10200 19TH AVE SE Geotech Report 2018-01-02 MF Import

, 5 percent tines f�r a �istance of at least 18 inches from the fac� of Lhe walL Raaining and loading dock walls should be designal with hydraulic c;mtinuity betwee,; the free-draining backfill, and drains tighUined to an appropriate discharge point so that hydrostatic pressures will not develop behind the walis. ' We recommend that we be provided the opportunity to review our recommendations if t211 (higher than 8 feeQ retaining walls wili be wnsUucted fur this project. Other types of retaining structures,such as geogrid reinforced soil embankmerts, aze more flexible and can be more cost- effective than cast-in-placz concrete retaining walls. We could provide the design for a geogrid reinforced wall if this option is appropriate. PAVEMENT � In car pazking azeas, we recommend a minimum pavement section consisting of at least 2 inches of Class B AC (azphalt concrete) over at least 4 inches of densely compacted crushed rock base course. In truck trafEic and drive azeas, we recoaunend that the pavement scction be increased to a minimum of 3 inches of AC over 6 inches of densely eompacted crushed rock base course. The underlyir,g subgrade should be compacted to at least 95 percent of its maximum dry i density (ASTM D-]557) and a firm and unyielding condition prior to p:acing the pavement section. Buring wet season consavction or if the suhgrade soils aze soft, it msy be necessary to • excavate. sofr soils, place a leyer of subbase, and/or a suitable geoteztile fabric such u Mirafi SOOX or other fabric as suggested by the geotechnical engineer. In this caze, a subbase thickness of at least 8 inches should be provided, alt}:ough a greater thickness may be required to stabilize very wet subgrade condi��o.�s. The subbaze should consist of well-graded sand and � �avel with a maximum particle size oti`1'h inches and with less than 5 percent finrs. Where site ' grades aze raised using suucmral fill that meets the subbase specifications,thc stnctural fill may be considered the subbase. It is critic�l that all traffic be kept of;the subbase and or subgrade soil if the on-site silh� subgrade soils aze wet. It is important to note that a thin subbaze layer will not prevent dismrbance (rutting and weaving) from occurring. It is imperative to pavement performance that 4ackfiq in utility line trenches be compacted to structural fill specifications. Trench bac�ll within 2 feei of pavement subgrade should be compacted to at least 95 percent of the maximum dry density(ASTbi D-1557). Trench baclffill more than 2 feet below pavement subgrade elevations should be compaaed W at Ieast 90 percent of the same standazd. DRAINAGE CONSIDERATIf.)NS We recommend tha: pavement surfaces be sloped a�vay from the buiiding area to route drainage away from foundations and floor slabs and towazd the storm drain system. We G e o E n y i n e e r � 9 FJe No.0Y75-01�-R73/062997