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MEMO REPORT
To: City of Renton CED
From: Alan Jacobson, PE
Date: August 28, 2023
Subject: Hazen High School – 2023 Portables
Drainage Memo Report
This project involves the installation of four double portables (or 8 classrooms) that will be
installed in the north central parking lot of the existing school property. These proposed
portables will be placed on top of the existing asphalt surface, and no asphalt will be removed
to install them. Splash blocks will be utilized to direct the storm runoff from the roofs, gutters
and downspouts on to the existing asphalt to directed towards the closest catch basins.
The new portables will require some new underground utilities (communication, fire and
power) to provide service. These utilities will be coming from the existing building, and be
installed under the existing asphalt, and then patched. The clearing limit for utility trenching, is
approximately 1,985 SF of disturbed area.
Also, this Project will not construct/ modify a pipe/ditch 12-inches or larger, nor does it receive
runoff from such a system. The Site is not in a flood, erosion, steep slope hazard or landslide
hazard drainage area. The project is not a redevelopment project of an existing high use site.
Based on these quantities and site characteristics, this Project falls below the thresholds for
drainage review (less than 2,000SF new/replaced impervious and less than 7,000 SF land
disturbing activity) as identified in Section 1.1.1 of the Renton Surface Water Design Manual.
Several ESC/SWPPP measures are specified on the plans and were chosen in consideration of
the lists in Section 1.2.5.1 of the Renton Surface Water Design Manual.
Please contact me should you have any questions.
DEVELOPMENT ENGINEERING
SAMorman 01/12/2024
SURFACE WATER UTILITY
jfarah 02/01/2024