Loading...
HomeMy WebLinkAboutSDP200900032 Calculations 2009-04-23 April 23, 2009 Title of Request Part of Minor Amendment 1. Submission to Reduce DI's to DI-3A Long Throats Unnecessary for Pervious Pavement Parking Lot 1 Foot#57 Stone Base The following computations show that long throats on drop inlets are not necessary for pervious pavement parking lots. All rainwater is immediately passed through the slab to the 12"base stone (#57). No water flows along the curb. All drop inlets should be reduced to DI-3A. This becomes a junction box for major storm piping as well as the subsurface SB-1 pipe. If the storage capacity in the 40%void ratio is used entirely,this will activate the small throat in the DI-3A. 1.49 Acre Parking Lot 1.49 x 43,560= 64,904 sq. ft. 1 Foot(64,904)=64,904 cu.ft. #57 Stone has void ratio approximately 40% Storage Area in Base 40% of 64,904 cu.ft. = 25,962 cu.ft. Storage 7.48 Gal/cu.ft.(25,962)= 19,196 gal. 1"/hr= 1 12(64,904)= 5,409 cu.ft. =volume of 1"/hr required 5,409(7.48) = 40,459 gal. This is without using the slab for storage. The carry capacity of the SB-1 6"diameter pipes at the parking lot gutter slope(2.25%). See computer printout for 6"diameter pipe. DITCH CALCULATIONS: NORMAL CRITICAL SLOPE (FT/FT): .0225 .0053 FLOW(CFS): 0.25 VELOCITY(FT/SEC): 4.2255 2.4839 LENGTH(FT): 100.00 DEPTH(FT): 0.1706 0.2549 MANNINGS N: .0110 TRAVEL TIME (MIN): 0.39 CIRCULAR CHANNEL DIAMETER= .5 FT PIPE CAPACITY= .9973656 CFS `....-) vv' K } , 1' GA -c3: LA-- 1 -ry 0 Is'i• "4% NM.:1--\A c.k C_.E.,, ' ::)...) .--i::). , i-A .. 1:\k-,?,rz ----- _ - -- -------- __ _ ____ _______Rli_t44- U_F_F- -tb_.--)..g.______\4 _,..J JNFkc,1,- _ _____ _,_ Q,,,, --1.- (e) .Z5-1 7. ;\1. ‘,4- z o. 2-4 qi__ J-5 t>_V__>/, tf4_2__ .1' (-0 ' Z" In i_=.4 14 ---- ca_. b_n_m__ c..t. - -- -'2 +a.- - - - -- --- io `t Ic - --- --- -- C- O 2. -- -- - z__— ►-5 . 61 ----- = ‘ $ . 13 - - III:1I::IT --: 0 i —i, ------- --- _ 0 f Z 4- ch) 2.---emu - 0---3 — nv_c,- ___Lca _ 'or tv.4 r?i'�ZAdJ _____-p.,,.; #,Ar...,4,x -- . us.A14 .‹._ pr-V---*:...- _ P.0 p-00 _ .. *A w., -r- -�e.. 1 ,_ As STATig _LtA 1441 Ltv ‘vt ‘Pw-i1/4-v.- -1-4-__e.,__ __17__ttrTle_e'rr._A--LC.E... - -- _ _DE.t.it 0 . 4V..t '°' a, ro c. Z .ct a ti � 5 -------- - rf 0. Co -o e.. c.r2.1s..,-r i --- ------------ c —4.: c=•.`Z' ___E_ETs .c)_k._-_ 2 * io -- N. :-- % -s Tc v2 v 4 - t4- "[) t'r 1 0-1:::. RiPer-1 e3 TA A ___Mtmm4-c__.i:)______ *_pfke.od1/41=› tik.iE ie.1--__ Aoa—pre_AiE,S>. Gg_ btiT itic-► 57o___ � MODIFIED RATIONAL METHOD (2-Y EAR STORM) PROJECT: ST. ANNES-BELFIELD JOB#: 07-029-00 AMOUNT CREDITED TO SAND FILTERS DESCRIPTION: USING 0.60 ACRE CREDIT SHEET 1 OF 1 2-YEAR CRITICAL STORM DURATION C=developed condition runoff coefficient 0.9 A=drainage area, acres 0.6 a2=2-year rainfall constant 106.02 b2=2-year rainfall constant 15.51 = 2CA a(b -t�/4) _ b tc=post-developed time of concentration,min. 5 Td q02=2-year allowable peak outflow, cfs 0.825 qo Td2=2-year critical storm duration, min 28.97755789 2-YEAR CRITICAL STORM INTENSITY a2=2-year rainfall constant 106.02 b2=2-year rainfall constant 15.51 a Td,=2-year critical storm duration, min 28.97755789 I b fTd I, =2-year critcal storm intensity, in./hr. 2.383138231 I 2-YEAR PEAK INFLOW C=developed condition runoff coefficient 0.9 I2 =2-year critical storm intensity, in./hr. 2.383138231 A=drainage area, acres 0.6 Q. = CIA I Q;2=2-year peak inflow, cfs 1.286894645 2-YEAR REQUIRED STORAGE VOLUME Q12=2-year peak inflow,cfs 1.286894645 Td2=2-year critical storm duration,min 28.97755789 t,=post-developed time of concentration,min. 5 r� °T 4 3 r q02 =2-year allowable peak outflow, cfs 0.825 V= Q. Td + Q - 2 d - 4 60 V2=2-year required storage volume, ft3 1431.161384 V2=2-year required storage volume, ac.ft. 0.032854945 NOTES MODIFIED RATIONAL METHOD (10-YEAR STORM) PROJECT: ST. ANNES- BELFIELD JOB# : 07-029-00 AMOUNT CREDITED TO SAND FILTERS DESCRIPTION: USING THE 0.60 ACRE CREDIT SHEET 1 OF 1 10-YEAR CRITICAL STORM DURATION C= developed condition runoff coefficient 0.9 A=drainage area,acres 0.6 a10= 10-year rainfall constant 161.6 b10= 10-year rainfall constant 18.73 2CA a( -tc/4) tc=post-developed time of concentration,min. 5 Td - — b g010= 10-year allowable peak outflow, cfs 1.065 qo Tdio= 10-year critical storm duration,min 34.79152338 10-YEAR CRITICAL STORM INTENSITY alo= 10-year rainfall constant 161.6 b,o= 10-year rainfall constant 18.73 I _ a Tdio= 10-year critical storm duration,min 34.79152338 b �7,d Ito= 10-year critcal storm intensity, in./hr. 3.019346046 10-YEAR PEAK INFLOW C=developed condition runoff coefficient 0.9 Ilo= 10-year critical storm intensity, in./hr. 3.019346046 A=drainage area, acres 0.6 Q. = CIA = 10-year peak inflow, cfs 1.630446865 10-YEAR REQUIRED STORAGE VOLUME Q;10= 10-year peak inflow, cfs 1.630446865 Tdio= 10-year critical storm duration,min 34.79152338 tc=post-developed time of concentration,min. 5 10-yearQ allowablepeak outflow, cfs 1.065 V- [Q, T + i c qo Td 34o rc goio= - d 4 - 2 - 4 60 V 10= 10-year required storage volume, ft3 2174.613156 V10= 10-year required storage volume,ac.ft. 0.049922249 NOTES MODIFIED RA IONAL METHOD (2-Y AR STORM) PROJECT: ST. ANNES- BELFIELD JOB# : 07-029-00 MAINTENANCE AREA DESCRIPTION: SHEET 1 OF 1 2-YEAR CRITICAL STORM DURATION C=developed condition runoff coefficient 0.9 A=drainage area, acres 0.14 a2=2-year rainfall constant 106.02 b2=2-year rainfall constant 15.51 2CA a(b _t /4) t,=post-developed time of concentration,min. 5 Td = — b q02=2-year allowable peak outflow, cfs 0.193 qo Td,=2-year critical storm duration,min 28.91989415 2-YEAR CRITICAL STORM INTENSITY a2=2-year rainfall constant 106.02 b,=2-year rainfall constant 15.51 a Td,=2-year critical storm duration,min 28.91989415 I - b +Td I, =2-year critcal storm intensity, in./hr. 2.386231208 I 2-YEAR PEAK INFLOW C=developed condition runoff coefficient 0.9 12 =2-year critical storm intensity, in./hr. 2.386231208 A=drainage area, acres 0.14 Q. = CIA Qi2=2-year peak inflow,cfs 0.300665132 2-YEAR REQUIRED STORAGE VOLUME Qi2=2-year peak inflow, cfs 0.300665132 Td,=2-year critical storm duration,min 28.91989415 t,=post-developed time of concentration,min. 5 q02=2-year allowable peak outflow, cfs 0.193 V= Q.Td + Q't` - q° Td - 3q0 r` 60 4 2 4 V2=2-year required storage volume, ft3 333.3909257 V2=2-year required storage volume, ac.ft. 0.007653603 NOTES MODIFIED RATIONAL METHOD (10-YEAR STORM) PROJECT: ST. ANNES- BELFIELD JOB#: 07-029-00 MAINTENANCE AREA DESCRIPTION: SHEET 1 OF 1 10-YEAR CRITICAL STORM DURATION C=developed condition runoff coefficient 0.9 A=drainage area, acres 0.14 ai0= 10-year rainfall constant 161.6 bio= 10-year rainfall constant 18.73 2CA a(b —tc/4) tc=post-developed time of concentration,min. 5 Td = — b q010= 10-year allowable peak outflow, cfs 0.249 go Tdio= 10-year critical storm duration,min 34.73775991 F 10-YEAR CRITICAL STORM INTENSITY alo= 10-year rainfall constant 161.6 bio= 10-year rainfall constant 18.73 I -= a Tdio= 10-year critical storm duration,min 34.73775991 b +7,d Iio= 10-year critcal storm intensity, in./hr. 3.022382091 10-YEAR PEAK INFLOW C =developed condition runoff coefficient 0.9 lio= 10-year critical storm intensity, in./hr. 3.022382091 A=drainage area, acres 0.14 Q. = CIA Q;io= 10-year peak inflow, cfs 0.380820143 I 10-YEAR REQUIRED STORAGE VOLUME Q;io= 10-year peak inflow, cfs 0.380820143 Tdio= 10-year critical storm duration,min 34.73775991 to=post-developed time of concentration,min. 5 q010= 10-year allowable peak outflow,cfs 0.249 V= Q,Td + Q't` _ 4°Td - 3q°t` 60 4 2 4 V 10= 10-year required storage volume, ft3 506.775767 V io= 10-year required storage volume, ac.ft. 0.011633971 NOTES • - -14e_ 00-ss-t.t) a::›leTrzet4.7‘o_a 07E, 110, 5-roger,Gete- vit 3 j (;.3 CA) , •7r, Z 17 ctur. A M V Vick‘14-tipAAAce iL • -3 3 c_ak P.7r. .%c1M _S 4? 7S C40, VT. CLA_ tA_G_ 4t . Xcp ck7 c.,et- VT, Z 7_4.Gt sac).ie ti e_13. C..AkE.c.< CA•re_tas_c-i'_CA' te-X> t.4 Cs, LAST-. M.Pg.1__Cei-Vr-V 3-> (0_„ t•A,) • A_PZ-+4--1 z 5)( 0,0 i=6 0 • 0 00 0 . es • •--- 0 . 5'11 0z (0 ..(64(,,7 6,4 C + O 3 Oq 0 Co3 2- A•Rram = O.• _1 PROJECT 07-029-00 RUN DATE 04-22-2009 INLET NUMBER 1 LENGTH 12 .0 STATION 1000 DRAINAGE AREA = 0 .630 ACRES C VALUE = .760 CA = 0 .479 DRAINAGE AREA = 0 .120 ACRES C VALUE = .760 CA = 0 .091 SUM CA= 0 .570 INT= 4 .00 CFS= 2 .280 CO= 0 .000 GUTTER FLOW= 2 .280 GUTTER SLOPE = 0 .0200 FT/FT PAVEMENT CROSS SLOPE = 0 .0333 FT/FT SPREAD AT A SLOPE OF .020 ( ft ./ft . ) IS 5 .46 ( ft . ) XXXXXXXXXX CURB INLET IN A SUMP XXXXXXXXXX P EFFEC . LENGTH = 15 .60 H = 0.550 / DEPTH OF WATER = 0 .16/ c . SPREAD = 4 .78 f O' • INLET NUMBER 1 LENGTH 12 .0 STATION 1000 DRAINAGE AREA = 0 .630 ACRES C VALUE = .760 CA = 0 .479 DRAINAGE AREA = 0 .120 ACRES C VALUE = .760 CA = 0 .091 SUM CA= 0 .570 INT= 6 .50 CFS= 3 .705 CO= 0 .000 GUTTER FLOW= 3 .705 GUTTER SLOPE = 0 .0200 FT/FT PAVEMENT CROSS SLOPE = 0 .0333 FT/FT SPREAD AT A SLOPE OF .020 ( ft ./ft . ) IS 6 .55 ( ft . ) XXXXXXXXXX CURB INLET IN A SUMP XXXXXXXXXX P EFFEC . LENGTH = 15 .60 H = 0 .550 DEPTH OF WATER = 0 .22 ✓ SPREAD = 6 .60 vi MOIL NEW IMPERVIOUS AREA G' A S N W IMPERVIOUS AR. A ,:35.05 _q.ft. 6,161 .47 sq.ft. 0.0 acres 0.14 acres GRASS -,229.32 0.12 acres OLD TOTAL AREA 26,651 .57 sq.ft. 0.61 acres SP T FOR SUMP 5,4 :.55 sq.f . 0. 2 acr-