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HomeMy WebLinkAboutExecutive SummaryOWNER Dr. Ketan Sukkawala Nivas Holdings, LP 17290 Eagle Pass Dr. College Station, Texas 77845 979 -450 -1116, sukkawala@gmail.com SUBMITTAL DATE: January 2012 GATTISENGINEERING ENGINEERS • CONSULTANTS EXECUTIVE SUMMARY REPORT Rock Prairie Professional Office Complex 1103 Rock Prairie Rd., Ste #101 College Station, Texas January 2012 PART 1.1 PROJECT ENGINEER Joe I. Gattis, PE #90964, Project Engineer GATTIS Engineering, LLC, Firm #7698 2010 Moses Creek Ct., College Station, Texas 77845 979 -575 -5022, joe@gattisengineering.com PART 1.2 The SCOPE of this project consists of the re- platting of Tract `A -1' into three lots and the development of Lot 1 into a professional office building site. Lots 2 and 3 will be developed into professional office sites in the future. PART 1.3 The Rock Prairie Professional Office Complex project (Tract `A -1) is located at 1103 Rock Prairie Road in College Station. It is a part of a larger, multi -tract development from 1993 called the Southwood Living Center' The project property is 2.763 acres and is located in the Bee Creek Drainage Basin. The property is located in the unshaded Flood Zone `X', outside of the 500yr floodplain, as shown on FIRM Map #48041C0182 C, dated July 2, 1992. There are no drainage ways or creeks that pass along or through this tract of land. PART 1.4 The Project Tract is vacant with only native grasses and a few trees on site. The site is relatively flat with grades between 1% and 2 %. It has a slight crown in the middle that causes sheet flow run -off in multiple directions. The stormwater un-off sheet flows to the North into an existing, shared detention facility, to the East into the shared, private drive storm sewer system, and to the south into the Rock Prairie Road storm sewer system. In 1993, the stormwater mitigation for this multi -tract development was designed by Hester Engineering. This design consists of shared detention facility, a private drive and its associated storm sewer system. All stormwater run-off to all directions was accounted for in this 1993 design. PART 1.5 As stated above, the stormwater run -off of Lots 1, 2 and 3 from the re -plat of Tract `A -1' has been accounted for by the 1993 Drainage Design by Hester Engineering. With the curtrent development of Lot 1 in the Rock Prairie Professional Office Complex Project, these storm water parameters have been maintained. Inside Lot 1, the stormwater run -off shall sheet flow to the surrounding parking lot areas, captured by grate inlets, and conveyed to the existing storm sewer system along the shared private drive. All roof drainage shall be captured via a roof gutter system and conveyed to the grate inlet boxes by under - ground storm pipe. PART 1 ? 6 , The storm water drainage for this site was designed in 1993, and its original intent was maintained with this re -plat and new development. There are no new or special permitting requirements associated with any local, state or federal agency. This project requires only a Development Permit to be issued by the City of College Station. PART 1.7 There is currently an approved drainage design titled Southwood Living Center' 1993 by Hester Engineering on file at the City of College Station Development Services Department for this site. For this development, an additional drainage report was provided to re -affirm the original design assumptions, calculations and also the drainage design for each individual lot. For this project, please see DRAINAGE SUMMARY REPORT, for the `Rock Prairie Professional Office Complex' for a complete hydraulic analysis and design for the development of Lot 1. This report consists of 94 pages of hydraulic analysis, calculations and summary with 4 drawings dated January 2012. Respectfully, GATTIS ENGINE NG, LLC Joe • s, PE Li • - ., ed Professional Engineer AO; 4 JOE I. GATTIS o 9 • : • ( 90964 0 : :Cr ��` C E N S isOf \SS �= FIRM # 7698 • 2010 Moses Creek Ct. • College Station, Texas 77845 • Tel. 979. j .5022 • Fax 979.690.6888 Part 2 — Project Administration Start (Page 2.1) Engineering and Design Professionals Information Engineering Firm Name and Address: GATTIS Engineering, LLC 20 I 0 Moses Creek Ct. College Station, Texas 77845 Jurisdiction City: Bryan College Station Date of Submittal: February 14, 201 2 Lead Engineer's Name and Contact Info.(phone, e fax): Joe Gattis, PE #90964; 979 - 575 -5022 Joe @gattisengineering.com Other: none Supporting Engineering / Consulting Firm(s): None Other contacts: None Developer / Owner I Applicant Information Developer / Applicant Name and Address: Phone and e-mail: Property Owner(s) if not Developer / Applicant (& address): Dr. Ketan Sukkawala 1 7290 Eagle Pass Drive, CS, Tx 77845 Phone and e-mail: 979 -450 - I 1 16 Project Identification Development Name: Rock Prairie Professional Office Complex Is subject property a site project, a single -phase subdivision, or part of a multi -phase subdivision? Multi - Phase Subdivision If multi - phase, subject property is phase _1_ of _3_ Legal description of subject property (phase) or Project Area: (see Section II, Paragraph B -3a) Lot 1(0.828 ac) of 3 of Southwood holdings Re -Mat of Tract 'A- I ' (2.763 ac) 1 103 Rock Prairie Road, Ste# I 01 , College Station, Texas 77845 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. This is the first phase. General Location of Project Area, or subject property (phase): 1 1 03 Rock Prairie Road next to Fortress health $ Rehab In City Limits? Bryan: acres. Extraterritorial Jurisdiction (acreage): Bryan: College Station: College Station: 2.763 acres. Acreage Outside ETJ: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 3 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 2 — Project Administration Continued (page 2.2) Project Identification (continued) Roadways abutting or within Project Area or subject property: Rock Prairie Road Abutting tracts, platted land, or built developments: The Esperanza of College Station Fortress Health $ Rehab Named Regulatory Watercourse(s) & Watershed(s): None Tributary Basin(s): Bee Creek Drainage Basin Plat Information For Project or Subject Property (or Phase) Preliminary Plat File #: unknown Final Plat File #: unknown Date: Status and Vol /Pg: V 7953 / Pg 025 Name: If two plats, second name: Not Applicable File #: Status: Date: Zoning Information For Project or Subject Property (or Phase) Zoning Type: A/P Existing or Proposed? Existing 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): Project Discussion, March 201 I Participants: Josh Norton, Morgan Hester Preliminary Report Required? No Submittal Date Jan 15, 201 I Review Date I - 1 - 20 12 Review Comments Addressed? Yes X No In Writing? X When? 02 I G - 2 Compliance With Preliminary Drainage Report. Briefly describe (or attach documentation explaining) any deviation(s) from provisions of Preliminary Drainage Report, if any. Previous Drainage Report was completed and approved in January 1 993. This 'New' report is an addendum. This addendum summary report evaluates and confirms original drainage designs $ assumptions to confirm that this new development conforms to original 1 993 drainage parameters. SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 4 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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 With Other Departments of Jurisdiction City (Bryan or College Station) Dept. Contact: Date: Subject: Coordination With Non - jurisdiction City Needed? Yes No X Summarize need(s) & actions taken (include contacts & dates): Coordination with Brazos County Needed? Yes No X Summarize need(s) & actions taken (include contacts & dates): Coordination with TxDOT Needed? Yes No X Summarize need(s) & actions taken (include contacts & dates): Coordination with TAMUS Needed? Yes No X Summarize need(s) & actions taken (include contacts & dates): 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 X Yes US Environmental Protection Agency No X Yes Texas Commission on Environmental Quality No X Yes Brazos River Authority No X Yes SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 5 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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? Development of vacant lot into 5,945 scj ft office bldg $ associated parking lot area Site Development Project (select all applicable) + Redevelopment of one platted lot, or two or more adjoining platted Tots. Building on a single platted lot of undeveloped land. _X_ Building on two or more platted adjoining lots of undeveloped land. Building on a single lot, or adjoining lots, where proposed plat will not form a new street (but may include ROW dedication to existing streets). Other (explain): Subdivision Development Project Construction of streets and utilities to serve one or more platted lots. Construction of streets and utilities to serve one or more proposed lots on lands represented by pending plats. Describe Nature and Size Of Proposed Site projects: building use(s), approximate floor space, impervious cover ratio. Subdivisions: number of lots by general type of use, linear feet of streets and drainage easements or ROW. Proposed 5,495 sci ft medical office building, with parking Impervious Cover ratio is approximately 80% Project Is any work planned on land that is not platted If yes, explain: or on land for which platting is not pending? X No Yes FEMA Floodplains Is any part of subject property abutting a Named Regulatory Watercourse (Section II, Paragraph B1) or a tributary thereof? No X Yes Is any part of subject property in floodplain area of a FEMA - regulated watercourse? No X Yes Rate Map Encroachment(s) into Floodplain areas planned? No X Encroachment purpose(s): Building site(s) Road crossing(s) Utility crossing(s) Other (explain): 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. Not Applicable SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 6 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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 X Reference the study (& date) here, and attach copy if not already in City files. Drainage Analysis, Southwood Living Center, 1 2.44 ac, Jan. 1 993 by Hester Engineering Is the stormwater earlier study? management plan for the property in substantial Yes x No If not, explain how conformance with the it differs. No If subject property plan for the property is not part of multi -phase project, describe stormwater management 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 Describe them (include approximate size, volume, outfall, model, etc). A portion of the shared detention facility 'A -1'. Total capacity = 66,189 c.f., 14" orifi runoff? No X Yes is on Tract w x 37" tall Any known drainage or flooding problems in areas near subject property? Identify: X No Yes Based (see Table X on location of B -1 in Appendix Detention is required. study property in a watershed, is Type 1 Detention (flood control) needed? B) Need must be evaluated. Detention not required. If the need for Type 1 Detention must be evaluated: What decision has been reached? By whom? Detention will be provided; City College Station $ Gattis Engineering How was determination made? The decision is based on maintaining existing drainage design from 1 993. SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 7 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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? describe splits below. In Part 4 describe design concept X No Yes If yes, 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? Size(s) of area(s) in acres: 1) 2) 3) X No Yes 4) Flow Characteristics (each instance) (overland sheet, shallow concentrated, recognizable Watercourse or tributary); concentrated section(s), small creek (non - regulatory), regulatory Flow determination: Outline hydrologic methods and assumptions: Does storm runoff drain from public easements or ROW No Yes If yes, describe facilities in easement onto or across subject property? or ROW: Are changes in runoff characteristics subject to change in future? Explain Conveyance Pathways (Section II, Paragraph C2) Must runoff from study property drain across lower properties before reaching a Regulatory Watercourse or tributary? No X Yes Describe length and characteristics of each conveyance pathway(s). Include ownership of property(ies). Outfall of Detention Pond flows through established drainage easement through the Southwood Forest Ph 4 Subdivision SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 8 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 3 — Property Characteristics Continued (Page 3.4) Hydrologic Attributes of Subject Property (or Phase) (continued) Conveyance Pathways (continued) Do drainage easements exist for part of pathway(s)? X No any If yes, for what part of length? % Created by? plat, or instrument. If instrument(s), describe their provisions. Yes Pathway Areas Where runoff must cross lower properties, describe characteristics of abutting lower property(ies). (Existing watercourses? Easement or Consent aquired ?) Not Applicable Nearby Drainage Facilities Describe any built or improved drainage facilities existing near the property (culverts, bridges, lined channels, buried conduit, swales, detention ponds, etc). The detention facility outfall structure meter - releases stormwater downstream via a 36" diameter culvert under the shared private drive. Do any of design? these have hydrologic or hydraulic influence on proposed stormwater X No Yes If yes, explain: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 9 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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. Not Applicable Discharge(s) To Lower Property(ies) (Section II, Paragraph El) Does project include drainage features (existing or future) proposed to become public via platting? X No Yes Separate Instrument? X No Yes Per Guidelines reference above, how will runoff be discharged to neighboring property(ies)? Establishing Easements (Scenario 1) Release (Scenario 2) of the two Scenarios X Pre - development Combination Scenario 1: If easements are proposed, describe where needed, and provide status of actions on each. (Attached Exhibit # ) Not Applicable Scenario 2: Provide general description of how release(s) will be managed etc.). (Attached easements from 1 993 to pre - development Exhibit # ) conditions (detention, sheet flow, partially concentrated, Detention Facility has established drainage design Combination: If combination is proposed, explain how discharge will differ from pre - each area (or point) of release. development conditions at the property line for Not Applicable If Scenario 2 or Combination are to be used, has proposed design been No X Yes Explain coordinated with and provide into Harvey owner(s) of receiving property(ies)? documentation. Design will maintain existing drainage design of stormwater outfall Road Storm Sewer System. SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 10 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.2) Stormwater Management Concept (continued) Within Project Area Of Multi -Phase Project Will project result in shifting runoff between Basins or between Watersheds? X No Identify gaining Basins or Watersheds and acres shifting: Not Applicable What design and mitigation is used to compensate for increased runoff from gaining basin or watershed? Not Applicable Yes How will runoff from Project Area be mitigated to pre- development conditions? Select any or all of 1, 2, and /or 3, and explain below. 1. _X_ With facility(ies) involving other development projects. 2 Establishing features to serve overall Project Area. 3. On phase (or site) project basis within Project Area. 1. Shared facility (type & location of facility; design drainage area served; relationship to size of Project Area): (Attached Exhibit # 1 ) The existing shared detention facility and easements was designed in 1 993. Its watershed area is approximately 1 2.57ac. See Attachement #i 2. For Overall Project Area (type & location of facilities): (Attached Exhibit # ) 3. By phase (or site) protect: 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)? Are other Best Management Practices for reducing stormwater pollutants proposed? No Yes Summarize type of BMP and extent of use: If design of any runoff - handling facilities deviate from provisions of B -CS Technical 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 SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 11 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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 Yes Identify type and general size and In which phase(s). Not Applicable 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? X 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? ditches use Yes Steepest side slopes: Usual front s opes: Usual back slopes: Flow line slopes: least Typica distance from travelway: (Attached Exhibit # ) typical greatest 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? No Yes If yes explain: Bets with cL ;utter used Jo Are valley gutters proposed to cross any street away from an intersection? No Yes Explain: (number of locations ?) SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 12 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.4) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Are streets with curb and gutter used? (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. Will inlet size and placement prevent exceeding allowable water spread for 10 -year design storm throughout site (or phase)? Yes No If no, explain. Saq curves: Are inlets placed at low points? Yes No Are inlets and conduit sized to prevent 100 -year stormflow from ponding at greater than 24 inches? Yes No Explain "no" answers. 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. Is storm drain system used? No x Yes Are any 12 -inch laterals used? X No Yes Identify length(s) and where used. Pipe runs between system access points (feet): Typical Longest Are junction boxes used at each bend? Yes X No If not, explain where and why. There is a private drainage system along the private drive that has a 36" diameter 45degree bend - designed 1 993 Are downstream soffits at or below upstream soffits? Yes X No If not, explain where and why: Least amount that hydraulic grade line is below gutter line (system- wide): SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 13 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.5) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Storm drain system (continued) (on separate sheet provide same info. for more instances) Outfall(s) Describe watercourse(s), or system(s) receiving system discharge(s) below (include design discharge velocity, and angle between converging flow lines). 1) Watercourse (or system), velocity, and angle? 2) Watercourse (or system), velocity, and angle? 3) Watercourse (or system), velocity, and angle? For each ouffall above, what measures are taken to prevent erosion or scour of receiving and all facilities at juncture? 1) 2) 3) Are swales used to drain streets? x No Yes 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): Flow line slopes (minimum and maximum): Outfall characteristics for each (velocity, convergent angle, & end treatment). Will 100 -year design storm runoff be contained within easement(s) or platted drainage ROW in all instances? Yes No If "no" explain: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 14 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.6) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Roadside Ditches Are roadside ditches used? X No Yes If so, provide the following: ? Yes No Is 25 -year flow contained with 6 inches of freeboard throughout Are top of banks separated from road shoulders 2 feet or more? Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes No Yes No For any "no" answers provide location(s) and explain: (on separate sheet provide same information for any additional instances) 1 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? If "no" explain: Yes No Space for 100 -year storm flow? ROW Easement Width Swale Surface type, minimum Conduit Type and size, minimum and maximum and maximum slopes: slopes, design storm: Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): Access Describe how maintenance access is provided (to swale, into conduit): Instance 2 Describe general location, approximate length: Is 100 -year design flow contained in conduit/swale combination? If "no" explain: Yes No Space for 100 -year storm flow? ROW Easement Width Swale Surface type, minimum Conduit Type and size, minimum and maximum and maximum slopes: slopes, design storm: Inlets Describe how conduit is loaded (from streets /storm drains, inlets by type): Access Describe how maintenance access is provided (to swale, into conduit): SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 15 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.7) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Will swales without buried conduit receive runoff from public ROW or easements? x No Yes. Explain If "yes" provide the following information for each instance: Instance 1 Describe general location, approximate length, surfacing: Is 100 -year design flow contained in swale? Yes No Is swale wholly within drainage ROW? Yes No Explain "no" answers: Access Describe how maintenance access is provide: Instance 2 Describe general location, approximate length, surfacing: Is 100 -year design flow contained in swale? Yes No Is swale wholly within drainage ROW? Yes No Explain "no" answers: Access Describe how maintenance access is provided: Instance 3, 4, etc. If swales are used in more than two instances, attach sheet providing all above information for each instance. Channel improvements proposed? x No Yes Explain "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. Will design replicate natural channel? Yes No If "no ", for each instance describe section shape & area, flow line slope (min. & max.), surfaces, and 100 -year design flow, and amount of freeboard: Instance 1: Instance 2: Instance 3: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 16 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.8) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Channel Improvements (continued) Existing channels (small creeks): Are these used? X 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. Watercourses (and tributaries): Aside from fringe changes, are Regulatory Explain below. Watercourses proposed to be altered? X No Yes Submit full report describing proposed changes to Regulatory existing and proposed section size and shape, surfaces, alignment, length affected, and capacity, and provide full documentation and data. Is full report submitted? Yes No Watercourses. Address flow line changes, of analysis procedures If "no" explain: 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. Not Applicable 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 Yes No If not, identify location(s) and explain: maintenance space? SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 17 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.9) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) 1_ How many facilities for subject property project? 1 For each provide info. below. For each dry -type facilitiy: Faci ity 1 Faci ity 2 Acres served & design volume + 10% 14.Oac 42, I 23cf 100 -yr volume: free flow & plugged 42, 1 23cf 82,585 Design discharge (10 yr & 25 yr) 25.9cfs 27.5cfs Spillway crest at 100 -yr WSE? Berms 6 inches above plugged WSE? Explain any "no" answers: I00 year W.S.E. = 3 I 7.93', Spillway W.S.E. (Top of Curb) Existing Facility Designed in 1 yes X no yes no yes X no yes no Top of Pond =3 1 9.00' = 3 1 9.50' - flow over private 993 drive to channel For each facility what is 25 - yr design Q, and design of outlet structure? Facility 1: 27.5cfs, Orifice Box with 14" x 37" opening Facility 2: Do outlets and spillways discharge into a public facility in easement or ROW? Facility 1: X Yes No Facility 2: Yes No If "no" explain: Facility Outfall discharges into existing drainge easement/channel through Southwood Forest, Phase 4 For each, what is velocity of 25 -yr design discharge at outlet? & at spillway? Facility 1: 3.9 fps & none Facility 2: & Are energy dissipation measures used? X No Yes Describe type and location: For each, is spillway surface treatment other than concrete? Yes or no, and describe: Facility 1: No, concrete channel Facility 2: For each, what measures are taken to prevent erosion or scour at receiving facility? Facility 1: Concrete Channel Facility 2: If berms are used give heights, slopes and surface treatments of sides. Facility 1: No Grass Berms, 3: I Sloped walls; Top Elev =3 1 9.00' Max Depth = 5.5' Facility 2: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 18 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.10) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Detention Facilities (continued) Do structures comply with B -CS Specifications? Yes or no, and explain if "no ": Facility 1; Yes Facility 2: For additional facilities provide all same information on a separate sheet. Are parking areas to be used for detention? X No Yes What is maximum depth due to required design storm? Are culverts used at private crossings? No X Yes Roadside Ditches: Will culverts serve access driveways at roadside ditches? X No Yes If "yes ", provide information in next two boxes. Will 25 -yr. flow pass without flowing over driveway in all cases? Yes No _X_ Without causing flowing or standing water on public roadway? Yes No _X_ Designs & materials comply with B -CS Technical Specifications? Yes No _X_ Explain any "no" answers: Are culverts parallel to public roadway alignment? Yes No Explain: _X_ 36" culvert crosses underneath private drive Creeks at Private Drives: Do private driveways, drives, or streets cross drainage ways that serve Above - Project areas or are in public easements/ ROW? X No Yes If "yes" provide information below. How many instances? Describe location and provide information below. Location 1: Location 2: Location 3: For each location enter value for: 1 2 3 Design year passing without toping travelway? Water depth on travelway at 25 -year flow? Water depth on travelway at 100 -year flow? For more instances describe location and same information on separate sheet. SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 19 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.11) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) (for more instances of any type describe location and same information on separate sheet) J Named Regulatory Watercourses (& Tributaries): Are culverts proposed on these assumptions, support proposed ", explain: facilities? No Yes, then provide full report documenting that If "no criteria, analysis, computer programs, and study findings design(s). Is report provided? Yes No Arterial or Major Collector Streets: Will culverts serve these types of roadways? For each identify the No Yes How many instances? location and provide the information below. Instance 1: Instance 2: Instance 3: Yes or No for the 100 -year design flow: 1 2 3 Headwater WSE 1 foot below lowest curb top? Spread of headwater within ROW or easement? Is velocity limited per conditions (Table C -11)? Explain any "no" answer(s): Minor Collector or Local Streets: Will culverts serve these types for of streets? each identify the No Yes How many instances? location and provide the information below: Instance 1: Instance 2: Instance 3: For each instance enter value, or "yes" I "no" for: 1 2 3 Design yr. headwater WSE 1 ft. below curb top? 100 -yr. max. depth at street crown 2 feet or less? Product of velocity (fps) & depth at crown (ft) = ? Is velocity limited per conditions (Table C -11)? Limit of down stream analysis (feet)? Explain any "no" answers: SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 20 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.12) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Culverts (continued) All Proposed Culverts: For all proposed culvert facilities (except driveway /roadside boxes. ditch intersects) provide information requested in next eight 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 approaches thereto? No Yes If "yes" identify location(s), culvert and surfaced 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 No Yes If "yes" identify location(s), describe to culvert ends? outfall design treatment(s): Is scour /erosion protection provided to ensure long term stability of culvert structural 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 drainage easements/ ROW? Yes No if not, why in street ROW, and /or not? Do appreciable hydraulic effects of any culvert extend downstream neighboring land(s) not encompassed in subject property? "yes" describe location(s) and mitigation measures: or upstream to No Yes If Are all culvert designs and materials in compliance with B -CS Yes No If not, explain in Special Design Section Tech. Specifications? of this Part. SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 21 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.13) Stormwater Management Concept (continued) Within Or Serving Subject Property (Phase, or Site) (continued) Bridge(s) Is a bridge included in plans If "yes" provide the following for subject property project? X No Yes information. Name(s) and functional classification of the roadway(s)? What drainage way(s) is to be crossed? A full report supporting all aspects of the proposed bridge(s) hydrologic, and hydraulic factors) must accompany this summary provided? Yes No If "no" explain: (structural, geotechnical, report. Is the report Water Quality Is a Stormwater Pollution Prevention Plan (SW3P) established for project construction? No X Yes Provide a general description of planned techniques: I) Silt Fencing Around All Dirt Work 2) Sand Bags around exitsing inlet grate 3) Silt Fence $ hay Bale Combo at Spillway Special Designs — Non - Traditional Methods Are any non - traditional methods replication, BMPs for water quality, X No Yes If "yes" list (aquatic echosystems, wetland -type detention, natural stream etc.) proposed for any aspect of subject property project? general type and location below. Provide full report about the proposed expected benefits. Report must be compromised, and that maintenance solution(s). Is report provided? special design(s) including rationale substantiate that stormwater management cost will not exceed those of Yes No If "no" explain: for use and objectives will not traditional design SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 22 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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 B -CS Technical Specifications, check type facility(ies) and explain by Detention elements Drain system elements deviate from provisions of specific detail element. Channel features Inlets Outfalls Culvert features Swales Ditches 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? X Yes No Briefly summarize the range of applications made of the Rational Formula: The Rational Metod was used to evaluate the watershed basin for existing detention pond facility. The Rational Method was alsoused to develop hydrographs for PERVIOUS and IMPERVIOUS surfaces and produce an estimated stormwater run -off for Lot I . These surfaces included roof drainage, paved parking lot, and landscaped areas. What is the size and location of largest has been applied? 4.G acres Design Drainage Area to which the Rational Formula Location (or identifier): Episcopal Church Tract SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 23 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.15) Design Parameters (continued) Hydrology (continued) In making determinations for time of concentration, was segment analysis used? No X Yes In approximately what percent of Design Drainage Areas? 70 % As to intensity- duration - frequency and rain depth criteria for determining runoff flows, were any criteria other than those provided in these Guidelines used? X 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 N/A Storm drain system for local streets N/A Open channels N/A Swale /buried conduit combination in lieu of channel N/A Swales N/A Roadside ditches and culverts serving them N/A Detention facilities: spillway crest and its outfall 2,5, 1 0,25,50, 100 100 Detention facilities: outlet and conveyance structure(s) 2,5, 1 0,25,50, 100 100 Detention facilities: volume when outlet plugged 100 100 Culverts serving private drives or streets N/A Culverts serving public roadways N/A Bridges: provide in bridge report. N/A 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: n=0.013 For conduit type(s) RCP Coefficients: n=0.013 SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 24 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 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? X No Yes Head and friction losses X No Yes Explain any "yes" answer: In conduit is velocity generally increased in the downstream direction? Are elevation drops provided at inlets, manholes, and junction boxes? Explain any "no" answers: Yes No _X_ Yes No _X_ Are hydraulic grade lines calculated and shown for design storm? X Yes No For 100 -year flow conditions? X Yes No Explain any "no" answers: What tailwater conditions were assumed at outfall point(s) of the storm drain system? each location and explain: Not Applicable Identify 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 If "no" list locations and explain: Not Applicable flow? Yes No 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? Not Applicable Entrance, friction and exit losses: Bridges Provide all in bridge report Not Applicable SECTION IX STORMWATER DESIGN GUIDELINES Effective February 2007 APPENDIX D - TECHNICAL DESIGN SUMMARY Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY As Revised February 2009 Part 4 — Drainage Concept and Design Parameters Continued (Page 4.17) 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 * AutoCad Land Desktop 2005, Civil Design 2005; * hydraFlow hydragraphs 2007, hydraflow Express 2007 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: In the re -plat of Tract 'A- I ' and development of Lot I , I verified that the existing detention pond and storm sewer conduit system will perform as originally designed in 1 993 and to meets the standards as set forth in the D /CS Unified Drainage Design Guidelines. 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 by me (or under my supervision) in accordance with provisions of the Unified Drainage Design Guidelines for the owners of the property. All required by any and all sf to and federal regulatory agencies for the improvements r ave be- ,'ssued or fall under applicable general permits." (Affix Seal) Part B was prepared Bryan /College Station licenses and permits proposed drainage +``a`O .. 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