SITE HYDROLOGY. Created by PRE-CONSTRUCTION S>30% 10<S<30 5<S<10 0<S<5 .35>C>.28.28>C>.20.20>C>.14.14>C>.08 NO SOIL CLAY WELL DRAINED SAND

Transcription

1

2 AYS ENGINEERING GROUP, Inc Client job no location Date Created by PRE- & POST-CONSTRUCTION RUNOFF ANALYSIS PRE-CONSTRUCTION Area 112,364 SF 2.58 ACRES TOTAL AREA OF ENTIRE PROPERTY. C FACTOR ADDITIVE METHOD= RELIEF Bill Johnson ALL VEGITATION NO STRUCTURES NOT FOR SIZING THE INDIVIDUAL PIPE RUNS S>30% 10<S<30 5<S<10 0<S<5.35>C>.28.28>C>.20.20>C>.14.14>C>.08 USE 0.35 SOIL INFILTRATION EXTREME HIGH NORMAL LOW NO SOIL CLAY WELL DRAINED SAND.16>C>.12.12>C>.08.08>C>.06.06>C>.04 USE 0.16 VEGITAL COVER EXTREME HIGH NORMAL LOW NO PLANTS POOR COVER 50% VEGITAL 90% + COVER GRASSLAND.16>C>.12.12>C>.08.08>C>.06.06>C>.04 USE 0.1 SURFACE STORAGE EXTREME HIGH NORMAL LOW NEGLIGIBLE WELL DEFINED LAKES PONDS GREAT AMOUNTS OF STORAGE DRAINAGE MARSHES SURFACE STORAGE.12>C>.10.10>C>.08.08>C>.06.06>C>.04 USE 0.1 TOTAL C = 0.71 AREA IN LANDSCAPE OR NATURAL SITE HYDROLOGY AREA HARDSCAPE FOR EXISTING CONDITION 2.58 ACRES 1 Lincoln Park 10/6/2015 TKP 0 ACRES WEIGHTED C AVG BY AREA: C IMP X AREA IMP + C SEMI X AREA SEMI + C LANDSCA) + MARSHESX = TOTAL AREA THEREFORE: 0.95 X 0.00 ) + ( 0.60 X 0.00 ) X ( 0.71 X 2.58 ) = 2.58 WEIGHTED AVG C = 0.71 FOR PROPOSED CONDITION TIME OF CONCENTRATION FOR THIS BASIN IS THE TIME NECESSARY TO FULLY DEVELOP THE FLOWS FROM EXTREME REACHES OF THE BASIN. OVERLAND SECTION L= 475 ELEVATION CHANGE FEET S= 0.40 Tc= 1.8*(1.1-C)(L)^.5 = 4.5 MINUTES + 5 MIN = 9.5 MIN S(100)^.333 USE CALTRANS ZONAL METHOD TO DETERMINE THE INTENSITY FOR THE SITE: ZONE D3 I 100= 1.4 IN/HR From Design Rainfall intensities Map "I" 1hr FIND I FOR TC 100 YEAR- SEE CHART K ZONE D I1hr,100= 1.4 IN/HR I9.5 min,100= 2.6 IN/HR INTENSITY FOR KNOWN TIME OF CONCENTRATION IN/HR USE RATIONAL METHOD TO DETERMINE FLOW: Q1=CIA= 0.71 X 2.60 X 2.58 = 4.76 CFS C i* A *INTENSITY FOR 6.3 MIN TIME OF CONCENTRATION IS TAKEN AS THE SAME AS FOR 6.3 MIN (IN EXIST. CONDITION) & EQUALS 3.6 IN/HR Q1 = 4.76 CFS FROM OVERALL PROPERTY IN EXISTING CONDITION

3 AYS ENGINEERING GROUP, Inc POST-CONSTRUCTION C FACTOR IN PREDEVELOPMET CONDITION = 0.71 C FACTOR FOR POST DEVELOPMENT IS THE WEIGHTED AVERAGE OF THE UN IMPROVED PART OF THE LOT AND THE DEVELOPED PORTION OF THE LOT WITH A C FACTOR OF 0.95 FOR ALL JARDSCAPE. AREA OF HARDSCAPE- BUILDIING AND IMPERMEABLE PAVEMENT. AREA IMP ROOF = SQ FT AC AREA PAVED= AC AREA SEMI IMP 0.00 AREA PERV SQ FT AC WEIGHTED C AVG BY AREA: C IMP X AREA IMP + C SEMI X AREA SEMI + C LANDSCA) X = TOTAL AREA THEREFORE: 0.95 X ) + ( 0.60 X 0.00 ) X ( 0.71 X ) = WEIGHTED AVG C = 0.72 FOR PROPOSED CONDITION TIME OF CONCENTRATION FOR THIS BASIN IS THE TIME NECESSARY TO FULLY DEVELOP THE FLOWS FROM EXTREME REACHES OF THE BASIN. OVERLAND SECTION L= 475 ELEVATION CHANGE FEET S= 0.40 Tc= 1.8*(1.1-C)(L)^.5 = 4.4 MINUTES + 5 MIN = 9.4 MIN S(100)^.333 USE CALTRANS ZONAL METHOD TO DETERMINE THE INTENSITY FOR THE SITE: ZONE D3 I 100= 1.4 IN/HR From Design Rainfall intensities Map "I" 1hr FIND I FOR TC 100 YEAR- SEE CHART K ZONE D I1hr,100= 1.4 IN/HR I9.3 min,100= 2.62 IN/HR INTENSITY FOR KNOWN TIME OF CONCENTRATION IN/HR USE RATIONAL METHOD TO DETERMINE FLOW: Q1=CIA= 0.72 X 2.62 X 2.58 = 4.87 CFS C i* A Q2 = 4.87 CFS FROM OVERALL PROPERTY IN PROPOSED CONDITION PRE- & POST-CONSTRUCTION RUNOFF CHANGE Q CHANGE FROM PRE- TO POST-: PRE CFS POST CFS CFS CHANGE SO VERY LITTLE INCREASE IN RUNOFF FROM DRAINAGE BASIN BASED ON PROPOSED CONSTRUCTION

4

5 P:\2015-Jobs\ Johnson hydro 1-Lincoln sa\dwg\g&d 32 ranch.dwg, 10/12/2015 7:21:47 AM, DWG To PDF.pc3

6

7 P:\2015-Jobs\ Johnson hydro 1-Lincoln sa\dwg\g&d 32 ranch.dwg, 10/12/2015 7:23:01 AM, DWG To PDF.pc3

8 AYS ENGINEERING GROUP, Inc Client job no POST CONSTRUCTION STORM TREATMENT Bill Johnson location 1 Lincoln Park Date 10/6/2015 Created by TKP AREA OF DRAINAGE BASIN = 2.58 ACRES OR 112,364 SQ FT APPROX AREA OF PROPERTY = 0.67 ACRES OR 29,204 SQ FT AREA OF HARDSCAPE- BUILDIING AND IMPERMEABLE PAVEMENT. AREA IMP ROOF = SQ FT AC AREA PAVED= AC AREA SEMI IMP 0.00 AREA PERV SQ FT AC BAASMA GUIDELINES SUGGEST THAT 4% OF NEW HARDSCAPE IN BIO RETENTION WILL MEET THEIR GUIDELINES BIORETENTION PLANTERS = 0.04 X ( ' = SQ FEET

9 P:\2015-Jobs\ Johnson hydro 1-Lincoln sa\dwg\g&d 32 ranch.dwg, 10/12/2015 8:43:09 AM, DWG To PDF.pc3