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HomeMy WebLinkAbout951700008 Geotech AssessmentREPORT OF SLOPE AND SOIL SURVEY PROPOSED LAUGHLIN RESIDENCE TAX PARCEL 701-314-~1" QUILCENE, WASHINGTON ~-~ ~NflOO NOSB]JJ]r Prepared for: MR. JIM HEINS JENNING-HEINS & ASSOCIATES, INC. P. O. Box2198 POULSBO, WASHINGTON 98370 Prepared by: KRAZAN & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING DIVISION 20714 STATE HIGHWAY 305 SUITE 3 C POULSBO, WASHINGTON 98370 (360) 598-2126 & ASSOCIATES, INC. GEOTECHNICAL ENGINEERING · ENVIRONMENTAL ENGINEERING CONSTRUCTION TESTING & INSPECTION September 1, 2000 KA # 102-00019 Jim Heins Jennings-Heins & Associates, Inc. P.O. Box 2198 Poulsbo, Washington 98370 REPORT OF SOIL AND SLOPE SURVEY AND GEOTECHNICAL ENGINEERING STUDY, PROPOSED LAUGHLIN RESIDENCE LOCATED-ON EAST QUILCENE ROAD, QUILCENE, JEFFERSON COUNTY, WASHINGTON TAX PARCEL 701-314-001 This report presents the results of a soil and slope survey and geotechnicaI engineering study directed at evaluating potential erosion and landslide hazards at the referenced site in accordance with the requirements of the Jefferson County Critical Areas Ordinance. The scope of the study was developed during our site visit on August 21, 2000, and outlined in our proposal to you dated August 22, 2000. The services performed under the referenced proposal were in general compliance with requirements outlined in the Jefferson County Critical Areas Ordinance. As shown on the attached Location map, Figure 1, the site is located just off of the southwest comer of the intersection of East Quilcene Road and McDonald Road in Jefferson County, and overlooks Quilcene Bay to the west. Based on the conceptual development plan provided (plan dated June 29, 2000), we understand that the proposed residence is to be located near the top of the west facing slopes and approximately 75 to 80 feet, at the nearest point, from the top of a deep ravine to the north of the building site. The current layout of the structure is with a main floor at about the current site grade with loft areas above and a west-facing daylight basement below. The total building footprint of the structure, including the garage, will be about 2,850 square feet. Vehicle access into the residence will follow an existing driveway and minimal regrading of the site is anticipated for building site development. Based on our discussions, it is understood that no clearing of slope areas is planned. It is further understood that due to the Ten Offices Serving The Western United States 20714 State Route 305 Suite 3C · Poulsbo, Washington 98370 · (360) 598-2126 · Fax: (360) 598-2127 Jenningsll¢ins 102-00019 KA No. 102-00019 Page No. 2 location of the west property line near the top of the slope no trees will be felled on the west facing slopes. The currently considered building location is shown on the Site Plan, Figure 2. Previous development of the site has been limited in scope with the main feature being a small cabin. The existing driveway appears to be an extension of an existing logging (?) road which meanders down the west facing slope just west of the west property line. As previously noted, under the current development plan, minimal grading of the site, beyond that required for construction, is anticipated. All areas of bare soil and disturbed vegetation will be landscaped such that no erosion hazards are created or will remain following development. Construction of the proposed buildings (residence and garage) and driveway improvements will not result in an increase of the potential landslide or erosion hazards of the site: ....... SUBSURFACE EXPLORATION Site soils were explored and evaluated in existing septic design soil log holes and in natural outcrops both on the subject site and adjacent parcels. In general the septic log holes are located to the south of and adjacent to the building site. The observed natural exposures are located on the slopes to the west and north of the building site and along a dirt and gravel extension of East Quilcene Road that loops to the south of the property and extends to the beach. Due to the quality and depth of the existing soil exposures it is our opinion that completion of additional test pits or borings would provide little if any useful information. The approximate test pit locations are indicated on the attached Site Plan, Figure 2. Site soils were viewed in five test pits and in various road cut exposures in the area. Soil logs for the test pits are presented in Appendix A. The soil strata shown on the logs were observed at spot locations. Actual subsoil conditions and thickness may vary between the test pit locations or as exposed in excavations or slope exposures. Elevations and distances referenced in this report were established using handheld instruments, i.e., tape measure, altimeter, and inclinometer, etc., and should be considered approximate. The base drawing for Figure 2 was provided by Jennings-Heins & Associates. It is understood that this untitled, unsigned and undated drawing was prepared by Map, Ltd. Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 3 GEOLOGIC SETTING The site is located in the northwest portion of Puget lowlands, an elongate, north-south trending structural depression and topographic trough. The Puget lowlands have been filled several times by glacial ice, resulting in many topographic features, which are a result of glacial erosion and deposition and that caused by outwash streams. The site is in an area of glaciated bedrock and associated deposits. Site soils, topography and geology result primarily from the advance and retreat of the Vashon Stade (most recent glacial advance) of the Frazier Continental Glaciation. On a gross scale the typical soil sequence in the area consists of mixed sands and gravels (Recessional Outwash) over glacial till which in turn overlies sands, gravels and silts (Advance Outwash and pre-glacial deposits) or bedrock. In the general vicinity of the site the glacial till caps much of the region and overlies both pre-glacial deposits and the local bedrock, which is identified on geologic maps.as shale, siltstone, and mudstone. The site proper appears t0'be located on a flatter bench area sporadically cut by drainages. In this area it appears that the till has been severely eroded and weathered leaving a thin layer of material identified on geologic maps of the area with the general term glacial drift. The glacial till in the area is comprised of materials picked up by the ice sheet as it moved, then were deposited at the base of the glacier and overridden and densified by some 1500 or more feet of ice. The glacial drift materials are a mixture of silts, sands and gravels deposited in association with glacial ice and/or outwash streams. During the later stages of the glaciation, as the glaciers were beginning to melt and retreat, layers of silts, sands and gravels (glacial drift) were laid down by pro-glacial and subglacial streams. As indicated on the regional mapping the glacial drift materials typically overlie bedrock. Generally, the pre- and post-glacial, glacial materials are found to be dense to very dense, however, it is not uncommon to find a layer or mantle of looser, weathered or disturbed material over the denser soils or bedrock. SURFACE CONDITIONS As previously described, the site has been previously developed to a minor extent for a small cabin and adjacent grassed area, but it does not look to have been significantly graded or otherwise modified. Topographically the site appears as a flatter bench bounded on the north by a deep, steep sided ravine and on the ,,vest by moderate slopes that reach nearly to the shore of Quilcene Bay. The bench feature extends south of the site for some distance before dropping down moderate slopes to Quilcene and Dabob Bays. The vertical drop from the building site to the bottom of the ravine to the north is on the order of 90 feet down slopes ranging from about 43 Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 4 to 55 degrees. The west facing slopes are comprised of three sections. On the upper section, from the top of the slope to the logging road just below the west property line, slope angles range from about 20 to 28 degrees. Below the logging road and extending to about 50 vertical feet below the building site the slopes steepen and range to the range of 38 to 40 degrees. In the lower portion of the slope, slope angles range from near 25 degrees to 32 degrees with 28 degrees being about an average. The vertical height of the west-facing slope, from the building site down to the toe of the slope and residential development below, is on the order of 150 feet. The map "Relative Slope Stability In East-central Jefferson County, Washington" (OFR76-27, 1976, Washington State Department of Natural Resources, Division of Geology and Earth Resources) identifies slopes in the actual building site as Class 1 and those of the west facing slopes as-Class 2'stability. Slopes into the ravine north of the'building site are'identified as being of Class 3 stability. Class 1 slopes are considered stable while Class 2 slopes are considered "normally stable areas that may become unstable if modified by man". Class 3 slopes are considered to be "unstable areas". During our reconnaissance of the area it was observed that in the ravine there are many indicators of past and ongoing soil movement, i.e., bowed tree, bare ground, soil slumps, etc. In the ravine no indication of deep-seated or rotational landsliding was observed and the soil movement appears to occur primarily as shallow face failures effecting only the topsoil and weathered zones and exposing a broken bedrock slope core. On the west- facing slope the majority of the trees are straight with little indication of slope soil movement. Trees showing minor bowing are located primarily on the slightly steeper slopes just below the logging road. Based on our reconnaissance observations, it is our opinion that the slopes adjacent to the site generally reflect and match the slope stability mapping of the area. On both the slopes and flatter bench area the vegetative cover is comprised of an open, mixed- aged woods of deciduous and evergreen trees over an open to dense understory of ferns, brush and shrubs. Although most of the trees on the slopes are younger, on both the west-facing slope and the ravine slopes the oldest evergreen trees appear to be on the order of 100 to 150 years in age. This age estimate is based on diameter vs. growth ring counts made on downed fir trees around Puget Sound and near Port Ludlow. Above the slopes the evergreen trees are of Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 5 substantial size but do not appear as old as the oldest trees on the slopes and are perhaps more in the range of 50 to 100 years old. A general reconnaissance of the property and adjacent areas was made to identify areas of ground water seepage. No obvious springs or seeps were located on the slopes. However, scattered sedges located.just above the residential development at the bottom of the west-facing slope tend to indicate a possible wetter year around soil condition. During our preliminary site visit on August 21, 2000, standing water was observed in shallow utility excavations along the extension of East Quilcene Road to the south and down slope of the subject property. This water was not observed at the time of our fieldwork and may have been as a result of work on the water service piping exposed in the excavations. At the bottom of the ravine to the north of the building site a slight, discontinuous trickle of water was noted atop the bedrock. The appearari~e' ' and disappearance of this water appears joint and fracture controlled. However, based on the "washed" appearance of the channel and lack of accumulated debris, it is suspected that this ravine receives a substantial amount of runoff from up slope areas during the wet season and may flow as a periodic or intermittent stream. Considering the generally shallow soil cover and the proximity of the bedrock surface the development of seasonally perched water or the development of temporary zones of outwatering should not be unexpected on slopes or in excavations in areas back of the slopes. SOIL PROFILE AND SUBSURFACE CONDITIONS The "Geologic Map Of East-central Jefferson County, Washington" (OFR76-26, 1976, Washington State Department of Natural Resources, Division Of Geology and Earth Resources) indicates that the site and adjacent areas are underlain by "thin (glacial) drift over shale, siltstone or mudstone." On maps prepared by the Soil Conservation Service (SCS) it appears that the site lies on or very near the contact between two soil units. Based on the SCS mapping it appears that the upland portion of the property is underlain by Alde~vood gravelly loam, 0% to 15% slopes (soil type AmC) while the slopes below the building area are underlain by Quilcene silt loam, 30% to 50% slopes (soil type QuE). The SCS indicates that the AmC-type soils are typically located in areas of nearly level to rolling terrain on glacial terraces and derived from a glacial till parent material. Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 6 The QuE-type soils are typically located on steeper upland areas where a 20 to 24 inch thickness of covering soil overlies a weathered shale bedrock. As observed in the test pits and slope exposures it appears that below the forest duff layer there is a 16 to 36 inch thick layer of silty, gravelly sand with cobbles and occasional boulders. In this unit all of the gravels and larger material are rounded and the layer appears to be a weathered glacial till or drift. Below this upper layer ofglaciaI material at most locations is a 6 to 8 inch thick layer of severely weathered, fractured and broken shale bedrock which grades downward into a less weathered and broken shale. The contact between the weathered shale and overlying glacial material is to a degree gradational with some angular pieces of bedrock being incorporated into the glacial materials. Although locally there are some glacial-type materials on the-steeper slopes in general it appears that the glacial materials are absent on the ~10pes." Based on the soils observed in the test pits and exposed at various locations in the area, it is our opinion that the site soils are generally consistent with the regional maps of the area. Differences between the mapped and observed soil conditions appear as a result of mapping scale, availability of exposures, and intended map usage. These differences are generally minor and not unexpected. CONCLUSIONS AND RECOMMENDATIONS GENERAL Based upon our site observations and review of pertinent materials, it is our opinion that the potential for ground movement in the area back of the site slopes is minimal. Similarly, the potential for large scale landsliding on the west facing slopes on this property, in either the natural condition or resulting from the proposed development, is low. The west facing slopes are mapped as a Class 2 stability and the overall slope stability under the present conditions appears good and should remain unchanged with the proposed development. The potential for larger scale landsliding on the ravine slopes north of the proposed building site is considered moderate to high. However, the following setback recommendations address this potential and as presently proposed none of the site slopes will be disturbed for site development. Away from the ravine slopes no evidence of erosion was observed and following proper construction and landscaping no erosion hazard will be developed. Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 7 The Soil Conservation Service indicates a severe building site restriction for the AmC-type soils on slopes greater than' 15% for structures without basements. Although the structure will be adjacent to areas meeting the slope portion of this criteria, slopes in the actual building siteare less than 15% and the residence is to have a basement area. Following our review of the Jefferson County critical areas ordinance, it is our opinion that portions of the subject property meet the requirements for definition as a landslide and erosion hazard area. Although it is our opinion that the property meets the requirements of the ordinance for definition as a critical area, it is also our opinion that the proposed building site can be safely and satisfactorily developed through geotechnical design and sound site planning. The following recommendations for site development are provided to address the concerns of the critical areas ordinance and should be incorporated into the site development plan. As previouslY noted; itis our opinion that overall the proposed development in and of itself will create a minimal risk of erosion or landslide damage, no disturbance of the steeper slopes is expected, and the development will have little if any effect on adjacent properties. The site does not appear to meet the classification requirements to be designated as a seismic hazard area as defined in the Jefferson County ordinance. However, the property is located in seismic zone 3 as defined by the Uniform Building Code (UBC), as is much of western Washington. In the event of an earthquake of adequate magnitude and/or duration some soil movement on the slope is possible if other conditions are right, but the potential for soil movement on this property is no greater than that on the adjacent developed lots or for properties elsewhere with similar slope and soil conditions. Additionally, the slope core soils appear to be primarily bedrock which, although fractured, appears to be generally hard and sound. The recommendations contained in this report were developed considering the potential for slope failure, and that future structures are expected to be designed in accordance with current UBC seismic zone 3 requirements, or potentially more stringent future requirements. The SCS classifies the QuE-type soils to be of severe erosion hazard in the disturbed state. These soils are located on the site slopes, which we understand will not be disturbed. It is also our experience that the erosion hazard risk for disturbed areas can be mitigated through normal residential landscaping and re-vegetating of the disturbed areas. During construction and until fully landscaped the exposed site soils will be subject to erosion. Erosion of the exposed soils Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 8 will be most noticeable during periods of rainfall and may be controlled by the use of normal erosion control measures, i.e., silt fences, hay bales, mulching, control ditches or diversion trenching, and contour furrowing. A native vegetation buffer is required from the edge of all slopes that are geologically hazardous areas. It is our opinion that a vegetation buffer having a minimum width of 30 feet should be maintained parallel to the top of the ravine north of the building site. We recommend that a similar buffer be established on the west facing slopes. On the west-facing slope we recommend that the buffer be measured from the top of the road cut located just west and down slope of the property line. In addition to the maintenance of buffers we recommend that all disturbed areas be replanted as soon as possible after construction is complete. The following site preparation and foundation design recommendations are provided to aid in minimizing potential erosion and landslide damage risks and should be incorporated into site planning, design and construction. RECOMMENDATIONS Site Preparation and Gradim, Water Related Concerns: Only minor storm water related problems are anticipated if site grading and preparation are undertaken during the normally drier portions of the year. If site work is undertaken during wet weather the near surface sands and silty soils may become over- saturated and temporarily unworkable. If the site work is undertaken during wet weather the contractor should be fully prepared to deal with possible elevated water levels in addition to other soil and water problems normally encountered in these materials during wet weather work including the filtering of runoff, as needed, to prevent the siltation of down slope areas. It should be anticipated that silt fences and other erosion control devices could be used to control sediment transport off the site. Depending upon the final site grades and weather conditions it is possible that areas of perched water or seeps may develop in some areas. In that we are unable to predict where or when this might occur we recommend that any development of springs or seeps be treated as a construction/maintenance problem. The contractor should be prepared to deal with any water- related problems during construction. Water seepage can cause failure of the excavation walls Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 9 and the contractor should be observant for possible cave-in or other hazardous conditions and provide shoring for all cuts and excavations in accordance with local, state, and federal regulations. Development Recommendations: Under all buildings, pavements and fill areas, it is recommended that all sod, organic soil, and debris be removed. Over most of the site it is anticipated that a stripping depth of 12 inches will be adequate. However, localized deeper stripping depths may be required to remove tree root balls. Stripped soils, contaminated with organics or debris, should be wasted off site or used in landscape areas. Stripped soils free of organics and debris may be used as structural fill subject to the following considerations. ' Following stripping of the site and prior to the placement of any fill, the exposed subgrade should be proof rolled to a firm, unyielding condition using suitability sized equipment. Compaction of the stripped subgrade should be continued until field density tests in soil areas show that a minimum compaction of 95% of the maximum dry density, as determined by ASTM method D-1557, has been achieved in the top 12 inches of subgrade beneath all building, driveway, and parking areas. In areas of bedrock exposure the architect, engineer, geologist or other qualified person should inspect the subgrade to confirm adequacy and absence of excessive amounts of disturbed/loose material. Any soft or weaving areas disclosed during proof rolling should be excavated and replaced with compacted structural fill. With the exception of driveway side slopes, it is recommended that permanent cut slopes not exceed 2H: 1V (50%). Driveway side slope cuts may be made at 1H:iV (100%) where the vertical height is five feet or less and the slope is provided with erosion protection and not subject to over slope water flows. Fill slopes should not be steeper than 2H: 1V (50%) for fill placed in accordance with the requirements of appendix chapter 33 of the Uniform Building Code (1997 edition) or 3 to 4H:IV (33% to 25%) for uncontrolled fills of moderate quality material. In areas where steeper slopes are required, retaining structures should be provided. In areas where fills are to be made on slopes steeper than 5H: 1V the subgrade should be benched and prepared in accordance with UBC (1997) requirements prior to fill placement. Benches should be cut at a maximum vertical height of 24 inches. It should be anticipated that, if steeply Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 10 cut, the more granular near surface soils may be subject to caving, and sloughing will occur as the soils are exposed to drying. All temporary cuts and excavations should be sloped or shored in accordance with local, state and federal requirements. Areas which are to be filled to bring the building or pavement grades up to the desired elevations should be filled with compacted granular material free from roots, trash or other deleterious materials. During wet weather most of the on site soils are not expected to be suitable for use as fill. These soils are sufficiently fined grained, such that with the addition of small quantities of water they become overly saturated and are difficult or impossible to compact to the desired density. As a result, we recommend that all site grading and preparation be undertaken and completed during dry weather. If grading in building or pavement areas is necessary during wet weather, we recommend that all excavated-soil be removed from the site and that materials used as structural fill (fill placed on slopes or under buildings or pavements) consist of free draining sandy gravel with a maximum particle size of 3 inches and not more than 5.0% fines, material passing a U.S. No. 200 sieve. All imported fill material should conform to the above recommendation regardless of the weather. All structural fill should be placed in layers approximately 8 inches in loose thickness, conditioned to a moisture content suitable for compaction, and compacted to 95% of the maximum dry density as determined by ASTM D-1557. Field density tests should be made at a frequency adequate to assure that the required compaction is achieved. To preclude the possible build-up of ground water or storm runoff in the soils adjacent to the residence, it is recommended that a four inch diameter perforated, rigid pipe be placed, perforations down, around the outside of the building foundation at the footing subgrade elevation. All of the drainage system should be bedded in a drainage sand and gravel and designed to carry any accumulated water away from the structure to an appropriate discharge area. Roof drainage should not be connected to the footing drains but may use the same outfall piping provided that the connection between the systems is located at least 10 feet down grade of the house and designed to prevent water from backing up into the footing drain. All runoff from roofs, driveways, patios and hard surfaced areas should be intercepted, collected and disposed of away from structures and site slopes, and discharged where the water will not Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 11 effect down slope structures, slopes, walls or properties. Specific recommendations for and design of a storm water disposal system are beyond the scope of our services and should be prepared by other consultants fully familiar with design and discharge requirements. However, from a geotechnical perspective tight lining of the collected water to the bottom of the ravine north of the building site would be an acceptable means of disposal provided that no down slope properties or structures are placed at risk due to the potential periodic' increased water flow. Building Siting For the siting of structures we recommend that the following top of slope setbacks and foundation embedments be maintained. From the top of the ravine north of the proposed building site we recommend that a minimum top of slope setback of 60 feet be maintained. For development adjacent to the west facing slopes we recommend that a slope setback of 25 fedt measured eastward from the west property line be maintained. Additionally, all footings on gentle slopes (<15%) should bottom a minimum of 18 inches below the lowest adjacent exterior grade and 12 inches below the lowest interior grade. Footings on or within 10 feet of slopes steeper than 15% should be designed so that the bottom of the footing is a minimum of 36 inches below the lowest adjacent exterior finished grade and a minimum of 60 inches back of the finished soil slope face. Additional foundation design considerations should be in accordance with Uniform Building Code requirements, as modified by local codes and regulations, in effect at the time of construction, for structures within seismic zone 3 as defined by the Uniform Building Code (1997) or the UBC seismic zone in effect at the time of construction. Construction Considerations As a preliminary guideline for temporary cuts less than 10 feet in height, excluding driveway cuts under five feet, we recommend temporary slopes be made no steeper than 1.5H: 1V for the loose to medium dense silty soils and 1 H: 1V in the fractured bedrock or dense soils. For temporary cut slopes over 10 feet in height we recommend temporary slopes no steeper than 2H: 1V for the full height of the cut. Temporary slopes or excavations should be benched as required by safety regulations in effect at the time of construction. These temporary slope recommendations are for native soils and fill materials, flatter slopes may be required in wet weather or if soil conditions other than those previously described are encountered. The Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 12 contractor should be aware that slope height, slope inclination, and excavation depths (including utility trench excavations) should in no case exceed those specified in local, state, or federal safety regulations; e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1-926, or successor regulations. Such regulations are strictly enforced and, if not followed, the owner, the contractor, or the earthwork or utility subcontractors could be liable for substantial penalties. The contractor should be made responsible for the stability of all excavations and slopes during construction because he is continually on site and can observe the stability of the exposed soils. In addition, the contractor should be prepared to shore any unstable slope area and provide shoring as required by local, state, or federal laws or codes. In no case should excavated soils be placed on the slope or stockpiled within the defined buffer -or slope setback areas along the steep slopes or within 20 feet of the top ofany'6tIier existing or excavated slope, rockery or retaining structure. Failure to comply with these guidelines may lead to destabilization of the slope. The site soils may be easily eroded by channelized water or sheet flow storm runoff. Therefore, it is recommended that all site preparation and excavation work be completed during the normally drier portion of the year. During periods of heavy rainfall, ditching should be used to divert water away from stripped areas and visqueen should be used to cover the slopes and soil stockpiles to aid in preventing excessive surface erosion. This covering also aids in preventing infiltration of water into the unprotected soils. All disturbed soil areas and slopes should be replanted with fast-growing, deep-rooted grass, shrubs and other ground cover as soon after final grading as possible. If the vegetation is not fully established prior to the on set of wet weather, the slopes should be covered with visqueen to aid in preventing excessive erosion and water infiltration. It should be anticipated that there could be a number of additional site development or construction problems, particularly, if the earthwork has not been completed and the site properly protected at the onset of wet weather. It is recommended that the architect, structural engineer or their representative make periodic inspections of all excavations and slopes to provide early recognition and recommendations. Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 P:~ge No. 13 REPORT LIMITATIONS This report has been prepared for the exclusive use of Jennings-Heins & Associates, Inc. and their agents for use in planning of the referenced development. The conclusions and recommendations in this report are based on our interpretation of site conditions as they presently exist, anticipated future construction activities, and the expectation that the exploratory efforts adequately define the subsurface conditions throughout the building site. The soil conditions described in this report and the conclusions and recommendations contained in this report are provided for this specific site only and should not be expanded for use on adjacent properties without additional exploration and review of those sites by our firm. The data and report should be provided to prospective contractors for their bidding or estimating purposes, but the report conclusions and interpretations should not be construed as a warranty of the subsurface conditions.: There are possible variations in subsurface conditions. In the event that the' sc0pe'or location of the project should change or subsurface conditions different from those encountered during this study be observed or suspected, we should be advised. At that time a review of the changed conditions will be made, and alternative or remedial recommendations given as required. NOTE: Although we have explored subsurface conditions as part of this study, we have not conducted analytical laboratory testing of samples obtained, nor have we evaluated the site for the potential presence of contaminated soil, and have not evaluated or addressed ground water conditions or concerns except as noted in this report. The evaluation of possible environmental or geo-environmental considerations is beyond the scope of this report. The owner and the contractor should make themselves aware of and become familiar with applicable local, state, and federal safety regulations, including current OSHA excavation and trench safety standards. Construction site safety generally is the sole responsibility of the contractor. The contractor shall also be solely responsible for the means, method, techniques, sequences, and operations of construction operations. The firm, Krazan & Associates, Inc., (including consultants and subcontractors) is providing the preceding information and recommendations solely as a service to Jennings-Heins & Associates, Inc. Under no circumstances should the provision of this information or recommendations be construed to mean that the firm Krazan & Associate, Inc., (including consultants and subcontractors) is Krazan & Associates, Inc. Offices Serving The Western United States KA No. 102-00019 Page No. 14 assuming responsibility for construction site safety or the contractor's activities; such responsibility is not implied and should not be inferred. Within the limitations of scope, schedule, and budget for this work, it is warranted that the work has been done in accordance with generally accepted practices followed in this area at the time this is report was made. No other warranty, expressed or implied is made. Should you have any questions or concerns which have not been addressed, or if we may be of Sincerely, additional assistance, please Allen L. Hart, CPG, RPG/CEG Senior Engineering Geologist Shawn E. Williams, Senior Environmental Geologist Krazan & Associates, Inc. Offices Serving The Western United States Jennings-Heins & Associates KA No. 102-00019 rip *°~'' Y¢-:."- . 'x\ ! - ..;;~'::~,: _:,'.. ~-.'.: . .;. - -z :; 4.~$4¢".~:~' - - -'- - - / .- ~. ~,'~:~. . .... ~ ;~:';: SITE.._ · · SITE LOCATION MAP Reference map: Portion of slope stability map "Relative Slope Stability in East-Central Jefferson County, Washington", OFR76-27, Washington State Department of NamraI Resources, Division of Geology and Earth Resources, 1976 Krazan & Associates, Inc. Offices Serving The Western United States . · . Reference drawing unsigned, untitled, undated drawing by MAP ltd. APPROXIMATE TOP OF ROAD CUT -- PROPERTY LINE ~ ~ .--.- EDGE OF RECOMMENDED 30' VEGETATION BUFFER Depth-Inches 0 - 16/20 16/20 - 28 28 - 48 -No ground water observed. Depth-Inches 0 - 36 36 - 43 -No ground water observed. Depth-Inches 0 - 24 24 - 30 30 - 48 :No ground water observed. Jennings-Heins & Associates KA No. 102-00019 SOIL LOGS TEST PIT 1 Soil Brown, loose, silty, gravelly SAND, moist. Gravels rounded. (Looks like weathered glacial till.) Contact grades Brown, highly weathered, highly fractured and broken SHALE, moist. (Weathered bedrock) Contact grades Tan to gray with some iron staining, weathered, fractured and broken SHALE, moist. (Weathered bedrock) TEST PIT 2 Soil Brown, loose to medium dense, silty, gravelly SAND with occasional cobbles, moist. Gravels and cobbles rounded. (Looks like weathered glacial till.) Contact varies up and down and is gradational. Light brown to tan, weathered, fractured SHALE, moist. (Weathered bedrock) TEST PIT 3 Soil Brown, loose, silty, gravelly SAND, moist. Gravels rounded. (Looks like weathered glacial till.) Contact grades Brown, highly weathered, highly fractured and broken SHALE, moist. (Weathered bedrock) Contact grades Tan to gray with some iron staining, weathered, fractured and broken SHALE, moist. (Weathered bedrock) FIGURE 3 Krazan & Associates, Inc. Offices Serving The We. stern United States Depth-Inches 0 - 20 20 30 30 - 48 -No ground water observed. Depth-Inches 0 - 32 32 - 36 36 - 48 -No ground water observed. Jennings-Heins & Associates KA No. 102-00019 TEST PIT 4 Soil Brown, loose, silty, gravelly SAND, moist. Gravels rounded. (Looks like weathered glacial till.) Contact grades Brown, highly weathered, highly fractured and broken SHALE, moist. (Weathered bedrock) Contact grades Tan to gray with some iron staining, weathered, fractured and broken SHALE, moist. (Weathered bedrock) TEST PIT 5 Soil Brown, loose, silty, gravelly SAND, moist. Gravels rounded. (Looks like weathered glacial till.) Contact grades Brown, highly weathered, highly fractured and broken SHALE, moist. (Weathered bedrock) Contact grades Tan to gray with some iron staining, weathered, fractured and broken SHALE, moist. (Weathered bedrock) FIGURE 4 Krazan & Associates, Inc. Offices Serving The .Western United States