1920 MERRILL CREEK PKY 2018-01-01 MF Import

dur�-z�-�q wrU 16�26 SIERRA CONSTRUCTION FHX N0. 206 885 4330 P, 04 . ., , . - `�. �.. Sierra Construction Servlces, Inc. SHANNON�WILSON.WC. , Attn: Mr. George Constantlne , March 18, 1994 I Page 4 � flattening of select slope areas, as discussed in the follawing section, should . decnease the risk of local instabiiity. Both measures should at least maintain and most likely increase 1he curnnt stability of the slope. ► Development of the sitq as shavn in Figure 1, will not deciease the �tabilily aC the slope, in our opinion. lnstead, collxfing and controlling sudace Kat�r upslope as part of site development and prcvenflng Its flvw over the slope wi11 decreasc site erosion. Addidonally, flattening of selxt slope areas wlll dxrease the risk of locai instabiliry. ► It is our understanding that the owner has elected to effect slope mitiga6on measures within its property limit�. We recommend cutting back the near-vertical glacial slopes wlthin �he subject propeRy limits only to 1H:1V in Gll and 1.SH:1V ' in outwash. The eaisting heavlly vegetace� 8l1/colluvlum wvnld not bt disturbed, as movemcnt of these soils is uNikely to affat the seability of the upslope development and it was felt that disturbances to these muginally st�ble solls wuld increase the potential Por instability. It is understood that theae is some dsk fhat , surflclal movements of the ea�isting slopes could develop in the fi�!�.:ce due to the marginal stability of the existing flll/colluvial slopes and on-s�te acflvities, such as futute remwal of esisling vegetation, or off-site activlfles, such as undercutting the toe of the ezisdng slope by the adjacent property owner. Such surficial mwements will likely result in the accumulation of dcbris at the tce of the aisting slope. It is unllkely that thcae movements would affect the proposad structure on the upper plateau, It is also recommended to provide a ditch along the top of the slope or regrade in such a manner as W reduce surface gtuundwater flow wer the slope. Slopes requiring remediadon in accordance with this plu► are shown on Figure 2. ► Adhuence to these slopes will requiro regnding the steep hills(de areas shvwn on Figune 2 to a flatter slope. The areas indicated for regrading on Pigure 2 exclude a 5- to 10-foot-high scarp (see 1ocaGon on Figure 1) at the centrat portion of the sita 1'his area was ezcluded fmm midgation btrause of the limita! hcight of the slope and the acis6ng 60-degree inclination of the scarp is telaHvely close to the rocommended 1H:1V euccavation face In the till, Additionally, any attempt at t�egrading would disturb native vegetation upslope and possibly cause reneroved erosion. ► Buildings which will be located near the eastem slope will be constructed on � undisturbed, nadve, glacial soils. It is our opinion that the minimum 25-foot' setback distance from the top of the slope (as required by 'EMC 19-8� m� be usod in finalizing the developmcnt. T'hesc minimal setback distances witl cormspond to a stability factor of safety of at least 2, pravide�l the W-6693-01 t ;