06-038 Wright Drainage.doc.pdfDRAINAGE REPORT
FOR
A SINGLE FAMILY RESIDENCE
BEING A PORTION OF THE NE 1/4 OF SEC. 24, T. 27 N., R. 3 E., W.M.
CITY OF EDMONDS
SNOHOMISH COUNTY, WASHINGTON
JRR # 05-91
PREPARED FOR:
ALEXANDER BAY CONSTRUCTION CO.
RYAN WRIGHT
PREPARED BY:
JRR ENGINEERING, INC.
18609 76TH AVENUE WEST, SUITE B
LYNNWOOD, WA 98037-4149
PH. (425) 697-5108
FAX (425) 697-4506
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Development Impacts
The parking configuration, landscaping and drainage improvements are proposed to provide access and
parking for the proposed use and improve the collection of surface water runoff on the site.
No significant erosion has been observed on-site and no significant erosion is anticipated on the subject
property or adjacent properties, due to the proposed development.
Post development peak flows are expected to have no significant impact on existing downstream
conditions.
a r
It is also the case that: 6_ 4
FV
(1) Modification to the existing drainage syste will cause runoff to be diverted away from
the adjacent downstream property.
(2) The proposed improvements are not expected t6, aggravate an existing drainage problem
or create anew drainage problem adjacent to dow'2astream properties.
(3) A single orifice control structure is proposed for treatmean
rd for releasing runoff at pre -
developed rates.
(4) The proposed project conveyance system will contain and conve�ye 10 and 100 -yeah
design storms. ;
(5) The Clearing Limits that are anticipated consist of and coincide with the property lines,
which will be marked prior to construction to indicate and delineate proposed
improvements.,
Erosion/Sedimentation Control Design
Silt fencing, construction entrance and typical cover techniques will be employed to minimize the
potential for erosion and sedimentation. Erosion and sedimentation control details have been provided
in the construction drawing submittals.
Off Site Analysis:
The site is generally at the same grade as the abutting properties, and is generally not affected by
it off-site areas". Storm runoff generally is limited to that which is generated "on-site".
Downstream conditions consist of a closed (pipe) drainage system draining along SR 524. No
significant erosion has been observed around the existing grading. No significant erosion is anticipated
on the subject property due to the proposed development.
Post development peak flows are expected to have no significant impact on existing downstream
conditions.
AMARY OF INPUT ITEMS
1) TYPE OF FACILITY: TANK
2) TANK DIAMETER(ft) , STORAGE DEPTH(ft) : 3.00, 3.00
3) VERTICAL PERMEABILITY(min/in): .00
4) PRIMARY DESIGN HYDROGRAPH FILENAME: bay100po
5) PRIMARY RELEASE RATE(cfs): .05
6) NUMBER OF TEST HYDROGRAPHS: 1
TEST HYD 1 FILENAME: baylOpo TARGET RELEASE(cfs):
7) NUMBER -OF -ORIFICES, RISER-HEAD(ft), RISER-DIAM(in): 1, 3.00,
8) ITERATION DISPLAY: NO
w"
ENTER ITEM NUMBER TO BE REVISED (ENTER ZERO IF NO REVISIONS ARE REQUIRED):
0
INITIAL STORAGE VALUE FOR ITERATION PURPOSES: 975 CU -FT
SINGLE ORIFICE RESTRICTOR: DIA= 1.03„
PERFORMANCE: INFLOW TARGET -OUTFLOW ACTUAL -OUTFLOW PK -STAGE STORAGE
DESIGN HYD: .22 .05 .05 2.99 530
TEST HYD 1: .12 .02 .03 1.35 230
SPECIFY: D - DOCUMENT, R - REVISE, A - ADJUST ORIF, E - ENLARGE, S - STOP
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ROUTING DATA:
STAGE (FT)
.00
.30
.60
.90
1.20
1.50
1.80
2.10
2.40
2.70
3.00
3.10
3.20
3.30
3.40
3.50
DISCHARGE(CFS)
.00
.02
.02
.03
.03
.04
.04
.04
.04
.05
.05
.26
.63
.97
1.12
1.24
STORAGE (CU -FT)
.0
27.7
75.7
134.1
198.5
265.7
333.0
397.4
455.8
503.8
531.5
531.5
531.5
531.5
531.5
531.5
PERM -AREA (SQ -FT)
.0
.0
.0
.0
.0
.0
.0
.0
.0
0
.0
0
_0
.0
.0
.0
AVERAGE VERTICAL PERMEABILITY: .0 MINUTES/INCH
SPECIFY: F - FILE, N - NEWJOB, P - PRINT IF/OF, R - REVISE, S - STOP
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