Special Inspections_memo_Permeable Pavement SubgradeRILEYGROUP
May 13, 2022
Mr. Dennis Parker
323 &327 Daley Street
Edmonds, Washington
RE: Geotechnical Special Inspections: Alley/Driveway Permeable Paving
327 Daley Street: Permit # BLD2021-0172/ENG2021-0233
323 Daley Street: Permit # BLD2021-0170/ENG2021-0230
Edmonds, Washington
RGI Project No. 2020-654-3
References: Litchfield Engineering, Plan sheet Site Improvement Plan Parker Edmonds Daley West — SFR
Site Improvement Plans, dated October 18, 2021.
Litchfield Engineering, Plan sheet Site Improvement Plan Parker Edmonds Daley East — SFR
Site Improvement Plans, dated October 18, 2021.
Dear Dennis,
As requested, The Riley Group, Inc. (RGI) is providing this letter documenting our Special Inspection of the
permeable pavement subgrade and placement of the permeable pavement sand treatment layer and rock
reservoir layer in the alley north of 323 and 327 Daley Street sites and the driveways for each site.
RGI observed the excavation of the permeable pavement area of the alley and the driveways for the east
and west site residences. The permeable pavement areas were excavated to a depth of 20-inches to allow
for the placement of the permeable pavement section. The excavated subgrade surface in the alley and
driveway areas consisted of sandy gravel. This surface meets our recommendations for an infiltrative
surface. A 6-inch layer of C33 sand treatment layer was placed in the base of the excavation. Washed drain
rock was placed on top of the sand layer to the proposed pavement subgrade. RGI understands the
pavement section will consist of a choker course and 4 inches of permeable asphalt.
Based on our special inspection oversite the permeable pavement treatment layer and rock reservoir layer
in the alley and driveway areas was constructed in conformance with the approved plans and material
specifications.
Respectfully submitted,
THE RILEY GROUP, INC.
I
David J Baumgarten, LHG
Associate Hydrogeologist