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Home My WebLink About38 Development Permit 604 Quality Assurance BrakesDEVELOPMENT PERMIT PERMIT NO . 604 Quality Assurance Brakes FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA RE : CHAPTER 13 OF THE COLLEGE STATION CITY CODE SITE LEGAL DESCRIPTION: Lot 6-12, Block 1 Brentwood Subdivision OWNER: CCG Venture Partners 14450 T .C. Jester Blvd. Houston, Texas 77014 (281)893-8331 DRAINAGE BASIN: Wolfpen Creek SITE ADDRESS: 109 Brentwood Drive TYPE OF DEVELOPMENT:This permit is valid for the construction of the site for the Quality Assurance Brakes. The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate construction site in accordance with the approved erosion control plan as well as the City of College Station Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion control. The Owner and/or Contractor shall also insure that any distwbed vegetation be returned to its original condition, placement and state. The Owner and/or Contractor shall be responsible for any damage to adjacent properties , city streets or infrastructure due to heavy machinery and/or equipment as well as erosion, siltation or sedimentation resulting from the permitted work. Any trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before any operations of this permit can begin . 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 development of an area outside the special flood hazard area. All de opment shall be in accordance with the plans and specifications submitted to and approved by the ngineer in the development permit application for the above named project and all of the codes and ances of the ty College Station that apply. Date Contractor Date FOR BRENTWOOD SUBDIVISION BLOCK ONE, SECTION ONE, LOTS 6 -12 0.603 ACRES COLLEGE STATION, BRAZOS COUNTY, TEXAS AUGUST, 1998 REVISED: SEPTEMBER 11, 1998 REVISED : SEPTEMBER 25, 1998 MUNICIPAL DEVELOPMENT GROUP I l!4 I •I!J 2551 TEXAS AVENUE. SOUTH , STE . A COLLEGE STATION, TEXAS 77840 Ph : (4 09)69 3-5359 Fx: (4 09) 693 -4243 ~Consu lting Engineers · Environmental · Surveyors· Planner s Brentwood Subdivision, Section One Drainage Report DRAINAGE REPORT Municipal Development Group TABLE OF CONTENTS PROJECT SUMMARY ................................................................................................ 3 DRAINAGE AREA DESCRIPTIONS .......................................................................... 3 DRAINAGE CALCULATIONS ................................................................................... 4 RESULTS ..................................................................................................................... 4 DRAINAGE MAPS & DETAILS SECTION #1 -DRAINAGE AREA: PRE-DEVELOPMENT SECTION #2 -DRAINAGE AREA: POST-DEVELOPMENT SECTION #3 -DRAINAGE AREA HYDROGRAPHS 2987-000 129 Drainage Report.doc Drainage Report -2 Brentwoo d Subdivi sion, Sec tion One Dra in age Report PROJECT SUMMARY Muni cipa l Development Gro up This report outlines the drainage plan for the Brentwood Subdivision, Section One 0 .603 acres . The subject property site is situated on the north side of Brentwood Drive approximately 200 linear feet east of the Texas Avenue and Brentwood Drive intersect ion and adjacent to the existing Dairy Queen. The development is established within B lock One of Brentwood and consisting of Lots 6 through 12 . This t ract generally slopes to the south with a grade of approximately 1.33% being fairly uniformly distributed . The site is currently vacant and unimproved with native grasses, weeds, small brush and several small trees . The natural drainage of the site is by sheet flow to the south and on to Brentwood Drive . Runoff is then collected into an exist ing 36" CMP storm sewer drainage structure. This site is in the Bee Creek sub-drainage basin, which is a part of the Carter Creek drainage basin . Since the current topography allows the entire property to drain onto Brentwood Driv e and thence int o the existing storm sewer, which has no unused capacity, it will be necessary to provide for detention . Detention will provided for the necessary storage of runoff to ensure that the discharge from the site will be equal to or less than the pre- development runoff discharge . This design is further illustrated and explained in the section, "RESULTS ". DRAINAGE AREA DESCRIPTION The pre-development drainage area consists of 0 .603 acres of land . The post- development drainage area will consist of the same site and total acreage , but runoff coefficients will change due to the development. Impervious areas will be introduced by t he 3,77 2 square foot building and from the concrete parking area and driveway . The tot al impe rvi ous area will be 0 .370 acres . Runoff from t he bu ilding ro oftop will be ch ann eled into the proposed parking lot . F rom there, runoff collected in the parki ng lot and into the proposed detention pond located at the southwest comer of the property . The 2987-000 129 Drainage Report.doc Drain age Report -3 Brentwood Subdi vision, Section One Drainage Re port Muni ci pal Development Group provided detention areas will exceed the required storage amount. The restricting orifice for discharge will be the proposed grate inlet constructed in-line with the existing storm sewer. DRAINAGE CALCULATIONS The drainage calculations are presented in three basic sections : I. Drainage Area: Pre-Development -Contains the calculations for the amount of runoff prior to the development of the site . II . Drainage Area: Post-Development -Contains the calculations for the amount of runoff after the proposed development. ill. Drainage Area : Hydrographs -Graphical representation of the volume of water that is detained on the site . The drainage area calculations are summarized accordingly using the Rational Method : (Q=CIA) where "Q" is the runoff in cubic feet/second , "C" is the runoff coefficient, "I" is the storm intensity in inches/hour for each selected frequency, and "A" is the drainage area in acres . We will assume a minimum ten-minute time of concentration for all calculations. The selected frequencies will be 2, 5, 10, 25, 50 , 100-year rainfall events . Tabulations of the pre-development and the post-development hydrographs of the drainage areas are provided . The hydrographs are based on the standard SCS unit hydrograph with time to peak discharge set to equal the time of concentration and the total base time set at 3 . 00 times the time of concentration . Grate flow calculations were determined from the following orifice flow equation (Q = CA(2gh)112 ), where "C" is the orifice coefficient, "A" is free-open area in ft 2 , "g" is constant at 32.2 ft/sec2 , and "h" is the head , in feet , on the grate. RESULTS 2987-000129 Drainage Report.do c Drainage Report -4 Brentwood Subdivision, Section One Drainage Report Municipal Development Group From the drainage calculations the following results were determined : + Detention Calculations : The required detention required during the 100-year rainfall event has been calculated to be 2,495 ft:3 . Detention provided for in the proposed parking lot is at 1,028 ft 3 . Therefore, the remaining detention required is equal to 1, 467 ft 3 . Since this detention will be stored in a pond an additional I 0% of volume will be required for sedimentation to bring the total volume to 1,614 ft 3 . The detention pond proposed will contain a volume of 1,930 ft 3 allowing for the required storage and the addition 0.5 ' of freeboard . + Proposed Grate Inlet : The proposed detention pond will be drained by a grate inlet placed inline with the existing 36" CMP storm sewer. The grate inl et will have a capacity of 2 .265 cfs with one and a half-foot of head during the 100-year rainfall event. A Neenah grate model R-1879-AlG or approved equal will be used. Once the grate size and free-open area was determined for the I 00-year event , all other storms water depth was back calculated with the free-open area and its pre-development discharge rate. Next the comparison was made between the required calculated depth and the actual water depth in the detention facilities . As shown all storms (except for the 2-year) actual water depths were less than the calculated depths . Therefore , the actual discharge rate during those storms will be less than the pre-development discharge rate . 2987-000129 Drainage Report.do c Drainage Report -5 Brentwood Subdivision, Section One Drainage Report GIVEN Capacity= Grav ity , g = Actual Water Depth = Capacity= Gravity, g = Actual Water Depth = Capacity= G ravit y , g = A ct ual Wate r Depth = Capacity= Gravity , g = Act ua l Water Depth = Capacity= G ravity , g = Actual Water Depth = Capacity= Gravity, g = 2987-000129 Drainage Report.doc Municipal Development Group GRATE INLET CALCULATED (2-YEAR RAINFALL EVENTI 1.231 cfs Depth= 0.44 ft FT Free-open A rea = 0.38 ft2 32 .2 f sEC 0 .54 ft -(5-YEAR RAINFALL EVENTI 1.497 cfs Depth= 0.66 ft FT Free-open Area = 0.38 ft2 32.2 fs EC 0.65 ft (10-YEAR RAINFALL EVENTI 1.680 cfs Depth= 0.83 ft FT Free-open Area = 0.38 ft2 32.2 fsEC 0.73 ft (25-YEAR RAINFALL EVENTI 1.919 cfs Depth= 1.08 ft FT 32 .2 f sEC Free-open Area = 0.38 ft 2 0.84 ft ~ (50-YEAR RAINFALL EVENTI 2 .169 cfs Depth= 1.38 ft FT 32.2 f sEC Free-open Area = 0.38 ft2 0.94 ft -(100-YEAR RAINFALL EVENTI 2 .265 cfs Depth= 1.50 ft FT 1.Free~e~h .Are~ = o;38 «:.~;·mii'· .. ··-32 .2 f sEC ... Drainage Re port -6 DRAINAGE MAPS & DETAILS fENT!ON REQUIREMENTS ~·o VOL. = 2 495 cuft 'JV. VOL. = 2 958 cyft Porki09 Lot = 1,028 cult • d = 1,930 cuft rd > 0 .5 ft 25' Front Building Line 20 LF. EROSION CONTROL ,., 11 I! I I PROPOSED 4' CONCRCTE PILOT CHANNEL SEE DETAIL THIS SHEET BRENTWOOD DRIVE (70' R.0.W .) ARE4 El<ISTING CURB TO BE CUT & MATCH EXISTING PAVEMENT GRADE \ EXISllNG 8" V.C.P. SANITARY SEWER \ 1__ k_ ~---_" _____ i· ___ •• ___ s· ---" - GRADING Pwt 1"=20' 25' Front Building Line s· -II PROPOSED .-n .'"x 1'2. GRATE INLET MODEL. ~-:-J.e."l}\-:;..,.A l.Q AS MANUFACTURED BY NEENAH OR APPROVED EQUAL . #4 BARS @ 1 SIDE W 4 . 5' ... 4 .. ~- . :. ... • : ... . ·.• ·. ·-.. 4 --· . ... - ,.#· .. - . •. A .... -4..4 . _.d • . . .. •.. .d .a . · ..... 4 . ·• .. ·. #4 BARS @ 6" O.C.E .W. TOP & BOTTOM ELEVATIO N GRATE INLET DETAIL N.T.S. EXISTING 36" CMP STORM SEWER @ 1 .09% SLOPE EXISTING 36" CM P STORM SEWER @ 1.093 SLOPE R-1878 Series Frames Heavy Duty Lids, Grates These shallow frames are suitable for use in thin or deep con- crete slabs. All sizes of frames are reversible and can be installed with flange at base or to p . S1-1ecify : 1. Catalog number . 2 . To be i nstalled with flange at base or top. Square Di mensions in in che s Catalog Number A B c D E F Solid lid I Open Grate R-1878-A 1l R-1878-AlG 13 34 x 1334 lY2 12 x 12 14 x 14 18 x 18 4 R-1878-A2l R-1878-A2G 18 x 18 1'h 16 x 16 18V..x1 8 V.. 22 x 22 4 R-1878-A3l R-1878-A3G 20 x 20 l Y2 18 x 18 20'4 x 20 '4 24 x 24 4 R-1878-A4l R-1878-A4G 21Y.x21Y. l Y2 20 x 20 22 x 22 26 x 26 4 R-1878-ASl i R-1 878-ASG 23 Y2 x 23Y2 1 Y2 22x 22 24 x 24 28 x 28 4 R·1878-A6l I R-1878-A6G 25Y. x 25Y. 1 Y2 24 x 24 26 x 26 30 x 30 4 R-1878-A7l , R-1878-A7G 27 Y2 x 27% 1 Y2 26 x 26 28 x 28 32 x 32 4 R-1878-A8l : R-1 878-A8G 29Y2 x 29 Y2 1 Y2 28x 28 2934 x 2934 34 x 34 4 R-1878-A9l I R-1878-A9G 3134 x 3 ]34 l Y2 30 x 3 0 32 x 32 36 x 36 4 R-1878-A 1 Ol *! R-1878-A 1 OG • 37 x 37 1 Y2 36 x 36 37% x 37 Y2 42 x 42 4 Rectangular R-1878-B 1 l I R-1878-BlG 14 x 20 1% 12x 18 14'4 x 20'4 18 x 24 4 R-l 878-B2l R-1878-B2G 13 Y2 x 25% 1 Y2 12 x 24 13 34 x 2 5 34 18 x 30 4 R-1878-B3l R-1 878-B3G 19Y2 x 25 Y2 1 Y2 18 x 24 19 34 x 2534 24 x 30 4 R-1878-B4l R-1878-B4G 19Y2x3 1Y2 1 Y2 18x 30 20 x 32 24 x 36 4 R-1878-BSl R-1878-BSG 1934 x 37 34 l Y2 18 x 36 20 x 38 24 x 42 4 R-1878-B6l R-1878-86G 25 Y2 x 31 Y2 1 Y2 24 x 3 0 25 34 x 31 34 30 x 36 4 R-1878-B7l R-1878-B7G 25 Y2 x37 Y2 1 Y2 24x 36 26 x 38 30 x 42 4 R-1878-B8l * R-1878-B8G * 25 34 x 4934 1 Y2 24 x 48 26 x 50 30 x 54 4 R-1878-B9l * R-1878-B9G * 3 l34 x 37 34 l Y2 30 x 36 32 x 38 36 x 42 4 R-1878-B 1 Ol * R-1878-B lOG * 3 1V2x49Y2 1% 30x 48 3H4 x 4934 36 x 54 4 *Cover in two pieces. G 1 x5Y2 1Y.,x4Y., 1 15/,. x 3:i.il 1Y.x3 Y2 1Y2x6Y2 2Ysx7 Y., lx5 l l-fl x5 Y2 l x6:i.il 1Y.x3Y2 Y.x5 Y2 1 x4 Y2 r's x 5 2x5 2x5 1Ysx5 l :i.il x 5 l5!i.x6 '31i• 1:Yax 4 ¥a 1Y2 x 4 :Y. R-1 879 Series Fra m es Li gh t Du ty Li d s, G ra t es These sh allow frames ore suitable for use in thin or deep con- crete slabs. All sizes of frames are reversible and can be ins talled with flange at base or t op. Specify : 1. Catalog number. 2 . To be installed with flange at base or t op . Square Dimensions in inches Catalog Number A B c D E F Solid lid Open Grate R-1879-AlL 'R-1879-AlG 13 34 x 13 34 1 Y2 12 x 12 14 x 14 18 x 18 4 R-1879-A2l R-1879-A2G 18 x 18 1 Y2 16 x 16 18 V..x18 V.. 22 x 22 4 R-1879-A3l R-1879-A3G 20 x 20 1 Y2 18 x 18 20 '!.s x 20 '4 24 x 24 4 --R-1879-A4G 21 Y.x2-1"¥.-Tv; 20X-20 26 x 26 4 R-1879-A4l 22 x 22 R-1 879-A5L R-1879-A5G 23 )/:z x 23V2 1 Y2 22 x 22 24 x 24 28 x 28 4 R-1879-A6L R-1 879-A6G 25 Y. x 25Y. 1 Y2 24 x 24 26 x 26 30 x 30 4 R-1879-A7l R-1 879-A7G 27 V2 x 27 Y:z 1 Y2 26 x 26 28 x 28 3 2 x 32 4 R-1879-A8l R-1 879-A8G 29 Y. x 29Y. 1 Y2 28 x 28 2934 x 2934 34 x 34 4 R-1879-A9L R-1879-A9G 31 Y.x 31Y. 1 Y2 30 x 30 32 x 32 36 x 36 4 R-1879-A 1 OL • R-1 879-AlOG * 37x37 l V2 36 x 36 37% x 37 V2 42 x 42 4 Re ctangular R-1879-B 1 l I R-1 879-B 1 G 14 x 20 h V2 12 x 18 14 14 x 20 '!.s 18 x 24 4 R-1 879-B2L R-1879-B2G l 3 V2 x 25 % h \2 12 x 24 13 ~· x 25 34 18 x 30 4 R-1879-B3L I R-1879-B3G l 9 V2 x 25 \2 h V2 18 x 24 1934 x 25 34 24 x 30 4 R-1879-B4L R-1879-B4G 19 Y2 x 31 % h y, 18 x 30 20 x 32 24 x 36 4 R-1 879-BSL R-1879-B5G 1934 x 3n• h y, 18 x 36 20 x 38 24 x 42 4 R-1 879-B6L R-1 879-B6G 25 Y2 x 31 Y2 h Y2 24 x 30 25 34 x 3 ]34 30 x 36 4 R-1879-B7l R-1879-B7G 25 34 x 3n4 V2 24 x 36 26 x 38 30 x 42 4 R-1 879-B8L • R-1879-B8G * 2534 x 49l, n Y2 24 x 48 26 x 50 30 x 54 4 R-1879-B9L • R-1 879-B9G * 3 ]34 x 37 3/.i h Y2 30 x 36 32 x 38 36 x 42 4 R-1 879-B 1 OL • R-1879-Bl OG * 31 V2 x 49 V2 n\12 30 x 48 3H4 x 493/.i 36 x 54 4 ~cover in two p ieces. G 1x3 y. x 4 % Y.x 5 y. x 4 Y.x6V2 lx5 y. x 7 ¥8 1Va x511,. lx4 Y. 1x4'l's Y. xS Y:z ¥-x 4 V2 Ysx5 V. y. x 5 1Yax 5 l x 5 Ya 1 x S Vs Y.x 5 Ya l x6 V2 1x5 Wt Lb s w/ w/ H li d gra te 1 130 115 1 180 170 1 220 210 1 235 220 ¥< 2 65 300 y. 330 280 1 370 325 1 415 485 1 470 465 1Y2 790 700 l 185 160 1 220 185 1 245 240 1 285 249 1 365 295 1 385 360 1 460 425 1 510 575 l 500 515 1 695 680 Wt. Lb s. w/ w/ H lid grate 1 1 15 100 :v. 165 150 :v. 195 185 :v. 200 185 y. 235 255 y. 245 215 y. 290 260 1 340 390 y. 360 310 1 485 445 l 185 160 l 165 180 l 210 195 1 230 215 1 295 310 y. 290 260 ~ y. 335 295 l 395 405 l 400 380 1 480 425 R-1878-ASL Manhole Frame and Solid Lid 'IN4~:b • ----1 I ~------· - • Heavy Duty R-1 878 Sections R-1879 -B 1 G Catch Basin Grate and Frame ----·---...; I ~·;·1~ A&H=-:~ I • ' ·---- Light Duty R-1879 Sect ions ., I i ! SECTION#! DRAINAGE AREA PRE-DEVELOPMENT SECTION #1 DRAINAGE AREA -PRE-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site before development. Drainage Area (A PRE) = 0.603 acres TIME OF CONCENTRATION CTcl GIVEN Maxi mum T rave l Distance (D PRE) Velocity of Runoff (VPRE ) = Coefficient of Runoff (C pRE) = 215 ft ft 0.75 f sec 0.32 **NOTE: Minimum Tc allowed = 10 min . 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .806 Coefficient (b) = Coefficient (d) = 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coeffic ient (e ) = 0 .785 Coeffi cient (b) = 76 Coefficient (d) = 8 .5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coe ffi cient (e ) = Coe ffi c ient (b) = Coefficient (d) = 0 .763 80 8 .5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .754 Coefficient (b) = 89 Coefficient (d ) = 8 .5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e ) = Co effi cient (b) = Coe ffi c ien t (d) = 0.745 98 8 .5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .73 Coefficient (b) = 96 Coefficient (d ) = 8 2987-000129 Detenti on Facilities Evaluati on.xis RESULT Tq PRE) = 4 .8 min. Rainfall Intensity (1 5) = 7 .693 i%r llJ.a:•: : tI : :::.::::.•••• ••• I:::.:.::::~:~gi l•l li.:.·:.: Rainfall Intensity (1 10) = 8 .635 in/hr :_•_ra.··.:.'_:_•_·.=_=.~.k.•.•.•.=.•.:.:.:.·.•.•• •• • ?• • • • = == = ====•=== • • • ::u11110.ai.s>:: ., "· . . . . . . . . . . . . . . . . . . . . . . . . . . . ~trrr )i/ ·=·=·=·=·=·=·=·=·:·:·:·=<·=·=-=·=·:·:·=·=·=·:·=·:·:-:-:-:·:·=·=<·=·>=·=·=·>=·: Rainfall Intensity (1 25 ) = 9 .861 in/hr •.a,.· .. ·,_:,._·,·.=,~_·=.~.··=_:.•.·.'.,',~ .. =,.· .. •,· .. =_ ... ,...,...,...,...,...,.:::::?•?•?•""•=•=•======· .•.•.•.•.•.•.•.•.•,•.•,•.•,•.•,•.•,•.•,•.•,•.•,•.•,•.•,•.•.•.•.•.•,• .•.•.•.•.1.•.·.=_:.~.•.•.1.=_·.=_·.=_1.•.·.=_·.:_1.=_·.=_:.•.•.•.•.•.c.'.=.•.=.1.=.=._·.s.'.'.'.'.:.:_•.•.•.·.J.•• ~Jill ::::::::::::::::::::::::::::::::;:;:;:::::::::::;:;:;:::::;:;. Rainfall Intensity (1 50 ) = 11 .148 i%r -l~ij•ffi• ....... •••••·•·•••·•••••••••••••• •••••.• • •:•=••. • •••• g~11~ it~t ? Rainfall Intensity (1 100) 11 .639 in /hr =_.=,.a.=,·_=,:_=,=_=,~_:•.·• ..... •·.••.'.".•'.·'.•,.= . .=,• .. ·,.= .. •,.= .. ·,•.:,".",='.••,;_:•.==.• 1n•)( ··•=:::::=•=•=•=•=•=•=•=•=•=•=•=•=::::::::•= .=••.•.•=.'•.'•.·•-••.••.• ... 2i.·.•···.·.·.:.2.•.·····.•.s.•.·.·.·.•.1.=.·.•.·•.•·.•~.··.=·.==.·•.•s.'.'.·.•·•.•= .• :•.•.rn.·=•=• :~ =·=:=:=·=·=:::::::::::::::::::::·:;:;:::::::::::::::::::::::::·:-:-:- SECTION#2 DRAINAGE AREA POST-DEVELOPMENT SECTION #2 DRAINAGE AREA -POST-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site after development Drainage Area (A1) = 0.370 acres (impervious area) Drainage Area (A~ = 0.233 acres (landscaped area) TIME OF CONCENTRATION CTc> GIVEN Maximum Travel Distance (D 1) = Velocity of Runoff (V1) = Coefficient of Runoff (C 1) = Maximum Travel Distance (D~ = Velocity of Runoff (V2) = Coefficient of Runoff (C 2) = 200 ft ft 3 .00 fsec 0 .88 40 ft ft 1.00 fsec 0.43 **NOTE: Minimum T c allowed= 10 min. 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.806 65 8 5 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.785 76 8 .5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .763 80 8 .5 RESULT Tc1 = 1 .1 min . Tc2 = 0.7 min . T C(POST) = 1.8 min . Rainfall Intensity (1 2) = 6.327 in/hr QAREA 1 = 2 .077 cfs QAREA 2 = 0 .639 cfs ::-.·a.: :·. ::::::::::::::::::::::::::•r J< :•:::::: r ::1~711 :£m • Rainfall Intensity (Is) = 7 .693 in/hr QAREA 1 = 2 .526 cfs QAREA2 = 0 .777 cfs :,Qi 5::::::: :::::::: • ::::::::::: ... ••:: :: ::• ,: : .. ::1~1i : ~ ••:::• Rainfall Intensity (1 10) = QAREA1 = 8.635 in /hr 2 .835 cfs QAREA 2 = 0 .872 cfs f#Mit =• •r ::= _:.•=_,_:_:.•=_,=_, '.='.·'.='.·'.='.·'.='.·'.='.·'_,= ... _:= ... •:.:·_,-_, .•.•.•.•.•.•.•.•.•.•.•.•.•.•.:.:_ •. :_ •. •.•'i ii.di a'i t .•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.•.• :·:·:·:·:·:-:-:-:-:-:-:-:-:-:-:-:-:·:·:·'.•'.•'.•'.•'.•'.•"•"•"•""" 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Rainfall Intensity (1 2s) = in/ 9.861 hr Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .754 89 8 .5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .745 98 8.5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 2987-000129 Detention Facilities Evalu ation.xls 0 .73 96 8 QAREA 1 = 3 .238 cfs QAREA 2 = 0.996 cfs ·······:··· ·:-:.;·:::::::::::::;:;:::::::::::::·:.;-: ······:::::::::::::::::::···· ............ ··:·····::······················· .:.:.a.• .. •.·.• .. ~.==.=•.=•.=.•.:.•.•.•·.=.•• ...•.•. •.: = · • • : : ............. • • ••• iU234. tfi ? • • ~.. :::::::::::::::::· ·.·.··.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.···· Rainfall Intensity (Isa) = 11.148 in/hr QAREA 1 = 3 .660 cfs QAREA 2 = 1 .126 cfs •:QI# • : :::: :: ::::: : : .:: , : , i~lli •Pti' ::: Rainfall Intensity (1 100) QAREA 1 = 11.639 i%r 3.821 cfs QAREA 2 = 1 .176 cfs ·:n :·:·:·:·:·:·:·:·:·:·:·:·:·:·:·:·:·: ~~~~~~~~~~~~~1~1~1~1~1~1~1~j~~~j\/~j~~~~~1.~1.~ :::::::::::::::::::::===========:::j=:='.ft:.ft:i;i ::::~: ::::::::::: $.jk a • , ...... , .... , ............ , ... :: :: : : ., JfiP:''!~ : ~~e. •< SECTION#J DRAINAGE AREA HYDROGRAPHS SECTION #3 -HYDROGRAPHS Chart 4 2-YEAR HYDROGRAPH Volume Con eyed= 1,337 ft tS ~-~ ~ 2 -------- u -00. ~ ~ 1----- 0 10 El Post-Development Im Pre-Development HYDROGRAPHS Chart 4 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 5 5-YEAR HYDROGRAPH 3.5--------------------.-------------------,--------------------, 2 .5------- Volume Co 2------ 1 .5----- 0 .5 0 10 II Post-Development El Pre-Development HYDROGRAPHS Chart 5 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 6 10-YEAR HYDROGRAPH 3.5 --------- 3--------- Volume Conve 2 .5------- ~-~~ 2-----u- rJ) ~ ~ 1.5---- 1--- 0 .5 0 10 El Post-Development E1 Pre-Development HYDROGRAPHS Chart 6 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 7 25-YEAR HYDROGRAPH 4.5...--------------------.-------------------.--------------------. 3 .5 -------- 3------- ~ 2 .5------~~~ u- 00. s 2----- 1 .5---- 1-- 0 .5 0 10 Im Post-Development 8 Pre-Development I HYDROGRAPHS Chart 7 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 8 50-YEAR HYDROGRAPH 6---------------------.-------------------...,......------------------, Volume Conveyed 2 ,355 ft3 ~-~ ~3------u- 00 ~ ~ 2---- o .............. ......,.......,.......,.....,.....,.-. ...... ....,. ...... ...,....,....,....,....,....,.~~~~,.......,.......,.......,.......,....... .. 0 10 l!I Post-Development E1 Pre-Development HY DROGRAPHS Chart 8 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 10 100-YEAR HYDROGRAPH 6--------------------..------------------------------------~ Volume Conveyed 2 ,459 ft3 tS i::i:::_ ~ ct3------u- VJ. lo-( ~ 2---- 1-- 0 0 10 •Post-Development Pre-Development HYDROGRAPHS Chart 10 TIME (min) 20 30 DRAINAGE REPORT FOR BRENTWOOD SUBDIVISION BLOCK ONE, SECTION ONE, LOTS 6 -12 0.603 ACRES COLLEGE STATION, BRAZOS COUNTY, TEXAS AUGUST, 1998 REVISED: SEPTEMBER 11, 1998 ; ~ I :'J I •I-= 2551 TEXAS AVENUE . SOUTH, STE. A • ~-~ • -~ COLLEGE STATION, TEXAS 77840 lillllliillliifElllilfiildlll Ph : (409)693-5359 Fx: (409) 693-4243 : ~ Consulting Engineers · Environmental· Surveyors· Planners Brentwood Subdivisio n, Section One Draina ge Report DRAINAGE REPORT Municipal Development Group TABLE OF CONTENTS PROJECT SUMMARY ................................................................................................ 3 DRAINAGE AREA DESCRIPTIONS .......................................................................... 3 DRAINAGE CALCULATIONS ................................................................................... 4 RESULTS ..................................................................................................................... 4 DRAINAGE MAPS & DETAILS SECTION #1 -DRAINAGE AREA: PRE-DEVELOPMENT SECTION #2 -DRAINAGE AREA: POST-DEVELOPMENT SECTION #3 -DRAINAGE AREA HYDROGRAPHS 2987-000 129 Drainage Report.doc Drainage Repo rt -2 Brentwood Subdivision, Section One Drainage Report PROJECT SUMMARY Municipal Development Group This report outlines the drainage plan for the Brentwood Subdivision, Section One 0.603 acres . The subject property site is situated on the north side of Brentwood Drive approximately 200 linear feet east of the Texas Avenue and Brentwood Drive intersection and adjacent to the existing Dairy Queen . The development is established within Block One of Brentwood and consisting of Lots 6 through 12 . This tract generally slopes to the south with a grade of approximately 1.33% being fairly uniformly distributed . The site is currently vacant and unimproved with native grasses, weeds, small brush and several small trees . The natural drainage of the site is by sheet flow to the south and on to Brentwood Drive. Runoff is then collected into an existing 36" CMP storm sewer drainage structure. This site is in the Bee Creek sub-drainage basin, which is a part of the Carter Creek drainage basin . Since the current topography allows the entire property to drain onto Brentwood Drive and thence into the existing storm sewer, which has no unused capacity, it will be necessary to provide for detention. Detention will provided for the necessary storage of runoff to ensure that the discharge from the site will be equal to or less than the pre- development runoff discharge . This design is further illustrated and explained in the section, "RESULTS". DRAINAGE AREA DESCRIPTION The pre-development drainage area consists of 0 .603 acres of land . The post- development drainage area will consist of the same site and total acreage , but runoff coefficients will change due to the development . Impervious areas will be introduced by the 3 , 772 square foot building and from the concrete parking area and driveway . The total impervious area will be 0 .3 70 acres . Runoff from the building rooftop will be channeled into the proposed parking lot. From there, runoff collected in the parking lot and into the proposed detention pond located at the southwest corner of the property . The 2987-000129 Drainage Rep ort .doc Drainage Report -3 Brentwood Subdivision, Section One Drainage Report Municipal Development Group provided detention areas will exceed the required storage amount . The restricting orifice for discharge will be the proposed grate inlet constructed in-line with the existing storm sewer. DRAINAGE CALCULATIONS The drainage calculations are presented in three basic sections : I. Drainage Area : Pre-Development -Contains the calculations for the amount of runoff prior to the development of the site . II. Drainage Area : Post-Development -Contains the calculations for the amount of runoff after the proposed development. ill. Drainage Area : Hydrographs -Graphical representation of the volume of water that is detained on the site . The drainage area calculations are summarized accordingly using the Rational Method : (Q=CIA) where "Q" is the runoff in cubic feet/second , "C" is the runoff coefficient, 'T ' is the storm intensity in inches/hour for each selected frequency, and "A" is the drainage area in acres . We will assume a minimum ten-minute time of concentration for all calculations. The selected frequencies will be 2, 5, 10 , 25, 50, 100-year rainfall events . Tabulations of the pre-development and the post-development hydrographs of the drainage areas are provided . The hydrographs are based on the standard SCS unit hydrograph with time to peak discharge set to equal the time of concentration and the total base time set at 3 . 00 times the time of concentration. Grate flow calculations were determined from the following orifice flow equation (Q = CA(2gh)112 ), where "C" is the orifice coefficient, "A" is free-open area in ft:2 , "g" is constant at 32 .2 ft/sec 2 , and "h" is the head, in feet , on the grate . RESULTS 2987-000129 Drainage Report.do c Draina ge Report -4 Brentwood Subdi visi on, Section One Draina ge Re port Muni ci pal Devel opment Group From the drainage calculations the following results were determined : ;Vo &!_ + Detention Calculations : The required de tion required during the 100-ye rainfall event has been calculated to be 2,495 ft:3 . Detention provided for in t parking lot is at 1,028 ft:3 . Therefo e, the remaining detention requir a is equal to 1,467 ft 3 . Since this detention wi! bek .stored in a pond an additio · 10% of volume will be required for sedimentation ring the total volume to 1,614 ft 3 . The detention pond proposed will contain a volume of 1,958 ft 3 allowing for the required storage and the addition 0 .5 ' of freeboard . • Proposed Grate Inlet: The proposed detention pond will be drained by a grate inlet _JIJ'-'_.,_~e existing 36" CMP storm sewer. The grate inlet will have a Capacity= Gravity, g = Capacity= Gravity, g = 2987-000 129 Drainage Repo rt .d oc GIVEN A Neenah grate model R-1879-B2G or GRATE INLET CALCULATED .-'""!,.,,-.~R RAINFALL EVENT) Depth= Free·open Area = INFALL EVENT) Depth= Fre~~.e !~:.~~~!.~ 0 .72 ft 0 .93 ft2 1.00 ft 0.93tt2" ~;)< Drainage Report -5 DRAINAGE MAPS & DETAILS fEl)'JJQN REQUIREMENTS YD VOL = 2 495 cuft ':N . VOL. = 2 958 cyft Parking Lot = 1,028 ond = 1,930 cuft ~board > O.~ ft 'ROPOS ED GRATE INLET iEE DETAll. THiS SHEIT 25' Fron\ Building Line ~-----__,/ j20 L.F . EROSION CONTROL! _EXISTING 8" V.C.P. \ SANITARl' SE',;£;< \ J -....._. ~ I I I I ii j'tl--. I ;_tf'7 I . EX!STING s• V.C.P. SloWfloRY SEWER LINE ..... \ i I PROPOSED 4 · CONCRETE I PILOT CHA.NNEL SEE DCTAJL THIS SH EET ' ! ! 11 j i, L,....,J __ --c BRENTWOOD DRIVE (70' R.0.W.) GRAQ!NG PLAN I 0=20' AFZE4 I ING U 0 BE CUT lt. .... .ATCH EX!STI~JG I I PAVEME NT GRADE . . . -----~4 . .... ... I ! JI. ··~I ' -----_J \ l•_I PROPOSED 13"x 25 " GRATE INLET MODEL R-1879-82G, AS MANUFACTURED BY NEENAH OR APPROVED EQUAL. I ~ #4 BARS @ 1 SIDE W .• ·oc•w 1 11 ··~--~1 LS If I I I I I I 5' • . .... 4 ·. -4 .. . _.a • . ' . .d ~- . .. · .. _. TOP ELEV=29 i .00 FL=287.22 L... ... • <I \\_#4 BAR S @ 6" O.C.E.W. TOP & BOTTOM ELEVATION GRATE INLET DETAIL N.T.S. I I ---~-I EXISTING 36 " CMP STORM SEWER @ 1.093 SLOPE EXISTING 36 " CMP STORM SEVIER @ 1.097. SLOPE R-1878 Series Frames Heavy Duty Lids, Grates These shallow fra mes ore suitable for use in thin or deep con - crete slobs . All sizes of frames ore reversible and con be installed with fl ange ct base or top . Sµecify : 1. Catalog number . 2 . To be instc ll ed with flange at base or lop. Square Dimensions in inches Catalog Number A I B I c D E F So li d lid Open Grate R-1878-A IL R-1878-AIG 13 34 x 13*1 l'h l 12 x 12 1 14 x 14 18 x 18 4 R-1878-A2L R-1878-A2G 18xl8 l l 'h 16xl6 18 '4x 18 14 22 x 22 4 R-1878-A3l R-l 878-A3G 20 x 20 I 'h 18 x 18 I 20'~ x 20 '4 24 x 24 4 R-1878-A4l R-1878-A4G 21y.x2 l y. / 1 v2 , 20 x 20 I 22 x 22 26 x 26 4 R-1878-ASL R-1878-ASG 23 V2 x 23 V2 ll'2 22 x 22 24 x 24 28 x 28 4 R-1878-A6L R-1878-A6G 25 ¥. x 2S Y. 1 \12 24 x 24 I 26 x 26 30 x 30 4 R-1878-A7l R·l 878-A7G 27'12 x 27 % 11 'h 126 x 26 28 x 28 32 x 32 4 R-1878-A8L R-l 878-A8G 29 Y2 x 29 Y2 l 'h 28 x 28 29 3i x 29'1> 34 x 34 4 R-1878-A9L R-1878-A9G 31 ~x3 rn/1v2 30x30 32 x 32 36 x 36 4 R-1878-AIOL.; R-1878-AIOG • 37 x 37 /1 Y2 I 36 x 36 37 \12 x 37 Y2 42 x 42 4 Rectangular R-1878-B I l R-1878-BlG 14 x 20 I rn 12x 18 , 14'.• x 20 '4 18 x 24 4 R-1878-B2L ; R-I 878-B2G l 3 'h x 25 \12 1'h 12 x 24 1334 x 25 ~ 18 x 30 4 R-1878-B3L : R-1 878-B3G l 9 Y2 x 25 \12 l 'h 18 x 24 19 3• x 25~• 24 x 30 4 R-l 878-B4L i R-1 878-B4G 19 Y2x31'h 1 'h I 18 x 30 I 20 x 32 24 x 36 4 R·I 878-BSL I R-1878-BSG 1934 x 37~• rn 18 x 36 20 x 38 24 x 42 4 R-1878-B6L 'R· 1878-B6G 25 Y2 x 31 \12 rn 24 x 30 2s3• x 31 ~• 30 x 36 4 R-l 878-B7l I R-1 878-B7G 25 V2 x 37 V2 l \12 24 x 36 26 x 38 30 x 42 4 R-1878-B8L • i R-1878-B8G• 25 34 x 49 3i 1!'2 24 x 48 26 x 50 30 x 54 4 R-1 878-B9L. I R-1878-B9G . 3 ]l,4 x 37 3i 1112 30 x 36 32 x 38 36 x 42 4 R-1878-B I OL • j R-1 878-B I OG* 31 \12 x 49 \12 1% 30 x 48 31'• x 49~ 36 x 54 4 G l xS l.-2 1Y.x4)4 l 1 s;,.x 3~ l V4 x 3 Jti 1V2 x6 Y7 2 Ysx7)4 lxS l Vsx S Y2 l x6:1/i l:Y.x 3'12 Y.x5 '12 l x4'12 Va xS 2x5 2x5 l '.}8 x 5 1 ~x5 JS;,. x :i" 3/1 0 l :Ys x 4 Y3 l V2 x ..:.:;, R-1 879 Series Fr a mes li g h t Duty Lids, Gr ates Th ese shallo w frames ore suitable for use in t hin or deep con- cr et e slobs . A ll siz es of frames ore reversible and :on be installed with flange ct base or top. Specify : 1. Catalog num ber. 2 . To be insrcll e d with flange at base or top. Square Dimensio ns in inches I Cata log Number A B j c D E F Solid lid Open Grate R-1879-A I l . R-1879-AIG 13 3hx1 33<i l Y2 12 x 12 14 x 14 18 x 18 4 R-l 879-A2l ! R-1 879-A2G 18 x 18 1\-2 16 x 16 18 1• x 18 1'. 22 x 22 4 R-1 879-A3l I R-I 879-A3G 20 x 20 1112 18 x 18 20 ~. x 20'4 2 4 x 24 4 --21Y.x2-1°¥.-m 20~20 ~22 x 22 R-I 879-A4l I :: : :;:::;g 26 x 26 4 R-1879-ASL 23 V2 x 23 Vi l V2 22 x 22 24 x 24 28 x 28 4 R-I 879-A6l : R-1 879-A6G 25 Y. x 25Y. 1!'2 24 x 24 26 x 26 30 x 30 4 R-1879-A7l : R-1 879-A7G 2 7 V2 x 27 V2 1!'2 26 x 26 28 x 28 32 x 32 4 R-1879-A8l · R-l 879-A8G 29 Y. x 29 V• 1 '·? 28 x 28 29i; x 29'4 34 x 34 4 R-1879-A9l R-1879-A9G 31Y.x31 Y. l '; 30 x 30 32 x 32 36 x 36 4 R-1 879-A I Ol • R-1879-AlOG• 3 7 x37 1" 36 x 36 37 1 2 x 37 ~'2 42 x 42 4 Rec t angular R-1879-B 1 l R-1879-81 G 14 x 20 n,' 12 x 18 l4 '.x201; 18 x 24 4 R-1 879-B2l R-1879-B2G 13 V2 x 25 1.: n,, 12 x 24 13'. x 25 3:. 18 x 30 4 R-1 879-B3L R-187 9-83G l 9 V2 x 25 '; ~ 1 : 18 x 24 19'. x 25'; 24 x 30 4 R-1879-B4l R-1879-B4G l 9 V2 x 31 'i , ,, 18 x 30 20 x 32 24 x 36 4 R-1879-85 l R-1879-BSG 19~> x 37'• ,, 18 x 36 20 x 38 2 4 x 42 4 R-1 879-B6l R-1879-B6G 2 5 Y2x31'2 " 24 x 30 25'· x 3 p; 30 x 36 4 R-1 879-B7L R-1879-B7G 25 ~~ x 37'• "'' 24 x 36 26 x 38 30 x 42 4 R-1879-BSL • ; R-1879 -B8G • 25 3 ~ x 49'• h 1; 24 x 48 26 x 50 30 x 54 4 R-1879 -B9l -, R-1 879-B9G" 31 ~ x 37'; n', 30 x 36 32 x 38 36 x 42 4 R-1879-BlO L-R-1879-BIOG• 31 1/2 x 49'2 n'= 30 x 48 3Jl,x4934 36 x 54 4 Cover 1n :w-: 60 NEEN AH ~~ FOUNC~Y COMPA NY ..!..._ ~ G 1x3 y. x 45/3 Y.xS y. x .! Y.x6Y2 lxS Y.x7¥s 1Y3 x5 '/., 1 x .!.'/, 1 .< ,.,/3 7.J. ..( 5 ~ ... 2 +..:. ,(.::. "'2 ~: ... 5 ·~ :h .(5 1/;"5 l X 5 ~I~ 1 .(5 .,3 }.:. x 5 ·.-3 ix ~:,2 l x: Wt. lbs. w/ w/ H lid grate l 130 115 l 180 170 l 220 210 l ~ 235 220 :y. 265 300 y. 330 280 l 370 325 l 415 485 1 4 7 0 465 lV2 790 700 l 185 160 l 220 185 l 245 240 l 285 249 l 365 295 1 385 360 l 460 425 l 510 575 l 500 5 15 l 695 680 Wt. lbs. w/ w/ H li d grate I 115 100 y. 165 150 y. 195 185 :y. 200 185 y. 235 255 y. 245 215 y. 290 260 1 340 390 :y, 360 310 1 485 445 1 185 160 1 165 180 1 210 195 1 230 215 1 295 310 :y. 290 260 y. 335 295 1 395 405 1 400 380 1 480 425 R· 1878-ASL Manhole Frame and Solid Lid -· ' ;&i "" .;,,c ~ o ·~ -------· - -·---~ • He<1vy Duty R-1878 Sections R-1879 -B 1 G Catch Basin Grate and frame ---·----. _______ , --- ----·--~ 2f:µ:z;~tttt16 . Light Duty R-1879 Sections SECTION#! DRAINAGE AREA PRE -DEVELOPMENT SECTION #1 DRAINAGE AREA -PRE-DEVELOPMENT GENERAL INFORMATION Description: Drainage area of site before development. Dra in age Area (APRIJ = 0 .603 acres TIME OF CONCENTRATION CTJ GIVEN Maxim um Travel Distance (DPRE) Velocity of Runoff (VPRJ = Coefficient of Runoff (CpRJ = 215 ft It 0.75 fsec 0.32 **NOTE: Minimum Tc allowed = 10 min. 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.806 Coefficient (b) = 65 Coefficient (d) = 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.785 76 8.5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .763 80 8.5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.754 Coefficient (b) = 89 Coefficient (d) = 8.5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.745 Coefficient (b) = Coefficient (d) = 98 8.5 100 YEAR FREQUENCY, RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 29 87 -0 001 29 Detention Faciliti es Evalu ation.xis 0.73 96 8 RESULT T qP RE) = 4.8 min . Rainfall Intensity (lz) = 6.327 in /hr ,li.!:~r .. ::::_::•f:.II0:::.'::::.:.·:::1:::::=::·-::=•:?.':::::::::::.:::::.::::•:!.:~1Mt~e-.:::::: Rainfall Intensity (1 5) = 7.693 in/hr :;;2;;: •::::::· :::?:::::::::'·:: .••.••.•.:.:.:.:.•'.:•.:.•.:.:r · :t.i'.i'_,1:'.''_f~_,.,,"_ .. _,,·_.,·..,,:,:_',·_,_._·,,',•'_,,,,="'_, .. ,·',·_a.·,:·_',·.·. ·s.,_.,_ .. · .. '.'.•_,•.•,•,•,•,•,'.·.',•,• }i'\',i;(::::/{{} }{{tf'{ :;:; .. :::·:·:·:·:·:·:·:·:·:·C:~:J:: ow: Rainfall Intensity (1 10) = 8.635 in/hr :d;; :· ,.,:,,.,,.,::::::: '•:'': ::::. _:·:: :.:·::_::::::::'_:·:•:,::::;::::·:::::,:::::::1tuo ::·~t~£: :: Rainfall Intensity (1 25 ) = 9.861 in/hr ····· ·.·.,.,.,.,.,.·.·.·.·.·.·.·.·.· ............. ,.,. __ ,,,., ....... ,.,., ..... _:_·_._ .. ,_ .. _.,_.1'_.,_ ..• ,_··.-~ .. , .. ,_,.._,._, .. _ .. 9,_.,.,_.:a_.,,,.,.s,.,,,,.,,,,,, __ .,,,,,,,, .. •,•.a,.,·.·,.·,·~.·.'~_''.'·.•,:_:,~_:,:_:_ .. ·.:_ .. · ,,,,,,,,,,,,,.,.,.· ':::''••::::':::::::::::: ,,,,,,,,,,,,,,,,,,,, ,::::,,,,,,,.,. "1':• -, ~~ :::::::·:·::~:~:::: ... :::::::::::::::::::::::::: :;:;:;::::::::::::::::::::::::::: Rainfall Intensity (1 50) = 11 .148 in/hr :m~·~:.::i:.r,:::.r.:.:::::::::_:::::•:::::::,::' .. :.:::::•:.:,:.r.:.\:::::_r ,· ::·•::::i~1:ij,:st'-::::::- Rainfall Intensity (1 100) 11 .639 in/hr :_9 ~~~·11:.•,_:_:.::::::,::::.:::::::::.:,::::.:-:,:r::::::.:]:•:-: \•:.::,::•::f:?.;~~~r:lit::=::: SECTION#2 DRAINAGE AREA POST-DEVELOPMENT SECTION #2 DRAINAGE AREA -POST-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site after development Drainage Area (A1) = 0 .370 acres (impervious area) Drainage Area (A2J = 0.233 acres (landscaped area) TIME OF CONCENTRATION CTc> GIVEN Maximum Travel Distance (D 1) = Velocity of Runoff (V1) = Coefficient of Runoff (C 1) = Maximum Travel Distance (D2J = Velocity of Runoff (V2) = Coefficient of Runoff (C2J = 200 ft ft 3 .00 f sec 0 .88 40 ft ft 1 .00 fsec 0.43 *"'NOTE : Minimum Tc allowed= 10 min . 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .806 65 8 5 YEAR FREQUENCY, RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .785 76 8 .5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.763 80 8 .5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.754 89 8 .5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .745 98 8 .5 RESULT T c1 = 1 .1 min . TC2 = 0 .7 min . T q POST) = 1 .8 min . Rainfall Intensity (12J = 6 .327 in/hr QAREA 1 = 2 .077 cfs Q AREA 2 = 0 .639 cfs ::s~::a.:::::::•••]:••:1•::::·::•=rn::::::::J::::•:::1-:::+v. •• .::-:•:::::• .. 1~71~=·-~:::-: .. I Rainfall Intensity (1 5) = 7 .693 in/hr Q AREA 1 = 2 .526 cfs a AREA 2 = 0 . 777 cfs "ii :.~".:_:·::· ... :.:.·::-.:::·.::.,:···:.:·:::-:::::: =:.:::.:,,::•::1~~~.:1!:.::. ::: Rainfall Intensity (1 10) = QAREA 1 = 8 .635 in /hr 2 .835 cfs Q AREA 2 = 0 .872 cfs •_,·•_,.'_,A=_,·,_:_:.,:_·.=,=,••:='_'•.'.~.'.•.'.·'_,·'_,·'_,i=_,'_,'_,'_,'_,'_,'_,:•:·':.:::=:::::·::•::.• .... :·'.·.·.·'.":"_:':·'.•:f_•.•• .. =.•_.• .. • .. • . .-_:_••.·_:_==:: ·=·==::::=: .. ,. ========:====·=-//_.•fj:_•.:~_·,.,._·_-. ... '~.::.:: .. ;d<: .... s'·'·•_ •. _ •• :_:,_·•.i.i.i.••.• ~v :~;;\;~;~;~;;;~;~;;;;~~~~~~;~;~;~;;;;;~;~;~;~~f~~f========:::!=·~fK~~L:}~!~=-=·=·=·=···=·=····- Rainfall Intensity (1 25 ) = 9 .861 in/hr QAREA 1 = 3 .238 cfs a AREA 2 = 0 . 996 cfs ................... ·············· .·.·.·.·.·.-..... -.·.·.· .. ·.·.· ... ·.·.· ····.·.··················-·.·.·.·.·.·.·. ••si::a ::•::•:••::•:::::r::::::•r:::::::::•:••·=rn:•::•::::r:: :::::=::::r•nmi~at4:9$r::::=: Rainfall Intensity (1 50) = Q AREA 1 = in/ 11 .148 hr 3 .660 cfs QAREA 2 = 1 . 126 cfs :m~rir=·: .... : ':•::::.:•::: •:•:=:::: ·=·· .:.:::::]•::::::::!~z1§•!t!:::::1:: 100 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Rainfall Intensity (1 100) in/ 11.639 hr Coefficient (e) = 0. 73 Q AREA 1 = 3 .821 cfs Coefficient (b ) = Coefficient (d) = 2987-000129 Detention Faci li ties Evaluatio n.xis 96 8 Q AREA 2 = 1 .176 cfs .•'.'1_ •... :_:_·.·.·.~.'.•:_0o_•' .. ''.=.•·.''_::_:_•.:_;;;_•_:.:_•·.:_·.•.: =_.:_.:_.'_:·.:•_.:_•_.:.•_ ... ·.:.-.•. < = = ., ,,, • t•::=::::::•::::••iU~t'·m t••:] :=J.: ·:·:::·:::::::::::::;:::::::::;:::;:;:: •.•·.•.·•·.•.•.·.·.•••.•.•••.••••· SECTION#3 DRAINAGE AREA HYDROGRAPHS SECTION #3 -HYDROGRAPHS Chart 4 2-YEAR HYDROGRAPH 3.,._~~~~~~~~~+l ~~~~~~~~~~~~~~~~~~--J Volume Con eyed= 1,337 ft 0 0 10 El Po st -Development El Pre-Development TTh1E (min) HYDROG RAP HS Chart 4 20 30 SECTION #3 -HYDROGRAPBS Chart 5 5-YEAR HYDROGRAPH 3.5....-------------------.------------------_,...------------------, 2 .5 -------- Volume Co 2------ 1 .5 ----- 1 --- 0 .5 0 0 10 mJ Post-Development EJ Pre-Deve lopment ! HYDROGRAPHS Chart 5 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 6 10-YEAR HYDROGRAPH 0 10 EJ Post-Development EJ Pre-Development HYDROGRAPHS Chart 6 Tll\'IE (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 7 25-YEAR HYDROGRAPH 0 10 Im Post-Development [J Pre-Development I HYDROGR.APHS Chart 7 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 8 50-YEAR HYDROGRAPH 6-----------------------------------------.-------------------, ! i 3 Volume Conveyed 1 2,355 ft 2---- 0 0 10 El Post-Development El Pre-Development HY DROGRAPHS Chart 8 T™E (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 9 100-YEAR HYDROGRAPH 6 ,.____ ______ _ s------- 3---- 2--- 0 0 10 El Pre-Development El Post-Developmen t HYDROGRAPHS Chart 9 TIME (min) 20 30 /, De~-H~ P~ s~lJ JLo-l--\:> '-. } •c ~ ) rl A-p..t,lk. "l>~~ ~~ e-m~A-1 ~~ rr1v41e,7 miJ,, -WNJ.. ?-. C}i~ ~ )111~dVS AreA-c~~~ DRAINAGE REPORT ~t sh."6 /e.s 5 . FOR INJf,~ll!>t/$ fl~ ftrVICCJS. BRENTWOOD SUBDIVISION tJfi/, ~ k.'Jr~ BLOCK ONE, SECTION ONE, LOTS 6 -12 ~Jiow3 1/'\e. °11~~ 0.603 ACRES ~' 8' ;~_'•elj • ~"J. r~IOu(. ~--~~p)~-- COLLEGE STATION, BRAZOS COUNTY, TEXAS J\9 ~ AUGUST, 1998 ~ ~o~8/rN48. 'f ; COLLEGE STAT IO N, TEXAS 77840 MUNIC I PAL DEVELO PMENT GROUP I ~ I~ I •I !' 2551 TEXA.S AVENUE. SOUTH . STE. A Ph: ( 4 0 9)693-5359 Fx: ( 409) 693-4243 ·. l Consu lt ing Engineers ·Environmental· Surveyors-Planners DRAINAGE REPORT FOR BRENTWOOD SUBDIVISION BLOCK ONE, SECTION ONE, LOTS 6 -12 0.603 ACRES COLLEGE STATION, BRAZOS COUNTY, TEXAS AUGUST, 1998 i · COLLEGE STAT IO N , TEXAS 77840 MUNICIPAL DEVELOPMENT GROUP Id I~~ I •IC:J 2551 TEXAS AVENUE. SOUTH, STE. A i Ph: ( 409)693-5359 Fx: ( 409) 693-4243 · ' ~Consul ting Engineers · Environmental· Surveyors · Planners Brentwood Subdivisi on, Sect io n On e Drainage Rep ort DRAINAGE REPORT Munici pal Developm ent Grou p TABLE OF CONTENTS PROJECT SUM1\1AR Y ................................................................................................ 3 DRAINAGE AREA DESCRIPTIONS .......................................................................... 3 DRAINAGE CALCULATIONS ................................................................................... 4 RESlJLTS ..................................................................................................................... 4 DRAINAGE MAPS & DETAILS SECTION #1 -DRAINAGE AREA: PRE-DEVELOPMENT SE CTION #2 -DRAINAGE AREA: POST-DEVELOPMENT SE CTION #3 -DRAINAGE AREA HYDROGRAPHS 2987-0001 29 Drainage Report.d oc Drainage Rep ort -2 Brentwood Subdivision, Section One Drainage Report PROJECT SUMMARY Municipal Development Group This report outlines the drainage plan for the Brentwood Subdivision, Section One 0 .603 acres. The subject property site is situated on the north side of Brentwood Drive approximately 200 linear feet east of the Texas Avenue and Brentwood Drive intersection and adjacent to the existing Dairy Queen. The development is established within Block One of Brentwood and consisting of Lots 6 through 12 . This tract generally slopes to the south with a grade of approximately 1.33% being fairly uniformly distributed . The site is currently vacant and unimproved with native grasses , weeds, small brush and several small trees . The natural drainage of the site is by sheet flow to the south and on to Brentwood Drive. Runoff is then collected into an existing 30" CMP storm sewer drainage structure. This site is in the Bee Creek sub-drainage basin, which is a part of the Carter Creek drainage basin . Since the current topography allows the entire property to drain onto Brentwood Drive and thence into the existing storm sewer, which has no unused capacity , it will be necessary to provide for detention . Detention will provided for the necessary storage of runoff to ensure that the discharge from the site will be equal to or less than the pre- development runoff discharge . This design is further illustrated and explained in the section, "RESULTS". DRAINAGE AREA DESCRIPTION The pre-development drainage area consists of 0.603 acres of land . The post- development drainage area will consist of the same site and total acreage , but runoff coefficients will change due to the development. Impervious areas will be introduced by the 3, 750 square foot building and from the concrete parking area and driveway . The total impervious area will be 0.250 acres . Runoff from the building rooftop will be channeled into the proposed parking lot. From there, runoff collected in the parking lot 2987-000129 Dra inage Report.do c Drain age Report -3 Brentwood Subdivision, Section One Draina ge Report Municipal Development Group will drain across the pavement and into the proposed detention facility located at the southwest corner of the property . DRAINAGE CALCULATIONS The drainage calculations are presented in three basic sections : I. Drainage Area : Pre-Development -Contains the calculations for the amount of runoff prior to the development of the site . II. Drainage Area : Post-Development -Contains the calculations for the amount of runoff after the proposed development. III. Drainage Area: Hydrographs -Graphical representation of the volume of water that is detained on the site . The drainage area calculations are summarized accordingly using the Rational Method : (Q=CIA) where "Q" is the runoff in cubic feet/second , "C" is the runoff coefficient, 'T is the storm intensity in inches/hour for each selected frequency, and "A" is the drainage area in acres. We will assume a minimum ten-minute time of concentration for all calculations . The selected frequencies will be 2, 5, 10, 25, 50, 100-year rainfall events . Tabulations of the pre-development and the post-development hydrographs of the drainage areas are provided . The hydrographs are based on the standard SCS unit hydrograph with time to peak discharge set to equal the time of concentration and the total base time set at 3.00 times the time of concentration. Grate flow calculations were determined from the following orifice flow equation (Q = CA(2gh)112), where "C" is the orifice coefficient, "A" is free-open area in ft 2 , "g" is constant at 32.2 ft/sec 2, and "h" is the head , in feet , on the grate . RESULTS From the drainage calculations the following results were determined : 2987-000 129 Draina ge Report .do c Drainage Report -4 Brentwood Subdi visi on, Section One Drainage Report Municipal Development Group + Detention Calculations : The proposed detention pond shall have volume no less than 1,987 ft:3, which is required by the 100-year rainfall event. An additional 10% will be required to accommodate a decrease in pond storage due to sedimentation. Therefore, the total required detention volume equals 2, 186 ft3 . As shown on the Grading Plan, the proposed detention pond is sized at 3, 145 ft3 . This extra volume will allow for a one-half foot of freeboard during the 100-year rainfall event. + Proposed Grate Inlet : The proposed detention pond will be drained by a grate inlet placed inline with the existing 30" CMP storm sewer. The grate inlet will have a capacity of 2.25 cfs with one foot of head . A Neenah grate model R-1879-B2G or approved equal will be used . Capacity= Gravity, g = Capacity= Gravity, g = 2987-000 129 Drainage Report.do c GIVEN GRATE INLET CALCULATED (25-YEAR RAINFALL EVENT) 3 .79 cfs Depth= FT 32 .2 /sE c Free-open Area = (100-YEAR RAINFALL EVENT) 4.4 7 cfs Depth = 32 .2 FT'sEc Free.~P~~ ,Ar~~)= 0.72 ft 0.93 ft2 1.00 ft 0.93 ft2 Drainage Report -5 DRAINAGE MAPS & DETAILS # .·'. - 17 599' ~ . I 't -~<i ---·---·-2~ ~ Public Uta.t>l Easement ! I ............... ~ --t----1 ----: ' . ·-- ··1-----; . . ~.i .---~1 ~-~ ____ ...... 293 GR AD I N G PL AN PROPOSED 13"x 25" GRATE INLET MODEL R-1879-B2G. AS MANUFACTURED BY NEENAH OR APPROVED EQUAL. 6 I· . . . 4 . . • #4 " O.C.E .W.ltl 1 c:: I ~ \ I I I 5 ' 4 -. • . ... . . .-. . 4 . .. . . : . . : • .... . . . .. _4 _.d .. . . .. ., • .. ELEV=291 .00 FL=287 .42 ... #4 BARS @ 6" O.C.E.W . TOP & BOTTO M ELEVATION GRATE INLET DETAIL N.T.S . EXISTING 36" CMP STORM SEWER C 1.09% SLOPE EXISTING 36" CMP STORM SEWER @ 1.097. SLOPE R-1 878 Series Frames Heavy Duty Lids, Grates These shall ow fram e s a re suitable fo r use i n thin or d ee p con - crete sla b s. A l l si zes of frames are revers ibl e an d co n b e installed with fla nge ct base or top . Sµe cify : l . Cata l og number. 2 . To be in s;c ll e d w ith Aange at base or t o p . Squa r e Dimensi ons in inc hes Catalog N u mber A B I c D E F So li d Lid Open Grate R-1878-A 1l R-1 878-AlG 13 34 x 1334 i 1\"z 1 12 x 12 1 14 x 14 18 x 18 4 R-1878-A2L R·l 878-A2G 18 x1 8 1\"z 16x16 i 1814x1 8 14 22 x 22 4 R-1 878-A3L R-1 878-A3G 20 x 20 Im 18 x 18 120 14 x 20 14 2 4 x 24 4 R-1878-A4L R-l 878-A4G 21Y.x2 1Y,,1Y2 20 x 20 I 22 x 22 2 6 x 26 4 R-1878-ASL R-1878-ASG 2 3 Yix23Y2 1112 22 x 22 24 x 24 28 x 2 8 4 R-1878-A6L R-1878-A6G 2 5 Y. x 2 5Y. I ll'2 24 x 24 r 26 x 26 30 x 30 4 R-1878-A7L R-1 878-A7G 27% x 27% l!"z 26 x 26 1 28 x 28 32 x 32 4 R·1 878-A8L R-1 878-A8G 29 Y2 x 29Y2 r l~ 28 x 28 j 29 34 x 29 34 34 x 34 4 R-1 878-A9L R-1878 -A9G 3 1'4x3P~ 1"2 30 x 30 I 32 x 32 36 x 36 4 R-1 878-AlOL"· R-1878-AlOG" 37 x 37 1\12 36 x 36 i 37 Y2 x 37 Y2 42 x 42 4 Rec t angular R-1 878-81 L R-1878-BlG 14x20 11',2 1 12x18 1 14 14x 20 14 18 x 24 4 R-18 78-B2L : R-1 878-B2G 13Y2 x 25 Y2 ('' 12 x 24 13 34 x 2534 18 x 30 4 R-1878-B3L : R-1 878-B3G 19% x 25 Y2 . 11/o 18 x 24 19'~ x 2 5"4 24 x 30 4 R-1878-B4L R·l 878-B4G I 19% x 31 y, I 1 \'2 I 18 x 30 I 20 x 32 24 x 36 4 R-1878-85L i R-1 878-BSG 19'4 x 37~~ 1:; 18 x 36 20 x 38 24 x 42 4 R-1878-B6L R-1 878-B6G 2 5% x 31Y2 l "i 24 x 30 25 3', x 3P~ 30 x 36 4 R-1878-B7L ; R-1 878-B7G 25 Yi x 37 Y2 I l "2 24 x 36 1 26 x 38 30 x 42 4 R-1878-B8L • : R-1 878-B8G • 2 534 x 49 3~ '1112 24 x 48 26 x 50 30 x 54 4 R-1 878-B9L • !R-1 878-B9G • 3 1'4x37 3~/1 1 1 30 x 36 32 x 38 36 x 42 4 R-18 78-BlOL · I R-1878-BloG · 31 Y2x49\1,11'2 30 x 48 131'', x 4934 36 x 54 4 •cover in two ;::1 ~ce s. G l xS Y2 1Y.x4 Y• 1 15/,. x 341 1Y.x3 )12 1Y2x6 Y2 2~x7 !1• lxS 1 Yax5 !12 1x6~ 1Y.x3 '12 Y.xs :12 1 x4 '/2 ~sxS 2x5 2x5 l ~x S l ~x S is;,. x 6 ·3;,. 1:Yax4V9 1)Ii x4 Y, R-1 879 Series Frames Light Duty Lids, Grates These sh al l cw frames are sui tab le for use i n thin or d eep co n- crete slabs . ,!. i i si zes of frames a re r ev ers ible and ~on be in st a l led with fla n g e :::7 base o r to p . Specify : 1. Cata l og :ium ber. 2 . To b e in s:a ll ed with A a ng e a t bas e or t o p . Squa re Dime ns ions in inches I Catalo g N umber A B i c D E F So li d Li d Open Grate R-1 8 79 -A 1 L R-18 79-AlG 13 34 x 13'; 1 ~':z 12 x 12 14 x 14 18 x 18 4 R-18 7 9-A 2 L '. R-1 879-A2G 18 x 18 1'·: 16 x 16 18 1'. x 1 8 1 ~ 22 x 22 4 R-1879-AJL : R-1 879-AJG 20 x 20 112 18 x 18 20 \~ x 20'1. 24 x 24 4 ---------R-1 879-A4L j R-1 879-A4G 2 l:Y.x21 11< E2 2 0 x 20 22 x 22 26 x 26 4 R-1 879-A5L . R-1 879-A5G 23 V2 x 23 l/i l '·i 22 x 22 24 x 24 28 x 28 4 R-18 7 9 -A6L ' R-1 8 79-A6G 25 ¥. x 25¥. 1'· 24 x 2 4 26 x 26 30 x 30 4 R-1 879-A 7 L : R-1 8 79-A7G 27 Y2 x 27 Vi n \'2 26 x 26 28 x 28 32 x 32 4 R-18 7 9 -A8L R-1 879-A8G 29 Y.x29 y4 l ''' 28 x 28 29''.i x 29 " 34 " 34 4 R-18 7 9-A9L R-18 79-A9G 31 Y.x 3l lt, 11': 30 x 30 32 x 32 36 x 36 4 R-1 879-A 1 CL· R-1 8 7 9 -AloG • 37 x37 11,, 36 x 36 37 1·2 x 37 \12 42 x 42 4 Rect angula r R-1 8 79-B 1 L R-1 879-81G 14" 20 ~I • 12 x 18 14 1• x 20 \~ 18 x 24 4 R-1 8 7 9 -B2 L R-l 87 9 -B2G 13 !fz X 25 1 : I : 12 x 2 4 13 '~ x 25'• 18 x 30 4 R-1879 -BJ L R-187 9 -83G 1 9 ~2 x 2 51 : p 1 : 1 B x 24 19 3, x 25''. 24 x 30 4 R-187 9 -8 4 L R-18 79 -84G 1 9 \2 x 31 1 , r, 18 x 30 20 x 32 24 " 36 4 R-187 9 -BS L R-1879 -BSG 19''4x 37 '• 1 : 18 x 36 20 x 38 24 x 42 4 R-1 879 -86 l ~-1 87 9-B6G 25 Y2 x 3 1'i ': 24 x 30 25l ~x31~'4 30 x 36 4 R-1879 -8 7L R-18 79-87G 25 34x37', ~1 : 24 x 36 26 x 38 30 x 42 4 R-1879 -BS L • R-1 87 9-B8G • 25l ~ x 49 :;.i 1 1 24 x 4 8 26 x 50 30 x 54 4 R-187 9 -B9 L • R-1 87 9 -89G • 31 ~ x 37 ', h1 : 30 x 36 32 x 38 36 x 42 4 R-1 8 7 9 -8 1 O l • R-187 9 -BlOG ' 31 Y2x•9':P': 30 x 4 8 3P ~ x 49~~ 36 x 54 4 Cove r 1n ~ ...... -:: :: -?:~s . ,,..: ·L.,:.·.,.:.,.. ····1' ~ ...... i ~~ •• ( ,,.,_""-.,~ ..... G 1x3 ¥ .. Jf. ~513 :y." .3 y. x .! Y.x6 V2 1"5 ¥ .. x7¥s 1 l-3 x 5 '/., 1 x a,:/ .. 1 x ~113 ~-x 5 ·,2 '.¥.:.,( 4'.12 ~13 ,( 5 . ~ } .. x = l /: x 3 1 x 5 -/~ 1x5 ·.3 ~'.. x 5 A ix ~:,:z l x 5 Wt. Lbs . w/ w/ H lid grate 1 130 1 15 l 180 170 1 220 2 10 1 235 220 :v. 2 6 5 300 y. 33 0 2 80 1 370 325 1 41 5 48 5 1 470 465 1Y2 790 700 1 185 160 1 220 18 5 1 245 240 1 285 249 1 365 295 1 385 360 1 460 425 1 510 575 1 500 515 1 695 680 Wt. Lbs. w/ w/ H li d grate 1 1 15 100 y. 165 150 y. 195 185 y. 200 185 y. 235 255 y. 245 2 15 y. 290 260 1 340 390 :y. 360 310 l 485 445 1 185 160 1 165 180 1 210 195 1 230 215 1 295 31 0 ¥. 290 260 ¥· 335 295 1 39 5 405 1 400 380 1 480 425 R-18 7 8-A5L Manhole Frame and Solid Lid . _____.; --------~ ' --------- ~c'1 ==1=i===tt~A==~=:1=__.==\~~;r.~ .. ~: -·---..; • Heavy Duty R-1 878 Secti ons R· 187 9-B 1 G Ca tch Ba sin G r a t e and fram e ---· -----; -------' -------·---2JF-=-==:ttttlS! I . Li ght Duty R-1 879 Sect i ons ---------------------------------------------------.. ~-.. t<:iio:;;::~~l':·~~~.<41!1:s:.,."!'~~;u:s:..,'-~!%~}<~ .... :\'."'ll«'~-'~'*3~;¥~..,RWl'llll[l!:$Er.!&!llJµ;;;§Qt'9!:, !:!lll'll!Wlllll&ll!ld1Snlll.!!l!J#?.1.p"IP.~.,;~ SECTION#! DRAINAGE AREA PRE -DEVELOPMENT SECTION #1 DRAINAGE AREA -PRE-DEVELOPMENT GENERAL INFORMATION Description : Drainage area of site before development. D rai nage Area (ApRE.) = 0.603 acres T IME OF CONCENTRATION CTc) GIVEN Maximum T ravel Distance (DpRE.) Ve locity of Runoff (VpR E.) = Coefficient of Runoff (Cp RE.) = 215 ft ft 0.75 fsec 0.32 **NOTE: M i nimum Tc allowed = 1 O min . 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e ) = Coefficient (b) = Coefficient (d) = 0 .806 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e ) = Coefficient (b ) = Coefficient (d) = 0.785 76 8.5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e ) = 0 .763 Coe ffi cient (b ) = 80 Coefficient (d) = 8.5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.754 Coefficient (b) = 89 Coeffi cient (d ) = 8.5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0.745 Coe ffi cient (b) = Coefficient (d) = 98 8.5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e ) = 0 .73 Coefficient (b) = 96 Coe ffi c ient (d) = 8 2987-0001 29 Detention Facilities Evalu at ion .xis RESULT T C(PR E) = 4.8 min . Rainfall Intensity (I i) = 6.32 7 in/hr J§i:,i:::::::::::::.:::::::::::::::::=::::[_[:l· :: ::·:=:::,::<. '/ ·;? ::::::J.il@M~~t::::t::::: Rainfall Intensity (1 5) = 7 .. 693 in/hr :9~:::m::.r1::r::·::::::::::::::.:.:.::·:r·:::::r::r::: ':::::::: ·:::::1s~~:::m·,:::.::··: Rainfall Intensity (1 10) = 8.635 in/hr :sjij·::i ::=:::::=t:r.:::·i:·::r.:r ·::::::.::·:.:·::·:·::-.:::::::: :::::1~1P:.::1~·:::::::::::: Rainfall Intensity (1 25 ) = 9.861 in/hr ::g~j :ffi::::: :::::1 :·;·:::·:::::;:::_:::::.:.,:_:·:::-:::,::':::_:::.:;:;I: .[1i%1~i!:fli: ! ... } Ra infall Intensity (1 100) 11 .639 in/hr ::mjj~ m.:::,,.:::;:::::::::::1::,:::::::::.:::,:::·:.:.:.:=··1::··:::,:.:.:::=-:: ::.~1~::,~t . ::::: SECTION#2 DRAINAGE AREA POST-DEVELOPMENT SECTION #2 DRAINAGE AREA -POST-DEVELOPMENT GENERAL INFORMATION Description: Drainage area of site after development Drainage Area (A1) = 0.250 acres (impervious area) Drainage Area (A2) = 0.363 acres (landscaped area) TIME OF CONCENTRATION CTc) GIVEN Maximum Travel Distance (D 1) = Velocity of Runoff (V1) = Coefficient of Runoff (C 1) = Maximum Travel Distance (D:i) = Velocity of Runoff (V:i) = Coefficient of Runoff (C:i) = 200 ft ft 3 .00 fsec 0 .90 40 ft ft 1.00 fsec 0.43 **NOTE: Minimum Tc allowed = 1 O min . 2 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.806 65 8 5 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = 0 .785 Coefficient (b) = 76 Coefficient (d) = 8 .5 10 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0.763 80 8 .5 25 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .754 89 8 .5 50 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 0 .745 98 8.5 100 YEAR FREQUENCY. RA TE OF DISCHARGE (Q) Coefficient (e) = Coefficient (b) = Coefficient (d) = 2987-00 0 l 29 Detent io n Facilities Eva lu ati on.xis 0.73 96 8 RESULT T c1 = 1.1 min . 0.7 min . T q POST) = 1.8 min . Rainfall Intensity (Iv = 6.327 in/hr Q AREA 1 = 1 .435 cfs Q AREA 2 = 0 . 996 cfs ·:·:·:·:·:·:·::·:·:·:·: :::::::::::::::;::;::: :;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:::::=::::::::: :;::::;::: ·=·=· ·······1···:.;~:: .... ::Si m ::::::::::::& :::::::: ::::t?:.J:::::::: ?:=::::J iJ@ :=~~~:::: fl Rainfall Intensity (1 5) = 7 .693 1 /hr Q AREA 1 = 1 .745 cfs Q AREA 2 = 1.211 cfs .... ·:::·:;:·:·:-:·:::·:· ::::::::: ·::: :·:·:·:·'.·'.· ............ :. ············.··:······· :~,a :::: t::::::r: ,,,,,,,,,,,,,, f::,,,,,s' ·:t'': =:1~~~r1m::::::=:: Rainfall Intensity (1 10) = Q AREA 1 = in/ 8 .635 hr 1.959 cfs QAREA 2 = 1.359 cfs :lii::a:. ,,,:::::::::::::·:·:::,:.:::::: : : ... r.:-::=:·:.J:.:·::::: :::::::-::,::!*!~!: crsm:m:r Rainfall Intensity (1 25) = QAREA 1 = 9 .861 in /hr 2 .237 cfs QAREA 2 = 1.552 cfS -~::;;= :::::=::==:=::::::=:=::===::===:=::::==:==::?:=::=:_==;::::=:::::==:=· :·=·::·=·3 :7 391 E&< :: Rainfall Intensity (1 50) = Q AREA 1 = Q AREA2 = 11 .148 in/hr 2 .529 cfs 1.755 cfs ·B.ffi:"=],_l _ji('i;::, :::::::::;=;:; :::= ::::i ,2i4 Mtifl ::r Rainfall Intensity (1 100) 11 .639 in/hr Q AREA 1 = 2 .641 cfs Q AR EA 2 = 1.832 cfs sj*-a :.::::: :::.:::::::::: ::t==, ,)1::t:::::J : ::~~,,t:~·~::m:::: SECTION #3 DRAINAGE AREA HYDROGRAPHS SECTION #3 -HYDROGRAPHS Chart 4 2-YEAR HYDROGRAPH Volume Con\feyed = 1,080 ft ~ r.!) ~-~ ~ 2 -------- u -rJ1 .... ~ 1---- 0 0 I I 10 El Post-Development El Pre-Development HY DROGRAPH S Chart 4 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 5 5-YEAR HYDROGRAPH 0 10 mJ Post-Development EJ Pre-Development HY DROGRAPHS Chart 5 Tll\1E (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 6 10-YEAR HYDROGRAPH 0 10 El Post-Development El Pre-Development HYDROGRAPHS Chart 6 Tll\ilE (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 7 25-YEAR HYDROGRAPH 2.5 ~ ~ ~-~~ 2 = ~ u- 00. .... ~ 1 .5 0 10 Im Post-Development Cl Pre-Development I HYDROGRAPHS Chart 7 TIME (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 8 50-YEAR HYDROGRAPH 4.5.------------------------------------.--------------------------------------.-----------------------------------. 3 .5 -------- 3 ,,._ _____ --j 2 .5------ 2----- 1 .5---- 1--- 0 .5 0 0 10 8 Post-Development D Pre-Development HY DROGRAPHS Chart 8 1,903 ft 3 T™E (min) 20 30 SECTION #3 -HYDROGRAPHS Chart 9 100-YEAR HYDROGRAPH a -----------------------------------------.------------------~ i 3 Volume Con vey ed =11,987 ft i 7--~~~~~~~-I,__~~~~~~~--+--~~~~~~------< I 2 ----- 1 0 10 8 Pre-Develop ment 8 Post -De velo pment HYDROGRAPHS Chart 9 T IME (min) 20 30 1 Figure XU Development Permit City of College Station, Texas Site Legal Description: \?r2.~N~0' ~C.-\li:;:)N 0Nl'.i...) ~~C.'t.. D~E. J l~:51':> (o-l'Z_ Site Owner: CciZ \fru-rv"2.Y.. f'AeJNr"..J?5 1 LLC.. J""C\4N. Kt L \-Z., Architect/ Eng ineer : mul\l\C.\'£1\1,,. W\IE.\.tRM@ fu-Jf Date Application Filed : _______ _ \-\C\)SfT cN I \)C. 7 70 \ Y Address : 1£1450 l.C.. Jeei1£Jt fu.'Jt/. ~c Telephone: ( '2..f>\) 8'\3-87'':> I cs" l"t.. 1-re'1-o Addr~ss : 25"5 l \'E,'fA:;, F'N£. S, S\e.. A Telephone No : C:-icrr') <.o'1o-S'!>S°t Address : ------------ Telephone No :---------- Approved : __________ _ Application is hereby made for the following development specific waterway alterations : -rmerz.ove.MF....NTS -f t:f;:.v&..oPm;;gr oF-6rCo03 &eFZ.<> oN Be.~-rwcco _t~ @%;;JN Z?~ CeEFX. 0@1NAu..-e.t>i...i ~ Application Fee ~ Signed Cenifications ~ Drainage and erosion control plan, with supporting Drainage Report two (2) copies each. 0" Site and Construction Plans, with supporting Drainage Report two (2) copies each. 0 Other: ----------------------------- ACKNOWLEDGME NTS : I, @e;n..1 B, 63J?QQ,L l Ji?, , design eng ineer/owner, hereby acknowledge or affirm that : The information and conclusions contained in the above plans and supponing documents comply w ith the current requ irements of the City of College Station, Texas City Code, Chapter 13 and its associated Drainage Policy and Design Standards . As a condition of approval of this permit application, I agree to construct the improvements proposed in this application according to these documents and the requirements of Chapter 13 of the College StatioLJCity 11Co~~ ~~Ir Prp0~9L1Jr Contractor ~ ~-----------------------__J Figure XrI Continued CERTCFICATIONS : (for proposed alterations within designated flood hazard areas.) A. I, No~n+ B. &!,eoe.u.,~. , certify that any nonresidential structure on or proposed to be on this site as part of this application is designated to prevent damage to the structure or its contents as a result of flooding from the 100 year stonn. 1)-;\ ~ ~' Di Q r: ,..1Ji 1\ If} I If// o ~ ~---,-WU~!./ 1~ Ir-0-::-r . j 7, '17 D ----;.~-----..,~------~~-- Engineer Date - B . C, No(?.Jt+ 6. ~12t?£LL 1 Jie. , certify that the finished floor elevatio~ of the lowest floor, including any basement, of any residential structure, proposed as part of this application is at or above the base flood elevation established in the latest Federal Insurance Administration Flood Hazard Study and maps, as amended . ~s:tv13 .·'I~ l Engineer Date C I, l\fo~:n.t 13. &mu. .Jt. , certify that the alterations or development covered by this permit shall not diminish the flo~d-carrying capacity of the waterway adjoining or crossing this permitted site and that such alterations or deve lopment are consistent with requirements of the City of College Station City Code, Chapter 13 concerning encroachments of flood ways and of f1 oodway fringes . V{L~ fjl ~J!A} ~- Engineer 1 ~ 7 Date I, Abl2:rt+ 13 . ~l Jg , do certify that the proposed alterations do not raise the level of the l 00 year flood abov~ elevation established in the latest Federal Insurance Administration Flood Hazard Study/] !f/p-'Tt:f 6 ii);Jf ~' Engineer / Conditions or comments as part of approval ------------------- In accordance with Chapter l3 of the Code of Ordinances of the City of College Station, measures shall be taken to insure that debris from construction, erosion, a0d sedimentat ion shall not be deposited in city streets, or existing drainage facilities . [ hereby grant this permit for development. All d ev elopment 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 appl y. MUNICIPAL DEVELOPMENT GROUP 2551 Texas Ave. South , Ste. A •College Station , Texas 778 40 • 409-693-5359 •FAX: 409-693-4243 •E-mail: mdgcs@gte .n et Engineering, Surveying, Planning and Environmental Consultants January 13 , 1999 0 ~ 1/;w/1ft r~fid~~J1 J..·w~~ . Shirley Volk, Development Coordinator Development Services I College Stati ~ft'le ""f ~pJ--'7t:O~,t au;,ot, · ·f c6 ~ ~~ Ur-> ~CJUJ Re: Q.A.B. -Revised Site Plan MDG Job No. 000129-2987 Dear Shirley : I ~ oJJ i,J ot µ~--. ~ -. ,\) As you know, over the last sev eral months Mr. John Kiltz as been attempting to adjust his · approved parking lot to accommodate an outdoor quick alignment station . Due to this , the parking requirements have increased to a total of 36 parking spaces . This number take s into consideration the square-footag e of the new working bay s . Attached are two revised sets of plans that reflect the above changes . Please note the following two items . > The area of impervious cover has decreased from the original site plan . Therefore , detention requirements have also decreased . This will gi v e the site 's detention area more buffer and also decrease the rate of discharge from the pond due to a lower head on the grate inlet . > Per the PRC meeting in December the 20 ' access alley east of the building has been opted to be removed . Please feel free to call me if you have any questions . --::.--::.----' --/-~>----_// ·~~/ -Rabon Metcalf, E.I . T. R.J.Wtm Cc : John Kiltz , CCG Ventures Enclosures : (2) Revised Construction Plans 00 0 129-c.06 .d oc ~ID G -1