4711 GLENHAVEN DR 2016-01-01 MF Import

. � SUBSURFACG CONDITIONS In order to evaluatc subsurfacc conditions ai the sitc, we �erformcd a series of hand-augcr borings within t!ie proposed porc:h footprint. The approximate locations of the borings arc slio��'Il 011 IIIC :IL18Jhed Pigurc 2. Sedim�nts encountered in our cxploration borings ecnerallJ, consisted of about 2 to 3.5 feet of till, overlying brown gravclly sands with fcw silt. 'I'hc underlying soil unit �va� ntcrpreted to be weathered advance outwash deposit. Thesc sediments extcnded to th� ,ull depth of our explor�uions, with a tnaximum cxploration depth of approximately 5 fect. l.and-auger refusal was encountercd at relati��ely shallow dcpths, duc tu incrcased soil density and gravel content within the advance outwash. E�i�loration lues documenting the subsurfacc conditions cncomuered ��ilhin our hand-augcr esplorations are attachcd with this Icttcr. Wc rcvicwed gcologic data for tlie site, based on thc United States Geological Survcy (USGS) Disn�ibrnioii nnd Descriprron of Geologic Units irr rLe Everen Qrrndrnngle, R�nshurgron by Minard, dated 1981. This map indicates that the ncar-surface scdiment in the site vicinity consists of advance outwasli deposits. Asseciated Garth Scicnccs, Inc.'s (AGSI's) gculoeic findings arc in general agreemcnt �vith the published map. Ground �vatcr was not encountered in any of our e�ploration Uorings. Ground ��atcr conditions should be expected to vary in responsc to changes in season, amount ot precipitatimi, un- and off-sitc land usagc, and othcr 1'actors. GEOLOGIC HA'J,ARDS AND RL'CODiNiGNDEll n11TIGATION 7'he near-surl��ce, advance outwash soils are glacially consolidatcd, medium densc to vcry densc, and not typically prone to landslide movement in the absence of ground water. 1'hese properties make it resistant to landsliding under the topogriphic condiiions pmsent 8[ (Ill' SIIL'. According to the L-veret� Municipal Code (L'MC) Title 19, e'haptcr 37, Section 37.080A I.g, the slope along the cast properry boundary would bc classified as a medium risk landslide hazard due to the inclination of 40 percent or greater in d�e height of 15 feet. 7'hese slopes woui•I also classify as a vcry high erosion hazard area per Section 37.OSO.A.3.a.ii. Based on our site visit, ��e did not obsen�e obviotis indications oP past or pmsent shallow or deep- seated slope movement. Roof drains are currently tighUined [o a storm water conveyance system, and the proposed deck �vill not add additional impervious area to tl�e property. The inclusion of the proposcd deck will not significandy incrcasc loading conditions adjacent to thc slope. The load increasc is not expected to exceed 500 pounJs per square foot and will be conswcted more than 20 fect 1'rom the top of d�e slope. Provided tliat the recommendations in tliis Ietter arc adhereJ to and sound construction practices are implemented, in our opinion, the proposed porch will not adversely impact the stability of the adjaccnt slopc. We reconunend diat the porch foundations extend tlirough the existing fill and into meclium densc ro very dense advance out�vash soils. The porch foundations should not be placed closer tl�an 20 tcet to ihe top of the slope. If required, the porch foundations can Ue deepened to cmate a Z � �