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HomeMy WebLinkAboutGEO-Tech Review - BLD Engineering / Geo-tech Reports - 1/29/2007 MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER Shelton, Washington 98584 lop DATE: January 29, 2007 INTER-DEPARTMENTAL COMMUNICATIONS TO: Kell McAboy PARCEL# 32232-52-14005 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-01882 SUBJECT: Geo-Tech Report Review NAME: Buechel Richard Kell, The Geotechnical Report and addendum letter prepared for the proposed new single-family residence with garage located at 51 East Spruce Street Union has been received and reviewed by Public Works. The original report was dated August 29, 2005. An addendum dated January 29, 2007 confirms the geotechnical report is still valid. The letter noted no substantive change of any nature has occurred. The proposed residence and garage will be built on a slope that approaches approximately 27% near the south end of the lot. The lower end of the lot has slopes near 13%. The structure will have a daylight basement. The new residence will be keyed into the existing stable slope by the daylight basement and the garage concrete walls. Nine to ten foot concrete walls will be utilized. The report's author affirms that all potential Landslide Hazards can be overcome in such a manner as to prevent harm to property and public health and safety, and no significant Environmental Impacts will result if this project is permitted as outlined within the Report and its attachments. Public Works does not review retaining walls. The building department should review the concrete walls for the basement. The basement walls should be engineered or prescriptive. The keystone concrete block walls for the driveway may also need to be reviewed. Based on the contents of this report and addendum, I recommend accepting this report as satisfying the County's requirements for geotechnical reporting. Recommendations and comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. Adequate erosion and sediment 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. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. cerely, John S iva rograms Engineer MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER Shelton, Washington 98584 NC DATE: January 16, 2007 INTER-DEPARTMENTAL COMMUNICATIONS TO: Kell McAboy PARCEL # 32232-52-14005 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-01882 SUBJECT: Geo-Tech Report Review NAME: Buechel Richard Kell, The Geotechnical Report prepared for the proposed new single-family residential with garage located at 51 East Spruce Street Union has been received and reviewed by Public Works. The geotechnical report is dated August 29, 2006. We need a more recent report preferably done within the last six months. A new report is not necessary if conditions or the report have not changed. The engineering firm that wrote the report can send an addendum letter stating that the report is current and/or note any changes or recommendations. A licensed geologist or a professional engineer must stamp the letter. The Geotechnical Report is on hold and no further action will be taken by Public Works until we receive what is requested above. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. �ery John Sliva� Programs Engineer Monday, January 29, 2007 9.30 AM Kenneth W Martig Jr 360 705 0789 p.02 Martig Engineering "'t �+�~� �-Ij P.O. Box 11850 Olympia, WA 98508-1850 .m 2 q 2007 (360) 754-9687 Fax (360) 705-0788 I cculIn PURM ►;u-4 January 29, 2007 Mason County ,,.t'=�►r�"��it!, Department of Public Works P.O. Box �6 2007 ` Shelton WAA 98584 G Attn: John Sliva, Programs Engineer: -%4,'NCOU11TYPUROCW'0 -+$ Re: Geo-Tech Report Compliance Report for: * Owner: Richard Buechel (360) 898-3995 P.O. Box 249 Union, WA 98592 Site Location: Union, Mason County, Washington; North side of Pine St. between Port Townsend St. & Tacoma St. (Lots 5, 6, 11, & 12 of Block 14; Tax Parcel No.: 32232-52-14005; " Mason County: Sec 32, Township 22 N, Range 03 W; ` Proposal: Construct a new 3-Bedroom Single Family Residence; " RESPONSE: to John Sliva communication requesting confirmation that the August 29, 2005 Geotechnical Report is still valid. Dear Mr. Sliva: At your request, I am with this letter confirming that the Original August 29, 2005 Geotechnical Report for the above referenced site remains valld. No substantive change of any nature has occurred. Only the removal of heavy brush so that site can be more easily inspected by the County for approval of the remaining Permits. _ Sin erely: A� ��" OF W A" eth artig, J r ti 4 0- /0 Ai- EXPIAGG t-a o �v - i C-�����/� MARTIG ENGINEERING C-(Ftt/7 �� � --- P.O. Box 11850 �f1 ? Olympia, WA 98508-1850 ill() �V 2 (360) 754-9687 Fax (360) 705-0789 August 29, 2005 �Gr �Glii Mason County Department of Community Development 426 W. Cedar P.O. Box 578 Shelton, WA 98584 Attn- Planning Re: Geo-Tech Report Compliance Report for: * Owner: Richard Buechel (360) 898-3995 P.O. Box 249 Union, WA 98592 * Site Location: Union, Mason County, Washington; North side of Pine St. between Port Townsend St. & Tacoma St. Lots 5, 6, 11, & 12 of Block 14, * Tax Parcel No.: 32232-52-14005; * Mason County: Sec 32, Township 22 N, Range 03 W; * PROPOSED NEW SINGLE FAMILY RESIDENCE. Dear Mason County Planner: I, Kenneth W. Martig, Jr., PE, of Martig Engineering have completed my engineering investigations regarding the Geotechnical Report requirements associated with the above referenced property. As a result of our investigations outlined within this Report, we can affirm that all potential Landslide Hazards can be overcome in such a manner as to prevent harm to property and public health & safety, and no significant Environmental Impacts will result if this project is permitted as outlined within this Report and its attachments. 1 PROPOSED PROJECT The proposal is to construct a new 3-bedroom single-family residence on the above referenced property. An approved onsite Septic System has been installed on the property, except for wiring and connection to the future residence (see the Attachment 4 Property Site Plan). The Attachment 1 Vicinity Map & Tax Parcel # Map show the location of the property, with a view overlooking Hood Canal, and directions to it. The following discussion summarizes our: Site Investigations; Research of Site Conditions; Analyses; Residence & Driveway Placement; and Conclusions, allowing this Geo-Technical Report to be completed for the above referenced site. GEO-TECHNICAL REPORT 1. Geology, Soils, Groundwater, Landslides: This site was found to be geologically stable, with no landslides found on or near this site. Stereo Aerial Photos were examined for signs of unstable geology. The Mason County Soil Survey shows that the soils are an Alderwood gravely, sandy, loam (15% to 30%) with its till layer approximately 24" to 32" deep. Attachment 6, Page 3 of 7, shows three Soils Test Pit Logs confirming these soils. The dominant site soil, at depths greater than 34 to 37 inches, is a dense consolidated cemented till. These consolidated soils can remain quite stable and stand at steep slopes, as long as no runoff water is directed onto or over them. The surface soils are granular and, where undisturbed, allow infiltration of moderate precipitation and will support a Septic Drainfield as shown upon the Attachment 4 Site Plan. No signs of significant groundwater bearing soil lenses were found at this site. Major groundwater would be located well below the surface of this site. No groundwater induced instability of the existing stable steeper slopes was found. 2. Site Plan of Important Geologic Features: A portion of the USGS Union Quadrangle Topographic Map (1" = 500') is attached (as Attachment 2) to show the general topography of the site and its surrounds. The small area of land that could develop Surface Water Runoff has been delineated on this map, in Blue. If any small amount of offsite runoff from the south could develop, it would bypass the site due to the construction of the East-West 2 16-foot wide Pine Street via this roadway's south drainage ditch. The Attachment 5 Building Site Plan topography and Attachment 7 35mm Photographs (7-Pages) also show the features on and near the property. The Elevation View (Section A-A), shown on Attachment 6, show the existing and proposed improvements on the site. No unusual or difficult Geologic Features were found. 3. Location of Soil Exploration Holes/Probes: The above described Alderwood soils formation that exists at and near the site are exposed as cut-slopes along the roadways leading to the property. Attachment 7, Page 5 of 7, shows the Pine Street roadbed cut-slope bank immediately across from the subject property. Additionally, Page 6 of 7 shows stable driveway cut slopes along Pine Street near the subject property. Attachment 6, Page 3 of 7, shows three Soils Test Pit Logs confirming these soils. No additional soils test borings or test pits were required to confirm the conditions and type of the site soils. 4. Cross Sections showing slope disturbances: The Section A-A Elevation View (see Attachment 6) shows the slopes on and adjacent to the property where improvements are proposed. Since the site has already been cleared, the only new Clearing is the removal of new brush. Grading for the Driveway and Residence footings will be required. Keystone concrete block walls or Large stone Rock walls will be required to place the necessary Driveway Fill. The cut slopes will stand stable at 0.5-feet Horizontal to 1.0-foot Vertical, but would look nicer if dressed with the same wall used for the fill slopes. The new residence will be constructed by excavating into the existing bench so that the building foundation and daylight basement are constructed upon structurally stable soil. The Finish Floor Elevation of the Basement was found to be 285.0, with the Main Floor and Parking Pad at Elevation 295.0. The height of the concrete walls needed for the Daylight Basement and Garage Floor construction is 9' to 10' maximum. The Septic System Tank, Pressure pump system, and Drainfield have already been Permitted and constructed on the northerly portion of the property where the slopes are gentle. See Attachments 4 & 6. 3 5. Slope Stability Discussions: As discussed within this report, the proposed activity will not create significant environmental impacts and no landslide hazard will be induced when the proposed new improvements are constructed. The geologic features found at this site support that the proposed improvements can be made without creating any slope instability problem. Martig Engineering found that the site slope is 27.3% where the new residence is proposed. The Pine Street cut slope across the street from the Site has remained stable for Decades at a steep slope of 0.20' to 0.5' Horizontal to 1.0' Vertical. The slope immediately south of the cut slope 12-foot high top-of-bank is 20.0%. and remains stable. The slopes at the lower, northerly, portion of the property drop off to 13.3%. These slopes are shown on the Attachment 6 Elevation View, Section A-A. Given the lesser slopes above and below the proposed new residence construction site and the minor excavations into the slopes to construct the proposed improvements, the slopes will remain stable. All follow-up research and investigations showed that this land is stable and will not become unstable if a single-family residence is developed here. A review of DNR stereo aerial photos, including the most recent 7/21/03 DNR photographs with stereo glasses confirmed a stable terrain, no slide zones, wet areas or other signs of instability were visible on or adjacent to the site. Numerous single-family residences have been developed on lots within this Union housing development. No visible signs of slope instability were found around them. The new residence will be keyed into the existing stable slope by the daylight basement and garage concrete walls. Once these walls are constructed, the space between the walls and the excavation soil walls will be filled with washed pea (with perforated drain pipes placed within these fills to eliminate any water accumulation and minimize basement moisture). The face of the property slopes adjacent to the residence and driveway construction shall remain well vegetated with native grasses and brush-type Understory to prevent erosion. 6. Drainage, Septics, Water, Placement: This proposal is for a new 3-bedroom Single Family Residence. An existing Septic system has been designed and Permitted with the designated Tanks and Drainfield already installed as shown on the Attachment 4 Site Plan. 4 The water supply for the new residence will be from the existing water supply serving the homes within this area of Pine Street. The roof drains for the new residence gutters & downspouts will be connected to a new onsite storm drain system.The Storm Drainage Plan will be placed upon the Architectural Plans for the new residence that will be submitted to secure the necessary County Permits. 7. Clearing & Grading Plan: Only minor new clearing and grading is necessary as discussed within the Slope Stability Discussion section above. The areas of fill and excavation for the footings, the daylight basement, and the driveway are shown on the Attachment 5 Building Site Plan and on the Attachment 6 Elevation View. 8. Erosion Control Plan: During construction, a solid row of staked straw/hay bales shall be placed parallel to Pine Street along the 280-foot contour for erosion control protection as shown on Attachment 5. Any existing bare ground upon the property, outside of the House Footings and Driveway areas shall be covered with 4" to 6" of loose straw/hay bale material or coarse Beauty Bark, until new groundcover vegetation can be established. After construction, any disturbed soil should be planted with grass seed and covered with mulch or simply covered with 4 to 6 inches of loose straw/hay. The new portion of any driveway or roadway improvements should be covered immediately with several inches of crushed rock surfacing to prevent soil erosion. The installation of the new storm drain system, including its tight-piped outfall to the south Fir Street ditch, should be completed prior to the completion of the house roof. Roof gutters and downspouts should be connected to the storm drain system, immediately upon completion of the roof construction. The basement wall drains should also be immediately connected to this new drainage system at a point where the roof drainage cannot backfeed water into the wall footing areas. 9. On-Site & Off-Site Impacts: In summary, no adverse environmental impacts or landslide triggers will result if this proposed development is permitted as presented within this Geo-Technical Report. 5 I i 10. Final Development Conditions: No special conditions are necessary at this site. Just follow the parameters outlined within this Geo Tech Report and the specifications developed by the Architect and �I Septic System installer. I, Kenneth W. Martig, Jr., PE, of Martig Engineering have completed the required Geo- Technical Report as documented within this letter Report and its attachments. I am familiar with this site, having visited, inspected, & analyzed the site and its surrounds. As documented, potential landslide hazards have been overcome and no significant environmental impacts will result if this proposal is permitted as discussed above. Certified by: Kenneth W. Martig, Jr., PE i Attachments: #1- Vicinity Map & Tax Parcel Number Map; #2- Topography Map, Union Quad. (1" = 500'); #3- Aerial Photo 7/21/03, (1' = 500'); #4- Property Site Plan Map (1" = 30'); #5- Building Site Plan Map (1" = 20'); #6- Elevation View (Section A-A); & z #7- 35-mm Photographs, 7-Pages. 9 ISTEP�O ?� ASS/oNAI ENG` EXPIRES 1-9- i i I i I i I I i I I I i 6 V%�;�� , map I 1 t 1 Z,HE 'I I 1 ------------ CANA 1 1 1 I 1 1 I I 1 � I I 1 , GREAT 1 I I I 1 1 I i I 1 I 1 t 1 1 1 1 I 1 1 1 1 1 I 1 I 1 I i 1 I I ------------- -------------------;--------------BEND 1 1 1 CANAL : � 1 1�i•� 1 I I I I F 1 �• „� i i CALM COVE -------------------1--------—-------I--- — -- ------------------ K C i 1 1 5� awe ec 1 1 ® I m 1 1 wwoc�. 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