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Home My WebLink About821103011 Geotech AssessmentNORTHWESrERN.. . TERRITORIES, INC. Engineers · Land Surveyors · Planners . Construction Coordination · Materials Testing Nil GEOTECHNICAL REPORT for CARROLL SILVERA DYER- " for - . . . - . ' " ' .Parcel #821-103-011 " --'.. "' i(Tala' pOint Partners SurVey.LotS 14 and 'i5) -' .-'... i-' ~'- N I~ ' . .. . . : -. · -- ·".--" Sec.lO':(T 28 R IL) ~--'~" . -.~- - · -- . .... : -. ,',. ~ - . '. t- -, .. : -. . . - - . .- .; :- . _ : -. .. . - . · · . . . _ ~ . . . . . o .. _ - : - . ~ - . . .: · . : -~: ... - - . . · .. NORTHWESTERN -'"'~"-" . :.,'!::.:; ........... ..-..-_ .... · : ' ..-'.... TERRITORIES,: INC.'.; : . - .. -- -.:: --..-- , - 2 " · . ~ - ' ' · ' ' .... : : -' -x -. - :'. 717 South. Peabody.. Street'-... .. ' "-~,- - ' .. . :'... Port Angeles, ' Washington '98362 --' .... ~:. --·~ .,.. - · . '-, -:(.,36.0)-452-8491- "1~800-654:55~5.TM "-.'. '_ . '_- . · . .-. . . . .: :.. -. ~ · . .., __: . ;' . .. = . · .. -.. ':~.- , : - :,: ,' .:: .... .'..-:- .. .:.-. ; - .- .-.. ~--..?,': . :,-. 717 SOUTH PEABODY, .pORT ANGELES, WA 98362 :. . , - MaY, '1996..' -. (360) 452'}8491 . . · : . _ · .. ~ - . , :- · -.. .- . _ .. 1-800-654-5545 ''FAX452-8498, - "" . . . .. , . . . CARROLL SILVERA DYER GEOTECHNICAL REPORT Parcel #821-103-011 INTRODUCTION This report was prepared in direct response to questions contained in a-letter dated .May 9,. 1996 from· Linda Atkins, Jefferson County Environmental Health. to Ray .-- Bradford. Northwestern Territories, inc. The questions are: -" " · 1. "is ~the slope above stable and not likely to .. ~ · .. :. ,.- -slide over the drainfield" and,.. . . . . · - . . 2... "is the drainfield area itself.sUbjecttO.slide aCtivity ... .._--.. -. -.: "'- '- encrOaChing 'on the required setbacks as well as'the '. . ...:~." -. drainfield itself"..' - ' ' '"' -, : ''~ ' . ..~.-' ".' . ~ -. · ... · ~· In .additiOn, a question was-.r, aise'd in the letter.concerning the sl°Pe adjacent tO-the-- '-~. ' ' drainfields being steeper.than 1't-(100%). ~-- '~' .... · -' .'-" -'''~' ' '- · _' _ , .: ... ' - : - .,- . .' -. Reference is-made t°. plans and septic Perm,. apPlication for "PresSure. Drainfield '-: '.-~-. ..'_ '~ System; LOt 15 for-Carrol Silvera" dated 3/22/96 (9 sheets). -" .' .- .. ".- . ' pROjECT SITE . - .. . · - :'--' - The above referenced site .was'investigated by.the undersigned on 5~20/961' it'is '.' .. '-' cleared'and graded .with significant.drainage and erosion control features.' GraSs :"-'i ~:- '~ ':"'- ~:'.. .coVer has-been established on all exposed' areas eXcept.under.'t, he i:JlaCk plastic' on . the''-. .'..'"- . fill. face:.- ':.~ :'. -. -' -. ... ---"'-': - -The site is'boUnded 'bY a Cut slOpe'along the sOutherly property.line'of Lot 15.'- A§" "." '" , ":.-.-.._ , _Shown.on the. Site 'Plan, (sheet_8 Of' 9) a large bench area ("upPeri'bench") extends'to - .. ,.. - .. the'north 'varying from approximately 50 feet to over 100 feet in Width land 250 'feet~0r. - ~ ----- . · 'more in'length. The north face'of the "upper bench" is fill Currently; COvered With' black" - .-.. :--.' plastic for~erosion .control. The upper bench is "back sloped, away from'the face'::~_:.:.,-'~=-i::~.~.:'.._ -.-, ~- ' toward the'toe of the cut. SlOpe:. A-drainage channel has' bee. nconstrUCted along .the -" -.toe of the :cUt .t0-a'.detention pbnd. This Provides controlled-releaseltO a:nother-.ditch i"~..:-'-'~-.i'i ~": -,-"-. and 'detention. )0nd Whichl. releases ' into a ravine in. the sOuthwest. c0rr~-er ib~ the'site'i'~'~'-:::.- ~,!: ,: :'-i:-' ..-- -,:.. (This ravine :is west of' the ravine, eXtending along' the westerly maCgin-bf the prOpoSed '-..:.'.-':-/.,.. .: :.-; .'drainfie!d.) - . .' : · " . -- . -.~-. .... . -. . . · . . . - . . . _ - ' ~ 21 . . . . . . , .In addition to the "back slope", a trench drain has been installed about 10'feet back from the "top of fill" (see Site Plan Sheet 8 of 9). Currently, this trench is open with. drain pipe installed but not back filled. From the "upper bench", the fill slope extends ' down to the "lower bench" some 30 to 40 feet below Where the proposed drainfield will be located.' The "lower bench" slopes gently from west to east in the area of the' - proposed drainfield and then more steeply to the east forming a '~unnel" or '.'chute". extending from the-toe of fill (upper bench) northerly for several hundred feet... . "Evidence-of previous erosion from the face of the' fill (now covered, with black-'plaStic) : "WAS:' Observed. This sediment flow across the "lower bench'' was clearly down'gradient ~. and well over 50'feet east of the Proposed drainfield. . -- :'- .-' -" OPen test hOles in the Proposed drainfield area confirm the general soil conditions as c.oarse sandy gravels near-the Surface becoming slightly more dense at depths t°'5-- . 1, -" The site'.has:.been extensivelY graded to form i~(2) distinct ~ :'''~ ~: ':i'.' '~ · ' benches.With .a 30 foot+ ~high fill slope Separating them. - i'.. ': ' - ' 2, :Drainage and-eroSion control measures-have been inStalle~iiand ?:.'"."."~' ' ' ' · appear to- be. working remarkably'Well.- . ' ...-: ... 3. -Witho~t'these drainage and erosion Confr01 measures, the"~ '- '-- ' ".-.~. '_ Unconsolidated fill'along_.the north face.of the uPper bench .-~ "- ' '- '- .- .. would be subject'.to saturation and lOCal.iZod, landslides. "' '. ...i_" -. . ;4: :..-The .proPosed d'rainfie!d is located sufficiently west of and 'i-.---." - - ~- .. upgradient of the.fill area to make a. slide 'intO the .drainfield:. -. :- .. -..-~ 5. · No evidence oflerosion or S°il instability was observed in the: '.: -' 6. The side slopes of the'Small ravine along the'westerly margin of...: ."¢linometer". - The'slopes Were found to average between-65% and-'..::-i-.:.:i'~-:L.-.-. 75% Which is significa.ntly leSs than the 100%1(1-1) requiring. ": ' ' -' . .. _ : CONCLUSIONS 1. The sloPe above the drainfield (fill) has been stabiliZed and is not likely to slide over the drainfield. 2. The drainfield area is stable and ne.potential slide activity could "-: be determined` from this. inVeStigation .... . "_ - ' 3.~ The .slope' adjacent to ihe drainfield is significantly less than the- .- '": -- .-. 1:1. (100%) 'requiring additional setback. ' - " . , ._ . . . - . . .- - - - . LIMITATIONS . ' - .. .': '-"' .. _ ~This repdrt' is ,based on a visual inspeCtiOn,of-the exiSting -site' conditionsj' No scientific ' - - -- measurements, tests' or calcUlatiOns Were Pe~ormed.' The findingS-and report.-al;e :';:'-::" limited tO- the-normal-Standard Of Care Of: the-industry for'an in~)estigatiOn withOUt- ' -::' :-'-~.---'. ~-::.. -benefit Of: ScientifiC:data land calcula'tionS!-. 'unless construction plans .are r'eviewed:and:: - ,-...-~..;,-.:? . . the C0nst.r.i~ctiOn :wo.rk:isinspected'bY the. Engineer; no warran~ is ' made-- by 'tl~e -~'' 'i -'::-'.:,;i.;:-?-' '..' .. Engineer concerning confqrmity'ofthe construction to the.conclUsions'i~and i:-~ '-..-::-';: ~' ~::..-.-recomrnendationS of this'-rep0rt. ~ ~ ~': - '- '- -' ' ';. ' 'ii~,: :~ ;:--:~':.' .' -. ;"':--""~" ~...,-.." '; . ' ' " -.-- ... " .... :_. ' ' '" ,' ' .... ,-_-: .i-;..'i'"i' i~:.'' :':':-. :'Ti~.o:s°!e -Objective Of :this;inves~igati0nhas'b'een t°. diagnos'e the ge0techni:cai '.- i :"~i ' ':'-~.' ;"-:-;conditiOns'at the :site.". The rePOrt' has .been prepared ~or the exclusiVe use--':of ' '- -.- i';~':.' '.'' :. "-Si"~era 'DYer.,and may.be'-used.-by--others onlY"With expressed Written permissi0no~-the '.'.-"?., i; :-!: i-i'i:' Engineer, The report has' not-been prepared for use by' Others ,~,-,: ~.i:i.' .- , 'observations,. interpretationS,'aha~conCiuSions herein are based'on gener'..a.!ly:a.Ocepi~-~:d , --.'- .... ' prOfessiOnal engineering and'geoIogiCp~in'cipleS and practico.'.'ThiS warrantg is in-ilii~u. '-"'~ ': ~":.'.: i.,'.:..: "of.' ali OtherS,'e~her expreSSed :0r:' .implied'..;. :._':.-:':-'., :.' -~. i:'' .:~" :-.-:'; ."_' ~': NORTHWESTERN TERRITORIES INCi · _ , .. ':':'i- :i:'J.;R.:.Jerry'Newlin,. P.E. ., ii Pri'nbipal 'Engineer :' "-.:' ..'~: · fc: Carroll' -- dir: J~rr~. . Jefferson County Health & Human Services CASTLE HILL CENTER · 615 SHERIDAN · PORT TOWNSEND, WA ° 98368 May 9, 1996 RAY BRADFORD NORTHWEST TERRITORIES 717 S PEABODY -'PORT ANGELES WA 98362 RE: Sewage Disposal Permit Application, Carroll Silvera Dyer Section 10 Township 28N Range 1E Parcel # 821-103-011 Tala Point Partners Survey Lots 14 and 15 Dear Mr. Bradford: Staff from this department completed a site visit to the above referenced property on May 3, 1996 to evaluate the site an~ the proposed designs for pressurized distribution onsite sewage systems to serve a three bedroom home for each lot 14 and lot 15. Due to indications of an unstable slope above the area and a recent history of instability in the immediate area a Geotechnical report addressing the suitability of placing drainfields in this location is required. The two questions are: is the slope above stable and not likely to slide over the drainfield area and is the drainfield area itself subject to slide activity encroaching on the required setbacks as well as the drainfield itself. Measurements made onsite show that the slope adjacent to the drainfields-is a l:l'requiring a minimum of a 25' setback. The current configuration does not meet this cetback. The application cannot be approved until these two items are addressed. You may choose to dig holes in another area on the site to find more suitable soils or have the system redesigned to meet the constraints of the current area if the geotechnical report shows that the area can be used. In addition, an Eagle Management Plan with the Dept. Of Wildlife will need to be signed prior to release of the permit and completion of any other critical areas review requirements. Please contact this office if you have further questions. S. inc,grely Linda Atkins Environmental Health Specialist cc Carroll Silvera Dyer HEALTH DEPARTMENT 360/385-9400 ENVIRONMENTAL HEALTH 360/385-9444 DEVELOPMENTAL DISABILITIES 360/385-9400 ALCOHOL/DRUG ABUSE CENTER 360/385-9435 FAX 360/385-9401 POP-'- . . .. POPE* ~ TALBOT 51.3 ~ A'/ PO40 ,~ ~,IKO~ ZELLEI~- pcpe ~, TALBOT. INC. ~TATE STATE GTATE i NORTHWESTERN TERRITORIES 717 s0~rH ~ · PORT AN~LES. WASHINGTON WDFW MOMTESRMO W~SHINGTON STATE DEPAR~MEL tTM brand fax transmittal memo BaXd_E*-gl_e _Si~e ~g~t -- F~x # On behalf-of ~he people of the State o£ Washington, to which its wildlife belows, ~"~e following a~re~nt is hereb~ enacted for ~he ~u~oie of protecting bald eagles and their habitats. The Landowner a~d Washington $~a~e D~par~nt of F£eh and Wildlife agree to the conservation measures described in the at~ached site management plan. SAte Name: ~ala Point '#689 Legal Description of proposed pro,eat: T28N, RI~, Sectioa 10 ~he ~dersigned herelr~ agree to the terms of the ~ald Eagle Si~e The State of Washington, Depar~nent of Fish and Wildlife Da~ .... ~n Coun~,j' ~nspec~.~i B~ Date 0 Z t:1:1 0 .< F) i /~' i I 'X