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� <br />L..� <br />� <br />� <br />� <br />� <br />' .; <br />� :f� <br />Report <br />Sho�t Plat <br />May 4, 1990 <br />Page 3 <br />with depth, fine sand with silt. <br />Boalevard from the site. <br />� <br />i'his material waz also observed in tha rockery cut across Mukiltea <br />Shallow test holes on the lower porcion of the slope to the north encountered medium dense to <br />dense silty sand and med�um sciff to stiff silt. These soils most likely are part of the Whidbey <br />Formatioa. 'Ibe silt within the Whidbey is fairly impermeabie ano a�ill perch ground water. The <br />ezistence uf the horsetai►s most likel} marks the aPProximace contact becween the Whidbey and the <br />advanced outwash• <br />Groundwater was not obseraeti in tlie test pits. The lower portion of the slope near Madrona <br />Avenue appeared wet and some seepage was observed in this area• I ea�Pecc �� �°st of the ground <br />water is perched on top of the Whidbey Formation. Ground water is aiso ea�PeMed �° ss�d seams <br />within the Whidbey Formation. <br />CONCI,USIONS AND RECOMMENDATIONS <br />GENERAL <br />1'he site is suitable for the planned short plat. I did not observe stabiliry problems assoc�ate� <br />with the site. Precautions should be taken to maintain the stabiliry. The recommendations provided in <br />this report should be considered guidelines. A review of the plans and specifications shculd be made <br />when specific development planc have been developed. <br />I understand that you do not anticipate that the development will include structures on the lower <br />portion of the slope Hhere the Whidbey Formation is noted (see Figure 3). Tiiis area can t�e developad <br />but special considerations should be made with resPect to ground water and s�ability. 'Chese have not <br />been covaed in th9s report. Additional explorations would most likely be required for <br />r000mmendations to develop this area. <br />$IAPE SI'ABILITY <br />'Ihe underlyin8 advanced sand unit is stabie with resPect to dcep seated slides. '�l►e Whidbey <br />Formation usually consists of hazd silGs with some sand and clay. Usually the Whidbey is considered a <br />stable fotmation except 9n thr'reas where it is standing in steep bluffs or if it has predisposed failure <br />planes that aze associazed with ice loading from past glacial activity. I walke� the site and also to the <br />CpUyRETfE GEOTECHNICAL ENGINEE1tII�IG <br />