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Home My WebLink About5 Development Permit 201 R Bradley Subd;- DRAINAGE REPORT FOR LOT 38R, BLOCK 14, SOUTHWOOD -SECTION 25 PREPARED FOR: Walter Bradley 1302 Augustine CT. College Station, Tx. 77840 PREPARED BY: Municipal Development Group P.O. Box 9249 College Station, Tx. 77842 Approved by North Bardell, P.E. E '0719 ~ TABLE OF CONTENTS I. General Location II. Property Description III. Drainage Basin Descri ption IV. Drainage Facility Design V. Runoff Calculations A. Creek Drainage 8. Southwood Drainage VI. Conclusions VII. Proposed Detention Facilities LIST OF FIGURES 1. Figure 1: Site Drainage Plan 2. Figure 2: Drainage Area Map 3. Figure 3: Storm Volume Hydrograph 4. Figure 4: Storm Volume Hydrograph (Creek Drainage) (Southwood Drainage) 5. Figure 5: Flow Regulating Weir (Creek Drainage) LOCATION OF STUDY SITE General Locat_ion: The subject tract is Lot 38R, Block 14 of the Southwood Section 25 Subdivision of the City of College Station. The tract is positioned on the west side of Southwood Drive, approximately one block north of FM 2818 (West Bypass). The vi" Valley View Drive-Southwood Drive intersection is across from this tract, and it will allow a joint intersection with the proposed street serving this tract. Property Description: Lot 38R, Block 14 of the Southwood Section 25 Subdivision of the City of College Station is a total of 2.78 acres. The land is currently unimproved grass, weeds, and trees in its natural state. It is rolling in nature, with elevation variation from 286+ down to 272-. The 100-flood lain encroaches a roximatel .008 acres on the southwestern corner of the tract at an elevation of approximately 270.50 feet. Approximately one quarter of the tract (the most easterly) drains rn a sheet-flow manner over the existing curb onto Southwood Drive. The remaining three quarters of the tract drains onto surrounding properties, with / most of the area (95%) draining into a defined channel on the most westerly end of the tract. In addition, this tract currently drains the neighboring lots (Lots 39D and 39E) through a concrete headwall located at the southern portion of the tract. Drainage Basin Description: The subject tract is located in Basin #5 of the Bee Creek Primary Drainage System on Tributary "B" confluence, and thus requires detention facilities for a ~ 100-year ultimate rainfall. (See Page 10 of the City of College Station "Drainage Policy and Design Standards"). .008 acre of the tract, or proposed construction thereon, is within the FEMA established flood plain (elev. 269.5). Drainage Facility Design: There is no proposal to change the existing drainage patterns, as they currently create no flooding problems or hazards to surrounding properties. The proposed ~ development on this tract will add approximately 44,680 square feet of impermeable roof, street, parking lot, or sidewalk surface area. The increased runoff due to this impervious area will necessitate the prov1s10n of two detention areas. The first detention area will be situated north of the southern depressed area of the tract which currently drains Lots 39D and 39E. This depressed area (.1063 acres) will be left in its natural state in order to keep existing drainage conditions which currently does not pose a flooding threat. This bermed detention area will be located at the western end of the tract with a control outlet which will detain the projected increase in runoff calculated for a 100-year frequency rainfall. A second detention area will be located at the northwestern parking area. This area will detain the projected increase in runoff calculated for a 100-year frequency rainfall. A curb cut will be located at the western end of the parking lot, which will drain water in a sheet-flow manner onto Southwood Drive. 000278-C.02-04(2270) RUNOFF CALCULATIONS I. Drainage to Creek A. Pre-Development Description Grassland B. Post-Deve lopment Description buildings sidewalks access drive & parking landscaped area Area 2.079 Area 0.211569 0.014091 0.59656 1.27 2.079 c 0 .35 c 0 .9 0 .9 0.9 0.35 (c)(Ar ea) 0 .72765 (c)(Area) 0 .190412 0.012682 0.536904 0.4445 1.184498 Useful c = 1.184498/2 .079 = .566 ••• Use Tc = 10 minutes ••• C. Runoff O=clA Opre = 1(.35)(2.079) = .72765(1) Qpost = 1(.566)(2.079) = 1.1767(1) Storm Fre . 5 10 lntensit 7.7 8.6 5.603 6.258 0 ost 9.061 10.1 2 0 25 9.9 7.2 04 11.649 50 11.1 8.077 13.061 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......... . < :::: < :t oo <<< ..... > t2 :s:::<: : : :: 9A s:a :: < :::::f .. t 82 :6> Projected allowable rote of release from detention = 9 .2 c. f.s. Storage Volume Hydrograph Drainage to Creek figure 3 16 -.----~~~~~~~-~~~~~~~~~~~ 14.83 14 ....................................................................................................................................................................................... . 12 ····---····---··································· ""1"334 7"6".f .............................................................................................................. . 1 0 ..................................................................................................... ··········--~~-g~---~~-~~-~~-!g _~---························ 9.17 5094 c.f. 8 ................................................................................................................................................................................... . 8253 c.f. 6 ..................................................................................................................................................................................... . o ----~~~~~~~~~~~-.-~~~~~~ 0 10 20 . 30 Time (m in) Storm 5 10 25 50 100 Storm 5 10 25 50 100 BRADLEY REGULATORY WEIR DESIGN Detention Characteristics Allow. release rate Req. detention 'Waterline height ft ...... 3/sec ft ...... 3) ft 5.6 3112 1.90 6.26 3476 2.10 7.2 4000 2.50 8.08 4486 2.75 9.17 5094 3.13 Regulated Flow Characteristics for Weir y ft 1.35 2.1 2.5 2.75 3 A Release Rate ft 0.45 0.7 0.833 0.917 1 Flo~ Regulating Weir Figure 5 ft"-3/sec 1.82 4.41 6.25 7.57 9.00 II. Drainage to Southwood A. Pre-Development Description Grassland B. Post-Development Description buildings sidewalks access drive & parking landscaped area Area 0.7 Area 0 .0827 0.0058 0.0827 0.424 0.5972 g_ 0.35 c 0.9 0.9 0.9 0.35 (c)(Area) 0.245 (c)(Area) 0.07 443 0.00522 0.07 443 0.1484 0.30248 Useful c = 0.30248/.5972 = .506 •••• Use Tc = 10 minutes •••• C. Runoff Q=clA Qpre = 1(.35)(.7) = .245(1) Qpost = l(.50_6)(.5972) = 0.302(1) 5 7.7 1.887 2 .325 10 8.6 2.107 2.597 25 9.9 2.426 2.990 50 11.1 2.720 3.352 . . . . . . . . . . . . . . . . . . . . . ... ' ..... ><::::: >>::totL>::::::::: ::::::::: ::::::t2 ;s:<::: : : >3:;o:a:7 : :<<<3J3os : . : : Projected allowable rate of release from detention = 3.09 c.f.s. ·o Storage Volume Hydrograph Drainage to Southwood figure 4 4 -r-~~~~~~~~~~~~~~~~~~ 3 .81 3.5 ...................................................................... ·················································································································· 3 ·············-~-~:~.~:~: .......................... -=-3. . .9~ .................................... .13.~q~ ... P..~~-~D~~.Q~L ........................ . 648 c.f. 2.5 ................................................................................................................................................................................... . 2781 c.f. 2 .................................................................................................................................................................................... . 1.5 .................................................................................................................................................................................... . 1 ...................................................................................................................................................... ································ 0.5 ...................................................................................................................................................................... ··············· o ~~~~~~~~~~~~~~~~~~~ 0 10 20 30 Time (min) CONCLUSIONS From the previous pag es of calculations of runoff quantities for the drainage to the creek and to Southwood Drive, it can be seen that a maximum pre-development runoff rate for the creek is 9.2 c.f.s. The maximum pre- development runoff rate of 3.09 c.f.s. exits for runoff to Southwood Drive. A V-Notch Weir having a top width o feet and a length o 5.7 eet will simulate pre-development discharge rates or a 100, 50, 25, 10 5 year frequency storms for the planned drainage to the creek (see fi g. 5 ): **Table 111-2, College Station Drainage Policy And Design Standards: V (overland flow at 3% grade with:;_..-.1.,......,...s"-!c::!a:..!p::.:e::_-d area) = 3.0 ft/sec aterline: Q = (3.0 ft/sec)(3.0 ft.)(1.0 ft. = c.f.s. In the northwestern parking area, a flume having a standard section of 2 feet by 0.5 feet will provide a maximum discharge rate of approximately 8.0 c.f.s. for the pavement surface. The discharge rate will adequetly satisfy the need for 3.09 c.f.s. in the event of a 100 year storm: **Table 111-2, College Station Drainage Policy And Design Standards: V (impervious area at 3% grade) = 8.0 ft/sec Q= (1 ftA2)(8 ft/sec) = 8.0 c.f.s. Due to the infinitesimal difference between pre development and post development flow rates, water will be allowed to drain in a sheet like manner onto Southwood Drive. Proposed Detention Facilities Bermed Detention Area The enclosed site drainage plan depicts this detention facility in the southern portion of the subject tract. This facility will provide a capacity of approximately 6280 cubic feet of storage space which satisfies the requirement of 5094 cubic feet. The centerline grade to the weir will be at .51% in order to maintain a volumetric flowrate of 9.0 c.f.s. which is comparable to the pre- development flow rate. In addition, the weir is a v-notch design in order to simulate predevelopment conditions for various frequency storms. The outlet structure leading to the bermed area will utilize an 18 inch RCP in order to balance inlet and exit flows. Northwestern Parking Area The enclosed site drainage plan depicts this detention facilit;y in the northwestern portion of the subject tract. This parking area is designed to provide 650 cubic feet of storage space which is the projected requirement for a 100 year frequency storm. The flume is designed to have a volumetric flowrate of 8.0 c.f.s which satisfies the projected allowable release rate. A 5 foot by 5 foot block of sod will be provided in order to keep erosion at a minimum and to convert the concentrated stream into a wider flow pattern which will sheet flow on to Southwood Drive. In addition, an access drive will exist in the most northern portion of the tract, which will allow for further drainage. This access drive will mirror predevelopmental tendencies for sheet flow action onto Southwood Drive. £b/ slj lo p, f\ 11 Zl <Z6/b}6 P1°0 zJ I \ ' I ' I \ I ~ .• :;,_~:_. •' ' .. ~:".!~ MUNICIPAL DEVELOPMENT GROUP P.O. Box 9249 203 Holleman Drive East College Station, Texas 77840-9249 ( 409) 693-5359 DATE JOB NO . 2Z'70 ATTENTION RE : WE ARE SENDING YOU ~ttached D Under separate cover via _________ the following items: COPIES D Shop drawings D Copy of letter DATE D Prints D Change order NO. ~I ans D Samples D Specifications o ______________________ _ DESCRIPTION ll1t.. C..o THESE ARE TRANSMITTED as checked below : ~For approval D For your use D As requested D Approved as submitted D Approved as noted D Returned for corrections D Resubmit __ copies for approval D Submit __ copies for distribution D Return __ corrected prints D For review and comment D ------------------------- D FOR BIDS DUE _________ 19 ___ D PRINTS RETURNED AFTER LOAN TO US REMARKS ----------------------------------------~ COPY TO _____________________ ~ ~ /" SIGNED : QA=-~ f'0, ~ It enclo s11res are not as noted, kindly notify us at once. ·- Figure XII Application Form Development Permit Inside/Outside Established Flood Hazard Areas City of College Station, Texas (re: Ordinance No. 1728) Site Legal Description: ~ot 178 f? J @ )i?O'~ 14 1 0ov-±tt woad 9ev VS JZrj(Le., Site Address: i I ~Cl g~llfh lUtJOd Owner: lAfi . l f.el( /;,. t?rur d {e V, Address: I ?;Jo1--tl ll4fl.Jf?ffn~ Cf .C:..17v Telephone No.: ~?.7-qg8'2 7 Architect/ Address: U'IJ ~~ w~t~ \x Engineer: -'M:........:.iotZ'--'~""4o---------------Telephone No.: ~2-4 Contractor: _Joe-~~ ]sk,W\e.? Address: ~O '? 1wa~ Ave . No l0f3 ~ Telephone No.: 0 q& l/zoB' Date Application Filed: _q--=--J_/ o__,_l q_,_Q---=----------Approved:---------- Attached as part of this application: D Application Fee 0' Signed Certificate D Site and Construction Plans, with supporting documentation: two (2) copies of each{pY.evidV~VJ «1bm1"/W j D Other:----------------- ACKNOWLEDGEMENTS: I, Na,lf.&V l· ~(~ , as owner, hereby acknowledge or affirm that: The above Drainage Plan and supporting documents complies wiht the requirements of Ordinance No. 1728, and Date .~~I°! 11 0,3 Oat Page 1of2 Figure XII Continued CERTIFICATIONS: A. I, certify that any nonresidential structure on or proposed to be on this site as part of this application meets flood-proofing requirements as set out in Section of Ordinance No. 1728 Architect/Engineer Date B. I, N OR.TH B l3rtBJ:>ELL-JR.;, certify that the finished floor level of the lowest floor, including any basement, of any residential structure as part of this application is or proposed to be at or above the base flood elevation as established in the latest Federal ¥' l~n~ ha~~ study and maps, as ;;~nd;~ '! 3 Architect/Engineer J--~;;;;;D-a....,t F--''--~=--t7-_,__.._-=~---- C. I, certify that the alterations or development covered by this permit shall not diminish the flood-carrying capacity of the adjoining waterway or crossing this permitted site and that such alterations or development are consistent with requiremenrs concerning encroachments of floodways and of floodway fringes as illustrated in the latest Federal Insurance Study. Architect/Engineer Date D. I, do certify that any alterations, addressed in Certification ''D" do not raise the level of 100-year flood as referred to Certification 11 8 11 • Architect/Engineer Date· REVIEWED FOR AP PROV AL: ----~=---..,~..,..-~-,........,.--~ Floodplain Administrator Date APPROVAL: Special conditions or comments as part of approval: ------~--- Pal!e 2of2 y..,.~PI'·"°" l::M DEVELOPMENT PERMIT PERMIT NO. 0201R FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 38R, Block 14, Southwood Sec 25 SITE ADDRESS: 2100 Southwood Drive OWNER: Walter L. Bradley 1302 Augustine Ct. College Station, Texas 77840 DRAINAGE BASIN: Bee Creek TYPE OF DEVELOPMENT: This permit valid for all construction associated with the Bradley Subdivision. All construction shall be in accordance with the plans submitted. Contractor shall prohibit all debris from construction including dirt and silt, from entering public streets and drainage facilities. Contractor shall be responsible for any damage to existing streets, curbs, or public infrastructure due to the construction activities. Contractor shall prevent construction vehicles from tracking dirt, mud, and debris from all exit points of the project, onto any public street. Contractor shall use appropriate erosion control measures such as silt fencing and hay bales to prevent silt and debris from exiting the project site. It is the contractor's responsibility to erect and maintain the erosion control measures throughout the project. Should sufficient mud and dirt accumulate on public streets, it is the contractor's responsibility to install a washdown facility for the construction vehicles entering and exiting the site. SPECIAL CONDITIONS OF THIS PERMIT: 1) Erosion protection , in the form of silt screens , shall be installe d in accordance with plans submitted and approved. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station , measures shall be taken to insure that debris from construction, erosion , and sedimentation shall not be deposited in city streets, or existing drainage facilities. I hereby grant this permit for the construction of improvements as shown on the approved plans and construction both inside and outside the special flood hazard area. All construction shall be in accordance with th e plans and specifications submitted to and approved by the City Engineer in the development permit a ·cation for the above named project and all of the codes and ordinances of the C of College St ion that apply. Date / / DEVELOPMENT PERMIT PERMIT NO. 0201R FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 38R, Block 14, Southwood Sec 25 SITE ADDRESS: 2100 Southwood Drive OWNER: Walter L. Bradley 1302 Augustine Ct. College Station, Texas 77840 DRAINAGE BASIN: Bee Creek TYPE OF DEVELOPMENT: This permit valid for the grading, dirt work, and construction of the following: l)slabs associated with the fourplexes, 2) water and sewer main construction. All construction shall be in accordance with the plans submitted. Contractor shall prohibit all debris from construction including dirt and silt, from entering public streets and drainage facilities. Contractor shall be responsible for any damage to existing streets , curbs , or public infrastructure due to the construction activities. Contractor shall prevent construction vehicles from tracking dirt, mud, and debris from all exit points of the project, onto any public street. Contractor shall use appropriate erosion control measures such as silt fencing and hay bales to prevent silt and debris from exiting the project site. It is the contractor's responsibility to erect and maintain the erosion control measures throughout the project. Should sufficient mud and dirt accumulate on public streets, it is the contractor's responsibility to install a washdown facility for the construction vehicles entering and exiting the site. SPECIAL CONDITIONS OF THIS PERMIT: 1) Erosion protection , in the form of silt screens , shall be installed in accordance with plans submitted and approved . In accordance with Chapter 13 of the Code of Ordinances of the City of College Station , measures shall be taken to insure that debris from construction , erosion , and sedimentation shall not be deposited in city streets, or existing drainage facilities. I hereby grant this permit for the construction of improvements as shown on the approved plans and construction both inside and outside the special flood hazard area. All construction shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the development permit ap ·cation for the above named project and all of the codes and ordinances of the Ci of College St tion that apply. Date Requirements for Final Drainage Report and Drawings Developement: So.,./4.,001; 5ec.. 2 ~ 8/0c.! /'/, LJ~R Permit #: ---:---- Developer: W11/./cl' Brc.J/~v submitted By: /'Jor/~ f5o.rJ,// 1 P.£ Address: / .302 A.,llSJ;,,( Cl. Address: RO. Bew t:Jz tl'/ Col .. 'ik. TX 778~ Cl.51,, IA' 778Yd2 > > Phone: Phone: Date Submitted: Date Reviewed: D. Final Drainage Report and Drawings 1. The purpose of the Final Drainage Report is to identify and define conceptual solutions to the problems which may occur on site reports and off site as a result of the development. All shall be typ ~on 8-1/2 " x 11" a er and bo ~ together. The report shall include a cover presenting the proposed design for review and shall be pr ~d by a Registered Professional Engineer lic ~d in Texas. The report shall(z rntain a certification she"€]) 1.s follows: "I hereby certify that this report (plan) for the drainage design of (Name of Develo pment ) was prepared by me (or under my supervision) in accordance with the provisions of the City of College Station Drainage Policy and Design Standards for the owners thereof." Registered Professional Engineer State of Texas No. (Affix Seal) 2. Report Contents The Final Draina ge Report shall be in accordance with the following outline an d contain the applicable information listed: a. General Location and Je s c r i ption (1) Location ~ Local streets development withi n and adjacent to Primar y Dra i.:.;:qe Sy stem drainageways facilities ~Names of surr ound ing developments 0 1 the and ... (2) Property Description of ~~ Acreage tL~ f' ..... ,/ '-·•~;_. llf'K .\o..-WH . ) Land cover .}"' "°"'"" 1 <-__ _,,,.,. c . ) Primary and Seconda ry System drainageways within the property DL9$CI; ,,_, :111 "l'°,J #fJ ~II'\ p/,t ~-----,1~.,;d.) General project descri ption b. Drainage Basins and Sub-Basins (1) Primary Basin Description ~ Reference to Primary Drainage System planning studies such as flood hazard delineation reports, and flood insurance rate maps. Primary Basin drainage characteristics. Secondary Drainage Basin Description -Discussion of offsi te drainage flow patterns, and impact of • development on existing and proposed pathways to Primary Drainage Sy stem. (<.Ct.'rs ..}, JL. c . Drainage Design Crite r ia C·J , ''[); . ~(l) Regulations -Discussion of the optional criteria 1 ys ""'~ selected or the deviation from the Standards, if Po !•c.y ,..,, ~.s1)'- ~.J.Js." any. (2) Development Criteria Reference and Constraints '' .J / ,,a .) Discussion of previous drainage studies for ""''ti\ .... o~#" . - c"';.) .J"''' ii ~ ~,_I. 'Z~ 'f_N ~°'"" ~°'i;o"-"'' HeJl.J (3) the site in question that influence or are influenced by the drainage design and how the plan will affect drainage design for the site. b.) Discuss ion of the drainage impact of site constraints such as streets, existing structures, and development or site plan. Hydrological Criteria ~ Identif y design rainfall ~ Identify runoff calculation method 6 Identify detention disc harge and calculation method, if any storage ~Identify design storm recurrence intervals N,~ ~*;/i•~ ""'iJL ~.;./i~ J,,,_ critH~. (4) e.) Discussion and justification of other criteria or calculation methods used that are not presented i n or Standards . referenced by the H ~raulic Criteria ~) Identify various capacity references /) Identify detention/retention outlet type, if a n y . c.) Discussion of other drainage facility design criteria used that are not presented in the Standards. d. Drainage Facility Design (1) General Concept 0" Discussion of concept and typical• drainage patterns v.) Discussion of compliance with offsite runoff co nsiderations t'J;"';n..,.I ~~ c.) Discussion of the content of tables, charts, figures, or drawings presented in the report d.) Discussion of drainage patterns. (2) Specific Details anticipated and proposed Noftt j,,.tLJ~J~ a.) Discussion of drainage problems encountered and solutions at specific design points ~Discussion of detention storage and e. outlet design, if any Discussion of maintenance access and aspects of the design Con_5J.-usions ~ Compliance with Standards of the City of College Station Drainage Policy and Design Standards ~ (2) Effectiveness of drainage design to control damage from stormwater flows rz. (3) Explanation of the effectiveness of existing and proposed improvements with regard to controlling the discharges of the 100 year storm with ultimate development conditions of the secondary system basins affected by the proposed development. E. f. g. References Reference all criteria and technical information used. Appendices (Where Applicable) (1) Hydrologic Computations a.) Land use assumptions '· properties re gardin g a djacent b.) Minor and major storm runoff at specific design points c.) Historic ~nd fully developed computations at specific design points d.) Hydrographs at critical design points (2) Hydraulic Computations a.) Culvert capacities b.) Storm s~wer capacity c.) Street capacity runoff d.) Storm inlet capacity including inlet control rating at connection to storm sewer e.) Open channel design f.) Detention area/volume capacity and outlet capacity calculations Final Drainage Report Drawing Contents 1. Sheet #1 -General Location Map that a. Depicts drainage flows entering and leaving the development site; b. Identifies major construction along path of drainage; c. Illustrates general drainage flow within entire basin; and d. Is drawn at a scale of l "=500' to l "=2000' . 2. Sheet #2 -Floodplain Information a. Copies of existing City of College Station 100-year floodplain maps showing the location of the subject development. .. . ' • , . • , ! ' 3. Sheet #3 Drainag e Plan Map(s) of the proposed development at a scale o f l "=20 ' to l "=200' on a 24" x 36" d rawing shall be i nc lud e d. The plan shall show t h e fo llowing : a . Exist ing an d pr o po s ed co n t o urs at 2-f e e t maximum i nterva l s . b. Propert y l i n e s, a n d e a s em ents wi th purposes noted. c . Stree ts . d. Existing dra i n ag e f a ci lit i e s, r o adside di t ches , draina gewa ys, g utter f l o w d irections, and culv e r ts . All pertinent i n fo rm ati o n such as material, s ize, shape, slope, and loc a ti o n s hall also be included. e. Overall drainage ar ea bo und ary and drainage sub-area boundaries. f. Proposed type o f st r eet f l ow, roadside ditch, and/ o r gutter flow dire c t io ns . g . Proposed st o rm sewer s an d o pen drainageways, includin g inlets, manholes, c ulv e r ts , a nd other appurtenances. h. Proposed outfall po in t fo r runoff from the dev e l op e d area and facilities to co nve y flows along the propos ed pathways to the f inal o u tfa ll points in the pr i ma r y drainage system wi th o u.t damage to downstream properties, or e xceeding the capacities of the receiving faciliti es as ~e f in ed in these standards. i . Routing and ac c umulat !.•J n )f f lows at various crit ical points for the min o r 5::r~ runo f f . j. Path(s) chosen '.·'r :a mp utation o f t i me-of- concentration. k. Details of dete n t i •J'.". ~ »: ~~ t. i o n storage facilities a nd outlet works. 1. Location and el e\· 1:: .-; affecting the pr o per : .. m. n. Location and el ev 3t:.:-.-; utilities affect ed b~ .. Routing of of fs i t.e development. n :; )f a ll defined floodpla i ns a ll e xisting and proposed 1::ect ing the drainage desi g n. :~J i nag e flow through the Mr. Ray Havens Electric Transmission & Distribution Superintendent City of College Station P. 0. Box 9960 College Station, Texas 77842 McCORD ENGINEERING, INC. 7607 Eastmark Drive, Suite 102 , P.O. Box 10047 College Station , Texa s 77842 (409) 764-8356 Fax (4 09) 764-9 644 September 27, 1993 Re: Bradley 4-Plexes Electric Service Dear Ray: As requested, we have prepared a proposed electric distribution layout to serve the Bradley 4-Plexes being constructed on Southwood Drive. Shown on the enclosed five (5) copies of our electric distribution layout for these 4-plexes are our recommendations regarding underground primary cable runs, transformer locations and sizes required, ganged meter locations, service installations , etc. A diskette has also been enclosed which includes this project electrical layout for your use . I 1 The electric system distribution layout for this complex has been planned to be installed I underground, as per the request of the Developer. Two (2) standard stock 50 kV A and two '1 (2) standard stock 37.5 kVA, single-phase , 7200 volts to 120/240 volt transformers are proposed to provide service to this apartment complex. Y ,, ; In accordance with the new policy of your City, the Developer is responsible for "" j / reimbursing your City for 20 % of the total estimated cost of electric service installation, ..-I including labor, materials, and the standard fee percentages for engineering and overhead cost. j We compute that the 20% cost contribution required for the Bradley 4-Plexes amounts to ! $1, 750.00. This cost was calculated based on a total electric service cost estimate of $8,750.00. The total electric service cost estimate developed for this project includes on 1· standard allowance of 30% to cover your City's labor related overhead costs, 7 % for material handling costs, and 8.5% to cover your City's administrative and engineering costs . I Please advise if you need further information on this matter. IDM/mw Enclosures cc: Mr. David Pullen (w/encl.) Yours very truly, Mer]"~ ENGINEERI~, INC. 0 ~ "1;), M L7J!. Jimmy D. ~cCord , P.E. President ~~~ ~ ~~<L . fJ1i~ WU<-~.~~ OOf w ~¥db ;<w.cl~~- v~(µ 0 MUNICIPAL DEVELOPMENT GROUP P.O. Box 9249 203 Holleman Drive East College St at ion Texas 77840 9249 , - (409) 693-5359 Sh1rl-ey Volk CIT'( or ( ol!eq< S+1rh oVJ WE ARE SENDING YO U ~ Attached D Under separate cover via D Shop drawings D Prints oo' Plans D Copy of letter D Change order D COPIES DATE NO . llAT·« IJ °-;__~~-ZI~ I b ~£Pt"'"""\\(?.,' 11?~ ATTEN T I O N RC : C:::.1 I ~ ~~~ -,,,. \ Ol/ D Samples the ?'ing item" Specifications !/ DESCR IPTI O N f!P'i IS I b Sep~""\:.u ffB i-mq-1...7<& .fSrz A f'l LEY <;,, Rf")i• .,c;""" : f'Fl.n>">oSCO Wf\-TER Al.I"' sr::1 .• ~., T""""0 ~. --·rvr..S THESE ARE TRANSMITIED as checked below : ~ ,.31 For approval D For your use D As requested D For rev iew and comment ·o FOR BIDS DUE REMARKS D Approved as submitted D Approved as noted D Returned for corrections D 19 D Resubmit __ copies for approval D Submit __ copies for distribution D Return __ corrected prints 0 PRINTS RETURNED AFTER LOAN TO US COPY TO j ,/ cC/· /J --------SIGNED: ~~ It encloaurH •r• not •• noted, lr indly notify ue •t one•. --- ---- ------- Veronica Morgan Assistant City Engineer City of College Station, Texas North Bardell Municipal Development Group 203 Holleman Drive East College Station, Tx 77840 September 22, 1993 Re: F i re Flow calculations for Bradley Apartments (Lot 38R, Block 14, Southwood- Section 25) Veronica Morgan: Below find the head loss (p.s.i.) figure for the pipe run leading to the proposed fire hydrant shown on sheet 1 of 6 of the plans for the Bradley Subdivision. These figures were taken from a nomograph representing the Hazen-Williams formula using a coefficient of roughness of .017. This coefficient gives a factor of safety as it represents flow in cast iron pipes and would be less in the specified P.V.C. pipe. (We use this coefficient because of t!_le j fSt previously installed pipe condition§ being somewhat unknown). . 1 ~_a, N O u ;._ -r rr:r,J cl' ~ h~~~::J-,t:J.~~~1° J (1 tr; ~ ~j)ol e .. {,./f1e. t @ rM r1--a~s ~ z4~ {)(\ r 1'f.,'1,, • , ~ 11"'l 11 <7 I · '~ (Jdllt>f'Waf(? flJ!.1 VG t-I Head loss from pt. 1 to pt. 2 @ 1200 g.p.m. flowrate 175 ft/1000 x 55 ft. x .43 p.s.i./ft. = 4.13 p.s.i. Head loss from pt. 2 to pt. 3 @ 1200 g.p.m. flow rate 175 ft/1000 ft x 130 ft. x .43 p.s.i./ft. = 9. 7 p.s.i. Total head loss from supply line = 13.83 p.s.i. Indicated Residual Pressure in 8" Supply line at fire flow conditions = 50 p.s.i. Assumed residual pressure at proposed hydrant = 50-13.83 = 37.17 p.s.i. Sincerely, ~13~ North B. Bardell ~r MUNICIPAL DEVELOllMJ~N'I' GROUP ENGINEERlNC, PLANNING, SURVEYING ----~·-·-----· -----···-----~--·- • DATE 9. J''Z -7 3 FAX NO. 7 C,, 'l_ --~-<f.._2-'.t__._ NO. PJ\(1J.:S TO FOLLOW _ _L_~ l (I• d TO ·------- lf the1·e i:-; a pro )le/II with this trnnsmi.<;sfon, plt><l.'Sc ('<Jll 11s 11t 40a-693--.S:J5fl, CONFIDE:-iTIALlTY NOTICE: This fac:;imifo mt.'.'>sage t-tnd aer~o111p..:ill} l" commlinir.atiou ancl/or clot·1rnwnts ar·p intE-·11<frd for· tht• t:.·dw>ive mid < rmf1 '"nt · use of the in di vidiwl or entity to w hkh the lllP.!;.-agP i~ ;1dcfr e:;:;ed. COMMEN'I'S~--~------ ~-------------~~~~----~~----------------- --.-.. --.-·~-·.··--- -------~-·~-~------ MU NICIPAI. DE\ ELOPM ENT CROlJP 203 lfoll(>111<t11 J)dvt' E~i:-;l Collc!Je S l:.\ llon. TX 778 to TEL (409) CD3-5350 FAX (400) COJ-4243 ,. ,.1 • • z.0 • d Estimated Water and .,~~wer Loadings for the Bradley Subdivision Domes'tic Water: 400 g.p.d ./unit x 24 units = 9600 g .p .d • 9600 g.p.d. = 6.67 g .p.m . average flow Peak Flow = 3.0 x average ;:; 20.01 Irrigation Water: 10± g.p.m. at peak '.fotal_Peak _W~ter ~snand = 30.01 R'..!.E.tl!l..!. Sanitary Sewage: 392 g.p.d./unit x 24 units : 9408 g.p.d. Peak Flow = 2.25 x average ;;: 21.168 g.p.d. DEVELOPMENT PERMIT PERMIT NO. 0201 FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 38R, Block 14, Southwood Sec 25 SITE ADDRESS: 2100 Southwood Drive OWNER: Walter L. Bradley 1302 Augustine Ct. College Station, Texas 77840 DRAINAGE BASIN: Bee Creek TYPE OF DEVELOPMENT: This permit valid for the grading, dirt work, and construction of the Bradly Subdivision slab only. All construction shall be in accordance with the plans submitted. Contractor shall prohibit all debris from construction including dirt and silt, from entering public streets and drainage facilities. Contractor shall be responsible for any damage to existing streets, curbs, or public infrastructure due to the construction activities. Contractor shall prevent construction vehicles from tracking dirt, mud, and debris from all exit points of the project, onto any public street. Contractor shall use appropriate erosion control measures such as stltfenctng and hay bales to prevent silt and debris from exiting the project site. It ts the contractor's responsibility to erect and maintain the erosion control measures throughout the project. Should sufficient mud and dirt accumulate on public streets, it is the contractor's responsibility to install a washdown facility for the construction vehicles entering and exiting the site. SPECIAL CONDITIONS OF THIS PERMIT: 1) Erosion protection, in the form of silt screens, shall be installed in accordance with plans submitted and approved. In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage facilities. I hereby grant this permit for the construction of improvements as shown on the approved plans and construction both inside and outside the special flood hazard area. All construction shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the development permit a cation for the above named project and all of the codes and ordinances of the C of College Station that apply. DRAINAGE REPORT FOR LOT 38R, BLOCK 14, SOUTHWOOD -SECTION 25 PREPARED FOR: Walter Bradley 1302 Augustine CT. College Station, Tx. 77840 PREPARED BY: Municipal Development Group P .0. Box 9249 College Station, Tx. 77842 Approved by North Bardell, P.E. TABLE OF CONTENTS I. General Location II. Property Description III. Drainage Basin Description IV. Drainage Facility Design V. Runoff Calculations A. Creek Drainage B. South wood Drainage VI. Conclusions VII. Proposed Detention Facilities LIST OF FIGURES 1. Figure 1: Site Drainage Plan 2. Figure 2: Drainage Area Map 3. Figure 3: Storm Volume Hydrograph 4. Figure 4: Storm Volume Hydrograph (Creek Drainage) (Southwood Drainage) LOCATION OF STUDY SITE Gen e ral Lo ca tion: The subject tract is Lot 38R, Block 14 of the Southwood Section 25 Subdivision of the City of College Station. The tract is positioned on the west side of Southwood Drive, approximatel y one block north of F~t 2818 (West Bypass). The Valley View Drive-Southwood Drive intersection is across from this tract, and it will allow a joint intersection wi th the proposed street serving this tract. Propertv Description: Lot 38R, Block 14 of the Southwood Section 25 Subdivision of the City of College Station is a total of 2.78 acres. The land is currently unimproved grass, weeds, and trees in its natural state. It is rolling in nature, with elevation variation from 286+ down to 272-. The 100-year flood plain encroaches approximately .008 acres on the southwestern corner of the tract at an elevation of approximately 270.50 feet. Approximately one quarter of the tract (the most easterly) drains in a sheet-flow manner over the existing curb onto Southwood Drive. The remaining three quarters of the tract drains onto surrounding properties, with most of the area (95%) draining into a defined channel on the most westerly end of the tract. In addition, this tract currently drains the neighboring lots (Lots 390 and 39E) through a concrete head wall located at the southern portion of the tract. Drainage Basin Description: The subject tract is located in Basin #5 of the Bee Creek Primary Drainage System on Tributary "B" confluence, and thus requires detention facilities for a 25-year ultimate rainfall. (See Page 10 of the City of College Station "Drainage Policy and Design Standards"). .008 acre of the tract, or proposed construction thereon, is within the FEMA established flood plain (elev. 269.5). Drainage Facility Design: There is no proposal to change the existing drainage patterns, as they currently create no flooding problems or hazards to surrounding properties. The proposed development on this tract will add approximately 44,680 square feet of impermeable roof, street, parking lot, or sidewalk surface area. The increased runoff due to this impervious area will necessitate the provision of two detention areas. The first detention area will be situated north of the s outhern depressed area of the tract which currently drains Lots 39D and 39E. This d e pressed area (.1063 acres) will be left in its natural state in order to keep exi s ting drainage conditions which currently does not pose a flooding threat. This bermed detention area will be located at the western end of the tract wi th a control outlet wh i ch will detain the projected increase in runoff calculated for a 25-year frequency rainfall. A se c o n<l <letention ar e a will be located al the northwestern parking area. This area wi ll detain the projected increase in runoff calculated for a 25-year 'frequency rainfa ll. A curb cut will be located at the western end of the parking lot, which will drain water in a sheet-flow manner onto Southwood Drive. 000278-C.02-04(2270) RUNOFF CALCULATIONS I. Drainage to Creek A. Pre-Deve lopment Descriptio n Grassland B. Post-Development Desc ription bui ldings sidewalks access drive & parking landscaped area Area 2.079 Area - 0.211569 0.014091 0.59656 1.27 2.079 c 0.35 c -- 0.9 0.9 0 9 0.35 (c)(Area) 0.72765 (c)(Area) 0.190412 0.012682 0.536904 0.4445 1.184498 Useful c = 1.184498/2.079 = .566 *** Use Tc = 1 0 minutes *** C. Runoff Q=clA Qpre = 1(.35)(2.079) = .72765(1) Qpost = 1(.566)(2.079) = 1.1767(1) Storm F re . lntensit . re ost 5 7.7 5.603 9.061 10 8.6 6.258 10.120 :::::::::::::::::::::::2 :s ::::::::::::::::::::::::::i:::::::~;:#:::::::::):::::::t ~:¢:w.::::::~::::::::r:J.;~:4:s.::::::: 50 11.1 8.077 13.061 100 12.6 9.168 14.826 Projected allowab le rate of release from detention = 7 .2 c.f.s. Storage Volume Hydrograph Drainage to Creek Figure 3 12.,.--------------------. 10480.5 c.f. 10 .................................................................................................................................................................................... . Req. Detention = 4000 c.f. 8 ··································································································· .................................................................................... . 0 --. 0-r-------r----~----~ 0 10 20 30 Time (min) II. Drainage to Southwood A. Pre-Development Description Area c {c}{Area} Grassland 0.7 0.35 0.245 B. Pos t-Deve lopment Description Area c (c)(Area) buildings 0.0827 0.9 0.07 443 sidewalks 0.0058 0.9 0.00522 access drive & parking 0.0827 0.9 0.07 443 landscaRed area 0.424 0.35 0.1484 0.5972 0.30248 Useful c = 0.30248/.597~ = .506 **** Use Tc = 10 minutes •••• C. Runoff Q=clA Qpre = 1(.35 )(.7) = .245(1) Qpost = 1(.506)(.5972) = 0.302(1) Storm F re . lntensit re ost 5 7.7 1.887 2.325 10 8.6 2.107 2.597 ::1::::::u::::::::::~:s :::::::;:::::~:::::::/::::::::::$.~:~::::::::::::::::::::2 :1 ~i:~:::::::::::::::::~:;$.~o :::::::: 50 11.1 2.720 3.352 100 12 .6 3.087 3.805 Projected allowable rate of release from detention = 2.43 c.f.s. Storage Volume Hydrograph Drainage to Southwood Figure 4 3-.--~~~--~~~~~~~~~~ 2690.82~ 25 ....................................................................................................................................................................................... . · -426 Req. Detention = 500 c.f 2 .................................................................................................................................................................................... . 2182.95 1 ........................ ············································································································· ................................................ . 0.5 ................................................................................................................................................................................... . o-r-~~~-------,~~~~-,-~~~~~ 0 10 20 30 Time (min) CONCLUSIONS With the use of the Rational Method for the calculation of runoff quantities for the drainage to the creek and to Southwood Drive, it can be seen that a maximum pre-development runoff rate for the creek is 7.2 c.f.s. The maximum pre-development runoff rate of 2.43 c.f .s. exits for runoff to Southwood Drive. A weir having a cross-section of 6 inches by 3 feet will provide a discharge rate that will simulate a pre-development runoff at a rate of 7.1 c.f.s. for the planned drainage to the creek: Q = 1.49 AR111 s If! n Q = 1.49 (12.5)(.71428)2/J(,005)111 .015 Q = 7 .1 c.f.s. Velocity = Q/ A v =. 7 .1 1.25 V = 5.68 ft/sec In the northwestern parking area, a flume having a section of 2 feet by 0.5 feet will provide a discharge of 2.27 c.f.s. which is similar to the pre- development runoff rate of 2.43 c.f.s.: Q = 1.49 AR!/J S 111 n Q = 1.49 (1)(.3333)!/J(.00227)111 .015 Q = 2.27 c.f .s. Due to the infinitesimal difference between pre development and post development flow rates, water will be allowed to drain in a sheet like manner onto Southwood Drive. Proposed Detention Facilities Bermed Detention Area The enclosed site drainage plan depicts this detention facility in the southern portion of the subject tract. This facility will provide a capacity of approximately 4700 cubic feet of storage space which satisfies the requirement of 4000 cubic feet. The centerline grade to the weir will be at .51% in order to maintain a volumetric flowrate of 7.1 c.f.s. which is comparable to the pre- development flow rate. The outlet structure to the bermed area will utilize an 18 inch RCP in order to balance inlet and exit flows. Northwestern Parking Area The enclosed site drainage plan depicts this detention facility in the northwestern portion of the subject tract. This parking area is designed to provide 500 cubic feet of storage space which is the projected requirement for a 25 year frequency storm. The flume is designed to have a volumetric flowrate of 2.27 c.f.s which meets the requirements of predevelopment flow. A 5 foot by 5 foot block of sod will be provided in order to keep erosion at a minimum and to convert the concentrated stream into a wider flow pattern which will sheet flow onto Southwood Drive.