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Home My WebLink AboutGEOTech Assessment for BLD2005-00963 - BLD Engineering / Geo-tech Reports - 7/7/2005 Mc MASON COUNTY 0 A° �n PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER S N y O Shelton,Washington 98584 by N Y y DATE: July 7 , 2005 INTER-DEPARTMENTAL COMMUNICATIONS TO: Kell McAboy, DCD - Planner FROM: Alan A. Tahja, P/W - Co. Hydr. Engr. WO#PLG-05 SUBJ: Geo-Tech Assessment Review NAME: Archambeau SFR k Harding Hill Rd . BLD2005-00963 Kell, The geotechnical assessment prepared for the proposed Paul & Linda Archambeau Single Family Residence (SFR)to be constructed on Mason County Tax Parcel No. 12232-21-00020, has been received and reviewed by Public Works. The report appears to satisfactorily fulfill County requirements for geotechnical assessment reporting. From the contents of the assessment, I recommend accepting the report as satisfying the County's requirement(s) for stability investigation and geotechnical reporting. Recommendations contained in the assessment should be incorporated into the site's development and made conditions for permit issuance. Adequate Erosion and Sediment (E&S) control features need to be implemented during land disturbing activities to protect neighboring properties and State waters from adverse stormwater runoff impacts. The migration or release of silty water or mud from the applicant's property will be considered a violation of County and State water quality protection regulations. In summary, the geotechnical assessment prepared for the proposed Single Family Residence appears acceptable, and stability issues may be considered to have been adequately investigated and addressed. Please feel free to contact me at County extension 461 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sincerely, tAA. Tahj a File: H:\WP\GEO\Assessments\Archambeau.doc J i1 l WORK ORDER -'puk � O � t E (4, oats: PT. EN C� PERMIT#1:��t s �"iz:>'jc>3R"UNIed m C.q _o Authorized by: ► ck i,v��`�, � Type of work: L mac - Date: 7477-7 _" CHARGE TO., NAME AGENCY/C6MPANY BIUJNG ADDRESS PHONE Pub.Works M e;.Line. �.-- :(fnom-to d#tes) ProNot Bart irrti.• . 0� riou� IRMA= IO? _ Eh�plo »& _TOTAL / EQWIAEW uSEOc VATEN&UseM -� IFI Iletud Cost ;. 6ARis ' . GATE gi�„M PRtl,1>R f tift Hours ElderEdUKIA TOTAL$ -- EQWPMENT USED: .20 MATERIAL.USED: �^ 3) BILLED DATE TOTAL ALL PAID-DATE REOJ b1GX�� 2cH 41M3aA:v Z �vi - 4w19 � J Gl J cr 00 ku J �1 p)o 02J h-L 1-1,-.-I1 �-aW a Sdo � ¢ \ a y Geotechnical Assessment Harding Hill Road Grapeview, WA Parcel #122322100020 DILANNING Prepared for Paul & Linda Archambeau by Geotechnical Testing Laboratory Olympia, Washington Sept. 25, 2004 GEOTECHNICAL TESTING LABORATORY PAUL& LINDA ARCHAMBEAU P.O. Box 646 GRAPEVIEW, WA 98546 RE: GEOLOGICAL ASSESSMENT HARDING HILL ROAD GRAPEVIEW, WASHINGTON PARCEL 122322100020 N47021.409' W 122°50.322' PURPOSE The objective of the geological assessment is to assess the surface and subsurface conditions prevalent at the subject site according to Mason County Ordinance 17.01.100.E4. A single-family residence with a daylight basement is proposed on the partially cleared parcel. The septic system is approved. A groundwater well is proposed. k� .•k`�..2 � � ` � h +x � � �,n its ♦1 � �' 'I ll i . t SITE CONDITIONS The subject site is a parcel located approximately 2 miles south of Allyn, Washington. The lot is located inland and west of North Bay between State Highway 3 and Grapeview Loop Road, see attached vicinity map. The site is accessed from State Highway 3 and Harding Hill Road. The subject site (10 acres) is located in an area of sparse residential development. The site slopes toward the northeast and east. The steepest portion of the site has a slope approaching 19 percent. The building location is located on the east side of the property. Minimal grading is expected at the proposed building location except for the soil removed for a proposed daylight basement. The lot is heavily vegetated with maple, fir, hemlock, alder, and cedar trees as well as blackberry, bracken ferns, sword ferns, salal, and Oregon grape. Rapid stream incision was not identified at the site. Slope instability was not discerned on this site or on adjoining parcels. 10011 Blomberg Street SW, Olympia, WA 98512 1 Phone#: (360) 754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY ti !r -m ; • 1, �t �',� ) • Akc 77, 4 � rYt GEOLOGIC CONDITIONS The Soil Survey of Mason County, USDA Soil Conservation Service (1960) has mapped the western site soils as Alderwood gravelly sandy loam, 5-15 percent slopes (Ab). The report reads: The Alderwood soils typically formed from glacial advance outwash. They are described as having good natural drainage. Typically, there is no occurrence of a high water table. Internal drainage is described as medium. An erosion hazard may exist if the vegetation is removed; otherwise, the soil has a low erosion hazard in its present condition. Cementation is usually present. The soils are not considered hydric. it ��•� 'kc''AiC�t ...y �� *"'C 3�a t a.�j�`Y� �. w.,"tC.' f��'rl.`.5 xM�'.:��1t.�.,tfir�•# y�' J « f ,..'S`� 0 T t A 4 L `i?k: ,.i� "�� s•Z.- ,;ff,-_ .�� •fir;_._ .'� � '��r �=`I -.,R� „,�. ,. ar.t k r•,f �?ct-_ .r r :ti�� .aw �},r �` 4 ,, : 'Ir- "t'S.r.. `~'�J7.� - ;Y tea. '.•.. rr0'r�,arr. a+Sy'¢j:+a' ,�. .� a, �,`(� �S ,�� M1:: T} � ,�, .fw�I �yyyµyy� f j. A"�• �� ' •,�. (�.. � ,�.,7�,./,yy.� ,q)��,�;=t?.�, vii'- r 1)j..�t+� �`yi J"�';1^�u..w� '.{„t,�` ,t i iY_ - �-1�� !�•v V The Soil Survey of Mason County, USDA Soil Conservation Service (1960) has mapped the eastern site soils as a Sinclair shotty loam, 5-15 percent slopes (S,,), at the proposed building location. The Sinclair soils have typically developed from very compact Vashon gravelly till. Surface drainage is well to moderately well established. Internal drainage is restricted by the substratum of cemented till. Typically, there is no occurrence of a high water table. The soils are not considered hydric. 10011 Blomberg Street SW, Olympia, WA 98512 2 Phone#: (360)754-4612 Fax#: (360)754-4848 GEOTECHNICAL TESTING LABORATORY 9 y `+�^{� � ,�� `�� '��t.S.:w?, „'"tit' �� e � `; ti, L �� '� �, y t• _ ,�' The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the site geology as glacial till deposits (Qgt) of continental glacial origin. The report reads: Till— Unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and boulders deposited by glacial ice; may contain interbedded stratified sand, silt, and gravel. Includes part of the Vashon Drift undivided. GROUNDWATER CONDITIONS r , Groundwater seepage was observed near the proposed building location. However no wetland vegetation was observed at or near the proposed building location. Depth to static groundwater is unknown. PAST SLOPE INSTABILITY Near the proposed building location, trees were found straight and vertical. No indication of past instability was discerned at the proposed building location or throughout the site. Adjoining parcels display similar signs of stability as the subject site. The Coastal Zone Atlas, Volume 9, Mason County (MA-12) maps the site as having Vashon Till (Q,,) in the north portion of the site. The till is a tough, dense material of low permeability. It provides excellent foundation support. The site slope stability is described as "stable." DEPTH TO COMPETENT SOIL Typically, dense gravelly sandy loam is found throughout the site. Competent soil can be expected approximately 14 inches below the ground surface. 10011 Blomberg Street SW, Olympia, WA 98512 3 Phone#: (360) 754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY tiN y� VAL. 3 6 y s •. i Q.a 3.4♦E• i x.. _ w r t 1 tt , Proposed Building Location HISTORY OF LANDSLIDE ACTIVITY No historical landsliding was observed during our site investigation onsite or near the subject parcel. At the proposed building location, the slopes are dense, compact, and moderate in slope angle. Trees onsite and on neighboring properties are straight and vertical. The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977) describes the site area as Class 1. Class 1 is expressed as: Areas believed to be stable. Slopes generally less than 15 percent, but may be greater locally in areas too small to be shown at the map scale. Largely comprises rolling uplands underlain by very stable material such as young glacial till, mantled in places by a thin layer of sandy gravel or other permeable material; also includes flood plains, deltas, alluvial fans, and some beach deposits. Class 1 areas immediately adjacent to steep slopes of class 3 areas may be threatened by potential landsliding. Normal,proper engineering practices generally are adequate to insure stability in these areas. jSc..+r POTENTIAL FOR LANDSLIDE ACTIVITY This site has very little potential for landslide activity. Even though slopes approach 19 percent, the potential for landslide activity is not a concern. Surficial creep and sloughing at the proposed building location is not a concern. 10011 Blomberg Street SW, Olympia, WA 98512 4 Phone#: (360)754-4612 Fax#: (360) 754-4848 GEOTECHNICAL TESTING LABORATORY RECOMMENDATIONS There is no evidence of soil erosion or deposition onsite to suggest that the site should be included in the Erosion Hazard Area designation. Site conditions for the proposed development do not warrant a more comprehensive Geotechnical Report. We recommend no further action is needed unless areas of concern are unearthed during construction. If there are any changes in the loads, grades, locations, configurations or types of facilities to be constructed, the conclusions and recommendations presented in this report may not be fully applicable. If such changes are made, we should be given the opportunity to review our recommendations and provide written modifications or verifications, as appropriate. Respectfully, `e�%W IS8 GEOTECHNICAL TESTING LABORATORY � r �0 IJZ-13 Geob* w Harold Parks, L.G., L.E.G. `r0B'e 827 0�o yy Senior Engineering Geologist ed GO HAROLD PAWS 10011 Blomberg Street SW, Olympia, WA 98512 5 Phone#: (360)754-4612 Fax#: (360)754-4848 ti GEOTECHNICAL TESTING LABORATORY VICINITY MAP LV M51 v I ockc LZ I I I.- J, 53 f 1 � 1t1 `! % — ,! —'; ;• ,j,�t �.` }Atchambea Site ROGkY ✓ Ir` I!/ A�j�'rr/�i��% ��t`� �� f r�llt�� a �� • rhr i , � r IJ � �. rr' �( �% •�./ t � + '� I i Ifr l .�' / •�'/�.,� - 1, �,� r }rs 8M � 21t I�•',rr I , `,, ", l � r i { rj 1• � / iI "� `ram 8 � r1 i• � � i r f' / / r F,r r � 10011 Blomberg Street SW, Olympia, WA 98512 Phone#: (360)754-4612 Fax#: (360)754-4848