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HomeMy WebLinkAboutMLA16-00029-FPA16-00002 Jablonski Geology Hazard Assessment with StormwaterSTRATUM GROUP P.O. Box 2546, Bellingham, WA 98227 Phone (360) 714-9409 May 9, 2016 Ron Jablonski 250 Rhododendron Lane Brinnon, WA 98320 Re: Geology Hazard Assessment Tax Parcel 821333018, Jefferson County Port Ludlow, WA Dear Mr. Jablonski: GOFIVIE �D MAY 16 2016 j JEFFERSON COUNTY __ DEmOFOF C04'MONI The purpose of this geology hazard assessment was to determine if any landslide or erosion hazards were present on the subject property. This geology hazard assessment included a visual inspection of the property and vicinity, a visual inspection of the slopes on the property and vicinity, review of available geologic mapping in the area, and review of LiDAR imagery of the area. Based on my assessment of geology conditions, there are no landslide or erosion hazards at the site. Furthermore, development of the site will not increase the risk of landslides on or off the subject property. GENERAL GEOLOGY The Geologic Map of the Lofall 7.5 -minute Quadrangle, Jefferson and Kitsap Counties, Washington (Contreras and others, 2013) indicates the upland area of the property is underlain by glacial recession outwash and ice wasting deposits. The glacial recessional outwasb and ice wasting deposits were deposited as glacial ice retreated from the area approximately 14,000 years ago. Observations on the subject property and vicinity are consistent with the mapping described above. The site is underlain predominantly by sand and gravel units consistent with glacial recession deposits and ice wasting deposits. SPECIFIC SITE OBSERVATIONS The north end of the property is accessed via from Teal Lake Road on the north side of the property. The uppermost part of the property has very gentle slopes. The slopes then slope down to the south with slope on the order of 25 percent at the steepest. The only steep slopes on the site are along the road cuts down to Teal Lake Road. These slopes we as steep as 100 percent over short distances. Most of the property has been clear cut harvested of timber. The landing area and access for the May 9, 2016 Parml 821333018, Jefferson County, WA Geology Hazard Assessment timber was on the uppermost portion of the property at the north end of the property. A strip of trees were left along the northern boundary of site above Teal Lake Road. No indications of past slope movement or landslides was observed anywhere on the property. The site is underlain by well drained soils with sand and cobbles being the primary sediment. There are no indications of deep-seated landslides down gradient from the property. CONCLUSIONS AND Based on my visual inspection of the subject property, I conclude that the property is not at risk from landslides. Development of the property with a home and septic system will not be at risk from slope failures and will not increase the risk of slope failures on or off the site. Stratum Group appreciates the opportunity to be of service to you. Should you have any questions regarding please contact our office at (360) 714-9409. Sincerely yours, Stratum Group Dan McShane, M.S., L.E.G. Licensed Engineering Geologist MAY 1 62016 D IJ ul IEFFC DEPT. DE C0"'111JN11YDEVEL9F4'cNT Summ Group File. 2.26.16 R117, zo,s STRATUM GROUP P.O. Be. 2546, Bellingham, WA 98227 JEFFERSON COUNTY DCD Phone (360) 714-9409 May 23, 2016 Ron Jablonski 250 Rhododendron Lane Brinnon, WA 98320 Re: Proposed Stormwater Plan Geology Hazard Assessment Parcel 821333018 Teal Lake Road Port Ludlow, WA Dear Mr. Jablonski: Based on the observations I made on the subject property, the site is suitable for full dispersion of stormwater. Driveway water can be allowed to sheet flow off to the sides of the driveway. For roof run off, direct drippage onto the ground, splash blocks at gutter downspouts, dispersion trenches or drywells will all be acceptable approaches for infiltration of stormwater into the well drained soils at the site. Full dispersion of stormwater at this site will not cause erosion or landslides on or off the subject property. Stratum Group appreciates the opportunity to be of service to you. Should you have any questions please contact our office at (360) 714-9409. Sincerely yours, 0 as `0 St r tum Group 7 � a Dan McShane, L.E.G., M.Sc. c tux,ino fi,; r Licensed Engineering Geologist Dailld KlcShano