4828 DELAWARE AVE 2024-11-01 - Laserfiche WebLink

G-IE O TE C H 2401 — 10th Avenue East Seattle, WA 98102 CONSULTANTS, INC. (425) 747-5618 Memo JN: 22435 Project Temporary Cuts for New Egress Stairwell Et ieec Marc R.McGinnis, P.E. 4828 Delaware Avenue Everett,WA Date: December 22, 2022 Client: Bruce Christopher Construction Attention: Bruce Christopher via email: Christopher.con struction(a�hotmail.com On December 20, 2022 the undersigned principal geotechnical engineer visited the subject property to assess the soil and site conditions related to a new egress stairwell to be constructed on the south side of the existing house. Based on the information provided, the foundation wall for the new stairwell will extend approximately 4 feet from the outside of the existing basement wall. An excavation of approximately 8 feet will be needed for the construction of the stairwell. The southern property line is about 11.5 feet south of the existing house. Based on our measurements and site observations, the north foundation of the adjacent southern house is 18 feet from the existing residence, which would put it approximately 6.5 feet from the common property line. The neighboring house does not appear to have a basement. A test hole was excavated at the property line to assess the soil conditions. This test hole exposed a thin layer of topsoil over weathered, gravelly, silty sand that extended to a depth of 1.5 feet. Below this depth was dense, gray, gravelly, silty sand that has been glacially- compressed. This competent soil is referred to as glacial till. Published geologic maps for the area confirm that glacial till is the near-surface geologic unit for the area. No groundwater seepage was observed in the test hole. In order to provide worker safety, and to protect the neighboring residence, we recommend that the upper 1.5 feet of looser soil be temporarily excavated at a 1:1 (Horizontal:Vertical) inclination. The underlying gray glacial till can be cut as steeply as 0.25:1 (H:V). This temporary cut should not extend past the common property line, and it should be possible to leave at least 2 feet of undisturbed soil between the property line and the top of the temporary excavation. The temporary cut will not encroach into the bearing zone for the foundations of the neighboring house. The cut slope should be covered with plastic over its full height. Appropriate safety fencing should be installed around the top of the cut until the new stairwell walls are backfilled. C R McC 0 WAspYAl, xrAil r. 784 SvGi L cc: Design Build Services 12/22/2022 via email:rheide(@,dbsmonroe.com