollution Prevention Plan. E. CERTIFICATION Check "Yes" to the certifications below. _ ..ii._. c to certify 10 all items twill result in denial. al. I ✓ ( Yes 1 certify that I have obtained a copy and understand the terms and conditions of the general perrnit (q :XR 150000). I , ! Yes 1 certify that the full legal name of the entity (Operator) applying for this pernnit has been provided and is legally authorized to do business in Texas. I ✓ I Yes 1 understand thata Notice of Termination (NOT) must be submitted when this authorization is no longer needed. I ✓ I Yes I certify that a storm water pollution prevention plan has been developed and implemented prior to construction, and that is compliant with any applicable local sediment and erosion control plans and prepared and implemented as required in the general permit TXR150000. Operator Certifications I Alice Qwner Typed or printed name ; _ c q u i t _ d :17e.s1 he 14 'ihIe? Title (r . ` r r re ; °ri d'• f !c) certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the inlurrnation submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing. violations. 1 further certify that I am authorized under 30 I'c :a - Administrative Cade §305.44 to sign and submit this document, and can provide doctunentation in proof of such authorization upon request. Signature: Date:_ it f ,3 � / J (Use'blue ink) TCEQ -20022 (03!05!2008) Page 3 i CONSTRUCTION SITE NOTICE FOR THE Texas Commission on Environmental Quality (TCEQ) Storm Water Program TPDES GENERAL PERMIT TX 1 150000 The following information is posted in compliance with Part 11ILD 2a of the TCEQ General Permit Number TNa150000 for discharges of storm water runoff from construction sites. Additional information regarding the TCEQ storm water permit program may be found on the internet at: http: / /ww \v.tceq.state.tx.us/ permitting/ water_quality /storrnwater /TXR15 AIR. htm1 i 4 - Contact Name and Phone Number: Ali Jatfier f (973) 202 -1933 Randall's University Park - Lot 3R -2 Project Description: 5727 Richmond Ave, APT. 202 Dallas, TX 75206 N. (Physical address or description of the site's t location, estimated start date and projected end On the north side of Chimney hill Drive just west of its intersection date, or date that disturbed soils will be with Arguello Drive. ` 2. stabilized) 4 Estimated Start Date: 1/31/11 € w estimated End Date: 12131111 f. a Y ; _ Location of Storm Water Pollution 7607 Gastmark D consultin Drive, Suite 7607 rive, uite 250F , Prevention Plan : College Station, TX 77840 For Construction Sites Authorized Under Part II.D.2. (Obtaining Authorization to Discharge) the following certification must be completed: I Ali Jaffer (Typed or Printed Name Person Completing This Certification) certify under penalty Of law that I have read and understand the eligibility requirements for claiming an authorization under Part II.D.2. of TPDES General Permit TXRI50000 and agree to comply with the terms of this permit. A storm water pollution prevention plan has been developed and implemented according to permit requirements. A copy of this signed notice is supplied to the operator of the MS4 if discharges enter an MS4 system. I am aware there are significant penalties for providing false information or for conducting unauthorized discharges, including the possibility offine and imprisonment for -1! _ _ ations. if I 7 6 ( ( c S ignatue'an`d Title Date 7607 Eastrnark Drive, Ste. 250 -F <77840> P.O. Box 9253, College Station, TX 77842 Off /Fax: (979) 764 -0704 email: civil @rmengineer.com December 13, 2010 Josh Norton, P.E. Assistant City Engineer City of College Station Planning & Development Services 1101 Texas Avenue South College, Station, 77840 RE: Randall's University Park, Replat of Lot 3R -2 — College Station, TX Utility Availability Analysis RME No. 220 -0419 Josh Norton: There is sufficient capacity in the existing water distribution system and sanitary sewer collection system to support the above referenced development and the associated proposed improvements. The existing and proposed improvements and projected demands, for both water and sanitary sewer, are summarized below and are in accordance with the B /CS Unified Design Guidelines Manual (UDGM): WATER SYSTEM IMPROVEMENTS: •�• The subject property has accessibility to existing public water for both domestic and fire use at the following locations: o An existing 8" PVC public water line that traverses along the south right -of -way line of Chimney Hill Drive. This water line is located within the right -of -way of the street; o A flow test was obtained from one existing hydrant. Existing fire hydrant B -009, located near the project's southwest property corner, yields a flow of 1,300 gpm, from the 2.5" nozzle, with a residual pressure of 82 psi and a static pressure of 85 psi. The static pressure was obtain from existing fire hydrant B- 062(see attached CoCS Flow Test Report); o Fire flow will be accommodated from the existing hydrant B -009 located at the cul -de -sac bulb of Chimney Hill Drive. The existing 8" PVC water line will be tapped, along with a proposed 4" PVC water line, for residential domestic services (see attached sheet U -01 — Water Line "WI" Plan /Profile & Sanitary Sewer Service Plan); •e• Projected daily water demands are as follows: o The residential development is anticipated to have an average water demand of 7.5 gpm. This average water demand is as determined by B /CS UDGM for average demand calculations with average daily water consumption of 1.5 gpm per connection or dwelling unit at normal conditions. At domestic use conditions, whether residential or commercial, a minimum 35 psi pressure rating will be CD1- 220 - 0419- L04.docx Page 1 of 3 - 1 Randall's University Park — College Station, TX Utility Analysis Letter December 13, 2010 maintained and during fire flow use conditions a minimum 20 psi pressure rating will be maintained. o At average demand, for domestic uses, the proposed 4" domestic water service line would experience an approximate velocity of 0.19 fps with a pressure loss of approximately 1 psi. This pressure loss will allow the distribution system to remain above the minimum TCEQ domestic pressure requirement of 35 psi (see attached Domestic Hydraulic Analysis). Pressure losses reported are at worse- case scenario with the maximum line length calculated; o The fire flow demand, for residential developments, will require that each residence can be protected by a minimum 1,000 gpm. At fire flow conditions the existing 8" PVC water line would experience an approximate velocity of 6.39 fps (see attached Fire Flow Hydraulic Analysis). SEWER COLLECTION SYSTEM IMPROVEMENTS: The subject property has accessibility to public sanitary sewer at the following locations: o An existing 12" PVC public sanitary sewer line, flows in a northeastern direction along Chimney Hill Drive. This sanitary sewer line is located within the right -of- way of Chimney Hill Drive; Projected daily sanitary sewer demands, for this development, are as follows (peaking factor of 4.0). The sanitary sewer requirements, for the proposed development, were derived by Method 2 — "Land Use Determination" of the UTSDS. Land use coverage was assigned to the subdivision based on the Replat. Resulting average sanitary sewer flow values were calculated and are summarized in Table #1 — "Sanitary Sewer Flows" shown below. As calculated, the proposed Average Daily Flow (ADF) for this subdivision is 1,335 gpd and a 2 -Hour Peak Flow (PF) at 0.01 cfs. TABLE #1 - SANITARY SEWER FLOWS Average Average 2 -Hour Daily Flow Dwelling Daily Flow Peak Flow Peak Flow Section/Phase (gpd /cap) Units (gpd) (gph) (cfs) N/A 100 5 1,335 223 0.01 TOTAL EXPECTED FLOWS = 1,335 223 0.01 Flow Determination Notes: 1) Residential density is at 2.67 capita/Dwelling Unit; 2) Commercial uses were estimated at 30 capita/acre; 3) Average Daily flows, for each use, were assigned per Table HI-"Average Wastewater Generations" per the UTSDS; 4) Peaking factor of 4.0 was applied to the Average Daily Flows to determine the Peak Flow which is used for line sizing; The proposed development and correlating water and sanitary sewer improvements are designed and analyzed in accordance with the criteria outlined in the B /CS UDGM of the City of College Station (CoCS). CD1- 220 - 0419- L04.docx Page 2 of 3 W( roilete Station Utilities tL A: y ' ` Reliable, A le, Community Owned Date Thursday November,18 2010 Time 13:00 Test completed by Wyatt Jefferson Witness Justin Tamplin Location 607 University Dr. E Nozzle size 2.5 Flow hydrant B -009 Pitot reading 60 G.P.M. 1300 Static hydrant B -062 Static PSI 85 Residual PSI 82 Comments Requested Flow . College Station Utilities 4 1V- vt. Reliable, Affordable, Community Owned Date Thursday November,18 2010 Time 13:00 Test completed by Wyatt Jefferson Witness Justin Tamplin Location 607 University Dr. E Nozzle size 2.5 Flow hydrant B -009 Pitot reading 60 G.P.M. 1300 Static hydrant B -062 Static PSI 85 Residual PSI 82 Comments Requested Flow RA.NDALL'S UNIVERSITY PARK DOMESITC FLOW HYDRAULIC ANALYSIS PROPOSED 4" :MATER LINE HEAD FRICTION STATIC FLOW FLOW DIST. ID C LOSS LOSS VELOCITY HEAD TDH (g pm) (cfs) (ft) (in) VALUE (ft/100) (ft) (fps) (ft) (ft) i i 7.5 0.02 105 4 140 0.01 0.01 0.19 2.00 2.01 7.5 0.02 105 4 100 0.01 0.01 0.19 2.00 2.01 Domestic -Fire Water - Hydraulic Analysis.xlsx RANDALL'S UNIVERSITY PARK FIRE FLOW HYDRAULIC ANALYSIS EXISTING WATER LINE HEAD FRICTION STATIC FLOW FLOW DIST. ID C LOSS LOSS VELOCITY HEAD TDH (g pm) (cfs) (ft) (in) VALUE (ft/100) (ft) (fps) (ft) (ft) I I 1000.0 2.23 500 8 140 1.61 8.06 6.39 2.00 10.06 Domestic -Fire Water-Hydraulic Analysis.xlsx SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4i 7) Design Parameters (continued) Computer Software What computer software has been used in the analysis and assessment of stormwater management needs and /or the development of facility designs proposed for subject property project? List them below, being sure to identify the software name and version, the date of the version, any applicable patches and the publisher 7r4s — A'b Ce-,(J Part 5 — Plans and Specifications Requirements for submittal of construction drawings and specifications do not differ due to use of a Technical Design Summary Report. See Section III, Paragraph C3. Part 6 — Conclusions and Attestation Conclusions Add any concluding information here: Attestation Provide attestation to the accuracy and completeness of the foregoing 6 Parts of this Technical Design Summary Drainage Report by signing and sealing below. "This report (plan) for the drainage design of the development named in Part B was prepared by me (or under my supervision) in accordance with provisions of the Bryan /College Station Unified Drainage Design Guidelines for the owners of the property. All licenses and permits required by any and all state and federal regulatory agencip4; r1 e proposed drainage improvements have been issued or fall under applicable [y��►��y -F' F ,a -c o Q • / r l� Cpl -G * a .. (�` eeooe¢aegs000ea. , a•6 Licensed Professional Engineer � + e RABON A. METCALF . 0 9 4 ® 004 4 0 0 0 00490 - o State of Texas PE No. E : f; , $< r '' ` •' 7 —' $- c.@oo0 J� STORMWATER DESIGN GUIDELINES Page 26 of 26 IAPPENDIX. : TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.16) Design Parameters (continued) Hydraulics (continued) Street and Storm Drain Systems (continued) For the following, are assumptions other than allowable per Guidelines? Inlet coefficients? No Yes Head and friction losses No Yes Explain any "yes" answer: In conduit is velocity generally increased in the downstream direction? Yes No Are elevation drops provided at inlets, manholes, and junction boxes? Yes No Explain any "no" answers: Are hydraulic grade lines calculated and shown for design storm? Yes No For 100 -year flow conditions? Yes No Explain any "no" answers: What tailwater conditions were assumed at outfall point(s) of the storm drain system? Identify each location and explain: Open Channels If a HEC analysis is utilized, does it follow Sec VI.F.5.a? Yes No Outside of straight sections, is flow regime within limits of sub - critical flow? Yes No If "no" list locations and explain: Culverts If plan sheets do not provide the following for each culvert, describe it here. For each design discharge, will operation be outlet (barrel) control or inlet control? Entrance, friction and exit losses: Bridges Provide all in bridge report STORMWATER DESIGN GUIDELINES Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 - Drainage Concept and Design Parameters Continued (Page 4.15) Design Parameters (continued) Hydrology (continued) In making determipections for time of concentration, was segment analysis used? No Yes In approximately what percent of Design Drainage Areas? Coo % As to intensity- duration - frequency and rain depth criteria for determining runoff flows, were any criteria other than those provided in these Guidelines used? No Yes If "yes" identify type of data, source(s), and where applied: For each of the stormwater management features listed below identify the storm return frequencies (year) analyzed (or checked), and that used as the basis for design. Feature Analysis Year(s) Design Year Storm drain system for arterial and collector streets Storm drain system for local streets Open channels Swale /buried conduit combination in lieu of channel Swales Roadside ditches and culverts serving them Detention facilities: spillway crest and its outfall loo Z� Detention facilities: outlet and conveyance structure(s) 7 a r , Detention facilities: volume when outlet plugged Culverts serving private drives or streets Culverts serving public roadways Bridges: provide in bridge report. Hydraulics What is the range of design flow velocities as outlined below? Design flow velocities; Gutters Conduit Culverts Swales Channels Highest (feet per second) Lowest (feet per second) Streets and Storm Drain Systems Provide the summary information outlined below: Roughness coefficients used: For street gutters: For conduit type(s) Coefficients: STORMWATER DESIGN GUIDELINES Page 24 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.14) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Special Designs — Deviation From B -CS Technical Specifications If any design(s) or material(s) of traditional runoff - handling facilities deviate from provisions of B -CS Technical Specifications, check type facility(ies) and explain by specific detail element. Detention elements Drain system elements Channel features Culvert features Swales Ditches Inlets Outfalls Valley gutters Bridges (explain in bridge report) In table below briefly identify specific element, justification for deviation(s). Specific Detail Element Justification for Deviation (attach additional sheets if needed) 1) 2) 3) 4) 5) Have elements been coordinated with the City Engineer or her /his designee? For each item above provide "yes" or "no ", action date, and staff name: 1) 2) 3) 4) 5) Design Parameters Hydrology / Is a map(s) showing all Design Drainage Areas provided? ( Yes No Briefly summarize the range of applications made of the Rational Formula: What is the size and location of largest Design Drainage Area to which the Rational Formula has been applied? B - g acres Location (or identifier): STORMWATER DESIGN GUIDELINES Page 23 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.13) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Is a bridge included in plans for subject property project? v No Yes If "yes" provide the following information. Name(s) and functional classification of the roadway(s)? What drainage way(s) is to be crossed? a 1 a m` A full report supporting all aspects of the proposed bridge(s) (structural, geotechnical, hydrologic, and hydraulic factors) must accompany this summary report. Is the report provided? Yes No If "no" explain: Is a Stormwater Provide a general description of planned techniques: Pollution Prevention Plan (SW3P) Cl established for v project construction? co No Yes Special Designs — Non - Traditional Methods Are any non - traditional methods (aquatic echosystems, wetland -type detention, natural stream replic3tion, BMPs for water quality, etc.) proposed for any aspect of subject property project? No Yes if "yes" list general type and location below. Provide full report about the proposed special design(s) including rationale for use and expected benefits. Report must substantiate that stormwater management objectives will not be compromised, and that maintenance _co will not exceed those of traditional design solution(s). Is report provided? [/ Yes No If "no" explain: STORMWATER DESIGN GUIDELINES Page 22 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 • SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.12) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) All Proposed Culverts: For all proposed culvert facilities (except driveway /roadside ditch intersects) provide information requested in next eight boxes. Do culverts and travelways intersect at 90 degrees? Yes No If not, identify location(s) and intersect angle(s), and justify the design(s): Does drainage way alignment change within or near limits of culvert and surfaced approaches thereto? No Yes If "yes" identify location(s), describe change(s), and justification: Are flumes or conduit to discharge into culvert barrel(s)? No Yes If yes, identify location(s) and provide justification: • Are flumes or conduit to discharge into or near surfaced approaches to culvert ends? No Yes If "yes" identify location(s), describe outfall design treatment(s): 0 0 0) N Is scour /erosion protection provided to ensure long term stability of culvert structural v components, and surfacing at culvert ends? Yes No If "no" Identify locations and provide justification(s): Will 100 -yr flow and spread of backwater be fully contained in street ROW, and /or drainage easements/ ROW? Yes No if not, why not? Do appreciable hydraulic effects of any culvert extend downstream or upstream to neighboring land(s) not encompassed in subject property? No Yes If "yes" describe location(s) and mitigation measures: Are all culvert designs and materials in compliance with B -CS Tech. Specifications? Yes No If not, explain in Special Design Section of this Part. STORMWATER DESIGN GUIDELINES Page 21 of 26 APPENDIX, D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.11) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Named Regulatory Watercourses (& Tributaries): Are culverts proposed on these facilities? No Yes, then provide full report documenting assumptions, criteria, analysis, computer programs, and study findings that support proposed design(s). Is report provided? Yes No If "no ", explain: ,. Arterial or Major Collector Streets: Will culverts serve these types of roadways? = No Yes How many instances? For each identify the location and provide the information below. o Instance 1: ca Instance 2: c o Instance 3: c 0 o '2 Yes or No for the 100 -year design flow: 1 2 3 E o Headwater WSE 1 foot below lowest curb top? c cl, Spread of headwater within ROW or easement? E 0) N Is velocity limited per conditions (Table C -11)? • '2 Explain any "no" answer(s): cri o c t3 O CO 0 0 o Minor Collector or Local Streets: Will culverts serve these types of streets? L L 0 a No Yes How many instances? for each identify the - m a location and provide the information below: Q_ 0 -' a Instance 1: w = Instance 2: . 0) o Instance 3: O) co 0 For each instance enter value, or "yes" / "no" for: 1 2 3 n c N Design yr. headwater WSE 1 ft. below curb top? c 'c 100 -yr. max. depth at street crown 2 feet or less? E Product of velocity (fps) & depth at crown (ft) _ ? 9. Is velocity limited per conditions (Table C -11)? Limit of down stream analysis (feet)? Explain any "no" answers: STORMWATER DESIGN GUIDELINES Page 20 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.10) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Do structures comply with B -CS Specifications? Yes or no, and explain if "no ": Facility 1; � S c Facility 2: o c } o c U a.) For additional facilities provide all same information on a separate sheet. Are parking areas to be used for detention? No Yes What is maximum depth due to required design storm? Roadside Ditches: Will culverts serve access driveways at roadside ditches? L.7 Yes If "yes ", provide information in next two boxes. Will 25 -yr. flow pass without flowing over driveway in all cases? Yes No Without causing flowing or standing water on public roadway? �% Yes No Designs & materials comply with B -CS Technical Specifications? Yes No Explain any "no" answers: 0 Are culverts parallel to public roadway alignment? Yes No Explain: U N .\ U I Creeks at Private Drives: Do private driveways, drives, or streets cross drainage ways that serve A ove- Project areas or are in public easements/ ROW? a) z No Yes If "yes" provide information below. How many instances? f Describe location and provide information below. > Location 1: 0 U Location 2: Location 3: For each location enter value for: 1 2 3 Design year passing without toping travelway? / D O Water depth on travelway at 25 -year flow? O Water depth on travelway at 100 -year flow? O For more instances describe location and same information on separate sheet. STORMWATER DESIGN GUIDELINES Page 19 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 - Drainage Concept and Design Parameters Continued (Page 4.9) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) How many facilities for subject property project? For each provide info. below. For each dry-type facilitiy: Facility 1 Facility 2 Acres served & design volume + 10% (, cue 7.. o 0 100 -yr volume: free flow & plugged .2 j o(_3 3 jv o Design discharge (10 yr & 25 yr) Q .76 0- g3 Spillway crest at 100 -yr WSE? V yes C no yes no Berms 6 inches above plugged WSE? - ------ yes no yes no Explain any "no" answers: cn a) For each facility what is 25 -yr design Q, and design of outlet structure? Facility 1: ? cam— eve -e P 0 z Facility 2: I Do outlets and spi ays discharge into a public facility in easement or ROW? Facility 1: Yes No Facility 2: Yes No a If "no" explain: a) 0 . 0 0 °- For each, what is velocity of 25 -yr design discharge at outlet? & at spillway? Facility 1: 12-.. --. \r5 & Facility 2: & Are energy dissipation measures used? No LZ Yes Describe type and co a_ location: c 0 0 0 0 2 For each, is spillway surface treatment other than concrete? Yes or no, and describe: Q Facility 1: Facility 2: For each, what measures are taken to prevent erosion or scour at receiving facility? Facility 1: Facility 2: If berms are used give heights, slopes and surface treatments of sides. Facility 1: Facility 2: STORMWATER DESIGN GUIDELINES Page 18 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.8) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Existing channels (small creeks): Are these used? No Yes If "yes" provide the information below. Will small creeks and their floodplains remain undisturbed? Yes No How many disturbance instances? Identify each planned location: For each location, describe length and general type of proposed improvement (including floodplain changes): For each location, describe section shape & area, flow line slope (min. & max.), surfaces, and 100 -year design flow. a� Watercourses (and tributaries): Aside from fringe changes, are Regulatory Watercourses proposed to be altered? No Yes Explain below. Submit full report describing proposed changes to Regulatory Watercourses. Address existing and proposed section size and shape, surfaces, alignment, flow line changes, length affected, and capacity, and provide full documentation of analysis procedures 2 and data. Is full report submitted? Yes No If "no" explain: E All Proposed Channel Work: For all proposed channel work, provide information requested in next three boxes. If design is to replicate natural channel, identify location and length here, and describe design in Special Design section of this Part of Report. Will 100 -year flow be contained with one foot of freeboard? Yes No If not, identify location and explain: Are ROW / easements sized to contain channel and required maintenance space? Yes No If not, identify location(s) and explain: STORMWATER DESIGN GUIDELINES Page 17 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 Drainage Concept and Design Parameters Continued (Page 4.7) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) If "yes" provide the following information for each instance: Instance 1 Describe general location, approximate length, surfacing: Q. E w Is 100 -year design flow contained in swale? Yes No Is swale wholly s y ° '. within drainage ROW? Yes No Explain "no" answers: 0 • Access Describe how maintenance access is provide: 2 `- 0 • Instance 2 Describe general location, approximate length, surfacing: a� ' yam (\• • o ▪ E 0 within drainage design ROW? contained Yes No swale? Is swale wholly No E plain "no" answers: 0 To in • n Access Describe how maintenance access is provided: .Q 7 Q Instance 3, 4, etc. If swales are used in more than two instances, attach sheet providing all above information for each instance. "New" channels: Will any area(s) of concentrated flow be channelized (deepened, widened, or straightened) or otherwise altered? No Yes If only slightly shaped, see "Swales" in this Part. If creating side banks, provide information below. ▪ .E Will design replicate natural channel? Yes No If "no ", for each instance o Q describe section shape & area, flow line slope (min. & max.), surfaces, and 100 -year w design flow, and amount of freeboard: Instance 1: a) E Instance 2: a • Instance 3: n U STORMWATER DESIGN GUIDELINES Page 16 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.6) Stormwater Management Concept, (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Are roadside ditches used? No Yes If so, provide the following: Is 25 -year flow contained with 6 inches of freeboard throughout ? Yes No Are top of banks separated from road shoulders 2 feet or more? Yes No Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes No c For any "no" answers provide location(s) and explain: - (a 0 If conduit is beneath a swale, provide the following information (each instance). Instance 1 Describe general location, approximate length: > Is 100 -year design flow contained in conduit/swale combination? Yes No If "no" explain: I o m Space for 100 -year storm flow? ROW Easement Width z c Swale Surface type, minimum Conduit Type and size, minimum and maximum Tel and maximum slopes: slopes, design storm: c 0 T) Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): c T c c U C `t- a o Access Describe how maintenance access is provided (to swale, into conduit): �- ca E a , o = c 7 Q, Instance 2 Describe general location, approximate length: E 0 ) (0 ca N c a Is 100 -year design flow contained in conduit/swale combination? _ Yes No If "no" explain: E aa)i Space for 100 -year storm flow? ROW Easement Width o s U Swale Surface type, minimum Conduit Type and size, minimum and maximum - o cu and maximum slopes: slopes, design storm: m o 0 - Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): � o a) Access Describe how maintenance access is provided (to swale, into conduit): STORMWATER DESIGN GUIDELINES Page 15 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 - Drainage Concept and Design Parameters Continued (Page 4.5) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Describe watercourse(s), or system(s) receiving system discharge(s) below m (include design discharge velocity, and angle between converging flow lines). 0 o 1) Watercourse (or system), velocity, and angle? 0 2 ` a) o E 2) Watercourse (or system), velocity, and angle? ` 0 c ,, _, 0 o 0 4- U C cu E 3) Watercourse (or system), velocity, and angle? 1 (D C6 co (L) - 0 a Q E i For each outfall above, what measures are taken to prevent erosion or scour of � n N receiving and all facilities at juncture? O 1) co iii `0 2 a ) O 3) Are swale(s) situated along property lines between properties? No Yes Number of instances: For each instance answer the following questions. Surface treatments (including low -flow flumes if any): 0 a) • } Flow line slopes (minimum and maximum): T. 0 a O ,Z Outfall characteristics for each (velocity, convergent angle, & end treatment). a) - c - u < Will 100 -year design storm runoff be contained within easement(s) or platted drainage ROW in all instances? Yes No If "no" explain: STORMWATER DESIGN GUIDELINES Page 14 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.4) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Gutter line slopes: Least Usual Greatest Are inlets recessed on arterial and collector streets? Yes No If "no ", identify where and why. Will inlets capture 10 -year design stormflow to prevent flooding of intersections (arterial with arterial or collector)? Yes No If no, explain where and why not. rn - o Will inlet size and placement prevent exceeding allowable water spread for 10 -year design storm throughout site (or phase)? Yes No If no, explain. 5 rn c - S . Sad curves: Are inlets placed at low points? Yes No Are inlets and w conduit sized to prevent 100 -year stormflow from ponding at greater than 24 inches? _c 0 g Yes No Explain "no" answers. cn a) 2 Will 100 -yr stormflow be contained in combination of ROW and buried conduit on whole, length of all streets? Yes No If no, describe where and why. Do designs for curb, gutter, and inlets comply with B -CS Technical Specifications? Yes No If not, describe difference(s) and attach justification. Are any 12 -inch laterals used? No Yes Identify length(s) and where used. tn N Pipe runs between system Typical Longest n access points (feet): Are junction boxes used at each bend? Yes No If not, explain where m and why. 0 E Are downstream soffits at or below upstream soffits? Least amount that hydraulic Yes No If not, explain where and why: grade line is below gutter line (system- wide): STORMWATER DESIGN GUIDELINES Page 13 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.3) Stormwater Management Concept (continued) Within Project Area Of Multi -Phase Project (continued) Will Project Area include bridge(s) or culvert(s)? No v/ Yes Identify type and general size and In which phase(s). �C7 " � tX�SS� If detention /retention serves (will serve) overall Project Area, describe how it relates to subject phase or site project (physical location, conveyance pathway(s), construction sequence): Within Or Serving Subject Property (Phase, or Site) If property part of larger Project Area, is design in substantial conformance with earlier analysis and report for larger area? Yes No, then summarize the difference(s): Identify whether each of the types of drainage features listed below are included, extent of use, and general characteristics. Typical shape? Surfaces? -0 a Steepest side slopes: Usual front slopes: Usual back slopes: v >- o Flow line slopes: least Typical distance from travelway: a (Attached Exhibit # ) a) typical greatest as o ' 2 Are longitudinal culvert ends in compliance with B -CS Standard Specifications? °' Yes No, then explain: �, At intersections or otherwise, do valley gutters cross arterial or collector streets? .2 °' No Yes If yes explain: u , �, Are valley gutters proposed to cross any street away from an intersection? ai a No. Yes Explain: (number of locations ?) z a STORMWATER DESIGN GUIDELINES Page 12 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Continued (Page 4.2) Stormwater Management Concept (continued) Within Project Area Of Multi -Phase Project Identify gaining Basins or Watersheds and acres shifting: Will project result in shifting runoff between Basins or between What design and mitigation is used to compensate for increased runoff Watersheds? from gaining basin or watershed? cZNo Yes How will runoff from Project 1. With facility(ies) involving other development projects. Area be mitigated to pre- 2. 1- features to serve overall Project Area. development conditions? Select any or all of 1, 2, 3. On phase (or site) project basis within Project Area. and /or 3, and explain below. 1. Shared facility (type & location of facility; design drainage area served; relationship to size of Project Area): (Attached Exhibit # ) 2. For Overall Project Area (type & location of facilities): (Attached Exhibit # 3. By phase (or site) project: Describe planned mitigation measures for phases (or sites) in subsequent questions of this Part. Are aquatic echosystems proposed? No Yes In which phase(s) or project(s)? a) cn } Are other Best Management Practices for reducing stormwater pollutants proposed? n No Yes Summarize type of BMP and extent of use: cn o � If design of any runoff handling facilities deviate from provisions of B-CS Technical a I Specifications, check type facility(ies) and explain in later questions. Detention elements Conduit elements Channel features Swales Ditches Inlets Valley gutters Outfalls Culvert features Bridges Other T I S SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 4 — Drainage Concept and Design Parameters Start (Page 4.1) Stormwater Management Concept Discharge(s) From Upland Area(s) If runoff is to be received from upland areas, what design drainage features will be used to accommodate it and insure it is not blocked by future development? Describe for each area, flow section, or discharge point. Discharge(s) To Lower Property(ies) (Section II, Paragraph El) Does project include drainage features (existing or future) proposed to become public via platting? No , /Yes Separate Instrument? No Yes Per Guidelines reference above, how will �stablishing Easements (Scenario 1) runoff be discharged to neighboring r/Pre- development Release (Scenario 2) property(ies)? Combination of the two Scenarios Scenario 1: If easements are proposed, describe where needed, and provide status of actions on each. (Attached Exhibit # ) Scenario 2: Provide general description of how release(s) will be managed to pre - development conditions (detention, sheet flow, partially concentrated, etc.). (Attached Exhibit # ) Combination: If combination is proposed, explain how discharge will differ from pre - development conditions at the property line for each area (or point) of release. If Scenario 2, or Combination are to be used, has proposed design been coordinated with owner(s) of receiving property(ies)? No Yes Explain and provide documentation. STORMWATER DESIGN GUIDELINES Page 10 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX • APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Continued (Page 3.4) Hydrologic Attributes of Subject Property (or Phase) (continued) Conveyance Pathways (continued) Do drainage If yes, for what part of length? % Created by? plat, or easements instrument. If instrument(s), describe their provisions. exist for any part of pathway(s)? ✓N o Yes Where runoff must cross lower properties, describe characteristics of abutting lower property(ies). (Existing watercourses? Easement or Consent aquired ?) Pathway U�, p ej Areas Describe any built or improved drainage facilities existing near the property (culverts, bridges, lined channels, buried conduit, swales, detention ponds, etc). 62 � / 1 -C- e r�c� Nearby Drainage Do any of these ave hydrologic or hydraulic influence on proposed stormwater Facilities design? No Yes If yes, explain: - R&M • STORMWATER DESIGN GUIDELINES Page 9 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Continued (Page 3.3) Hydrologic Attributes of Subject Property (or Phase) (continued) Does subject property straddle a Watershed or Basin divide? L/ No Yes If yes, describe splits below. In Part 4 describe design concept for handling this. Watershed or Basin Larger acreage Lesser acreage Above - Project Areas(Section II, Paragraph B3 -a) Does Project Area (project or phase) receive runoff from upland areas? No Yes Size(s) of area(s) in acres: 1) 2) 3) 4 ) How Characteristics (each instance) (overland sheet, shallow concentrated, recognizable concentrated section(s), small creek (non - regulatory), regulatory Watercourse or tributary); Flow determination: Outline hydrologic methods and assumptions: Does storm runoff drain from public easements or ROW onto or across subject property? No Yes If yes, describe facilities in easement or ROW: Are changes in runoff characteristics subject to change in future? Explain Conveyance Pathways (Section II, Paragraph C2) Must runoff from study property dr ' across lower properties before reaching a Regulatory Watercourse or tributary? No Yes Describe length and characteristics of each conveyance pathway(s). Include ownership of property(ies). STORMWATER DESIGN GUIDELINES Page 8 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Continued (Page 3.2) Hydrologic Attributes of Subject Property (or Phase) Has an earlier hydrologic analysis been done for larger area including subject property? Yes Reference the study (& date) here, and attach copy if not already in City files. Is the stormwater management plan for the property in substantial conformance with the earlier study? Yes No If not, explain how it differs. No If subject property is not part of multi -phase project, describe stormwater management tz plan for the property in Part 4. If property is part of multi -phase project, provide overview of stormwater management plan for Project Area here. In Part 4 describe how plan for subject property will comply therewith. Do existing topographic features on subject property store or detain runoff? r/ No Yes Describe them (include approximate size, volume, outfall, model, etc). Any known drainage or flooding problems in areas near subject property? L/ No Yes Identify: Based on location of study property in a watershed, is Type 1 Detention (flood control) needed? (see Table B -1 in Appendix B) !/ Detention is required. Need must be evaluated. Detention not required. What decision has been reached? By whom? If the need for How was determination made? Type 1 Detention must be evaluated: STORMWATER DESIGN GUIDELINES Page 7 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 3 — Property Characteristics Start (Page 3.1) Nature and Scope of Proposed Work Existing: Land proposed for development currently used, including extent of impervious cover? U}� c fit �16� Fir �Ir Cc,,I' . Site Redevelopment of one platted lot, or two or more adjoining platted lots. Development Building on a single platted lot of undeveloped land. Project Building on two or more platted adjoining lots of undeveloped land. (select all Building on a single lot, or adjoining lots, where proposed plat will not form applicable) a new street (but may include ROW dedication to existing streets). Other (explain): Subdivision Construction of streets and utilities to serve one or more platted Tots. Development Construction of streets and utilities to serve one or more proposed lots on Project lands represented by pending plats. Site projects: building use(s), approximate floor space, impervious cover ratio. Describe Subdivisions: number of lots by general type of use, linear feet of streets and Nature and drainage easements or ROW. Size of (, c-tS Proposed Project Is any work planned on land that is not platted If yes, explain: or on land for which platting is not pending? No Yes FEMA Floodpiains Is any part of subject property abutting a Named Regulatory Watercourse No r/ Yes (Section II, Paragraph B1) or a tributary thereof? Is any part of subject property in floodplain No Yes t/ Rate Map (`i,1. C area of a FEMA - regulated watercourse? Encroachment(s) Encroachment purpose(s): Building site(s) Road crossing(s) into Floodplain areas planned? Utility crossing(s) Other (explain): No Yes If floodplain areas not shown on Rate Maps, has work been done toward amending the FEMA- approved Flood Study to define allowable encroachments in proposed areas? Explain. STORMWATER DESIGN GUIDELINES Page 6 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 2 — Project Administration Continued (page 2.3) Coordination For Project or Subject Property (or Phase) Note: For any Coordination of stormwater matters indicated below, attach documentation describing and substantiating any agreements, understandings, contracts, or approvals. Coordination Dept. Contact: Date: Subject: With Other Departments of Jurisdiction City (Bryan or College Station) Coordination With Summarize need(s) & actions taken (include contacts & dates): Non jurisdiction' City Needed? [� Yes No . Coordination with Summarize need(s) & actions taken (include contacts & dates): Brazos County Needed? Yes No c/ Coordination with Summarize need(s) & actions taken (include contacts & dates): TxDOT Needed? Yes Not-Z Coordination with Summarize need(s) & actions taken (include contacts & dates): TAMUS Needed'/ Yes No V Permits For Project or Subject Property (or Phase) As to stormwater management, are permits required for the proposed work from any of the entities listed below? If so, summarize status of efforts toward that objective in spaces below. Entity Permitted or Status of Actions include dates) ? Actions ( include US Army Crops of Engineers No Yes US Environmental Protection Agency No ` Yes Texas Commission on Environmental Quality No Yes Brazos River Authority No / Yes STORMWATER DESIGN GUIDELINES Page 5 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D - TECHNICAL DESIGN SUMMARY Part 2 — Project Administration • Continued (page 2.2) Project Identification (continued) Roadways abutting or within Project Area or Abutting tracts, platted land, or built subject property: developments: Named Regulatory Watercourse(s) & Watershed(s): Tributary Basin(s): Plat Information For Project or Subject Property (or Phase) Preliminary Plat File #: Final Plat File #: Date: Name: Status and Vol/Pg: If two plats, second name: File #: Status: Date: Zoning Information For Project or Subject Property (or Phase) Zoning Type: - 1 Existi1r Proposed? Case Code: Case Date Status: Zoning Type: Existing or Proposed? Case Code: Case Date Status: Stormwater Management Planning For Project or Subject Property (or Phase) Planning Conference(s) & Date(s): Participants: Preliminary Report Required? Submittal Date Review Date Review Comments Addressed? Yes No In Writing? When? Compliance With Preliminary Drainage Report. • Briefly describe (or attach documentation explaining) any deviation(s) from provisions of Preliminary Drainage Report, if any. STORMWATER DESIGN GUIDELINES Page 4 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 SECTION IX APPENDIX D — TECHNICAL DESIGN SUMMARY Part 2 - Project Administration Start (Page 2.1) Engineering and Design Professionals Information Engineering Firm Name and Address: Jurisdiction -v`IE CoSvLt vas City: Bryan Pc). ��X of Z53 LCollege Station C S - TY ? -7a`J'Z Date of Submittal: t2-1 tx3 Lead Engineer's Name and Contact Info.(phone, e-mail, fax): Other: Supporting Engineering / Consulting Firm(s): Other contacts: Developer / Owner / Applicant Information Developer / Applicant Name and Address: Phone and e-mail: Act_ SP , �-r —r2 Property Owner(s) if not Developer / Applicant (& address): Phone and e-mail: Project Identification Development Name: }�yspps - jl.,cl\JrV Z - u1 Is subject property a site project, a single -phase subdivision, or part of a multi -phase subdivision? ` If multi - phase, subject property is phase of Legal description of subject property (phase) or Project Area: (see Section II, Paragraph B -3a) I v IzXZ_s- IT`S L- 3 -z If subject property (phase) is second or later phase of a project, describe general status of all earlier phases. For most recent earlier phase Include submittal and review dates. General Location of Project Area, or subject property (phase): J�rl WI N 1•t Ott In City Limits? Extraterritorial Jurisdiction (acreage): Bryan: acres. Bryan: College Station: College Station: 3 .3 1 acres. Acreage Outside ETJ: STORMWATER DESIGN GUIDELINES Page 3 of 26 APPENDIX. D: TECH. DESIGN SUMMARY Effective February 2007 As Revised February 2009 Secti0n 3.0 HYDROLOGIC MOD FLING HydroCAD - Existing & Proposed Conditions Drainage Calculations Chimney Hill Rational 020911 TX Brazos County 2 - Year Duration =10 min, Inten =6.33 in /hr Prepared by {enter your company name here} Page 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Time span =0.00 -1.00 hrs, dt =0.01 hrs, 101 points Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment DA -P: Post - Development P Runoff Area =8.960 ac Runoff Depth = 0.71" Tc =15.6 min C =0.70 Runoff =25.39 cfs 0.530 af Subcatchment DA - P1: Post - Development P1 Runoff Area =0.960 ac Runoff Depth = 0.73" Tc =10.0 min C =0.46 Runoff =2.79 cfs 0.058 af Subcatchment DA - P2: Post - Development P2 Runoff Area =2.730 ac Runoff Depth = 0.73" Tc =10.0 min C =0.46 Runoff =7.93 cfs 0.165 af Subcatchment DA - Pre - Development "X" Runoff Area =3.620 ac Runoff Depth = 0.65" Tc =10.0 min C =0.41 Runoff cfs 0.196 af Total Runoff Area = 16.270 ac Runoff Volume = 0.949 af Average Runoff Depth = 0.70" HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill TX- Brazos County 2 -Year Duration =10 min, Inten =6.33 in /hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P1: Post - Development P1 Runoff = 2.79 cfs @ 0.17 hrs, Volume= 0.058 af, Depth= 0.73" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 2 -Year Duration =l0 min, Inten =6.33 in /hr Area (ac) C Description 0.960 0.46 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA -P1: Post - Development P1 Hydrograph 3- — Runoff 2.79 cfs TX- Brazos County 2 -Year Duration =l0 min, Inten =6.33 in/hr 2 Runoff Area =0.960 ac N _ Runoff Volume =0.058 af Runoff Depth= 0.73" Tc =10.0 min C =0.46 0 0 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill Rational - 020911 TX Brazos County 2 - Year Duration =10 min, Inten =6.33 in /hr Prepared by {enter your company name here} Page 5 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA - X: Pre - Development "X" Runoff = 9.37 cfs @ 0.17 hrs, Volume= 0.196 af, Depth= 0.65" Runoff by Rational method, Rise /Fall = 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 2 -Year Duration =l0 min, Inten =6.33 in /hr Area (ac) C Description 3.620 0.41 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 10 - —Runoff 9.37 cfs 9- TX-Brazos County 2-Year 8= Duration =l0 min, 7 - _ _ Inten =6.33 in /hr y 6 - Runoff Area= 3.620 ac = Runoff Volume =0.196 of O Runoff Depth =0.65" 4- _ - Tc =10.0 min 3- / C =0.41 0 j 0 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill- Rational- 020911 TX- Brazos County 5 -Year Duration =10 min, Inten =7.69 in /hr Prepared by {enter your company name here} Page 7 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P: Post - Development P [48] Hint: Peak <CiA due to short duration Runoff = 30.87 cfs @ 0.17 hrs, Volume= 0.644 af, Depth= 0.86" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 5 -Year Duration =10 min, Inten =7.69 in /hr Area (ac) C Description 8.960 0.70 Post Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.6 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P €;ydrograph 34 32- _ _ _ 30.87 cfs - -- -Runoff 30 TX- Brazos County 5 - Year 28= 26 Durafion = 10 min, 24= Inters = 7.69 in /hr 22 N 20= Runoff Area =8.960 ac . 18_ Runoff Volume =0:644 of 14 Runoff Depth =0.86" 12= Tc= 15:6 min 10_ C=0.70 8. __ 4 i _ 2- 0-6 1 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill - Rational 020911 TX, Brazos County 5 - Year Duration =10 min, Inten =7.69 in /hr Prepared by Center your company name here} Page 9 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P2: Post - Development P2 Runoff = 9.64 cfs @ 0.17 hrs, Volume= 0.201 af, Depth= 0.88" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 5 -Year Duration =l0 min, Inten =7.69 in /hr Area (ac) C Description 2.730 0.46 Proposed Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA -P2: Post - Development P2 Hydrograph 10- I 9.64 cfs ° - Runoff /\\\ 9- TX- Brazos County 5 -Year 8- Duran = Inten tio =7.69 l0 in / h r min 7 Runoff Area =2.730 ac s 6- Runoff Volume =0.201 af O 5 = Runoff Depth =0.88" 4- _ ._ Tc =10.0 min 3 C =0.46 2 1 0 0 - Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill Rational 020911 TX Brazos County 10 - Year Duration =10 min, Inten =8.63 in /hr Prepared by {enter your company name here} Page 11 HydroCAD® 7A 0 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Time span =0.00 - 1.00 hrs, dt =0.01 hrs, 101 points Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment DA -P: Post - Development P Runoff Area =8.960 ac Runoff Depth = 0.97" Tc =15.6 min C =0.70 Runoff =34.65 cfs 0.723 af Subcatchment DA - P1: Post - Development P1 Runoff Area =0.960 ac Runoff Depth = 0.99" Tc =10.0 min C =0.46 Runoff =3.81 cfs 0.079 af Subcatchment DA - P2: Post - Development P2 Runoff Area =2.730 ac Runoff Depth= 0.99" Tc =10.0 min C =0.46 Runoff cfs 0.226 af Subcatchment DA - Pre - Development "X" Runoff Area =3.620 ac Runoff Depth = 0.88" Tc =10.0 min C =0.41 Runoff =12.79 cfs 0.267 af Total Runoff Area = 16.270 ac Runoff Volume = 1.295 af Average Runoff Depth = 0.96" HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill- Rational- 020911 TX- Brazos County 10 -Year Duration =10 min, Inten =8.63 in /hr Prepared by {enter your company name here} Page 13 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA - P1: Post - Development P1 Runoff = 3.81 cfs @ 0.17 hrs, Volume= 0.079 af, Depth= 0.99" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 10 -Year Duration =l0 min, Inten =8.63 in /hr Area (ac) C Description 0.960 0.46 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA -P1: Post- Development P1 f ydrograph 4 _ __ 3 cfs __ - -- Runoff 7 \ TX- Brazos County 10 -Year Duration =l0 min, 3- - - - lnten =8:63 in /hr Runoff Area =0.960 ac Runoff Volume =0.079 af 2- Runoff Depth= 0.99" Tc =10.0 min C =0.46 1- / -/ 0 - 0 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill-Rational-020911 TX- Brazos County 10 -Year Duration =10 min, Inten =8.63 in /hr Prepared by {enter your company name here} Page 15 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA - X: Pre Development "X" Runoff = 12.79 cfs @ 0.17 hrs, Volume= 0.267 af, Depth= 0.88" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 10 -Year Duration =l0 min, Inten =8.63 in /hr Area (ac) C Description 3.620 0.41 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA -X: Pre - Development "X" Hydrograph 14- - 12.79 cfs — Runoff 13-: 12 TX-Brazos County-10- Year -- Duration =l0 min, 10= Inten= 8.63 in /hr F. 8- Runoff Area =3.620 ac Runoff Volume =0.267 of Runoff Depth =0. 88" 5 Tc =10.0 min C =0.41 3- 1- 0 -, 0 � Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill Rational 020911 TX Brazos County 25 - Year Duration =10 min, Inten =9.86 in /hr Prepared by {enter your company name here} Page 17 HydroCAD© 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P: Post - Development P [48] Hint: Peak <CiA due to short duration Runoff = 39.58 cfs @ 0.17 hrs, Volume= 0.826 af, Depth= 1.11" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 25 -Year Duration =l0 min, Inten =9.86 in /hr Area (ac) C Description 8.960 0.70 Post Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.6 Direct Entry, Proposed Conditions Subcatchment DA -P: Post - Development P Hydrograph 44 42' 39.58 cfs — Runoff 40= 38= TX- Brazos County 25 -Year 36_ 34 Duration =10 min, 32_ 30' .. Inten= 9.86 - in /hr 28= - 26 � Runoff Area =8.960 ac ,-. - 24 Runoff Volume =0.826 af 22. 20_ Runoff Depth =1.11" 16' Tc =15.6 min 14 C= 0.70 .. 10 8 6: 4- 2= 0= 0 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill - Rational- 020911 TX- Brazos County 25 -Year Duration =10 min, Inten =9.86 in/hr Prepared by {enter your company name here} Page 19 HydroCAD® 7.10 sin 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P2: Post - Development P2 Runoff = 12.36 cfs @ 0.17 hrs, Volume= 0.258 af, Depth= 1.13" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 25 -Year Duration =l0 min, Inten =9.86 in /hr Area (ac) C Description 2.730 0.46 Proposed Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment D -P2: Post - Development P2 Hy«« raph 13 12.36 cfs — Runoff '2= TX- Brazos County - Duration =l0 25 Year min, 10 Inten =9.86 in /hr 8- Runoff Area =2.730 ac - Runoff Volume =0.258 of 3 Runoff Depth= 1.13 " 5 min C =0.46 3 2 - 0 -y Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill - Rational 020911 TX Brazos County 50 - Year Duration =10 min, Inten =11.15 in /hr Prepared by {enter your company name here} Page 21 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Time span =0.00 -1.00 hrs, dt =0.01 hrs, 101 points Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc Reach routing by Stor- Ind +Trans method - Pond routing by Stor -Ind method Subcatchment DA - Post - Development P Runoff Area =8.960 ac Runoff Depth = 1.25" Tc =15.6 min C =0.70 Runoff =44.74 cfs 0.933 af Subcatchment DA - P1: Post - Development P1 Runoff Area =0.960 ac Runoff Depth= 1.28" Tc =10.0 min C =0.46 Runoff =4.91 cfs 0.103 af Subcatchment DA - P2: Post - Development P2 Runoff Area =2.730 ac Runoff Depth = 1.28" Tc =10.0 min C =0.46 Runoff =13.97 cfs 0.292 af Subcatchment DA - Pre - Development "X" Runoff Area =3.620 ac Runoff Depth = 1.14" Tc =10.0 min C =0.41 Runoff =16.52 cfs 0.345 of Total Runoff Area = 16.270 ac Runoff Volume = 1.672 af Average Runoff Depth = 1.23" • HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill- Rational- 020911 TX- Brazos County 50 -Year Duration =10 min, /nten =11.15 in /hr Prepared by {enter your company name here} Page 23 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P1: Post - Development P1 Runoff = 4.91 cfs @ 0.17 hrs, Volume= 0.103 af, Depth= 1.28" Runoff by Rational method, Rise /Fall = 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 50 -Year Duration =l0 min, Inten =11.15 in /hr Area (ac) C Description 0.960 0.46 Post - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA -P1: Post- Development P1 Hydrograph 4.91 cfs — Runoff 5- ._.. TX- Brazos County 50 -Year Duration =l0 min, 4 . Inten =11.15 in /hr Runoff Area =0.960 ac 3- Runoff Volume =0:103 of Runoff Depth= 1.28 °' Z Tc =10.0 min - - C =0.46 0 - Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill- Rational- 020911 TX -- Brazos County 50 -Year Duration =l0 min, Inten =11.15 in /hr Prepared by {enter your company name here} Page 25 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -X: Pre - Development "X" Runoff = 16.52 cfs @ 0.17 hrs, Volume= 0.345 af, Depth= 1.14" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 50 -Year Duration =10 min, Inten =11.15 in /hr Area (ac) C Description 3.620 0.41 Pre - Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Existing Conditions Subcatchment DA-X: Pre - Development "X" Herdrograph 18 4 16.52 cfs I — Runoff = i 16. 15_ TX- Brazos County 50 -Year 14. _ _. Duration =10 min Inten= 11.15 in /hr 12 11 Runoff Area= 3.620 ac -- 10 Runoff Volume =0.345 Runoff - Depth =1.14" Tc =10:0 min 6= 5= C - =0.41 4 2 0 - 0 1 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill Rational 020911 TX Brazos County 100 - Year Duration =10 min, Inten =11.64 in /hr Prepared by {enter your company name here} Page 27 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA -P: Post - Development P [48] Hint: Peak <CiA due to short duration Runoff = 46.71 cfs @ 0.17 hrs, Volume= 0.975 af, Depth= 1.31" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 100 -Year Duration =l0 min, Inten =11.64 in /hr Area (ac) C Description 8.960 0.70 Post Development Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ftlsec) (cfs) 15.6 Direct Entry, Proposed Conditions Subcatchment DA -P: Post- Development P Kydrograph 52- 50 48- 46.71 cfs Runoff', ... _ 46- 44` .. - - - -- - - TX- Brazos County -100- Year 42_ 40` - - - - - . - - _ .- Duration =l0 m i n , - 36 Inten =11.64 in /hr 34 32 _ Runoff- Area= 8.960 - ac m 30- 28_ Runoff - Volume= 0.975 af 26_ 0 24 Runoff Depth= l - .31" - u 22 - 20= Tc= 15.6 - min C= 0.70 12 10= 4 2= 0 1 0 Time (hours) HydroCAD- Existing & Proposed Conditions Drainage Calculations Chimney Hill - Rational- 020911 TX- Brazos County 100 -Year Duration =10 min, Inten =11.64 in /hr Prepared by {enter your company name here} Page 29 HydroCAD 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Subcatchment DA - P2: Post Development P2 Runoff = 14.59 cfs @ 0.17 hrs, Volume= 0.304 af, Depth= 1.34" Runoff by Rational method, Rise /Fall= 1.0/2.0 xTc, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs TX- Brazos County 100 -Year Duration =l0 min, Inters =11.64 in /hr Area (ac) C Description 2.730 0.46 Proposed Conditions Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.0 Direct Entry, Proposed Conditions Subcatchment DA -P2: Post - Development P2 Hydrograph 16 15: 14.59 cfs -° Runoff 14= TX- Brazos County 100 -Year 13 Duration =10 min, 12 11 _ Inten =11.64- in /hr 10- - Runoff Area =2.730 ac Runoff Volume =0.304 of 3 $: Runoff Depth =1.34 a = 6= Tc =10.0 min C= 0.46 4 2- - - - 0 Time (hours) STORMWA'1'ER DRAINAGE ANALYSIS RANDALL'S UNIVERSITY PARK SUBDIVISION UNIVERSITY & TARROW COLLEGE STATION, TEXAS } 1, M. L. HAMN1ONS , as Engineer for site grading and drainage of this development, by seal and signature, certify that these plans and supporting documents are to the best of my knowledge and intent in compliance with the City of College Station Ordinance #1728 for storm-00 ))))))9)))))) ) water management. �`��)), .0 .OF TE s '�� l M. L_. HAMMONS ;:k , . p 25308 4( ieirvrrrrr r A I ' TABLE OF CONTENTS I CERTIFICATION I II DEVELOPMENT PERMIT APPLICATION FORM II 1.0 INTI DWU1'ION 1 2.0 SITE 1 2.1 Site Topography 2.2 Easements 2.3 Drainage Basin 2.4 Existing Site Drainage 3.0 PROPOSED DRAINAGE PLAN 3 3.1 Run -off Calculation Criteria 3.1.1 Variable A, Drainage Area 3.1.2 Variable C, Run-off Coefficient 3.1.3 Variable I, Rainfall Intensity 3.2 Run -off Calculation 3.3 Run -off Control 3.3.1 Detention Volume Requirements 4.0 S'I'ORMW TER DETENTION 6 4.1 Detention Storage Inflow 4.2 Detention Storage Discharge Illustration 1.1 Site Location Map 7 Illustration 1.2 Proposed Plat (Randall's University Park) 8 { Illustration 2.1 City of College Station Drainage Basin Map 9 Figure 3.1 Triangular Hydrograph Chart 10 Figure 4.1 Detention Storage Input Schematic 11 Figure 4.2 Detention Storage Discharge 12 Appendix A Drainage Structure Plans 13 III SUBDIVISION DRAINAGE 1.0 INTRODUCTION The Ranlall's Grocery Company hereby proposes the Development of a 9.28 acre real estate tract located in the Northwest quadrant of the University Drive and Tarrow Drive intersection in the City of College Station. The site fronts on University Drive with property line frontage on Tartu Drive, Arguello Drive and Chimney Hill Drive as illustrated by the vicinity map (Illustration 1.1). The site to be developed is lot 1, of the recently proposed Ran all's University Park subdivision (Illustration 1.2). By physical nece and by agreement between owners of lot 1 and lot 2, all of lot 2 drainage will be through lot 1 via surface or underground drainage. With all lots and the small perimeter areas, the total development area for drainage consideration is 11.0 acres. All of lot 2 and 8.65 acres of lot 1 are zoned C -1 commercial and is to be developed accordingly. The remaining 0.63 acres of lot 1 is zoned R -3 and is included in this development proposal for use as stormwater drainage detention only. Roof coverage of lot 1 is approximately 94,000 square feet, equivalent to 23% of the lot area and 19.6% of the 11.0 acre drainage site. Roof coverage of lot 2 is projected to be 4,000 square feet, equivalent to 7.2% of the lotd area and .8% of the 11.0 acre drainage site. 2.0 S.v.i.E The drainage site is presently undeveloped and is vegetated by grass and weeds with a few trees located at the Northwest end of the property. 2.1 Site Topography The existing terrain is open land on a hillside site with an average slope gradient of approximately 4% - 5 %. Surface downslope is in a Northwesterly direction away from the University Drive, Tart Drive intersection toward an existing drainage ravine which collects and discharges all drainage fruit this site, as well as other upstream areas. The maximum elevation of the site is approximately 331' at the intersection of University and Tarrow descending to a law of 298' elevation at the natural drainage discharge point. 1 } 3.0 Proposed Drainage Plan To achieve stormwater control according to City Ordinance #1728, Chapter 13 of the code of ordinances of the City of College Station, the following controls are proposed. 1. The entire Randall's University Park Subdivision, 11.0 acres, is to be considered as the drainage development site. 2. The site's post - development stormwater run -off rate is not to exceed the pre- development run-off rate. 3. The upstream, offsite stormwater inflow is to be managed through the site but without detention or other control that would limit the flow rate. 4. The site stormwater detention control is to be designed for the one huts (100) year (1% annum probability) storm event frequency. 5. All stormwater will continue to discharge at the intersection of the North property line and the Chimney Hill Drive R.O.W., which is the current discharge point. } 3.1 Run -Off Calculation Criteria Stormwater run -off is calculated herein according to methods presented in the City of College Station DP & DS manual. Peak discharges (Pre - Development & Post - Development) are calculated by the Rational Formula (Q = CIA) since: A. The run -off area is less than fifty (50) acres. B. The discharge is not a primacy system discharge. C. The flour being calculated is overland and street flow as required by the DP & DS manual (Section III, ParagrajDh B.2.d., page 17) for rational formula calculation. 3.1.1 Variable A, the development area, is the 10.54 acres as defined by subdivision plat plus a small perimeter (curb to property line) area. The area used for calculation herein is 11.0 acres. 3.1.2 Variable C. the run-off coefficient, is determined by use of Table III -1 of the previsouly referenced DP & DS manual. Three major slope areas are considered in the determination. A. The broad area between University Drive. and Arguello Drive which is approximately 8.5 acres at an average existing slope of 2.7 %. . ' I { 3 3.3.1 Detention Volume Requirement Detention volume for this site is determined by comparison of 1 hydrographs representing the uncontrolled post-development flaw and the "design" flew as allowed by the College Station DP & DS manual for the conditions represented at this site. The triangular approximation hydrograph is used. The project "c9PSign" hydrograph is the flow to which the discharge orifice is designed and is limited to the maximum flaw calculated for the pre- development site conditions. Figure 3.1 presents both the Pre and Post Q100 run -off hydrograph. In addition the "design" hydrograph is shown. The required detention volume is represented on Figure 3.1 as the graph area exceeding the "dPgign" Q100 run-off flow, but within the Post-development, Q100 run -off flow. Calculation is by conversion of the hydrograph areas to the numerical units represented thereon. The area of volume calculation is from the time of run -off onset until the time at which the uncontrolled Post - development flaw rate, during decline, is equal the predetermined allowable discharge flow rate. By such application the required storage volume is 49,500 cubic feet as calculated thus: Incoming Volume /100 yr. Hydrograph: 105,210 CF* * 30 minx 60 X 116.9 CC'S x .5 = 105,210 Discharged Volts /100 yr. 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O m - t� 0 = i COLLEGE STATION, BRAZOS COUNTY, TX _ i _ _ v HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill- Rational- 020911 TX- Brazos County 2 -Year Duration =10 min, Inten=6.33 in/hr Prepared by {enter your company name here} 2 Page 1 1 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 0.73" for 2 -Year event Inflow = 2.79 cfs @ 0.17 hrs, Volume 0.058 af Outflow = 0.48 cfs @ 0.44 hrs, Volume= 0.034 af, Atten= 83 %, Lag= 16.4 min Primary = 0.48 cfs © 0.44 hrs, Volume= 0.034 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.13' @ 0.44 hrs Surf.Area= 4,060 sf Storage= 1,900 cf Plug -Flow detention time =23.3 min calculated for 0.034 af (59% of inflow) Center -of -Mass det. time= 18.9 min ( 32.2 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x 0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.48 cfs © 0.44 hrs HW= 303.13' (Free Discharge) `_1= Orifice /Grate (Orifice Controls 0.48 cfs @ 4.4 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill- Rational- 020911 TX- Brazos. County 5 -Year Duration =10 min, Inten =7.69 in /hr Prepared by {enter your company name here} Page 3 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 0.88 for 5 -Year event Inflow = 3.39 cfs @ 0.17 hrs, Volume= 0.071 af Outflow = 0.51 cfs @ 0.45 hrs, Volume= 0.037 af, Atten= 85 %, Lag= 16.8 min Primary = 0.51 cfs @ 0.45 hrs, Volume= 0.037 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.25' @ 0.45 hrs Surf.Area= 4,181 sf Storage= 2,401 cf Plug -Flow detention time =23.8 min calculated for 0.036 of (51% of inflow) Center -of -Mass det. time= 19.0 min ( 32.4 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x 0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.51 cfs @ 0.45 hrs HW= 303.25' (Free Discharge) t-1= Orifice /Grate (Orifice Controls 0.51 cfs @ 4.7 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill - Rational 020911 TX Brazos County 10 - Year Duration =10 min, Inten =8.63 in/hr Prepared by {enter your company name here} Page 5 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 0.99" for 10 -Year event Inflow = 3.81 cfs @ 0.17 hrs, Volume= 0.079 of Outflow = 0.53 cfs @ 0.45 hrs, Volume= 0.038 af, Atten= 86 %, Lag= 17.0 min Primary = 0.53 cfs @ 0.45 hrs, Volume= 0.038 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.34' @ 0.45 hrs Surf.Area= 4,264 sf Storage= 2,749 cf Plug -Flow detention time =24.4 min calculated for 0.038 af (48% of inflow) Center -of -Mass det. time= 19.1 min ( 32.5 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x 0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.53 cfs @ 0.45 hrs HW= 303.34' (Free Discharge) '--1=-Orifice/Grate (Orifice Controls 0.53 cfs @ 4.9 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill Rational 020911 TX Brazos County 25 - Year Duration =10 min, inten =9.86 in /hr Prepared by {enter your company name here} Page 7 HydroCAD© 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 1.13" for 25 -Year event Inflow = 4.35 cfs © 0.17 hrs, Volume= 0.091 af Outflow = 0.56 cfs @ 0.46 hrs, Volume= 0.040 af, Atten= 87 %, Lag= 17.2 min Primary = 0.56 cfs @ 0.46 hrs, Volume = 0.040 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.44' @ 0.46 hrs Surf.Area= 4,370 sf Storage= 3,205 cf Rug -Flow detention time =24.8 min calculated for 0.040 af (44% of inflow) Center -of -Mass det. time= 19.2 min ( 32.5 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.56 cfs © 0.46 hrs HW= 303.44' (Free Discharge) 't-1= Orifice /Grate (Orifice Controls 0.56 cfs © 5.1 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill- Rational 020911 TX Brazos County 50 - Year Duration =l0 min, Inten =11.15 in /hr Prepared by {enter your company name here} Page 9 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 1.28" for 50 -Year event Inflow = 4.91 cfs @ 0.17 hrs, Volume= 0.103 af Outflow = 0.59 cfs © 0.46 hrs, Volume= 0.042 af, Atten= 88 %, Lag= 17.4 min Primary = 0.59 cfs © 0.46 hrs, Volume= 0.042 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.55' © 0.46 hrs Surf.Area= 4,478 sf Storage= 3,685 cf Plug-How detention time =25.0 min calculated for 0.042 af (41% of inflow) Center -of -Mass det. time= 19.3 min ( 32.6 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x 0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.59 cfs @ 0.46 hrs HW= 303.55' (Free Discharge) —1= Orifice /Grate (Orifice Controls 0.59 cfs @ 5.4 fps) HydroCAD - Proposed Conditions Pond Calculations - Pond 1 Chimney Hill Rational 020911 TX Brazos County 100 - Year Duration =10 min, Inten =11.64 in /hr Prepared by {enter your company name here} Page 11 HydroCAD® 7.10 s/n 003394 © 2005 HydroCAD Software Solutions LLC 2/8/2011 Pond P1: Pond 1 Inflow Area = 0.960 ac, Inflow Depth = 1.34" for 100 -Year event Inflow = 5.13 cfs @ 0.17 hrs, Volume= 0.107 of Outflow = 0.60 cfs @ 0.46 hrs, Volume= 0.043 af, Atten= 88 %, Lag= 17.5 min Primary = 0.60 cfs © 0.46 hrs, Volume= 0.043 af Routing by Stor -Ind method, Time Span= 0.00 -1.00 hrs, dt= 0.01 hrs Peak Elev= 303.59' @ 0.46 hrs Surf.Area= 4,519 sf Storage= 3,870 cf Plug -Flow detention time =25.3 min calculated for 0.043 af (40% of inflow) Center -of -Mass det. time= 19.3 min ( 32.6 - 13.3 ) Volume Invert Avail.Storage Storage Description #1 302.30' 5,803 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 302.30 0 0 0 303.00 3,928 1,375 1,375 304.00 4,929 4,429 5,803 Device Routing Invert Outlet Devices #1 Primary 302.30' 0.33' x 0.33' Horiz. Orifice /Grate Limited to weir flow C= 0.600 Primary OutFlow Max =0.60 cfs @ 0.46 hrs HW= 303.59' (Free Discharge) t-1= Orifice /Grate (Orifice Controls 0.60 cfs @ 5.5 fps) Section 5.0 STORM DRAINAG F, SYSTEM output.lis RUNING MESSAGES LIST: *Computation: Hydraulic jump occurs at culvert outlet. *Computation: outlet velocity is based on the outlet water depth. Computation: Hydraulic jump occurs at culvert outlet. NORMAL TERMINATION OF THYSYS, CULVERT. Page 2 output.lis TEXAS HYDRAULIC SYSTEM, CULVERT (ver. 1.2. Feb /2002) Mon Feb 14 19:23:57 2011 CULVERT HYDRAULIC COMPUTATIONS CULVERT NAME: C2 Input Units: English PROJECT NAME: Output Units: English PROJECT CONTROL: COUNTY: DESCRIPTION: ANALYZE SINGLE OPENING CULVERT MATERIAL: CONCRETE SHAPE: RCP CIRCULAR PIPE. ENTRANCE: MITER PROFILE: STRAIGHT CULVERT FREQUENCY: 100 yr DISCHARGE: 93.50 cfs TAILWATER: 297.87 ft n value: 0.0120 Ke value: 0.7000 CULVERT DIAM. = 3.00 ft BARRELS = 1 INLET station: 0.00 elevation: 296.48 ft OUTLET station: 124.00 elevation: 294.84 ft Road profile (xY coordinates) ft X Y X Y X Y 0.00 308.13 56.00 304.45 87.00 304.75 CULVERT OUTPUT RUN NO => 1 ANALYSIS for discharge frequency of : 100 yr Barls. Qpb Rise Span Length Max.HW Calc.HW HW Control Veloc. Out.depth elev elev cfs ft ft ft ft ft ft ft /s ft 1 93.50 3.00 0.00 106.00 0.00 304.30 7.94 Outlet 13.23 3.00 Inlet control depth = 10.53 ft outlet control depth = 7.94 ft Normal depth = 3.00 ft Culvert slope = 0.01323 Critical depth = 2.87 ft Critical slope = 0.01454 Road top width => 0.00 ft. Road pavement type => asphalt computed Weir coefficient => 3.00. No discharge over the road. RUNING MESSAGES LIST: Page 1 output.lis NORMAL TERMINATION OF THYSYS, CULVERT. Page 2 output.lis TEXAS HYDRAULIC SYSTEM, CULVERT (ver. 1.2. Feb /2002) Mon Feb 14 19:23:00 2011 CULVERT HYDRAULIC COMPUTATIONS CULVERT NAME: C1 Input Units: English PROJECT NAME: Output Units: English PROJECT CONTROL: COUNTY: DESCRIPTION: ANALYZE SINGLE OPENING CULVERT MATERIAL: CONCRETE SHAPE: RCP CIRCULAR PIPE. ENTRANCE: MITER PROFILE: BROKEN BACK CULVERT FREQUENCY: 100 yr DISCHARGE: 195.70 cfs TAILWATER: 297.87 ft n value: 0.0120 Ke value: 0.7000 CULVERT DIAM. = 5.00 ft BARRELS = 1 INLET station: 0.00 elevation: 296.48 ft OUTLET station: 115.00 elevation: 294.84 ft BROKEN BACK CULVERT CONFIGURATION UPSTREAM DOWNSTREAM Unit Slope Length Sta. Elev. Sta. Elev. 1 0.01000 51.00 0.00 296.48 51.00 295.97 2 0.01766 64.00 51.00 295.97 115.00 294.84 Road profile (XY Coordinates) ft X Y X Y X Y 0.00 308.13 56.00 304.45 87.00 304.75 CULVERT OUTPUT RUN NO => 1 ANALYSIS for discharge frequency of : 100 yr Barls. Qpb Rise Span Length Max.HW Calc.HW HW Control Veloc. Out.depth elev elev cfs ft ft ft ft ft ft ft /s ft 1 195.70 5.00 0.00 85.00 0.00 304.30 8.04 Inlet 15.26 3.11 Inlet control depth = 8.04 ft outlet control depth = 3.06 ft Normal depth = 2.56 ft Culvert slope = 0.01426 Critical depth = 4.00 ft critical slope = 0.00504 Road top width => 0.00 ft. Road pavement type => asphalt Computed Weir Coefficient => 3.00. No discharge over the road. Page 1 output.lis RUNING MESSAGES LIST: *Computation: Hydraulic jump occurs inside of the most downstream unit. NORMAL TERMINATION OF THYSYS, CULVERT. Page 2 ° CITY OF BRYAN O m °" c , y o ( p•ARENT) T.1 O AT P , DIS 4 5.15') CIT 4, � , T o o m 3 " ° z RIG t -OF-w; N 48 1 4 0 4,� W 454 80 ' . (MEASURED) 7.• .• .•••• --- �.. ° . —:. . 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P N WOE 0 000 H 7p \ 1. mc , ° m > » m m � oC > g F - i ii O V I ,gyp , P ° 1'� 1 o x-o p2a x ay �° z � m m _ a a m ° ° ��• ' _ JC n g ,� �p 1 -�• K m n I � v o g ° � °u $ I'13> I all NJ O_ '2i � F ,A � y AO = z N -. , - s O C1 2 $ a.,,3n f2 TA o y > > '^ •P 5 7 - O,, _ ,, i f °r �i W � � '� p m oa N O RO cOoN ° mgD y° m > � m ,, TJ^ ti, V e i m� r� 'o � ;' `� O ff % RANDALL S UNIVERSITY PARK: K \� LOTS 3R -2A thru 3\ CHIMNEY HILL DR., COLLEGE o ` `` STATION k ireliP PP #* r- V . 15f3 0 f ` I lift / 4 1 i, m tr; 4 1 Z %I • N 0 , N IP __„,. 4‘/, 30 ...4.. 4.1..1.74 ir •• , . f ).;.1:;-,-, ). ma. . \\ 114‘ ,, ,ziterte.k.P4, • 4\\ 0 v , J(„ 40 7074:47,,„‘ 44, ,1 4 >;04;11 !■■ ■ -, ' 4r# __)'' Illii it 4, v, v 4■,'• 0 \ 4 4 Pe N '' ' . 44 sl 1 I 1 I, ,, . • ‘ .. d* 1.;■1.-r i I& 4, 60 > .- fketpstssOW'or.-4 eV t A ileloPel \ *NI 1,4,544t d , , - . i , ` EASTE OOD # AIRPo = 2154 -,. VICINITY MAP City of Baran Map Output Page rage l of i —J — ,� 1 ,- f Q 4 I' ii Lv r _ =il 1 rt. 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I,r_ :n, 'i , X . 771S 1 http: / / ant(.gov /gi s /servl et/corn. esri . esrimap.Esri map? ServiceName= REGIONAL_... 12/12/2010 Section 2.0 WATERSHEDS & DRAINAGE AREAS - - - - _ 1111 -- – -- - — --- - -- -- - -.___ _ -- -- -- 1111 -- - �` Fl o :' 1 } 1 ' 71 t . . t1 ,- , - f ` j 1 t4ltlt i y ., , j`1 li ::_.:.,_•,...;,,,,;::..„3:\--.,--.. • - 6- ! - •' r'< \ 'i :ill ) ,, , r. th e =t ,, E', �iIi f f, Lr I' I , : I III . r 11 1 n li • '-- , i t � , 1 1` I r . t • Or. ,` • 1 • i ` IJ • i • r V r? 0 j 1 • 1• J \i i � _I ` C • i_ .I .�'r 1'rfJl r" , I • ti ' - of l ;'rrf, 1 '_ [ I . I I sf r ' ,, 1 • f 1 • • ' rl 1 n 4 r fj r/It) ` i t F � 1- �i 4 � ? li i 11 l's ' t `_ __ ,.� :.,� ._ ��..�__.�__.— .�_._.— ,_.__— __ ._` ����- �-------... �- ��_�......�.�--- .�------- -• - - -- il I - 1_____EM__J 1 Fe et n . 1 r3nn 31;00 7 ?nn Figur B -6: Burton Creek Watershed Area 7607 Eastrnark Drive, Ste. 250 -F <77840> P.O. Box 9253, College Station, TX 77842 Off /Fax: (979) 764 -0704 C email: civil @rmengineer.com December 13, 2010 Ali Jaffer 5727 Richmond Ave, APT. 202 Dallas, TX 75206 aliinksa @yahoo. conz RE: Randall's - University, Park, Lot 3R -2 — College Station, TX TCEQ SWP3 & NOI Submittal Package RME No. 220 -0419 Ali Jaffer: Please find attached two (2) copies (1 — 24x36 and 1 — 1 1x17) of the referenced SWPPP and two (2) copies of its associated Construction Site Notice and NOI with one (1) copy of the Payment Submittal Form. Please provide one full -size copy of the SWPPP, signed and completed Construction Site Notice and NOI to the TCEQ as directed below and retain one copy of each for your records. Near the middle of page one of the NOI, please complete the area requesting the e -pay voucher number or the check/money order number and name on the check/money order. The TCEQ requires that the permit documents and the payment for the application fee be processed separately. Application fees have increased to $225.00 for NOI's submitted on -line or $325.00 for mail -in forms. Both fees may be paid on -line at https://-, ww6.tceq.state.tx.us%epav /. Next, proceed to Section E and sign where indicated for certification. (Please note: The individual who signs in Section E must be authorized to sign for the permitted entity, according to 30 Texas Administrative Code 12 305.44, and is considered the Site Operator who is solely liable for all inspection reports and maintenance required by TCEQ, unless a Letter of Delegation is issued to the Site Operator's Representative responsible for all inspection reports and maintenance of the SWPPP). Submit the signed and completed NOI on -line per the instructions given at htti lAvw\-,-6.tceq.state.tx.us /steers/ or mail a signed copy of the NOI to: Texas Commission on Environmental Quality Storm Water Processing Center (MC228) P.O. Box 13087 Austin, Texas 78711 -3087 If mailing the payment for the application fees, complete the Payment Submittal Form as directed, staple the check/money order for the $325.00 or $225.00 mail -in application fee where indicated and mail to: CD1- 220 - 0419- L03.docx Page 1 of 2 7607 Eastmark Drive, Ste. 250 -F <77840> �,4 P.O. Box 9253, College Station, TX 77842 Off /Fax: (979) 764 -0704 " email: civil @rmengineer.com Texas Commission on Environmental Quality Financial Administration Division Cashier's Office, MC -214 P.O. Box 13088 Austin, Texas 78711 -3088 Finally, be sure to post a laminated copy of the half -sized SWPPP, signed NOI and Construction Site Notice at the construction site, at a location visible from the Right -of -Way. Please note that NOI's submitted on -line are valid immediately following submission and NOI's mailed to the TCEQ are considered valid seven (7) days after postmarked. If you have questions regarding the process for on -line payments or on -line submission of NOI's, please see the TCEQ website at http: / /v,rvw.tceq.state.ix.us/ or call the Storm Water Quality Division at (512) 239 -4671. - Please contact us should you have any other questions. S incerely, \ / / 4 Rabon A. Metcalf, I .E. No. 88383 Texas Firm Registration No. F -4695 rabonOrmengineer.co n cc: City of College Station Plamling & Development Services 1101 South Texas Avenue College Station, TX 77845 CD1- 220 - 0419- L03.docx Page 2 of 2 7607 Eastmark Drive, Ste. 250 -F <77840> P.O. Box 9253, College Station, TX 77842 i Off /Fax: (979) 764 -0704 email: civil @rmengineer.com r x January 6, 2011 David Loflin Texas Commission of Environmental Quality Water Supply Division MC 153 P.O. Box 13087 Austin, TX 78711 RE: Randall's University Park, Lot 3R -2 — College Station, TX TCEQ Exception Letter for Utility Improvements R1VIE No. 220 -0419 Mr. David Loflin: The above referenced project will install the following improvements within the distribution system of the City of College Station (CoCS): Approximately 106 linear feet of 4" PVC (C909, Class 200) water line; Applicable services, valves & fittings. Design and construction of these improvements will be in accordance with the latest Bryan/College Station Unified Water & Sewer Design Guideline Manual, Standard Details, and Specifications and Chapter 290 of the TCEQ Rules & Regulations. This quantity of water line is Less than 10% of the total length of water line within the City's current distribution system. Therefore, an exception for plan review is being requested for this project and its water system improvements. Please call should you have any questions or require assistance. Sincerely, OF TEA, I I1 : *: D A Metcalf, P.E. AT 44642 ®# • • •• Mahon A. v etcali, 1 L No. 88583 • Texas Firm Registration No. F -4695 o R .o A :�� rabon@rtnexigiacer.com • / • , :'. / CE NS• ' •• ��� xc: Josh Norton, P.E. I� F SSi EN G Assistant City Engineer � 10, 'tw o`o �. City of College Station 1101 Texas Avenue South College Station, TX 77840 CD1-220-0419-L08.docx Page 1 of 1 7607 Eastmark Drive, Ste. 250 -F <77840> P.O. Box 9253, College Station, TX 77842 Off /Fax: (979) 764 -0704 email: civil @rmengineer.com January 6, 2011 Josh Norton, P.E. Assistant City Engineer City of College Station 1101 Texas Avenue South College Station, TX 77842 RE: Randall's University Park, Lot 3R -2 — College Station, TX Acknowledgement of City Standards RME No. 220 -0419 Josh Norton: The purpose of this letter is to acknowledge that the construction plans for the public infrastructure improvements, for the above referenced project, to the best of my knowledge, do not deviate from the latest B /CS Design Guideline Manual. With the exception of the following items: The typical bottom slope of the detention pond built in this phase of construction does not meet the minimum cross slope of 5.00 %. The proposed detention pond is specified with a bottom cross -slope of 2.00 %, based on design constraints of the detention pond'' that cannot be changed. I also acknowledge, to the best of my knowledge that the details provided in the construction plans are in accordance with the B /CS Standard Details. Please do not hesitate to call if you have any questions. OF TE . Sincerely, Q, �� P �E �S �.. '\41 � * *', RABON A ETCALFF �••- 0,c, •. ' , c E NSA-., -S Rabon A. Metcalf, P.E. No. 88583 • 57 0NAL ' Texas Firm Registration No. F -4695 �� '\ mho Li @rF engineer.cern ..41 CD1- 220 - 0419- L07.docx Page 1 of 1 /./ . 11 /2;cfE. I Randall's University Park - Replat of Lot 3R -2 NWP Coverage Letter C'ew _ January 6, 2011 • January 6, 2011 Josh Norton, P.E. Assistant City Engineer City of College Station 1101 Texas Avenue South College Station, TX 77842 RE: Randall's University Park, Lot 3R -2 — College Station, TX NWP Coverage Letter RIM No. 220 -0419 Josh Norton: Please find below the latest Nationwide Permit information issued by the USACE. The drainage improvements for the above referenced project are covered by the general NWP 29 and the proposed improvements are below the maximum "losses ". It is the intent of the developer to submit proper notification to the USACE prior to commencement of construction. NWP 29 - Residential Developments: Discharges of dredged or . fill material into non -tidal waters of the United States for the construction or expansion of a single residence, a multiple unit residential development, or a residential subdivision. This NWP authorizes the construction of building foundations and building pads and attendant features that are necessary for the use of the residence or residential development. Attendant features izzay include but are not limited to roads, parking lots, garages, yards, utility lines, storm water management facilities, septic fields, and recreation facilities such as playgrounds, playing fields, and golf courses (provided the golf course is cm integral part of the residential development). The discharge iizust not cause the loss of greater than 1/2 -acre of non -tidal waters of the United States, including the loss of no more than 300 linear feet of stream bed, unless for intermittent and ephemeral stream beds this 300 linear foot limit is waived in writing by the district engineer. This NWP does not authorize discharges into non -tidal wetlands adjacent to tidal waters. Subdivisions: For residential subdivisions, the aggregate total loss of waters of United States authorized by this NWP cannot exceed 1/2 acre. This includes any loss of waters of the United States associated with development of individual subdivision lots. Notification: The permittee inz•ust submit a pre- construction notification to the district engineer prior to commencing the activity. o 1 1 ��'1! CD1- 220 - 0419- L06.docx Page 1 of 2 / Io .4 // Randall's University Park - Replat of Lot 3R -2 NWP Coverage Letter January 6, 2011 r Please do not hesitate to call should you have any questions. Sincerely, /' Ration A. ivietcairl r.E. No. 5 Texas Firm Registration No. F -4695 rabog@rme,igiaecs.com CD1- 220 - 0419- L06.docx Page 2 of 2 Page 1 of 2 Josh Norton - Randall's University Park Replat - Respones to Various Comments made at P &Z Meeting "Hear Citizens" - 2/3 From: "Ration Metcalf' <rabon @rmengineer.com> To: "'Josh Norton !" <Jnorton @cstx.gov >, Mali jaffer "' <aliinksa @yahoo.com> Date: 02/08/2011 8:25 AM Subject: Randall's University Park Replat - Respones to Various Comments made at P &Z Meeting "Hear Citizens" - 2/3 Josh, Below are my responses to comments made during the "Hear Citizens" portion of the 2/3 P &Z meeting. A lot of the comments were non - technical pertaining to integrity of subdivision, student housing vs. single family, noise, crime, property values, two -car garages, etc... These comments do not apply to the current ordinances and though they may be real concerns to the neighborhood HOA's they are not applicable to the technical completeness and adherence of this replat to the City's codes of governance. Therefore, I'm only addressing relevant technical questions. Duplicate comments (i.e. pertaining to drainage) will be addressed only once by the first party that mentioned that specific item. Paul Booth: 1. Comment in regards to floodplain: The current Zone A floodplain is illustrated on the Replat and relevant Construction Drawings. The floodplain, as illustrated on the DFIRM Brazos County website is practically identical to the effective FIRM with only a shift to provide better creek alignment. Regardless of the which floodplain limit is utilized the proposed project's fill and /or drainage improvements will not encroach in mapped floodplain; 2. Stormwater Quality: A SWP3 has been prepared for this project and will be filed with the TCEQ prior to construction activities beginning. Stormwater Quality measures are currently not required by the CoCS; Joe Armond: 1. Earthwork management or placement of the houses relative to the power lines and creek: As illustrated on the Grading & Drainage Plan the proposed residences are placed between the powerline easement and the dedicated drainage easement. Sufficient space exists for the construction and grading required without placement of fill in the creek; John Nichols: 1. The TCEQ Dam Safety Program has some exclusions in regards to the determination of whether a detention facility shall be classified as a dam or not as a dam. This office has not investigated whether this structure is classified as a dam or not, however, it is not the responsibility of the downstream developer to determine this. If this retaining wall structure is classified as a dam then the Probable Maximum Flood (PMF) that must be conveyed by the dam's principle and emergency spillway is determined by it hazard rating (downstream public safety conditions). If this structure is considered as a dam by the TCEQ then its hazard rating would be classified as Small Size w /High Hazard and it would be required to convey 75% of the PMF. This hazard rating does not change whether this development occurs or doesn't occur. Also, if the rating classification did change then it would be the responsibility of the dam owner to insure their structure satisfies the TCEQ Rules & Regulation and not a downstream owner; 2. 900 mm pipe: This actually is a 60" diameter pipe (1525 mm diameter). The drainage study illustrates that it will convey the 100 -year flood. file: / /C:\Documents and Settings \jnorton\Local Settings \Temp\XPgrpwise \4D5OFDECCit... 02/09/2011 ENGINEERING COMMENTS NO. 2 1. Submit revised engineer's cost estimate if applicable. Revised Engineer's Cost Estimate attached; 2. Submit revised fire flow report to incorporate the Fire Department's most recent comments. The changes worked out With the FD where drive oriented only. No revisions to the Fire Flovy report necessary; 3. Submit Letter of Acknowledgement. Attached; 4. Please revise plans per the Fire Department's most recent comments. Revised accordingly; 5. Please include BCS Construction Details. included; 6. Please check sidewalk ramp detail reference, as SW -01 does not correlate. Revised accordingly; 7. Is the existing culvert a 60 inch RCP? Yes; 8. Please reference commercial driveway detail (ST2 -03), instead of ST1 -06, as the driveway is intended as a fire lane. Please label curb return radii. Revised and labeled accordingly; 9. The City recommends the use of RCP in structural areas, the proposed fire lane is certainly considered structural and RCP should be utilized in this application. Per our phone conversations ADS will be acceptable; .. 10. Please provide flow line data for sanitary sewer manhole service connection. Revised accordingly; 11. How much of the existing vegetation on the tract is proposed to remain undisturbed? Is there extensive grading proposed in the "drainage easement area "? It is difficult to • determine this based on the grading plan? Areas that will be disturbed in the private drainage easement is as follows: v 9 Extension of 60' Culv © Water sanitary sewer service crossings; 12. Does the area inlet referenced on GP -01 and MD -01 correlate? Revised accordingly; 13. Please provide a blow up in plan and profile of the proposed detention area being created. Revised accordingly; 14. Please call me to discuss the drainage report and calculations. Comments addressed per our phone conversations; Reviewed by: Josh Norton Date: December 20, 2010 • .A(pi �,�. 1 W. Ig - ` --- Planning Development Services rte` � �, 1101 Texas Avenue, P.O. Box 9960 ry College Station, Texas 77842 Cu C)1' Col .i a .G� . STnTic �n Phone 979.764.3570 / Fax 979.764.3496 Home of Texas A&M Univenh " MEMORANDUM • 12/10/10 TO: Rabon Metcalf via email: rabon@rrnenqineer.com rmenc;ineer.cam FROM: Matthew Hilgemeier, Staff Planner SUBJECT: RANDALL UNIVERSITY PARK L3R2 (REPLAT FP) - Final Plat Staff reviewed the above - mentioned final plat as requested. The following page is a list of staff review comments detailing items that need to be addressed. If all comments have been addressed and the following information submitted by Monday, December 12, 2010, 10:00 a.m., your project will be placed on the next available Planning and Zoning Commission meeting scheduled for January 6, 2010, 7:00 p.m. in the City Hall Council Chambers, 1101 Texas Avenue. X One (1) 24 "x36" copy of the revised final plat; X Nineteen (19) 11 "x17" copies of the revised final plat; Ok Parkland Dedication in the amount of $ 10,105.00 must be submitted prior to the filing of the final plat; Ok One (1) Mylar original of the revised final plat (required after P &Z approval); and Ok One (1) copy of the digital file of the final plat on diskette or e -mail to: P &DS_Digital_Submittal ©cstx.gov. Upon receipt of the required documents for the Planning & Zoning meeting, your project will be considered formally filed with the City of College Station. Please note that if all comments have not been addressed your project will not be scheduled for a Planning & Zoning Commission meeting. Your project may be placed on a future agenda once all the revisions have been made and the appropriate fees paid. Once your item has been scheduled for the P &Z meeting, the agenda and staff report can be accessed at the following web site on Monday the week of the P &Z meeting. http://www.cstx.gov/pz Please note that a Mylar original of the revised final plat will be required after P &Z approval and prior to the filing of the plat. If you have any questions or need additional information, please call me at 979.764.3570. Attachments: Staff review comments cc: Case file #10- 00500267 NOTE: Any changes made to the plans, that have not been requested by the City of College Station, must be explained in your next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that have not been pointed out to the City, will constitute a completely new review. 1 of 4 STAFF REVIEW COMMENTS NO. 1 Project: RANDALL UNIVERSITY PARK L3R2 (REPLAT FP) - 10- 00500267 PLANNING 1) Please show and label Cooner Street on the platting document. Revised accordingly. 2) Please locate the adjacent property information on the respective properties. It is a little confusing with the information in the current location. Revised accordingly. 3) Please add a 20 -foot P.U.E. along the rear property lines which boarder -the City of Bryan. Revised accordingly. 4) Please note that any changes made to the plans, that have not been requested by the City of College Station, must be explained in your next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that the City has not been made aware of will constitute a completely new review. Adjustments to five (5) lot sizes. 5) Please note that you may be required to submit paid tax certificates if they are not current prior to the filing of your plat. Understood. 6) The construction documents and reports are still under review and may affect the plat. Understood. 7) Please be aware that each lot will be required to provide a minimum of two (2) trees of at least two inches (2 ") in caliper or one (1) tree of four -inch (4 ") caliper per Ordinance No. 3222. See Final Plat Note -r. Reviewed by: Matthew Hilgemeier, Staff Planner Date: December 8, 2010 ENGINEERING COMMENTS NO. 1 Please submit all required engineering documents and reports as required with t Development Permit Application submittal. Attached with this submittal. Please verify that all proposed /existing culverts have appropriate end treatments d erosion control measures. See Construction DravVlogs, sheet GP-01. Existing sidewalk along Chimney Hill should be extended to connect to proposed subdivision entrance, beyond this point will be considered cul -de -sac. See 'Construction Drawings, sheet GP-01. :Please verify and place a note on the plans that no sanitary sewer service will be left more than 3.5 feet deep at the point of terminus by developer's contractor. Se Plan • Note r5 on Construction Drawings, sheet U-01. Please verify and place note on plans that water services will be left between 2 and 3 feet deep at the point of terminus by developer's contractor. Also note that a ball valve is required at the point of terminus. See Plan Note ' 4 on Construction Dr a.v, it gs, sheet e: PI provide 'note the maintenance an e r sibil s i pease N ivviuc a iiC1�2 explaining the and ownership responsibilities of the "Variable Width Private Cross Access Easement ". The (0000 /000) can be removed as the easement can be dedicated with this document. Understood. see Final Plat Note `0. Please provide a private drainage easement thru the site for the conveyance storm. water from the upstream "Randal's" detention facility as well as the proposed detention facility. Revised accordingly. Please provide a note explaining the maintenance and ownership responsibilities of the "Private Drainage Easement ". See Final Plat Note `0. NOTE: Any changes made to the plans, that have not been requested by the City of College Station, must be explained in your next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that have not been pointed out to the City, will constitute a completely new review. 2 of 4 Please contact and provide correspondence from United States Postal Service concerning mail service for the proposed subdivision: Understood. a. Frank Borroni frank.e.borroni(?usQs.dov 979- 693 -4152 Reviewed by: Josh Norton Date: December 9, 2010 ELECTRICAL COMMENTS REQUIRING IMMEDIATE ATTENTION 1. Developer provides temporary blanket easement for construction purposes or provides descriptive easements for electric infrastructure as designed by CSU for electric lines (where applicable, including street lights) 2. Developer may be responsible for locating easements on site to insure that electrical infrastructure is installed within easement boundaries. 3. If applicable, the following easements will be required: 5' PUE on each side of interior lot lines in case of needed extension for electrical and other utilities. GENERAL ELECTRICAL COMMENTS 1. Developer installs conduit per CSU specs and design. 2. CSU will provide drawings for electrical installation. 3. Developer provides 30' of rigid or IMC conduit for riser poles. CSU installs riser. 4. Developer will intercept existing conduit at designated transformers or other existing devices and extend as required. 5. If conduit does not exist at designated transformer or other existing devices, developer will furnish and install conduit as shown on CSU electrical layout. 6. Developer pours electric device pads or footings (i.e. transformers, pull boxes etc) per CSU specs and design. 7. Developer installs pull boxes and secondary pedestals per CSU specs and design (pull boxes and secondary pedestals provided by CSU). 8. Developer provides digital AutoCAD 2000 or later version of plat and 1 or site plan. Email to: wdavis @cstx.gov or ehorton @cstx.gov. 9. Developer provides load data to CSU as soon as it is available to avoid construction delays. Delivery time for transformers not in stock is approximately 40 weeks. 10. Final site plan must show ail proposed electrical facilities necessary to provide electrical service, i.e. transformer(s), pull box(es), switchgear(s), meter location and conduit routing as designed by CSU. 11. To discuss any of the above electrical comments please contact Weldon Davis at 979.764.5027. Reviewed by: Weldon Davis Date: 12.9.10 SANITATION NOTE: Any changes made to the plans, that have not been requested by the City of College Station, must be explained in your next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that have not been pointed out to the City, will constitute a completely new review. 3 of 4 1. Sanitation is ok with this project. Reviewed by: Wally Urrutia Date: December 8, 2010 NOTE: Any changes made to the plans, that have not been requested by the City of College Station, must be explained in your next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that have not been pointed out to the City, will constitute a completely new review. 4 of 4 • 445 Chimney Hill Drive College Station, Texas 77840 -5800 13 February 2011 Mayor N. Berry City of College Station University Drive College Station, TX 77840 Dear Mayor Berry: I am writing today about the proposed development within the Chimney Hill Creek corridor. It is proposed to replat an area on the northern side of Albertsons'. In order to simplify matters I have called the creek Chimney Hill. I am writing this letter for two purposes: 1. To object to the development on the grounds of safety for the people who live in the Chimney Hill Creek corridor, because of the proposed changes brought by the development as it is immediately downstream of a dam. This dam should be reviewed by the TCEQ to determine if it is a notifiable dam, within the meaning of the relevant statute, it is a high hazard dam within the meaning of the TCEQ guidelines. 2. As a Chartered Corporate Member of the Institution of Engineers, Australia as part of my ethical responsibilities under Section 4 of the organizations code of ethics. These qualifications are recognized in the USA under the Washington Accord. The relevant section of the code of ethics is: 4. Promote sustainability 4.1 Engage responsibly with the community and other stakeholders a) be sensitive to public concerns b) inform employers or clients of the likely consequences of proposed activities on the community and the environment c) promote the involvement of all stakeholders and the community in decisions and processes that may impact upon them and the environment 4.2 Practise engineering to foster the health, safety and wellbeing of the community and the environment a) incorporate social, cultural, health, safety, environmental and economic considerations into the engineering task 4.3 Balance the needs of the present with the needs of future generations a) in identifying sustainable outcomes consider all options in terms of their economic, environmental and social consequences b) aim to deliver outcomes that do not compromise the ability of future life to enjoy the same or better environment, health, wellbeing and safety as currently enjoyed. I am raising the issue of safety associated with the drainage system that has been developed in the Chimney Hill Creek Catchment within your city as an engineer with expertise in drainage design of this type. I do not practice in Texas, but under my code of ethics I am bound to now draw this matter to the attention of the relevant authority. The areas of specific concern or issues are: _ 1. A set of two dams has been created within the Chimney Hill Creek Catchment that I am of the opinion should be referred to the Texas Commission on Environmental Quality for review now that houses are to be located within the immediate downstream vicinity of the spillway and the emergency egress for the residents is across the spillway area. Recent deaths in Toowoomba in Australia and US marines in Japan point to the folly of developing in these types of urban drainage systems. 2. The spillway design fails to conform to the requirements set out in the TCEQ manual and fails to conform to what would be considered normal accepted practice for the discharge point on a dam immediately upstream of residential housing. No notification system is in place if the dam fails, where new houses will be located immediately below the dam wall. This is,far from normal, when we consider that upward of 24 people will live in this situation. 3. A dam design, such as this one, is always undertaken using three flow criteria and other criteria: a. 1 in 5 to 1 in 25 years b. 1 in 100 years or what is termed an Act of God level in normal engineering design, but here is just one of the considered design flows c. Probable maximum flow which in this area of Texas is between 4 and 5 times the 1 in 100 year flow. d. Such other criteria as determined by the competent authority, in this case the analysis that follows provides a standard of 75% of probably maximum flow for Texas , which for the purposes of this letter is assumed to be 4 times the 1 in 100 year flow, as required it would appear from the TCEQ manual issue 1 Dam Safety TCEQ Requirements are: 299.11. General. The executive director shall evaluate the hydrologic, hydraulic, and structural adequacy of the dam in determining whether a proposed or existing dam is considered a deficient dam. (1) The executive director shall evaluate the hydrologic and hydraulic adequacy of the dam and spillways using the criteria in the most current version, at the time of the evaluation, of the agency's Hydrologic and Hydraulic Guidelines for Dams in Texas. (2) The executive director may also take into consideration the condition of the dam, including the possibility that the dam might be endangered by: (A) overtopping; (B) seepage; (C) piping; (D) settlement; (E) erosion; (F) cracking; (G) sinkholes; (H) earth movement; (I) uplift; (J) overturning; (K) failure of gates or operation of gates; (L) failure of spillways; (M) failure of conduits; or (N) other conditions, as appropriate. (a)The executive director shall classify all proposed and existi, intermediate, or large) and downstream hazard (low, signific physical condition of the dam. (b) The executive director may reclassify the hazard classification of a dam at any time based on: (1) an inspection and downstream hazard evaluation by the executive director; (2) a report of an inspection and downstream hazard evaluation by the owner's professional engineer; (3) a breach analysis performed by either the executive director or the owner's professional engineer as described in §299.15(a)(4)(A)(i) of this title (relating to Hydrologic and Hydraulic Criteria for Dams); or (4) a review of current aerial photography and topographic maps, along with information obtained in the field In terms of the size criteria set out in the TCEQ manual, the major dam in the Chimney Hill Catchment would fall into the small category considered by the TCEQ in terms of depth and potential loss of life. There is an automatic consideration if the dam is over 10 feet high and 50 acre feet in volume. The dam is over 10 feet in height, it would require a detailed hydraulic analysis using a program such as HEC -HMS 3.5 to determine the impoundment volume in a PMF storm, however a preliminary review using the available of the volume within the two linked western impoundment areas suggests that this question will only be answered with a full analysis completed in accordance with the requirements of the TCEQ. I think it is safe to assume until evidence is provided that the total impoundment volume is less than 5o acre ft. that it is assumed to be greater than 50 acre feet for an initial consideration. At that level of impoundment it is an automatic referral to the TCEQ. The second consideration is the hazard presented by the dam, as set out in the TCEQ manual as follows: 299.14. Hazard Classification Criteria. The executive director shall classify dams for hazard based on either potential loss of human life or property damage, in the event of failure or malfunction of the dam or appurtenant structures, within affected developments, that are existing at the time of the classification. The hazard classification may include use of a breach analysis that addresses the incremental impact of the potential breach over and above the impact of the flood that may have caused the breach, as defined in §299.15(a)(4)(A)(i) of this title (relating to Hydrologic and Hydraulic Criteria for Dams). The classification must be according to the following. (1) Low. A dam in the low- hazard potential category has: (A) no loss of human life expected (no permanent habitable structures in the breach inundation area downstream of the dam); and (B) minimal economic loss (located primarily in rural areas where failure may damage occasional farm buildings, limited agricultural improvements, and minor highways as defined in §299.2(38) of this title (relating to Definitions)). (2) Significant. A dam in the significant- hazard potential category has: (A) loss of human life possible (one to six lives or one or two habitable structures in the breach inundation area downstream of the dam); or (B) appreciable economic loss, located primarily in rural areas where failure may cause: (1) damage to isolated homes; (11) damage to secondary highways as defined in §299.2(58); NO damage to minor railroads; or (iv) interruption of service or use of public utilities, including the design purpose of the utility. (3) High. A dam in the high - hazard potential category has: (A) loss of life expected (seven or more lives or three or more habitable structures in the breach inundation area downstream of the dam); or (B) excessive economic loss, located primarily in or near urban areas where failure would be expected to cause extensive damage to: Texas Commission on Environmental Quality Page 4 Chapter 299 - Dams and Reservoirs (i) public facilities; (11) agricultural, industrial, or commercial facilities; (iii) public utilities, including the design purpose of the utility; (iv) main highways as defined in §299.2(33); or (v) railroads used as a major transportation system The dam will fit into the high hazard category as the potential loss of life is, for all those who will live below the dam wall, is in excess of the number 7 set out in the manual. The economic loss from the death of the 24 people who will live in the damage breach inundation zone is in the order of $140 million using the US government standards for value of life. A detailed breach analysis is required to determine the flooded area and also to consider if these people can be evacuated safely. As the dam is in excess of 10 feet, is located in an urban area and has more than seven people in the potential breach area of the dam wall that may be subject to significant and immediate flooding with failure of the wall, then this matter appears to fall within the statutory approval of the Executive Director of the TCEQ and not Council engineers or the Planning and Zoning Commission of the City Council. The executive director of the TCEQ has the power to declare the dam as acceptable, but given the future high hazard potential this is an issue that the executive director of the TCEQ should decide after reviewing the facts and analysis. I have not been supplied with any information that gives me any assurance that this analysis has been completed at this date. Issue 2 Spillway Design A normal spillway design for a dam such as this is not by overtopping the dam wall, which will drop clean water onto the foot of the dam, leading to potential white water scour and failure of the dam. This has occurred on other darns. Figure 1 shows a picture of the dam wall and the surrounding area. Figure 1 shows the rear of the Albertson's store, which is clearly located on fill, probably obtained from the excavation for their front parking lot. A low earth wall separates the two impoundment areas for this dam arrangement, but it is likely to be lost in a PMF storm given the volumes and slopes involved. Clearly this problem should be addressed in a full hydraulic analysis. . ? . . . •• ,.. , .., •,•. .;- 1. j A . - :).-4.!.. rt-?._.,*"42::A4z. _ -,7 `` ..-,,,-3-.,=4.:;-3-...:- � ' .1, c ' . 4gyp.' Y t,.,,i k. tk t y }.yai . � � a-: , • ) t ,n om`' s - : _ -*X -.. - ` ' 't�:'^ r . '-'[�- _ {clt' Y rt • ' � S ¢i i "r - . r E y i ,� ' .. ,4- 4 � i' ;= , �� t, , , r`r 3 -9d ��� k Y , z-, s S F.. ke, s8 '` .e- c,�a � .m ;� a, le-te ` -t- Ri t e -- - -t . ,,�g ? i ' l i r�7 ' .4 14, C4A9?r, v,., d ry ` ` ,6,0, w 1.. l . , t " �' C " '^73'' .� ,�`��,' e " w c+. ' s� ., V'`' -tea etty: ` ` " x. 'f "' ' .7, 5x-. ! 9 s ..�., . ' ". a 3- r- -'€'.t+ ¢ 4 'hc ,. ti r s a 7 Y " s r r # sr ck x4 7 y 7 L r +x a+ -n 7 - ... .-a+ � x ' , ref r .r ,*, j . 'v f t Vie -O _,:- C y 1 ; .+ Figure 1 Major D am W all and Surrounding Area —north we side of Alberton's' There are houses lower than where I am standing on the right hand side within the creek area. The arrangement of the p system from the Albertson's second dam, located on the left hand side of this photograph, (Figure2), flows into the major dam at the outlet arrangement. • • • PMF analysis as is required by TECQ guidelines. As a minimum the TECQ letter setting out an exemption should be included in any report that contains council's standard closure statement on responsibilities and actions. Issue 3 Capacity Calculations Council guidelines provide some standards for determination of the flood flows, but do not completely cover this type of system subject to design flows in excess of the 1 in 100 year event. In the brief time available to review this matter the following information was available or could be easily determined from available literature and mapping. The Executive Director of the TECQ can require a full report prepared by an engineer registered in the State of Texas with dam design skills. This letter merely draws attention to the significant issues in the catchment and asks as to the status of this analysis now that the dam will fall into the high hazard category if the replat is allowed. Figure 5 shows the pre - existing catchment from a late 1970's topographic map. ' / ' Chirnney Hui Dam site y � F Albertson 's 1 y r te , 1 {'7: Sr } c g • r s • - s .� r`'� r _�e. .'� T $ ..; - e q n 3 : L ��' \h• i r L yl e D 4 b , rv \ \f x. 57 1 CA\4 Figure 5 Pre - existing Catchment from a late 1970s plan Figure 6 shows the current catchment with an overlay of a set of the distinct catchment areas that drain to Chimney Hill Creek. This data is shown on a base map obtained from the City of College . Station's GIS data set of contours. The contour interval is 2 feet. ty \ { mot > '' \.'s - `\ xit% r :, ,-- ,\, ` . At I� 1 ,-,/ R. � . . irf�� ; 'r r ,` t , \�, �� ! � r , \ lam 'if y � t f - `� � ", fy^R �•yR py v F{-{' 4 f ` [ p �` - -, 1 \- � , I. r r' - - j ' ,..r� . --- - ^ . , y { ''-„ EF�mne f II�E Cree f -` ,� �t \ t j YY � jib \t l i � - . ' - Y C e -- �.. � �� [ \�. • - • - - - . -=‘" - ' ls Z ., ,•--"=" , ''% ,•.--" / ( ,."-- t. -% \ ; 4 ? .'` '"" � ,' 1 L T �,- 1 e .1a t , `, 4� h � 4 r t } � 1 3 ! m Lower \ �' - ' it e -> ` � t y � \ .t ,' f t 4J t , f r mi l } , r3' I \ A rt •� j ' Dare - Upper , \N1 , 1} 1- +r J,,s'r c- r d t ( I .ti \ SC 'v'. f c . e tc S r . j, . ,._ . ' } , `i. f -.__ -f • 5 % 1 C I : \ t _ ti , `� �_,'. '� - s. �1� +! f ' fr f�_ ^. (f E f i \ n i ? .` 4 i ,,—..k r c! \ i �f r i �-r_ ) � . ‹ � • . - r S.-I,' c , , r' t. � =, _ Lis i r f f 1 \ ., 5 S r, r - ..� R S � , , - c `-i .1;'> /4, ;-• • ..c r,.. .rr'.. - 1 i Figure 6 Current Catchments and Dams • The catchment model developed for the analysis is shown in Figure 6. Time did not permit me to complete a HEC- HMS3.5 analysis. A simple analysis used to establish some of the parameters for a complete analysis is shown below. The analysis of the predevelopment flow at the outlet to the catchment at the Bryan City limits is shown in Table 1. I have assumed that e PMF - ev&tt'wi II occur in a period of sustained rainfall and depression storage will be limited and ground inflow capacity • similarly low. This is a reasonable first approximation. I have left the flows as total volumes assuming a linear rise. Figure 7 shows the catchments boundaries in my simple analysis, the dam location and Albertson's. The assumed north for the analysis is up the page. Table 1 Approximate Flow in Catchment at outlet Description Number Units • Area 89 Acres Time of Concentration 30 minutes Rainfall intensity (100 yr) 7 Inches per hour Rainfall Intensity - PMF 28 Inches per hour Total Flow Volume —100 yr . (7/12) *89 * 0.5 4 Acre feet Total Flow Volume —100 yr 26 Acre -feet Total Flow Volume - PMF (28/12) *89 *0.5 Acre -feet , Total Flow Volume - PMF 102 Acre -feet -- t r „ r fi r r A c 2 7 r f 1ti'i 8 GCS . 11 x'i Area 2: \re,, 19 Dam — lower _ _ rese3 2 ' Area i& \ • Dam — upper tI . ?� _ _ F :Area 21e € , . j r \-.1.„ c t - 21 Aft-, 17 . y (! ? at E .: Y N: r I �i f?sl 42 \ r rr vo ^ ' 'y - ,.„ . .f;c- 7: - .. .67e.4v ,.. - - : .. ..-7 - ' -, 2,.. Ae..:r.: ' : "'"-: ',/'.... \-- 1: 2:::::: W-41 . ''N's Albertson's '6, r \ -- t.:. � ` t , s � = . � ,` � ~; Figure 7 Current catchments • 'Assuming no change in time of concentration, some authorities would reduce the time of concentration. 2 Feet 3 Land area in acres 4 Total flow duration in hours may have this approval, but there is no evidence of this approval in the documentation I have seen to date. I will be suggesting to the Homeowners Association that they request this documentation. I appreciate this is a difficult matter, but it not of our making, but comes about from decisions made before our time of involvement. I am also aware of the tragedy of the loss of life in floods, that are usually preventable, having been involved in several matters on drainage that were subject to litigation. I will suggest to the Home Owners Association that they request a meeting with the Director and you at your earliest convenience. Whilst I understand you have recused yourself from the replat, I consider that you need to be involved in the discussions on the dam, as until this is resolved I fail to • see.how the matter can be considered by Council at this time. Yours faithfully Digitally signed by John Nichols - DN: cn =John Nichols, o, ou, J o h n email= jm.nichols1956 @gmail.com, Date: 2011.02.16 13:26:28 - 06'00' John Nichols, BE, PhD, MIE(Australia), Chartered Professional Engineer Dr. John M. Nichols 445 Chimney Hill Drive College Station Texas 77840-5800 30 December 2010 The Mayor City of College Station 1101 Texas Avenue College Station Texas Dear Mayor Berry: I normally do not become involved in local politics because of my prior work for local government authorities for inanyyears on drainage, planning and transportation matters. Since 1 moved with my family to College Station in 2002 I have only corresponded with the Mayor on a single occasion about a development issue in Chimney Hill. The previous letter concerned the rezoning application for a block of land at the end of Chimney Hill, which occurred I believe in the last two years. i assume that my previous letter on this matter is available to you, so that 1 do not have to repeat all of the calculations and observations about this matter. In my previous fetter, I raised a number of matters about the drainage for this land at the western end of Chimney Hill Drive, which is a part of the general drainage system for the area immediately upstream of the proposed development of land, I have reviewed the current application information available and again raise the following concerns about this property: 1. As a home owner I am situated about 60 metres from the land in question. In all the time this applicant has tried to rezone the property, the applicant has never made any attempt to contact either myself or I believe our home owners associations. Considering the severity of the concerns I raised about the drainage in my last letter, and given the distinctive change in nature of the proposed development from the current character of the area, one would assume that good planning practice would be to sit down with the local population to listen to their concerns. A second point is to address the planning issues in advance not in arrears. 2. The plan forwarded by Council shows a purported 100 year flood line. 3. A watercourse flows through this proposed development site, and in the strict legal sense this unnamed watercourse is defined in accordance with the common law definition of a watercourse, being bed, banks and water. This watercourse meets these criteria, as I have never observed the watercourse dry. A watercourse is by definition in the 100 year flood plain, as the 100 year flood plain concept was developed to overcome the limitations of the common law. I would refer you to Howarth's book and Angel's book on this matter, which as far as I understand from my time in courts on these types of matters are the definitive tracts. . 4. A significant portion of this land is below the legal definition for a 100 year flood plain and as such should be excluded from development. 5_ At some point, before 1 arrived in College Station, a detention basin was erected at the immediate upstream end of the subject property. The detention basin has: a. Dangerous side slopes, much steeper than is normally allowed for in this type of design b. A depth well past the drowning level for young children, which again is a problem if one considers that we should be designing to accepted standards c. An outlet that has a strong potential for white water scour and is not designed for child safety. White water scour is a particularly nasty form of erosion that occurs in large storm events at the downstream end of hydraulic structures, such as is constructed in reinforced concrete at the western end of Chimney Hill. d. This type of scour has the potential to undermine the wall, with serious consequences for all downstream. e. Excessive velocities and depths at the outlet, given its position next to a park area, again well outside accepted standards f, This is not the only location in College Station that has hydraulic structures that present a clear and present danger to children, the elderly and the sick. 6. The drainage system needs to be designed for the lots before the land is subdivided so that Council has obtained sufficient land for the works. The cost for an acceptable drainage system will be significantly greater than the return on the land. I have completed many of these cost studies, and would never have recommended that any of my clients touch such a block of land. In the end, it would appear that the land owner will learn the true cost of the drainage system and will either not proceed or assume that council will ultimately bear the cost. l fail to see why the citizens of College Station should accept a liability that will run to at least six figures. It would be cheaper to purchase the lot and turn it into parkland — detention basin, serving the community. (would suggest that the matter be deferred until these issues can be addressed. I also suggest that the applicant meet with the local associations to try and understand their perspective. • Yours faithfully b \v.) John Nichols, BE, MIE(Aust), Chartered Iirofessional Engineer Drainage Study FOR RANDALL'S UNIVERSITY PARK Lots 3R2 -A thru 3R2 -E College Station Brazos County, Texas December 13, 2010 Revision No. 1— January 6, 2011 Revision No. 2 — February 9, 2011 *. 1 � . * �i 4.0g ,; . a. - o� F /' o,�'•�!C ?•'$r kt S/ONAL - --- I; \ I \ Prepared For: Marcelino Diaz Barrera 1221 University Drive East College Station, TX 77840 Prepared By: RME Consulting Engineers 7607 Eastmark Drive, Suite 252A <77840> P.O. Box 9253 College Station, TX 77845 Texas Firm Registration No. F -4695 RME No. 220 -0419 1 t \ 0 GP LIST OF TABLES: PAGE Section 3.0 — Hydrologic Modeling Table #1: T Overland Sheet Flow 6 Table #2: Tt2 - Shallow and/or Concentrated Flow 6 Table #3: Tc Summary 6 Table #4: Drainage Basin Runoff Quantities 7 Section 4.0 — Detention Facility Routing Table #5: Detention Facility Routing 10 Section 5.0 — Storm Drainage System Table #6: Culvert Summary 11 4 220 -0419 Drainage Report-Rev2 Page - ii ATTACHMENTS: Section 1.0 — General Information Replat Vicinity Map FIRM Panel Map Section 2.0 — Watersheds & Drainage Areas Lick Creek Watershed Area Existing Conditions Drainage Area Map Proposed Conditions Drainage Area Map Section 3.0 — Hydrologic Modeling HydroCAD — Existing Conditions Drainage Calculations HydroCAD — Proposed Conditions Drainage Calculations Randall's University Park — Stormwater Drainage Analysis Section 4.0 — Detention Facility & Routing GP -01: Paving, Grading & Drainage Plan HydroCAD — Proposed Conditions Pond Routing Calculations — Pond 1 Section 5.0 — Storm Drainage System THYSYS — Hydraulic Computations 220 -0419 Drainage Report-Rev2 Page - iii Drainage Study — Rev. No. 2 RA NDALL' S IJNEVERSITY PARK Lots 3R -A thru 3R -E College Station Brazos County, Texas 1.0 GENERAL INFORMATION 1.1 Scope of Report: This report addresses the existing conditions and proposed drainage improvements for the replat of Lots 3R -A thru 3R -E of the Randall's University Park Subdivision. This drainage study's scope will analyze the proposed detention facility design methods and proposed configurations, and the internal storm drainage system improvements designed for the development. All drainage system improvements (i.e. on -site detention facilities, stoma sewer, etc...) will be designed to accommodate the anticipated proposed/ultimate development conditions. The proposed development and drainage improvements are designed and analyzed in accordance with the criteria outlined in the "Unified Stormwater Design Guidelines" (USDG) manual of the City of College Station (CoCS). 1.2 Site and General Location: The replat development of Lot 3R -2 of the Randall's University Park Subdivision consists of 3.37 acres of land consisting of five (5) residential lots with the construction of their associated improvements of paving, drainage, and utilities. The existing and proposed conditions of this development is depicted on the Replat which is provided in the "Attachment — Section 1.0" portion of this report. Lot 3R -2 of the Randall's University Park Subdivision has access to Chimney Hill Drive along its southeast property line. Developments adjacent to these lots, to the west and east, are single - family residential (Beverly Estates and the Cooner Addition), property to the north is the CoCS Billie Madely Park, and to the south is the commercial development that occupies the Albertson's shopping center. A Vicinity Map, for this project site, is provided and is located in the "Attachment — Section 1.0" portion of this manual. This map is being provided as an aid in locating the site. Drawings describing the work and its specific locations are contained in the Construction Drawings prepared by RME Consulting Engineers, College Station, Brazos County, TX. These Construction Drawings are included as part of this Drainage Report by reference. 1.3 Description of Existing Conditions and Drainage Patterns: The 3.37 acres of land, which contains the proposed development, is a well sloping (approximately 7.0 %) substantially undeveloped site with natural overland drainage that 220 -0419 Drainage Report-Rev2 Page -1 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 conveys runoff to a secondary drainage system of Burton Creek. This secondary system consist of a natural drainage channel that collects runoff from the upstream commercial development of the Albertson's Shopping Center and drains to the northeast. Runoff collected to this point is conveyed in a 60" diameter storm sewer pipe, and then is further conveyed through the secondary tributary to Burton Creek. The subject development area is primarily an unimproved area with some thick brush, weeds, and trees along the secondary tributary. Elevations range on the site from approximately 296' Mean Sea Level (MSL) to approximately 326' MSL. The Brazos County soil maps indicate that this area is comprised of Type C and D soils which consist of clays or silty clay /sand mixtures. Both pre -and post - runoff from the subject development will drain in a northeasterly direction through the secondary drainage channel and then through the proposed drainage structures or detention facility. Runoff is then discharged into the unnamed drainage channel. Eventually the unnamed tributary discharges into Burton Creek, thence to Carters Creek, thence to the Navasota River, thence to the Brazos River and ultimately to the Gulf of Mexico. 1.4 FEMA Information: A small portion of the subject development lies within mapped 100 -year floodplain as graphically depicted by the Federal Emergency Management Agency (FEMA) — Flood Insurance Rate Map (FIRM) Community /Panel number 480083 0142C, with an effective date of July 2, 1992. A portion of this FIRM Panel Map is located in the "Attachment — Section 1.0" section of the Drainage Report. 2.0 WATERSHEDS & DRAINAGE AREAS 2.1 Detention Facility Watersheds (Existing Conditions): As previously discussed, the subject development area is located within a watershed of an unnamed tributary that drains into the Burton Creek Watershed Area. An exhibit of this watershed is taken from the USDG manual with the subject area identified and is entitled as previously mentioned and has been included in the "Attachment — Section 2.0" appendix of the report. Since this drainage study will include the hydrologic/hydraulic modeling of one (1) detention facility, an appropriate drainage area map called the Existing Conditions Drainage Area Map (which is located in the "Attachment — Section 2.0" portion of the Drainage Report), was developed for considerations of existing runoff patterns and analysis and is described as follows. Drainage Area "X" — This drainage area is approximately 3.62 acres and will consist of the proposed development area and upstream contributing areas, at pre- development or existing conditions. At the downstream limit of this drainage area is the secondary unnamed tributary of Burton Creek. Analysis of this drainage area will provide runoff characteristics for the appropriate portion of the subject development at its current existing conditions. This runoff data will be the "benchmark" data for the respective 220 -0419 Drainage Report-Rev2 Page - 2 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 post - development area analysis so that increased runoff can be measured and appropriately detained. 2.2 Detention Facility Watersheds (Proposed Conditions): For post - development conditions three (3) individual drainage basins were considered and analyzed and are as follows. The Proposed Conditions Drainage Area Map illustrates these drainage areas and is located in the "Attachment — Section 2.0" section of the Drainage Study. Drainage Area Map "P" — This drainage area consists of Drainage Area "X" and additional watershed area that will discharge to the unnamed tributary of Burton Creek. The comprised total of this watershed will be 8.96 acres. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions. The hydrologic data generated from this drainage area will be utilized to hydraulically size the proposed culvert structure (in addition to the discharge calculated from the Albertsons detention facility); Drainage Area Map "P1" — This drainage area consists of an area within Drainage Area "X" and comprises 0.96 acres of land. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions. The hydrologic data generated from this drainage area will drain into Pond 1, routed through the detention facility and discharged into the existing unnamed tributary of Burton Creek via this project's storm sewer system. Ultimately, routed flows, combined with flows from undetained flows from Drainage Area "P2 ", will be compared to the runoff values generated from Drainage Area "X "; Drainage Area Map "P2" — This drainage area consists of an area within Drainage Area "X" and comprises 2.73 acres of land. Proposed runoff conditions from this drainage area will be evaluated at the anticipated development conditions and released from the site undetained; 3.0 HYDROLOGIC MODELING 3.1 Rational Formula and Methodology: The Rational Method (Q =CIA) is one of the more frequently used methods to determine the peak runoff from a watershed and is typically reliable for small watersheds (< 50 acres). The Rational Method generates hydrologic data based on drainage area geometries, surface conditions, and rainfall intensities. The Rational Method will be employed to determine the sizes of watershed's runoff values for the sub - drainage areas, detention systems, and for the internal storm drain systems, and it is explained further as: Q = CIA where, Q = peak runoff rate (cubic feet per second); 220 -0419 Drainage Report-Rev2 Page - 3 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 C = runoff coefficient — This represents the average runoff characteristics of the land cover within the drainage area and is a dimensionless coefficient. Runoff coefficients are interpolated from either Table C -2 or C -3 of the USDG; I = average rainfall intensity (in/hr); A = area of land that contributes stormwater runoff to the area of study (acres); 3.2 Rainfall Intensity "I": Rainfall intensities (I) are the average rate of rainfall in inches per hour for a given rainfall event. The duration of "I" is assumed to occur at the computed Time -of- Concentration for each respective drainage basin. Rainfall intensities can be determined by use of intensity- duration - frequency (IDF) curves or from intensity equations which are provided in the TxDOT Hydraulic Manual. 3.3 Weighted Runoff Coefficient "C ": The runoff coefficient (C) for various sub - drainage basins was estimated from the USDG, Table C -2 and C -3 by comparison of runoff surface types to percentage of land coverage and total drainage area. The pre - construction runoff coefficient "C" for the proposed development area is approximated to be 0.41. This coefficient was determined by calculating the weighted average of the runoff coefficient for the different surfaces types. Calculations for the coefficient are as follows: Drainage Area "X" Runoff Coefficient "CwTD ": 2.01 Acres — Undeveloped (Pasture Areas) -› "C" = 0.35; 0.63 Acres — Undeveloped (Woodland Areas) - "C" = 0.40; 0.98 Acres — Single - Family Residential -) "C" = 0.55; Pre - construction runoff coefficient - "CwTD" (0.35 *2.01)/3.62 + (0.40 *0.63)/3.62 + (0.55 *0.98)/3.62 - "CwTD" = 0.41 The post - construction runoff coefficient "C" for the proposed development areas are as illustrated below. These coefficients were determined by calculating the weighted average of the runoff coefficient for the different surfaces types. Calculations for the coefficients are as follows: Drainage. Area "P" Runoff Coefficient "CwTD ": 1.31 Acres — Undeveloped (Pasture Areas) 4 "C" = 0.35; 0.72 Acres — Undeveloped (Woodland Areas) "C" = 0.40; 0.41 Acres — Sodded Yard --> "C" = 0.42; 1.55 Acres — Single - Family Residential -› "C" = 0.55; 4.97 Acres — Commercial /Impervious -) "C" = 0.90; Pre - construction runoff coefficient - "CwTD" (0.35 *1.31)/8.96 + (0.40 *0.72)/8.96 + (0.42 *0.41)/8.96 + (0.55 *1.55)/8.96 + (0.90 *4.97)/8.96 -) "CwTD" = 0.70 220 -0419 Drainage Report-Rev2 Page - 4 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 Drainage Area "P1" Runoff Coefficient "C ": 0.26 Acres — Undeveloped (Pasture Areas) -4 "C" = 0.35; 0.36 Acres — Undeveloped (Woodland Areas) 4 "C" = 0.40; 0.21 Acres — Sodded Yard -› "C" = 0.42; 0.13 Acres — Commercial/Impervious - "C" = 0.90; Pre - construction runoff coefficient 4 "Cwm" (0.35 *0.26)/0.96 + (0.40 *0.36)/0.96 + (0.42 *0.21)/0.96 + (0.90 *0.13)/0.96 -* "C = 0.46 Drainage Area "P2" Runoff Coefficient "C ": 1.05 Acres — Undeveloped (Pasture Areas) -) "C" = 0.35; 0.36 Acres — Undeveloped (Woodland Areas) - "C" = 0.40; 0.20 Acres — Sodded Yard - "C" = 0.42; 0.96 Acres — Single- Family Residential "C" = 0.55; 0.16 Acres — CommerciaUlmpervious -) "C" = 0.90; Pre- construction runoff coefficient --> "CwTD" (0.35 *1.05)/2.73 + (0.40 *0.36)/2.73 + (0.42 *0.20)/2.73 + (0.55 *0.96)/2.73+ (0.90 *0.16)/2.73 -› CWTD' = 0.46 3.4 Time of Concentration: The Time -of- Concentration (Tc), for each watershed, is used to determine the intensity of the rainfall event for the corresponding drainage basin. Time -of- Concentration is defined as the time required for the surface runoff to flow from the most hydraulically remote point in a watershed to the point of analysis. The Tc is the summation of the flow time for overland sheet flow plus shallow overland flow and/or concentrated flow to the lower reach of the watershed. Overland sheet flow is a method developed by Overton and Meadows and is typically used for flow distances of 300 feet or less. Concentrated flows are estimated by velocities determined by use of the Manning's Equation. These two types of flow time calculations are further explained as follows. Overland Sheet Flow, T = {0.007 (n L) (18 / {Pi S 4 } where, T = travel time (hours); n = Manning's roughness coefficient — This represents the flow - ability of runoff across a particular surface type and is a dimensionless coefficient. These 'coefficients are obtained from Table C -5 of the USDG; Pi = i -year recurrence interval for the 24 -hour rainfall depth (inches) — Rainfall depths are obtained from Table C -6 of the USDG; S = land slope (feet /foot) Shallow Concentrated Flow, T = D /(60V) where, T = Travel time (minutes); D = Flow distance (feet); V = Average velocity of runoff (ft/sec) — These values are determined from interpolation velocities recorded in Table C -4 of the USDG; 220 -0419 Drainage Report-Rev2 Page - 5 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 Table #1 — "T Overland Sheet Flow" and Table #2 — "T Shallow Concentrated Flow" illustrates the flow travel times for each segment of the sub - drainage basin in respect to the condition of the flow. The Tc's for each sub - drainage basin where then computed and are summarized below in Table #3 — "Tc Summary ". TABLE #1 Ttl - Overland Sheet Flow Overland Average Flow Land Travel Drainage Manning's Distance Pi Slope Time Area I.D. "n" (L) (100 -year) (S) (Tc) X 0.24 75 11.0 0.0400 0.077 P 0.24 60 11.0 0.0070 0.130 P2 0.24 75 11.0 0.0400 0.077 TABLE #2 Tt2 - Shallow and /or Concentrated Flow Shallow (Unpaved) Shallow (Paved) Channel Flow Average Flow Average Flow Average Drainage Distance Velocity Distance Velocity Distance Velocity Time Areal.D. (Dl) (V1) (Dl) (V1) (D2) (V2) (Tc) X 450 3.8 236 5.1 2.74 P 136 2.0 772 2.3 324 5.1 7.79 P2 450 3.8 125 5.1 2.38 1) Unpaved Shallow Flow average velocities were estimated using the following equation V = 16.135 *S where, V =fps S = average slope Assumptions — Manning's N = 0.05 & Hydraulic radius = 0.4 ft 2) Paved Shallow Flow average velocities were estimated using the following equation V = 20.328 *S where, V = fps S = average slope Assumptions — Manning's N = 0.025 & Hydraulic radius = 0.2 ft TABLE #3 Tc SUMMARY Combined Drainage Overland Channel Flow Tc Area I.D. Flow Time Time (min) X 0.077 2.74 7.4 P 0.13 7.79 15.6 P2 0.077 2.38 7.0 1) The minimum Tc utilized will be ten (10) minutes; 3.5 Stormwater Runoff Quantities: Stormwater runoff quantities were calculated, using the Rational Method with the assistance of the Hydrologic/Hydraulic Stormwater modeling program HydroCAD. 220 -0419 Drainage Report -Rev2 Page - 6 Randall's University Park - Replat of Lot 3R-2 RME Consulting Engineers Drainage Study - Rev. No. 2 February 9, 2011 Runoff values for the larger watersheds are summarized below in Table #4 - "Drainage Basin Runoff Quantities ". HydroCAD- Existing & Proposed Conditions Drainage Calculations and their supporting data are contained the "Attachment - Section 3.0" appendix of this Drainage Report. These calculated runoff quantities were reviewed and considered reasonable for the studied watershed. TABLE #4 DRAINAGE BASIN RUNOFF QUANTITIES Randall's Detention & Drainage Drainage Drainage Drainage Upstream Rainfall Area _ Area Area Area Uncontrolled Event (X) (P) (P1) (P2) (RDUU) (yr) (cfs) (cfs) (cfs) (cfs) (cfs) 2 9.37 25.39 2.79 7.93 5 11.40 30.87 3.39 9.64 10 12.79 34.65 3.81 10.82 25 14.61 39.58 4.35 12.36 50 16.52 44.74 4.91 13.97 100 17.24 46.71 5.13 14.59 247 The 100 -year runoff value of 247 cfs is taken from the Drainage Report prepared by ML Hammons (dated 2/15/91) which includes the metered flow from the Albertson's (Randall's) detention facility plus the uncontrolled flow from upstream drainage areas and is bypassing the detention structures. A copy of this Stormwater Drainage Analysis is located in the "Attachment - Section 3.0" section of the Drainage Report. 4.0 DETENTION FACILITY & ROUTING 4.1 Detention Facility Criteria STORAGE: 1. The storage ability of the detention facility is such that it can adequately detain the receiving stormwater runoff from upstream drainage areas so that runoff from the project site is controlled to pre - development "existing" conditions. The storage requirements are more fully explained in the following section; 2. The maximum storage depths for design and ultimate conditions shall be as follows: Facility Location Design Hydro graph Ultimate Hydro graph Parking Areas 0.50 ft 1.5 ft Rooftops 0.50 ft 1.0 ft Landscaped Areas 3.0 ft 4.50 ft 3. All detention facilities located on natural streams or water courses that are designed with a permanent storage component shall meet all criteria, in terms of design and construction, for Dams and Reservoirs as required by the Texas Commission on Environmental Quality (TCEQ); 220 -0419 Drainage Report-Rev2 Page - 7 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 4. Detention facilities shall have an additional 10% in storage to account for sedimentation, except those located in parking areas or rooftops. OUTLET STRUCTURES: The detention facility outlet structures are designed so that the system can be drained by means of gravity. Discharge velocities shall be verified that they are below the minimum velocities receivable by the type and nature of the receiving system or attenuated so that they are below these minimums. PHYSICAL CHARACTERISTICS: 1. Side slopes shall not exceed 4:1 for vegetative cover and 2:1 for non - vegetative cover; 2. Bottom slopes must be 2.00% or steeper to low flow outlet; 3. A low -flow invert shall be provided for all facilities which have a vegetative cover at the facility bottom; EMERGENCY OVERFLOW: 1. The geometry of the emergency overflow shall be that of a rectangular weir; 2. Surface treatment of the overflow weir shall be consistent with the expected velocities at ultimate conditions. Proper treatments shall be provided to accommodate or attenuate the discharge velocities; 3. A minimum of 0.5 feet of freeboard shall be provided around the perimeter of the detention facility as measured between the maximum water surface elevation and the pool elevation and the ultimate conditions. H y 4.2 Methodology: The purpose of a detention facility is to store the increased runoff created by the impervious and improved areas, and discharge it at a rate so that the immediate downstream structure and/or property experiences decreases or no change as compared to existing conditions. Using the peak runoff rates, generated and illustrated in Section 3.6 of this report, hydrographs for each rainfall event and respective drainage basins were created for existing conditions. These hydrographs were constructed by means of triangular approximation method which is limited to smaller watersheds located within the secondary drainage system of a major watershed. Other assumptions and geometric conditions that are used to build these hydrographs are as listed below. Using this data, and inputting it into HydroCAD, approximate hydrographs were determined for each drainage basin at selected rainfall events. Triangular Approximation: 1. Peak Runoff (Q) occurs at "Tc "; 2. The outflow portion of the triangular hydrograph is Tc x 2; Using this infolination, the storage volume of the detention facility can be estimated. This storage volume shall be such that the peak discharges of the development hydrograph, or the routed hydrograph, from the detention facilities will be equal to or less than the "Benchmark" discharges. For this project, at proposed development conditions, 220 -0419 Drainage Report-Rev2 Page - 8 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 the discharge values shall be such that the routed flows through Pond 1 (from Drainage Area "P "), are equal to or less than the peak discharge rates of Drainage Area "X ". 43 Detention Facility Configuration: The detention facility for the subject development will consist of one pond. With the construction of this detention facility, called Pond 1, an outlet structure will be installed to detain/meter increased runoff from Drainage Area "P 1". The proposed GP -01: Paving, Grading & Drainage Plan for this project more fully depicts these improvements and is contained under the "Attachment — Section 4.0" portion of this report. The detention facility is briefly summarized below: Pond 1: Runoff from Drainage Area "P1" is conveyed by means of overland flow. Pond 1 is "dry" pond with a bottom elevation of 302.30' and a maximum berm or ponding elevation of 304.10'. Sideslopes of the detention pond will be vegetative with 4H:1V sideslopes. Runoff routed through Pond 1 is metered through area grate inlet and then is discharged into the storm drainage system of the proposed development; 4.4 Detention Facility Outlet Structure: The detention facility outlet structure has been designed to accommodate and route collected stormwater runoff, from Drainage Area "P1" so that during analyzed /routed rainfall events the post - development discharge rates are near or less than the "benchmark" discharge values generated from Drainage Area "X" (less the undetained flows from Drainage Area "P2 "). These "benchmark" discharge values are illustrated in Table #4 contained in Section 3.5 of this report. The discharge structure of each detention pond will serve as the restricting or metering device, and are summarized below: Pond 1: Pond 1 discharge structure through grate inlet. Analyzed with 25% blockage. The maximum berm height will extend also to an elevation of 304.10' which will provide 0.51' of freeboard above the maximum pool elevation occurring during the 100 -year rainfall event. Tailwater considerations for the outlet of Pond 1 were set at a free discharge condition. 4.5 Routing Results and Conclusions: Once the project's detention facility and outlet structure was determined, then the hydrograph for Drainage Basin "P 1" could be routed through the detention system. The routing of this hydrograph, for each analyzed rainfall event, was accomplished by means of the Hydrologic/Hydraulic stonnwater modeling program HydroCAD. The program mathematically solves for continuity between the detention facilities storage capabilities, in respect to height versus storage and height versus discharge rate, with the inflow hydrograph and inputted tailwater conditions. HydroCAD — Proposed Conditions Pond Calculations - Pond 1 and its supporting data is contained the "Attachment — Section 4.0" section of this Drainage Report. 220 -0419 Drainage Report-Rev2 Page - 9 Randall's University Park - Replat of Lot 3R -2 RME Consulting Engineers Drainage Study - Rev. No. 2 February 9, 2011 As shown below in Table #5 - "Detention Facility Routing ", the designed detention facility system can accommodate inflow runoff and adequately detain this stormwater so that the facility's discharge rates are below the "benchmark" discharges without overtopping the maximum berm elevation. TABLE #5 DETENTION FACILITY ROUTING Routed D.A. "P2" Benchmark Diff. in Rainfall Storage Max. Discharge Discharge Discharge Discharge Max. Berm Event Volume Pool Elev Rate Rate Rate Rate Elev. Freeboard (yr) (cu.ft.) (ft) (cfs) (cfs) (cfs) (cfs) (ft) _ (ft) DETENTION POND 1 - PROPOSED CONDITIONS 2 1,900 303.13 0.48 7.93 9.37 -0.96 304.10 0.97 5 2,401 303.25 0.51 9.64 11.40 -1.25 304.10 0.85 10 2,749 303.34 0.53 10.82 12.79 -1.44 304.10 0.76 25 3,205 303.44 0.56 12.36 14.61 -1.69 304.10 0.66 50 3,685 303.55 0.59 13.97 16.52 -1.96 304.10 0.55 100 3,870 303.59 0.60 14.59 17.24 -2.05 304.10 0.51 5.0 STORM DRAINAGE SYSTEM The "system criteria" listed below in the follow sub - sections are only the main highlights of the CoCS - USDG. The proposed development and drainage improvements are designed and analyzed in full accordance with the criteria outlined in this manual. 5.1 Culverts SYSTEM CRITERIA: 1. Drainage culverts shall be designed to convey the 25 -year storm and analyzed during the 100 -year rainfall event; 2. For the design stoim, the discharge velocity shall not exceed 6.0 fps; 3. Roughness coefficients for stolid sewer pipes were assigned at 0.012 for smooth -lined High Density Poly - Ethylene (HDPE) pipe and 0.013 for RCP; TAILWATER CONSIDERATIONS: Tailwater for the drainage culvert was determined by calculating the water surface elevation of the open - channel immediately downstream of the structure. This resulted in a tailwater elevation of 297.87'. DISCHARGE & HEADWATER: Runoff values utilized for the hydraulic analysis of the culvert system will be a combination of the following Drainage Areas (see Table #4 and routing in Table #5). As illustrated below the runoff values conveyed through the culvert system actually decreases by 2.05 cfs between Post- and Pre- Development conditions. 220 -0419 Drainage Report-Rev2 Page -10 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 Total Drainage Areas for Culvert System: 100- Year Pre - Development: Drainage Areas: RDUU + (P — P1 — P2 + X) = 291.23 cfs 100 -Year Post - Development: Drainage Areas: RDUU + (P — P1) + P1 "routed" = 289.18 cfs Utilizing these flows the existing culvert system and proposed culvert extension system (60" diameter pipe and 36" diameter pipe) were calculated to verify capacity. For the proposed condition an iterative process was utilized to balance headwater in conjunction with the conveyance of each pipe. This balanced headwater was determined to be at 304.30' with a discharge of 195.7 cfs and 93.5 cfs through the 60" and 36" pipes respectively. METHODOLGY & CONCLUSIONS: The hydraulic analysis, for drainage culverts, and corresponding results, were determined by using the THYSYS hydraulic program for stormwater modeling. This TxDOT program's typical use is for modeling gravity drainage culverts. The THYSYS data is summarized, for each culvert, under the THYSYS - Hydraulic Computations (reference "Attachment — Section 5.0" portion of the report). Drainage culverts are summarized below in Table #6 — "Culvert Summary ". As illustrated below the existing 60" culvert system is currently under -sized and will not convey the 100 -year rainfall event by approximately 146 cfs. The culvert crossing, along with a portion of Chimney Hill Drive, is overtopped by an approximate depth of 0.98'. This existing culver structure was analyzed at as -built conditions. TABLE #6 CULVERT SUMMARY Rainfall Pipe Size Lowest Event Diameter Velocity Runoff Q HW Elev. Pvmt Elev. Freeboard (Yr) (in) (fps) (cfs) (ft) (ft) (ft) EXISTING CULVERT 100 I 60 1 14.11 291.23 I 305.58 304.60 -0.98 PROPOSED CULVERT 100 36 13.23 93.50 304.30 304.45 0.15 100 60 15.26 195.70 304.30 304.45 0.15 To assist in attenuating the discharge velocity a concrete sidesloped headwall will be constructed at the pipe outlet and appropriate sized rock rip -rap will be concreted in at the discharge. 220 -0419 Drainage Report-Rev2 Page - 11 Randall's University Park — Replat of Lot 3R -2 RME Consulting Engineers Drainage Study — Rev. No. 2 February 9, 2011 6.0 CERTIFICATION "This report for the drainage design of Randall's University Park Subdivision (Lots 3R2 -A thru 3R2 -E) was prepared by me (or under my supervision) in accordance with provisions of the Bryan/College Station Unified Drainage Design Guidelines for the owners of the property. All licenses and petniits required by any and all state and federal regulatory agencies for the proposed drainage improvements have been issued." 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