5105 CHINOOK DR 2016-01-01 MF Import

ngainst the wall to prevenl l6e build-up of hydrostatic pressurc on the wall. The chimney drain should consist of a minimum 12 inch width of pca gravcl or'/. inch washed drain rock placc immediatcly adjacent to concrcte wall extending from the footing drain to within 2 fcet of the ground surfacc. The upper two feet should be bac�llcd with a low permcability soil to discourase surface runoff from cntering the wall drainage systcm. Approved drainage boards, such as Inca Mat or Mira Drain,should be placed to extend from approximately two feet below the top of thc wall down to hydraulically tie into the footing drain syslem. Back511 of the foundation walls outside of thc chimncy draio chould be placed in approximate 12 inch loose litis and compacted to a medium densc condition around 90 percent of the modified Proctor mauimum dry dcnsity. A higher degrec of compaction is not recommended as this m¢y increase the pressures acting on the basement walls. The onsite soil may be used for wall compaction provided thet the soil moisture content will allow adequate compaction of the wall backfilL Keeping the excavated soil from the foundation excavation covered with plastic shecting will hclp insure that the soil may be used for wall backfill. Floor Support The residence will utilize both crawl space and slab-on grade tloors. The crawispace soil should bc covered wilh a moisturc burricr to rcduce thc potcntial for moisture Uansfer from the ground. Thc slab-on-gade tloor should be cast atop medium dcn.se or denscr nntive sand or compacted structural backfill around the foundaHon elements. A capillary brealc of 4 inches of pea gtavel should be placed atop the prepared tloor subgradc. A cioisture barrier should be placcd atop the capillary brcalc material prior to casting the floor slab. All concrete placements should be performed in accordance with current Amcrican Concrete Institute (ACI) stnndards. Drainegc Conaiderations A perimeter foundation drain should bc establishcd to protect thc foundation/crawlspace ftom ground water inwsion. The Icvel of thc foundation drain should be set at, or slighUy below, the basc of the footing cicvation. T'he drain should consist of 4 inch diameter, rigid, perforated, PVC drain pipe and should bc set to allow for gravity dischargc. Thc drnin pipe should be surrowded by a minimum oC 6 inches of pea gravcl or washed drain rock.. Roof drains should not tie into the footing drain bul should be collccted in a separatc,tightlinc drain. The property was underlain by dcnse sand sediments with a moderate capacity to infiltratc stortn watcr runofF. It is our understanding that an infiltration trcnch will bc cxcavatcd ncross thc north sidc of thc property. It is our opinion lhat a properly dcvelopcd infiltration trcnch will allow the majority of stortn watcr runolTto infiltratc back into thc gmund. Thc ovcrflow oul of thc trcnch should bc set to discharge ut the northcast c:omer of the property. Conclusion [3ascd on our sitc reconnaissancc and subsurface explorauons thc sitc appcars to bc suitablc for the I'I proposcd dcvclopmcnt providcd thc recommendations pr�scntcd hcrcin nre properly implemcnted. 'll�e proposcd replaccment of thc singlc family residence will not havc an adversc affect on thc �I subjcct property or on adjaccnt properties. I Our findin�.s and recommendations provided in this report were prepucd in accordance with Ii gencrally acccptal principles of engincering gcology and geotechnical cnginecring as precticcd in BGC, pllc 14267 209"' Avenue NE Waodlnvflle, WA 98077 (425) 273-5062 ��