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Home My WebLink About001301030 Geotech Assessment a' Prepared For Robert Heinith July 20, 2007 RECEIVED AUG 1 3 2007 JEfFERSOI COUNlY DCD GEOTECHNICAL REPORT For the Property Described As f if 0 0' 30i D3D Tax #~ Oal}l::ane De Chantal tJA--XJ ocated In Section 30, Township 30 North, Range 1 West, W.M., Jefferson County, W A 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 NTI ENGINEERING & SURVEYING 717 SOUTH PEABODY STREET, PORT ANGELES, WA 98362 Engmee~ LandSuNeyors Georog~ffi Construction Inspection Materials Testing (360) 452-8491 1-800-654-5545 FAX 452-8498 E-Mail: info@nti4u.com NTI www.nti4u.com RECEIVED AUS 13 ,.7 July 20, 2007 lfffllll mINTY ueD Robert Heinith 2937 NE 4ih Ave Portland, Or 97213 Subject: ~~J Geotechnical Report for the Property Described as Tax 301031.....-/ Lane De Chantal located in Section 30, Township 30 North, Range 1 West, W.M., Jefferson County, WA Dear Mr. Heinith: Background At your request, NTI Engineering & Surveying, Inc. (NTI) performed a geotechnical inspection of the above-mentioned property, which included office research and a site visit for visual observations conducted on July 6, 2007. No subsurface exploration was performed. The purpose of this inspection was to observe the subject property by visual means and make recommendations regarding the development of the property in accordance with the Jefferson County Unified Development Code (UDC). The property is currently undeveloped. It is our understanding that development plans include the construction of a house, small cottage, and a shop. Site Description The subject non-waterfront property is located on Lane De Chantal, with a partial view of Discovery Bay to the west (Figure 1). The property is bounded on the north, west, and south by residential property with Lane De Chantal to the north, and on the east by Cape George Road (Figure 2). There is an existing driveway on the property that leads to the proposed home site. The majority of the property slopes gently towards the southwest at approximately r. The northern half of the property is bisected by a ravine that trends in a southwesterly direction and drains over the bluff on the adjacent property (Figure 3). The steepness of the ravine side slopes are variable but are generally in the mid 200 to mid 300 range. The ravine was dry at the time of the site visit. There is a trail that leads through the RECEIVED 3 2007 OUNTY DCD Figure 1 ravine and down the bluff to the beach. The existing driveway passes around the head of the ravine and along the south side of it to the house site. There are also steep cut and fill slopes along the driveway. The property is well vegetated with young to mature trees, shrubs and brush. Site Geology The Washington State Department of Ecology's Coastal Zone Atlas maps the soil in the area of the subject property as Vashon advance outwash (Qva), with Vashon lodgement till (Qvt1) on the eastern edge of the property. The advance outwash is described as well stratified, well sorted sandy pebble to cobble sized gravel. In some places, sand predominates. This soil is good for seismic stability and good to excellent for foundation stability, but may be poor on slopes that approach the angle of repose of the material. This soil is generally stable in slopes up to the angle of repose, and may stand in steeper slopes for short periods. The till is described as a compact mixture of boulders, cobbles, pebbles, sand, silt and clay, generally overlain by 1-5 feet of ablation till. The Atlas also describes this soil as being excellent for foundation stability and good for seismic stability. The Atlas maps the stability of the property as Unstable. The Washington State Department of Ecology's "Geology and Ground-Water Resources of Eastern Jefferson County, Washington", April, 1981 gives essentially the same description of the soils in the area of the subject property. Figure 2 The Soil Survey of Jefferson County Area, Washington (United States Department of Agriculture, 1975), classifies the soil in the area of the property as being predominantly Cassolary sandy loam (CfD) over the majority of the property, with Tukey gravelly loam (TuD) on the east side of the property. The Cassolary soil formed in reworked glacial and marine sediments and consists predominantly of silty sand, with areas of clay. Runoff is listed as medium, and the hazard of water erosion as moderate. The Tukey soil formed in glacial till on terraces and consists predominantly of silty or clayey sand and gravel. Runoff is listed as medium, and the hazard of water erosion as moderate. Visual observations made in the area were consistent with the aboREG~D AU6 1 3 2007 JEffERSON &OUNft DCn 1l:(JJj;C~l VED AIlS 1 3 2111J7 JY DCD Figure 3 Conclusions and Recommendations The property appears grossly stable at present, and the proposal seems feasible from a geotechnical perspective. It is our understanding that all construction will be east of the existing driveway and thus avoid the steep ravine slopes. Setbacks will also be needed for the steep driveway cut slopes. We recommend that no construction take place on slopes steeper than 300, and that a 15' building setback line be established from where the slope becomes steeper than 300. Further, the foundation requirements of the International Building Code (IBC) will need to be followed (See Appendix). Also, the driveway may need to be improved in order to provide year round vehicular access (slope armoring, rock, vegetation, etc.). The following recommendations should also be considered with regards to the proposal: 1. It will be necessary to maintain ground cover to reduce erosion from surface runoff. Any bare areas that develop should be revegetated. Native deep-rooted vegetation that requires little or no irrigation would be the most beneficial. 2, Vegetation on the ravine slopes provides stabilization to the soils. Existing established vegetation should be left in as natural a state as possible. If a better view is desired, selective tree removal, thinning and pruning should be done in such a way that minimizes disturbance to the soil and root zone and that insures the continued health of the vegetation. Damaged trees or trees that are in danger of falling, due to undermining of the roots for example, should be evaluated for removal because of the damage potential to the slope caused by the root mass of a large tree being pulled out of the ground, and also due to the risk of a tree falling on the house. If trees are removed, the trunks should be left in place so that the root mass can continue to provide stabilization to the soil. A tree expert could provide valuable consultation in this matter should the need arise. 3. Heavy irrigation or other activities that would contribute large quantities of water to the soil should be avoided. 4. Surface water should not be allowed to flow over the face of slopes as an uncontrolled or concentrated flow and cause erosion of the slope face. This can be controlled with vegetation and using berms or swales to direct runoff to a drainage system, Please see the attached DOE publications for more information on this subject. 5. Surface runoff from hard surfaces such as roofs, driveways, walkways and patios should be controlled and routed to a drainage control system such that surface water discharge to adjacent properties does not exceed predevelopment conditions. 6. Silt fences or other sediment control devices may be needed during construction such that sedimentation to adjacent properties does not significantly exceed predevelopment conditions. 7. All drainage control devices should be maintained in good working order and inspected at least once a year. For further information please review the three attached copies of booklets published by the Washington State Department of Ecology (DOE) entitled: "Slope Stabilization and Erosion Control Using Vegetation", "Vegetation Management: A Guide for Puget Sound Bluff Property Owners" and "Surface Water and Groundwater on Coastal Bluffs". These publications are now out of print but can be reviewed at the DOE website at: http://www.ecv.wa.Qov/biblio/sea.html under the 1993 and 1994 year heading. The DOE website also contains more useful information regarding slope stability and site development and is highly recommended. Limitations This report has been prepared exclusively for you and your agents in conjunction with the above referenced project. The report has not been prepared for ~~ ~~ or for ... othe:r locations. Others may use it only with the expressed written pe<<~Jb~ED Engineer. AUG 1 3 .2007 JEFFERSON COUllY OCD Within the limits of scope, schedule and budget, this report was prepared in general accordance with accepted professional engineering and geological principles and practices in this or similar localities at the time the report was prepared. No other warranty, expressed or implied, is made as to the conclusions and professional advice included in this report. The observations, conclusions and recommendations presented in this report were based on our visual observations of the subject property at the time of our site visit; no laboratory tests were performed. Soil and geologic conditions can vary significantly between test holes and/or surface outcrops. If there is a substantial lapse of time, conditions at the site have changed or appear different than those described in this report, we should be contacted and retained to evaluate the changed conditions and make modifications to our report if necessary. Sincerely, NTI ENGINEERING & SURVEYING U Robert A. Leach, P.E., MBA Principal Engineer ~p~ EXPIRES 12/30/2008 Bill Payton, L.E.G. Engineering Geologist G:\Gen\Bill\Reports\HEIN0701.slope stability.30(30-1 ).Discovery Bay.doc RECEIVED AIlS 1 3 aU? JfffEISIII alUllY 001 Appendix RECEIVED AUG 1 3 2007 JEFffftSON COUNlY DCD 35' D Washington State Department of Ecology's Coastal Zone Atlas AUS 1 S 2007 JEFFERSON COUNTY OeD ->",'\..t 'I \'~' b';: Beckett D AU6 1 3 2007 JEFfE. COUNTY DCD . . 1805.3 Footings on or adjacent to slopes, The placement of buildings and structures on or adjacent to slopes sleeper tban one unit vertical in three units horizontal (33.3-percent slope) shall conform to Sections 1805,3.1 through 1805.3.5, 1805.3.1 Building clearance from ascending slopes. In general, buildings below slopes shall be sel a sufficient dis- tance from the slope to provide protection from slope drain. age, erosion and shallow failures, Except as provided for in Section 1805.3.5 and Figure 1805.3.1, the following criteria will be assumed to provide this protection. Where tbe exist- ing slope is steeper than one unit vertical in one unit hori- zontal (1OQ.percent slope), the toe of the slope shall be assumed to be at the intersection of a horizontal plane drawn from the top of the foundation and a plane drawn rangent to the slope at an angle of 45 degrees (0.79 rad) to th" horizon- tal. Where a retaining wall is constructed at tbe toe of the slope, the height ofthe slope shall be measured fn,m the top of the wall to the top of the slope. 1805.3.2 Footing setback from descending slope sur- face. Footings on or adjacent to slope surfaces shall be founded in firm material with an embedment and set back from the slope surface sufficient to provide vertical and lat- eral support fortbe footing without detrimental settlement. Except as provided for in Section 1805.3.5 and Figure 1805.3.1, the following setback is deemed adequate to meet the criteria. Where the slope is steeper than 1 unit ver- tical in 1 unit horizontal (1 OO-percent slope), the required setback shall be measured from an imaginary plane 45 degrees (0.79 rad) to the horizontal, projected upward from the toe of the slope, 1805.3.3 Pools. The setback between pools regulated by this code and slopes shall be equal to one-half the building footing setback distance required by this section. That por- tion of the pool wall within a horizontal distance of 7 feet SOILS AND FOUNDATIONS (2134 mm) from the top of the slope shall be capable of sup' porting the water in the pool without soil support. 1805.3.4 'Foundation elevation. On graded sites, the top of any exterior foundation shall extend above the elevation of the street gutter at point of discharge or the inlet of an approved drainage device a minimum of 12 inches (305 mm) plus 2 percent. Alternate elevations arc permitted sub- ject to the approval of the building official, provided it can be demonstrated that required drainage to the point of dis- charge and away from the structure is provided at allloea- tions on the site, 1805.3.5 Alternate setback and clearance. Alternate set- backs and clearances are permitted, subject to the approval of the building official. The bui lding official is permitted to require an investigation and recommendation of a registered design professional to demonstrate that the intent of this sec- tion has been satisfied. Such an investigation shall include consideration of material, height of slope, slope gradient, load intensity and erosion characteristics of slope material. For SI: 1 foot = 304.8 mm, H ~ FIGURE 1805.3,1 FOUNDATION CLEARANCES FROM SLOPES 2006 INTERNATIONAL BUILDING CODe8 347 RECEIVED AUG 1 3 2007 JEFfERSON COUNlY OeD .. .. .' '.. NTI ENGINEERING & SURVEYING 717 SOUTH PEABODY STREET, PORT ANGELES, WA 98362 Engineers 0 Land Surveyors 0 Geologists Construction Inspection 0 Materials Testing (360) 452-8491 1-800-654-5545 FAX 452-8498 E-Mail: info@nti4u.com NTI RIE:(:EliVED www.nti4u.com APR 1 7 2QOB April 16, 2008 " CD ~"J ~. ....,.."1-.. ~< '....,.... I' U Robert Heinith 2937 NE 4ih Ave Portland, Or 97213 Subject: Addendum to Geotechnical Report for the Property Described as Tax # ~-'t631, Lane De Chantal located in Section 30, Township 30 North, Range 1 West, W.M., Jefferson County, WA 00/30103 0 Dear Mr. Heinith: At your request, NTI presents this addendum to the geotechnical report that was completed by this office for the above referenced property dated July 20,2007. This addendum addresses all proposed development on the parcel including access easements, septic systems, buildable areas, driveways, etc. as illustrated on the two enclosed site plans provided by you, This additional information was requested by Zoe Ann Lamp of Jefferson County in a letter to you dated February 25, 2008. Based upon the attached site plans provided to us, the locations of the proposed development features are consistent with the recommendations of the geotechnical report, If you have any questions regarding this matter, or need further assistance, please do not hesitate to contact this office. Bill Payton, L.E.G, Engineering Geologist Sincerely, NTI ENGINEERING & SURVEYING t~'~ B:\Reports\HEIN0701.30(30-1 ).addendum.doc .; ,- .~ '~".\ .," , \'\ "1 . i..'. ~.... , ,~ K'" ! '~.,. : '\l~ f\\ ;, ~ \- ' ! it' 1.,1 \ \ j . -,- -..,.... "'~., , 0/ "> ' , ? ~ \ j,,~ ..l j.:. \ 4(.1 -.i-- ' \ ~ ~ ~- ~ ~ . \ -' . '" .. - ---"";' -', -'-~ ~"""T'~ ...... 0 0 - ~ I " 0 f~ ~ Ltu 0 r' l~ r \ -4 ~ ,.. . ~ "-, J [i I o o (-, JEFFEiui "".iilV nrn . ......... 1 .. ~ ~ ! t ~ ~ ~ I ~ .'"":l 8 t :::::: I b I :> I ~\'1. ill if \ ,/ i \ \ ,,~/ J- ~ ",."..... .,....~- ~.- ,- {' '" .- /-'~ t) / J / -~.....--/' I i I,r /,'''8 R~u" ! :J; M - 011 ~ ..... aJ /l,... i 1 d rr , ~ ~ J - ~ - . .. Zoe Ann Lamp ,~..i l~i~ 0'0/ if Qof ~ T/ From: Zoe Ann Lamp Sent: Tuesday, April 29, 20089:04 AM To: 'Jamie Sage' Subject: RE: Attn: Bill Payton - RE: Heinith Geotechnical Report Thank you, will do! Zoe Ann From: Jamie Sage [mailto:jamie@nti4u.com] Sent: Tuesday, April 29, 2008 8:51 AM To: Zoe Ann Lamp Subject: FW: Attn: Bill Payton - RE: Heinith Geotechnical Report :-----Original Message----- From: Bill Payton [mailto:bill@nti4u.com] Sent: Tuesday, April 29, 2008 8:35 AM To: 'Jamie Sage' Subject: RE: Attn: Bill Payton - RE: Heinith Geotechnical Report Hi Zoe, I think it would be ok to note the correction on the reports. Thank you for catching it. Regards, Bill Payton, L.E.G. Engineering Geologist NTI Engineering & Surveying 717 S Peabody Street Port Angeles, WA 98362 Work: 360-452-8491 Fax: 360-452-8498 Email: bill@nti4u.com Page 1 of2 From: Jamie Sage [mailto:jamie@nti4u.com] Sent: Tuesday, April 29, 2008 8:26 AM To: Bill Payton (E-mail) Subject: FW: Attn: Bill Payton - RE: Heinith Geotechnical Report -----Original Message----- From: Zoe Ann Lamp [mailto:zlamp@co.jefferson.wa.us] Sent: Monday, April 28, 2008 2:44 PM To: info@nti4u.com ' Cc: heib@critfc.org 4/29/2008 Page 20f2 Subject: Attn: Bill Payton - RE: Heinith Geotechnical Report Mr. Payton, As I was reviewing the information again for Robert Heinith, I discovered the cover of both the geotechnical report and the addendum reference the parcel along the shoreline owned by Daniel and Heidi Johns (001301031). Mr. Heinith owns parcel 001301030 which is the parcel he's doing the SPAAD. The report and the maps are for the correct parcel. Do you mind if I note this on the reports or would you like to submit corrected copies? Please advise. Thank you. Sincerely, Zoe Ann Lamp Associate Planner - Lead, DRD Jefferson County Department of Community Development 621 Sheridan Street Port Townsend, WA 98368 Phone: 360-385-9406 Fax: 360-379-4473 e-mail: zlamp@co.jefferson.wa.us All e-mail sent to this address will be received by the Jefferson County e-mail system and may be subject to Public Disclosure under Chapter 42.56 RCW. 4/29/2008