729 100TH ST SE Geotech Report 2018-01-02 MF Import

� D) ,D L. NELSON AND ASSOCIATES, INC. ^ I ' � Consuhmg Enginetring Geology � April 7, 1989 � Profect No. 3989 Dage 3 i I � The crushed rock layer appears to be completely filled wlth water, probably I transmits the water dovrn gradient, and may be under some hydrostatic head ' pressure from up-gradient. Standing water occurs ,just to the east of the site withln the drainage area. , This xtandTng water may contribute to the perched water noted within the crushed rock layer. 1 CONCLUDIN6 O�INIONS � In our opinion, plecement of foundation support for the proposed office , bullding within the deslred area can be performed if the recommendations as presented hereln are utilized for construction. The occurrence of the high ' perched water teble within the crushed rock layer, and surficlal artlficial fill create a condltion where beering support of the foundations could be adversely affecteA. Specific contrul of footing depths, and their Aistance , ebove the perched weter teble, is of main concern to minlmize potentiai beering support reduction. ' In generel , we are of the opinion that site development and construction � should proceed in a fashion where 1) dewatering eiong the upslope side 1s performeA, 2) proofro111ng of the existing fill area is performed, 31 eddltionul structural fill 1s placed wlthln the structure erea, and , 4) structure foundatlons are pleced a �nlnimum of 2 feet above the highest perchpd water encountered.' � Dewatering L1ne Installa;ion � In an attempt to reduce the bmount end possible hydrostetic head pressure of the perched water noted within the underlying crushed rock leyer, we recommend � construction of e dewaterfng draln 11ne along the upslope side of the proposed structure area. The draln should be placed along the upslope side of ' the structure through excevation lnto the basal glacial drlft es a trench. The trench could be 24 inches w1de, begtnning at a suitable dayllght area �