FIELD REVIEW REPORT - Brimmell Engineering Ltd.

FIELD REVIEW REPORT

Brimmell Engineering Ltd.
971 Bank St., Victoria B.C. V8S 4B1
250-889-3080 rbrimmell@shaw.ca

ASPECT OF PROJECT REVIEWED:

Subgrade conditions for two proposed retaining walls adjacent to the northeast P/L. Photos with notes are on Page 2.

OBSERVATIONS:

There will be two sections of wall, with a gap between where trees must be preserved. The back (SE) section has been excavated down to bedrock with small areas of dense till. This section is problematic because there is an existing mortared rock wall near the alignment. The front (NW) section has been excavated down to very stiff, silty/gravelly soil (probably till). Wall construction in this area should be straightforward.

REMARKS/RECOMMENDATIONS:

The rear wall could be stabilized with vertical dowels drilled and grouted into the bedrock. It is understood that the uplift resistance per 20M dowel is 12 kips. I calculate that the bars should be grouted 1.2 m into the bedrock. This discounts the first 45 cm and assumes that the holes will be at least 1 inch (25 mm) dia. The holes must be blown clean before placing minimum 30 MPa non-shrink grout.

The walls may be designed to resist static lateral pressure equivalent to that of a fluid of 30 pcf (4.7 kN/m³) density. Seismic loading may be simplified to a uniform lateral load of 200 psf (9.6 kPa). A coefficient of friction of 0.5 may be assumed between the footing and subgrade. An allowable bearing pressure of 150 kPa may be assumed in wall footing design.

Any loose soil must be removed from footing subgrades prior to placing concrete.

Sean Tisdall
Steve Malkow

Richard Brimmell, P.Eng.
for Brimmell Engineering Ltd.
11/15/2018