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'Shdrig Cakillad(VIS (per pg. 25 of RG handbook)
3
ISOH drairmge rate
Cori trib,iting area
1:1es4-ed pc)nding clepth
Desired peftramnce
levd
Rainfall Region
Sizing factor
RES UL'irs
Required size of top
SUrface of pondingi area
Design dimensions for
top suiface of ponding
area
Overflc)w containmerit
a a
T -F. inches Per hoi.,vr-
square feet
6 inches
13ES'
Region 2, Edaronds,
Washington
-7,1,','
Twide x 16' long = 112
SF
Ovvide x 18' long =_1,62"
SF IPWI1,0011,14,
per test clescxiL)ed on pg
15-17
per. as bUilt
ria..map on pg 22
per. Rain Garden sdrig
chart on pg 21
Gar'dr-,.w 1:11ans f6j, McCalfis-ter' Residetice
..... ..... ...... . .. . . .................. . .. . ............
'18019 Anclover Street,
Rain garden designed according t.o (lie I'Rairr Garden I landbookfor Western
Wasl"lington,
Per, handbook, steps were taken to design a rain garden to acco rn ryiod ate miater RU101f
frr rn rou
ghly 1700 sq Ft of existing bluestone patio. Per handbook (pg. "15) a 24" test
I-iolewas dug In the proposed rear garden area. It w,,:is filled to '12" with Water 3 tinies,
each time drained -fully wW-Jn 2 hours (first two tests drained instantly, third test reSUited
in, full drainage in two hOW"S), resulting in a drainage rate of Tv iri/hr (see PiCtUres of third
test attached), Accoi ding to the rain garden sizing chart (pg. 21) and 10'ased on w-ir
locadw sit(NA In region 2 (per neap on pg. 22), for a drainage rate of 2,13+ irift-ir and for a
rain gat -den with GOOD drainage, a sizing calculatrion of 6% of the '17(0 sq H. irripel-VIOUS
area results in a rain garden sized '102 sq -ft.
The pro�p�osed rain garden is sited more than 5 feet frorn the northern property line and
more than 1 Ofeet from any building stri.,ictures. A hose was run over -ffie patio area in
various liocations for '14- tiour each whiel"i resulted in a small aFnOUV'1t of water running -to
the northeast corner of the patio. (it ShOUM be rioted that based on observation it
wrind appegar that the majority of the water resolved Into the and joints between -the
pavers.) It was determined that a pickup drain shOUId be positioned in that location.
Proposed rain gar -den location is sited Such that water runoff will drain by gravity. Frown
the pickup drain, a 4, inch pipe will run under patio stairs and into proposed rain garden
for collection. See, attached as -built for rain garden location arid attached rain garden
schernatic for details.