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Home My WebLink About502082008 Geotech Assessment,~ GEOTECHNICAL REPORT Prepared For Jude Ashley and Gary Streid May 1, 2007 For the Property Described As Tax #'s 502082008, 502082004, 502082007 Section 8, Township 25 North, Range 2 West, W.M. Jefferson County, Washington Prepared by NTI Engineering and Surveying 717 S. Peabody Street Port Angeles, Washington 98362 Phone 360-452-8491 Fax 360-452-8498 Web Site www.nti4u.com E-mail info@nti4u.com ~~~EI~ MpE10 7 7~ JEfFEBSON000~1'IDCU D~.0p0°~ ~op7 s~ ~~p~. ~~~~ ~ ~~~ GEOTECHNICAL REPORT Q 7 200 For the Property Described As Tax #'s 502082008, 502082004, 502082007 JEff E~SD~ COU~1Y DCD 1.0 Background In April of 2007, Bill Payton, a registered geologist, and Steve Luxton, a .registered engineer with significant experience in geotechnical engineering, inspected a tract of property owned by Jude Ashley and Gary Streid. The 35- acre tract of land includes five parcels of land ranging in size from 15 to five acres all located in Section 8 of Township 25 North and Range 2 West, WM, in Jefferson County, Washington (Figure 1). Jude and Gary currently reside on Parcel D and they are making plans for the possible development of four five- acre parcels, namely Parcels A,B,C and E of the Jude Ashley Record of Survey which are discussed in this report. The land that was inspected was the subject of the Jude Ashley Record of Survey, recorded in volume 30, page 176 of the survey records of Jefferson County. Parcels A,B,C and E are approximately 5 acres each. 2.0 The Geologic Setting The subject property lies in the Duckabush Valley in Jefferson County on the north side of that glaciated valley in the Quilcene Range. The parent rock, which rises to over 3000 feet above the property, is a dense basalt mapped in that area as basalt flows and brecciated basalt. The rock is a part of the Crescent Formation, a volcanic island that collided with the continent and formed much of the Olympic Peninsula (Tabor and Cady, 1974). The lower portion of the south- sloping property shows glacial features including some glacially consolidated outwash deposits (lodgement till) that were observed in a road cut on the property. The upslope areas that include Parcels , B and C are principally basalt rock overlain in some parts by a thin colluvium of glacial drift. A small creek passes through the property from northeast to southwest and it has cut down through the older glacial deposits in recent time (Figure 2). A portion of the creek's flow is diverted to operate a small hydroelectric plant. 3.0 Geotechnicallndicators The northerly portions of Parcels A,B, and Cform asouth-facing slope lying at about 15 to 20 degrees from the horizontal. (25% to 33% slope) Due to the shallow depth of the consolidated rock, foundation conditions are generally favorable in areas where the overlying glacial drift is thin or absent. The slope above has a few loose boulders that could roll from the slope in an earthquake but they are not numerous. Mkt 0 7 SOOT SURVEY FOR.• cJ (JL L A Sl 1 IjLj Y , IN SECTION 8, TOWNSHIP 25 NORTH, RANGE 2 WEST W. M. JEFFERSON COUNTY, WASHINGTON S ~ '~_--Ji _._ ___ SBB 03'322' _._ _. _.. _~~SI.B~_ S B ~ IJ26:4J _~-- - FOUND ONR 1• ~ 1 IJ264J' _..- --- ~. -~ C~ ALUM/NUN CAP ~ ~r~~B~ I ON i/1" RE&W (NOVEMBER IWS). -~ (NOVEMBER N10S). ~ n ,. ~p~P ~,' G' g~ 1~ GChp.UB ~. ~E a mh O" ! W! e,~Bd: -~ F01/ND SE CDR. NE i/4, ~~ `DLO548'42'40 A'.F1u00' ,`v~lm ~g NE I/4, SEC ], RSN R1W, ~~h ONR NONUMEM $„ CALClHATEO Po9'riQN ;g Zi. ]I' I J 1/J" ALUM/NUM CAP ~ FALLS IN TREE NOT SET.-~ 'x~K _'I sBB'OJ'IO'E ~ - 1.778:78• ._- SBB'OJ70E /JJ0. 10' NI / ~ JJI.SJ' - JJZSJ' - - 663.03' _ L 20J IOC 1•,C j G SCALE IN FEEL N ,p,VA-y j FOUND SW CORNER GOVT LOT Z P~" SEC B. i15N RZW T ~ • pENOTES SET REBVt W/M PLASITC SURVEY CIP ! 1/1' R£flAR WRN CAP P y 6 ~ sTAMPED: tLWX 1111J" ST PED: 73 16896 ^ 6L '^ _ El / ~ OENO)ES fOUNp REBVt WIM P[ASiIC SURVEY ~ 560'16'31 W, 0.15' v~ p1~ ~z PPE' ~ SBT5434'E 3 P h' i 66334' CAP STAMPED: 15 16896" UNlE55 OTHERWISE I Y ~v NOTED. la ~ ~ DfTA2 A" =In Nor ro scaLE _D ^`e,~~ JJJOZ' - JJJOZ' u 58T46292' 686.0!' fOVNO g ``J•. I ! $ NIB'10'317Y. 1.01'. ~ ~ ~ (, SE CORNER ! n D / cov'r Lor s, I o ~ t `` d' i ~ / F" °i .j ~U~ nld> •..~ 1. ]B', SOUTH FOUND 1 //4" IRON PIPE NBTJB"03'W ¢ h0 •. ~ T~SECDON rWITH J" DNR BRASS CAP 6685J' h } ! / (NOVEMBER loos). ~ 1 H g / e So-~h T PP~A10 FWND 2' IRON PoPE ~h q0/ J I/1'ABOVE GROUND _ _._ ~ (NOVEMBER IOOS). 58T19'412' 66103' IJJ4.0]' 1 / - _.__SBT29'412' a ' ~ 16~BT1' _._- _ =".0'' 9 y0"~H°` NOTES'' SEE DfTAH. A" hG' I. DN5 SURVEY WAS PERFORMED BY FTELp TRAVERSE NEMO05 USING A J SECOND TOPCON OESCRlP7/OK' CTS-JIJ roTA( STATKAN AND STEEL TAPE 2. n@ BOSlS OF BEARING FOR TMs SURVEY rs NORTH 01'11'49' EAST BEING THE WfSr GNE ~ PARCEL a~ ME W I/2 OF ME NW i/4 OF ME SE 1/i OF ME NW l/4. SEC. B, TOWNSHIP THE NORTHWEST DUARTfR OF 3£CPON 8, ttIWNSMP 25 NORTH, RANGE 1 WEST, WN., A5 IS NORM, RANGE 1 WEST WM, IN JEFFERSON COUNTY, WASHINGTON. (TAX N0. B) SHOWN IN VOL I9 OF SURVEYS PACE 119. RECORpS OF JEFFERSON COUNTY, WASHINGTON. PARCEL B: ME £ 1/1 OF Mf NW I/4 OF ME SE 1% OF ME NW 1/4, SEC. 8. TOWNSHIP J SECONN SUBUMSION METHOD IN ACCORMNCE WIM TINT LETTER ISSUED BY DIE BUREAU OF 13 NORTH, RANGE Z WEST WM., IN JEFFERSON COVNIY WASHhVCTON (TAX N0. l) LAND MANAGEMENT, GOTED MAY 14, 1991 ON FILE AT CLARK LAND OFFICE. PARCFC C: MEN I/1 OF ME NE 1/4 OF ME SE I/4 OF THE NW I/4, SfC. 8. roWNSHIP 4 Mrs SURIRY DOES NOT PURPoRT TO SHOW i1lE EXISTENCE OF ALL EASEMENTS AND/OR 15 NORM, RANGE 2 WE3t. W.M., iN JEFFERSON COUNTY, WASHNJCTON. (1AX NO. 6) ENCUMBP.ONL'E5 RECORUEO OR UNRECORDED DNT MAY AFFECT MIS PROPER)Y. P RCEL D: THE SE I/4 OF ME SE I/4 M M£ NW I/A, ANO ME S 1/1 OF THE NE //4 5. MIS SURVEY W 5 PERFORMED ACCORDING ro WAC JJ1-IJO-090 SrAN6W05 FOR LWD OF ME SE 1/4 OF ME NW I/4, ALL IN SEC B. TOWNSHIP 13 NORM. RANGE 2 WEST; WM ~UNOARY SURVEYS. THIS SURVEY WAS NOT PERFORMED OR CERTIFIED TO MEET DIE LURRENi IN JEFFERSON COUNTY, WASH/NLTOK (TAX NO. !) ~' %IINIMVM Si LNRD RFOU/REMENT3' OR ACCURACY STANDMOS' FOR A(TA/ACSM LANG PTL£ SURVEY5 PARCEI E MEN 1/1 OF ME SW 1/4 OF ME SE i/1 OF ME NW I/4, SEC B, TOWNSHIP B THE NORM 1/16TH CORNER OF THE WEST UNE DF SEC. 8 WA5 SHOWN ON ME SURVEI' ZS NORM, ItaNGE 2 WEST WM., M JEFFERSON COUNTY, WASNMGTDN (N I/1 TAX NO 5) RECORDED IN VOL. 19 OF SURVEYS. PC. 149, RELLMDS OF JEFFERSON COUNTY, WASMNGTON ALL STUATf IN Mf COUNTY OF JEFFERSON. STATE OF WASHINGTON AS A CONCRETE ONR MONUMEM. IN ME COURSE OF MIS SURVEY IT WAS FOUND >FLaT ME NORM I/16M CORNER aF ME EAST LINE OF SEC ] IS MONUMENTED W/1H A CONCRET[ DNR MONUMENT AND Tll£ NORM I/16M CORNEA OF THE WEST LINE OF SEC. B lS MONUMENTEO SURVEYOR' -rRTlf7 d W!M A PGASTK SURVEY CAP STAMPED 75 18896' AFTER OrsCU55lON WRH CHRIS BUTLER, PLS, MIS SURVEY SFYILL CORRECT ME MONUMENT DESCRIPDON NOTE AS SHOWN ON SAID MI5 MAP CORRECTLY REPRESENTS A SURVEY AOnOE BY ME OR UNDER SURVEY RECORDED IN VOL. 19. PC. 149. MY DIRECTION IN CONFORMANCE WIM M£ RfOUIREMENTS OF ME SURVEY RECORLNNG ACi AT ME Rf0UE5T OF JUOE ASHLEY IN MARCH, 1006. LLFFpp //ppRR ~ '_`~y %~`~ AT 3: S3 R~~OF SURKYS. ON`'bACE~RlE 006. (` _, A. REQUEST OF KENNEM A. LURK V^J l9'.A~ 513~oC3 1. ~' ~ ~( .s /' COUNTY AUDITOR AUDRORS FILE NUMBER ~...••\4!aa~/I '/~_"___ ~ K l~~i N.T.S. - _ X NNEM A. LURK, PL 1.5. MBER 1111) % DOTE >/11/aG MAPPM nNG au. ~.S LEKLDPMENi CpN5Ul11NG - TC""" u LONSTRUC110N MANAGEMENT CQU~TY ~C~ Figure 1 The lower portion of the tract including the southerly portion of Parcel E and ®7 has a significant thickness of glacial drift. Thicknesses of more than 40 feet we observed in road cuts in the lower and southerly portion of the tract. Amon~t these, a consolidated outwash deposit was noted at the lowest section of tN~f~ FE~~Q~ c~~~~ ~~~ drift. That material, which is well consolidated, is probably in direct contract with the underlying basalt parent rock. In places the creek that crosses the property has eroded away the glacial deposits to form relatively steep slopes of 30 to 40 degrees from the horizontal. 1n one area, what appears to be a very old slide block now forms a bench in the southeast quarter of Parcel E. Observations at the site suggest that the historic slide block moved in the dip direction of the foreset bedding, which favored sliding in asouth-westerly direction. Figure 2 4.0 Specific Observations and Recommendations for the Various Lots 4.1 Observations and Recommendations Regarding Parcel E Only the northerly 150 feet or so of Parcel E is suitable for development due to the dissection of the southerly part of the parcel by stream erosion and a local access road. J[$~(~EIVE~ At the time of the inspection, the owners showed us the .prospective site of a Q 7 drainfield and a flat area where they hope to someday site a modest single fame y :residence nearby a 35 degree slope down to the creek. ~~CE[ppO~ pO~~N ~pD The Drainfield Site at Parcel E The proposed drainfield lies on a mild slope with little or no geologic hazards. The test pits that had already been dug at the drainfield site on Parcel E showed a jumble of colluvial soil mostly derived from glacial drift. The drainfield is set back substantially from the rim of the slope down to the creek on the south and it well away from the toe of the relatively mild slope on the north. This site is not endangered by slides or other geologic hazards. Prospective Building Site on Parcel E There is a possible house site near the north line of the parcel and close to the center of the parcel in the east-west direction. The descending slope south of the side falls at about 35 degrees to the creek below. The slope shows evidence of moderate soil creep. The topography of the slope suggests that small slides have occurred there that might remove a width of 5 to 10 feet from the rim of the nearly flat house site above. The potential for larger scale slides in asouth-westerly direction along the underlying bedding seems relatively low due to the position of the downslope slide block and a buttressing ridge that provides resistance to motion in the south-easterly direction. For safety and preservation of the value of the prospective house on this site, a setback of at least 40 feet from the house foundation line to the nearest point on the rim of the descending slope is recommended. If a larger house footprint is desired, the lot line forming the south line of Parcel A could be moved to the north or otherwise adjusted to make more space available. The current position of the access road to the house site on parcel E could be revised by moving the road to the west to obtain more building area. 4.2 Observations and Specific Recommendations for Parcel A Parcel A lies upslope of Parcel E. Most of the parcel has a southerly slope of about 15 degrees from the horizontal but there is an area of lower slope at the southeastern corner of the parcel. That zone may be a portion of the top of the ancient slide block mentioned above. No specific site for a house was selected on Parcel A, but the site seems to offer relatively safe house sites both on the upper area of uniform slope and within a flatter area near the southeast corner and lowest portion of the parcel. The ~~~a ~ ~~ steepes# slopes on this parcel lie above this nearly flat site near the southeast ®7 corner. If a house is built there, maintain a separation of 30 or more feet fr the toe of the more steeply-sloped areas to the house foundation line. ~~E~E~~U~ bUtl~11 D~~ To obtain more room for a house on Parcel E, it is .possible to adjust the lot line on Parcel A, so that a larger building site is available on Parcel E Parcel B Parcel B is similar to Parcel A. The sliding .potential in most of the site is low due to the thin overburden on competent rock. If a house is sited on the slope, loose material could be removed down to a rocky surface suitable for foundations. On this parcel and Parcels A and C it would be wise to do a thorough search for loose boulders above any proposed house site. With a relatively large area to choose from, rockfall hazard could be minimized by avoiding the zone directly below any large boulder that might be discovered among the small trees above. Parcel C A portion of a possible house site has been cleared at the time of the geotechnical inspection in April of 2007. The site, in the southwest quadrant of the parcel, is suitable for house construction provided that the loose alluvium is removed and foundations are placed on the rock. As with Parcel B, it would be wise to search #or boulders above the house site before making a final decision on the location. 5.0 Limitations of This Report The observations, conclusions and recommendations of this report were based upon observations of the surface soils, shallow open test pits and visible conditions at the site. No borings or deep test pits were completed, nor were any longer-term measurements made at the site, nor any soil samples tested. Soil conditions at depth could vary from the visible indicators in an unexpected way, thus affecting the recommendations made. Those who require a higher degree of reliability in findings are encouraged to obtain additional observations and testing that results in a more thorough assessment of the subsurface. The investigation of the site and the recommendations of this report were made to the standard of care of professional engineering and in accordance with the principles and practice of geologic engineering. No other warranty, neither implied or express, is provided herewith. Sincerely yours NTI ENGINEERING & SURVEYING ~~ ~~~ Bill Payton, LEG Engineering Geologist Steve S. Luxton, MSc. PE Professional Engineer ~, ~ ~ ~~ ~' s ~zd ~ ~~~~~~ ~~~~ ~Q~ William C. Pay#on Jr. ~~ L ~~'' ,~ c~ wAS,~~~ ~; ~ ~' ~~s~~,~ f' ~~~ I~IE~~I ®®~;~~~ ~~ 9~ ~eA~~a~~d;s`Ji Luz/~