STORM1_PLN20170059_18227 80th Ave_Civil Review (002).doc
To: Engineering Reviewer
Date: November 9, 2018
Project Name: Clear Vision (2-lot Short Plat)
Permit Number: PLN20170059
Address: 18227 80th Ave W
Review Type: Preliminary Plat (Feasibility)
Submittal Date: 10/19/2018
Reviewer: Zack Richardson, PE
City of Edmonds, Stormwater Engineer
Recommendation: I recommend approval of PLN20170059 be withheld until the comments below are adequately addressed.
Review Comments:
Drainage Report: Additional modelling must be shown to demonstrate that the flow control requirement is met. The engineer can demonstrate either:
The pervious pavement design infiltrates 100%; provide a WHMM model pavement basin (this appear to be the case based on trial runs, but it must be provided in the report)
The dispersion system could be reduced to a filter strip at the end of the roadway flow path if this is the case.
The combined project flow meet the flow control requirement; model all project areas, with allowable LID credits, and demonstrate the total flow increase remains under flow control thresholds.
Drainage Report: Drywell is modelled with a 4’ riser but only a 3’ depth is shown on the plans; updated for consistency as needed.
All C Sheets: Label contours sufficiently enough to determine direction of slope, including the enclosed contours near the east property line.
C0.2: Add notes to make clear that BMP T5.13 (amended soils) is required for all disturbed pervious areas and provide details/specifications sufficient enough for the contract to install
soils meeting the requirements.
C2.1: Update details 3 and/or 4 as needed to ensure there is not conflicting direction on the subgrade materials & thicknesses; use standard aggregate names rather than details specs
to the extent feasible.
Ballast/storage layer should be uniformly graded (‘clean’) aggregate with no fines
C3.1: Provide/show a drainage stub out for the Lot 1 roof drain connection (consistent with report) and add notes directing contractor to connect all roof drains lines.
C3.1: Add, show, and callout an observation well on the drywell, see detail SD-638 for guidance.
C4.1: Please address any impacts of the drainage along the new curb on the downstream properties.
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STORMWATER REVIEW COMMENTS
City of Edmonds
Engineering Division