HomeMy WebLinkAboutDrainage,Erosion Control Plan - PLN General - 9/18/1992 MASON COUNTY
PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
Shelton, Washington 98584
INTER-DEPARTMENTAL COMMUNICATIONS
DATE September 18, 1992
TO: JASON MANASSEE, Dept. of Community Development
FROM: ALAN A. TAHJA, P/W Engr. Support
SUBJ: Prince of Peace Catholic Facility Drainage/Erosion Control Plan
Jason;
Wednesday Sept. 16, 1992 I met with Pat McCullough, the P.E. representing the Prince
of Peace Catholic Facility to be built on the Sand Hill Road in Belfair Washington.
Mr. McCullough prepared the stormwater-erosion control plan with the assistance of
Lenny Kong author of "WATERWORKS", a hydraulic program developed by Engenious Systems
of Belview Washington. According to Mr. McCollough's calculations and the WATERWORKS
printouts, the facility as proposed will allow stormwater to be discharged in two
locations which currently receive the existing stormwater run-offs from the site at
0.40 cfs for a two year 24 hour storm event and 1 .06 cfs for a 100 year 24 hour storm
event. Under their proposal water would be discharged at these same locations at 0.19
cfs and 0.37 cfs respectively for the facility with graveled parking areas and at
0.42 cfs and 0.52 cfs respectively for the proposed facility with paved parking
areas.
I have reviewed the information underlying these calculations and feel they are
valid. Upon asking Mr. McCullough what criteria he was designing to he replied he was
designing to keep projected outflows at or below predevelopment conditions. Mr.
McCullough was not aware of Mason County Ordinance #815 (Mason County's Parking
Ordinance) and was not aware of the County's primary aim of retaining stormwater from
commercial sites on site as set forth in that ordinance.
Even though the design proposed by Mr. McCullough is not up to our ideal standard, I
do feel his design represents a sincere and responsible attempt to adapt the proposed
facility to the surrounding environment with minimal impact. I recommend accepting
Mr. McCullough's design upon submission and acceptance of the details of the outfall
control devices. The plans as submitted do not show any Oil/Water separating devices,
but I feel that the outflow devices could be constructed to satisfy this requirement.
In summary, I would recommend approval of the McCullough design for the Prince Of
Peace Catholic Facility upon receipt and acceptance of the outflow structures details
with the recommendations that some type of oil/water separator is designed into the
facility and I would like to see the lower Orifices designed to restrict the two year
st rm outflow to 1/2 (one-half) of the predevelopment outflow.
ALAN A. TAHJA
Engineering Support
cc:MLY,PM