HomeMy WebLinkAboutRS_Pavement Letter.pdf
Cobalt Geosciences, LLC
P.O. Box 82243
Kenmore, Washington 98028
www.cobaltgeo.com (206) 331-1097
September 16, 2018
Ms. Julie Chen
greenhousetex@comcast.net
RE: Permeable Pavement Comments
Proposed Development Expansion
711 Monroe Avenue NE
Renton, Washington
Dear Ms. Chen,
In accordance with your authorization, Cobalt Geosciences, LLC has prepared this letter to
discuss the suitability of the permeable pavement section with regard to temporary loading by fire
trucks with outriggers. We understand that potential loads could be 30 tons (fire truck) with 75
pounds per square inch on outriggers.
For temporary loading as described above, the proposed 6-inch thick permeable concrete section
over a minimum 6-inch thick base rock layer is adequate provided the underlying native soils are
consistent with medium dense or firmer glacial till. If loose or organic-laden native soils are
encountered during subgrade excavation, it may be necessary to remove these soils and increase
the base rock thickness accordingly.
We should be on site during construction to verify suitable native soil conditions, base rock type
and thickness, and concrete thickness during construction.
Sincerely,
Cobalt Geosciences, LLC
Phil Haberman, PE, LG, LEG
Principal
PH/sc