Burnstead-OldWoodway_Dec_2012_submittal.xlsx
Stormwater Management Review Checklist
Date:1/25/2013
(For New Developments with > 5,000 sq ft of new impervious surface and 1 acre
or larger.)
Site/Address:Woodway Elementary
Permit:PRD 07-17/PRD 07-18
Applicable Code: Pre-2010 ECDC 18.30
By: Jerry Shuster, P.E.
CompleteIncompleteComments
Minimum Requirements (ECDC 18.30.060 A. 1. - 10.)
1
X
Full infiltration is proposed, see clarifications needed related to the proposed pit drains in item 4(L)1.below.
1. Stormwater Detention/Stream Bank Erosion Control
Upstream run on is accounted for in calculations, but how it is to be routed to the street system is not in plans.
Figure DC in the Storm Drainage Report shows the off-site flows being conveyed though lot 11. The civil drawings
should include the piping and apprurtences that will capture this off-site flow and convey it to the street system,
X
including sizing calculations.
2. Preservation of Natural Drainage systems
3. Source Control of PollutionN/A
X
4. Runoff Treatment BMPs
5. WetlandsN/A
6. Water Quality Sensitive AreasN/A
Page 3-7 of the Storm Drainage Report states that the overflow route for the proposed infiltration facility is
directly tight-lined to the storm drainage system on 237th Pl SW. Provide more detailed information on the
X
overflow system.
7. Off-Site Analysis and Mitigation
8. Basin PlanningN/A
Describe how O&M responsibility will be transferred to Homeowners association; City Council approved
X
preliminary plat with the condition of 5-year maintenance bond-explain how this will be implemented.
9. Operation & Maintenance
Not reviewed by this Engineer
10. Financial LiabilityN/A
2Additional/Modified requirements per Hearing Examiner's Decision (3/7/2012).
X
This will be reviewed again during the building permit phase to ensure compliance on all 27 lots.
No individual lot or tract shall exceed 3,000 sf of impervious surface area (#2)
Page 3-3 of Storm Drainage Report states the developed condition assumes 90% impervious coverage for the
ROW. A breakdown of the proposed impervious and pervious surfaces shall be presented as follows:
Public Right-of-Way Square Feet
1. Road (incl. curb & gutter)
2. Sidewalk
3. Pervious
Private Property
1. Driveways/Walkways/patios
The final storm drainage design must account for 100% impervious surfaces within the 2. Roofs
X
public way including the road surface, sidewalk, curbs & gutter (#3)
The design infiltration rate for the plat to be determined using the methodologies in Section
5.4.1 of the 2005 KCSWDM for Soils, Infiltration Rates, Design Infiltration Rates, and
Performance Testing. The Applicant shall substitute the design infiltration rate for the f
d
value in the 1992 Ecology Manual. All other applicable provisions of the 1992 Ecology Additional information is required on how the proposed pit drains will affect the design infiltration
rate, see item
X
manual will remain in effect. (#8 and p.21)4.(L)1. below.
3Project Overview Narrative
X
5.61 acres
(A)Description of existing site (include area of site)
X
(B)Description of Proposed Development
6/30/2017Page 1 of 3
Stormwater Management Review Checklist
Date:1/25/2013
(For New Developments with > 5,000 sq ft of new impervious surface and 1 acre
or larger.)
Site/Address:Woodway Elementary
Permit:PRD 07-17/PRD 07-18
Applicable Code: Pre-2010 ECDC 18.30
By: Jerry Shuster, P.E.
CompleteIncompleteComments
The report should discuss the finished elevations of the lots compared to the adjacent properties. The intent will
Minimum Requirements (ECDC 18.30.060 A. 1. - 10.)
be to determine if any of the developed lots on the proposed development will be running off onto adjacent
X
properties and possibly causing drainage problems where not exist today.
(C)Discuss offsite drainage impacts to the site & from the site
X
(D)Nearest mapped surface water body where site stormwater discharges.
X
Discuss disposition of storm water runoff before & after development
(E)
X
Provide map showing general location of the site & geographical features
(F)
X
(G)Description of predeveloped assumptions for site
X
See item (K) 1. below.
(H)Description of post developed conditions of the site
X
(I) Description of Detention Requirements for Development
X
(J)Description of Water Quality Requirements for Development
(K)Other
The figure shows the off-site flow from the north passing though the most northwesterly parcel in the PRD. It is
unclear how this lot will accommodate this flow passing through to the PRD storm system and have a house on
X
it. Provide the proposed infrastructure for this lot to accommodate the flow and the house (See item 1.2 above).
1. Figure DC (developed time of concentration)
4Calculations
X
(A)Area Calculations
X
(B)Predeveloped Condition Runoff Curve Number
X
(C)Predeveloped Condition Time of Concentration
The model assumes 80% of the future lawn area will be on Type A soils with a relatively low curve number (will
produce very little runoff). The curve number for all the lawn should reflect the proposed post-development
condition such as the type of topsoil mix placed and whether the lawns will be from sod that may be grown on
X
clay (Type D) soils.
(D)Post Developed Condition Runoff Curve Number
X
(E)Post Developed Condition Time of Concentration
X
(G)Sub basin routing
X
(G)Predeveloped Condition Computer Model Results
X
See item (L) 1. below.
(H)Post Developed Condition Computer Model Results
X
See item (L) 1. below.
(I)Detention system assumptions
X
See item (L) 1. below.
(J)Detention system routing computer model results
X
(K)Water Quality Storm Calculations
X
(L)Other
Provide more information on the effect of installing the pit drains and how the number and spacing will be
1. Design Infiltration rate X
determined.
3. UIC registration X The Storm Drainage Report should state whether the infiltration facility needs to or does not need to be
registered with the state Department of Ecology under the underground injection control (UIC) program. If not,
the reason(s) for not registering should be stated.
6/30/2017Page 2 of 3
Stormwater Management Review Checklist
Date:1/25/2013
(For New Developments with > 5,000 sq ft of new impervious surface and 1 acre
or larger.)
Site/Address:Woodway Elementary
Permit:PRD 07-17/PRD 07-18
Applicable Code: Pre-2010 ECDC 18.30
By: Jerry Shuster, P.E.
CompleteIncompleteComments
Minimum Requirements (ECDC 18.30.060 A. 1. - 10.)
5Plan View- Drainage Conveyance
X
(A)Label and clearly identify existing & proposed systems
X
Pipe material not called out
(B)Identify slope, length, diameter & material for all pipes
X
Catch Basin size/type (check size based on depth, pipe size & angles)
(C)
X
(D)Catch Basin, invert elevations for all pipes
X
(E)Downspouts; provide connection (w/ adequate depth) to retention
X
(F)Pipe slope info versus inverts @CBs and existing pipe info
X
(G)Profile storm system and show utility crossings
X
(H)Flow arrows as necessary
(I)Other
6Plan View & Details- Retention/ Detention (R/D) & Water Quality
X
(A)Scaled drawing of R/D pond, vault or pipe, including tract boundaries
X
(B)Predeveloped & Finished Grade contours, show max water elev.
N/A
(C)Dimension all berm widths (Ponds only)
X
Cross section through vault shown
(D)Show 2 cross-sections through pond, 1 must show control structure
N/A
(E)Specify soils and compaction requirements for pond construction
X
See comment above on overflow (1.7. above)
(F)Location and detail of emergency overflow
N/A
(G)Rock protection details
X
Provide inverts of all pipes, grates, inlets, tanks, vaults & spot elev. of pond bottom
(H)
X
(I)Access road to control manhole and pond bottoms, plan & details
N/A
(J)Section and plan view of control structure
(K)Other
(L)
Maintenance plan
7Plan View: Other
Show location, identification and dimensions of buildings, property lines, streets, alleys &
(A)
X
easements
Show locations of structures on abutting properties within 25 feet of proposed project site.
(B)
X
Not shown
Show section details of all retaining walls & rockeries, sections through critical portions
(C)
N/A
(D)Other
6/30/2017Page 3 of 3