3829 SHORE AVE 2018-01-02 MF Import

We have enclosed a composite Air Photo Interpretation Map which combines the observed top-oS-slope chanbes and general drainage pattern cha�:iges from the three dates. As ehown, the genPr�l top-of-slope configuration has changed very little over the past 34 years except within the extreme west. extreme east and general central portion of the slope area. The major change noted Nas within the depression area noted sout'.� from Shore Avenue approximately in the east-central portion. It appears that development and construction of residences within this area has changed the depreasion from a larger and narrower area to a rounder and more localized depression area. The orginal outfall for this area was aPParently just west of the depression down the slape, but has been relocated due north. The upslope drainage into this area has changed very little. as has the drainage within the extreme eastly and westerly drain- age areas. HYDROLOGZC CONDITIONS i Ground water was encountered in the borings generally within the alluvial soils and sands and gravels overlying the dense ; Whidbey Formation sand/sili and dense glacial till. This ground i water appears to be perched above the denser underlying so9.ls � and derived Prom upslope surface water in£iltration. The depres- sion area (TB-4) and western portion (TB-1) indicate the greatest I amovnts and extent of ground water encountered back from the top- , of-slope. i Some ground water seepage was noted along the slope areasr partic- ularly within the more sandy materials of the Whidbey Formation above the sand/eilts. These aeepage areas are most noted towards the westerly portion of the slope area and are less apparent to- ward the east. Some local areas of seepage occur throughout the slope area. This local seepage may be due to the more granular nature of the upper elevation soils in these locals. (example STA 25*00) In general, however, we did not observe chronic ground water seepage within the majority of the slope area, and where observed was generally restricted to a local area. -5-