HomeMy WebLinkAboutC_Correspondence_Fitz-James_PGIS_Decision_180214_v1This message has been replied to orfonvarded,
From; Ian Fitz -James <IFitz-James-@5f2enton1Aa,gov>
To; 'David Kebzhum'; 'Ro€ale Timmons'
C€;
Subject: RE; Southport helipad RE; response to query
Hello David and Rocale,
Sent; Tu e 1,Sj2CF18 10:2
Based on the information provided in your emafl below, previously provfded information, and further review of the 2017 Renton Surface Water Design Manual {RSWDM} and the 2014 Washington Department of Ecology Stormwater Management Manualfor Western
Washington (SWMMWW) we are not going to consider the helipad pollution generating impervious surface (PCIS). No additfonak stormwater requirements will be applicable to the helipad. The approved drainage plans and report for the Southport Office Towers already
accountforthfs surface as non -pollution generating impervious surface. More fnformatfon on our decision can be found below.
The 2017 RSWDM defines "PGIS" as surfaces subjectto vehicular use, industrial activities, or storage of erodible or leachable materials, wastes, or chemicals and that receive direct rainfall orthe run-on or blow-in of rainfafl. The 2017 RSWDM also defines "subjectto vehicular
use" as a surface regularly used by motor vehicles fncfudfng but not limited to motorcycles, cars, trucks, buses, aircraft, tractors, and heavy equipment. The definition goes on to provide examples of surfaces subjectto vehicular use and not-subjectto vehicular use.
The folfowfng surfaces are considered regularly used by motor vehicles by the 2017 RSWDM: roads, un -vegetated road shoulders, bike lanes within the traveled lane of a roadway, driveways, parking lots, unrestricted access fire lanes, vehicular equipment storage yards, and
airporttaxi! ways and runways. The following surfaces are not considered regularly used by motorvehicfes bythe 2017 RSWDM: paved bicycle pathways separated from and not subjectto drainage from roads for motorvehicfes, fenced or restricted accessffre lanes, and
maintenance access roads with a recurring use of no more than one routine vehicle access per week.
The 20145WMMWW deffnes vehicular use as the regular use of an impervious or pervious surface by motor vehicles. The 2014 S MM W goes on to provide examples of surfaces subject to vehicular use and not subjectto vehicular use.
The following surfaces are considered regular vehicular use by the 2014 S MMWW: roads, un -vegetated road shoulders, bike lanes within the traveled lane of a roadway, driveways, parking lots, unrestricted access fire lanes, vehicular equipment storage yards, and airport
runways. The following are not consfdered subject to regular vehicular use by the 2014SWMMWW: paved bfcycfe pathways separated from and not subject to drainage from roads for motor vehicles, restricted access fire lanes, and infrequently used maintenance access
roads.
The proposed helipad is similar in function to that of a restricted access maintenance road which is not considered PCIS by bot the 2017 RSWDM and 2014SWMMWW. The risk of leaking fluids. is very love to zero and there is no pollution being emitting from braked pads,
since helicopters don't require runways to take off.
Please let me know if you have any other questions.
Thankyou,
Ian Fitz -James, P.E.
A
Civil Engineer III I CED
IFitz-JamespRentonwa.gov Phone: (425) 430-7258