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HomeMy WebLinkAbout001302014 Geotech AssessmentGeologic Slope Stability Evaluation 281 Lane Dechantal Port Townsend, Washington June 2003 JUN 2 6 JEFFERSON'COUNTY DEPT. OF COMMUNITY DEVELOPMENT At Shannon & Wilson, our mission is to be a progressive, well~ managed professional consulting firm in the fields of engineering and applied earth sciences. Our goal is to perform our services with the highest degree of professionalism with due consideration to the best interests of the public, our clients, and our employees. Submitted To: Partners in Well Being 281 Lane DeChantal Port Townsend, Washington 98368-9671 By: Shannon & Wilson, Inc. 400 N 34th Street, Suite 100 Seattle, Washington 98103 21-1-09921-001 _------Iii SHANNON &WILSON INC GEOTECHNICAL AND ENVIRONMENTAL CONSULTANTS SEATTLE RICHLAND FAIRBANKS ANCHORAGE DENVER SAINT LOUIS BOSTON June 24,2003 Partners in Well Being 281 Lane DeChantal Port Townsend, WA 98368-9671 Attn: Mr. Bruce Tapper GEOLOGIC SLOPE STABILITY EVALUATION, 281 LANE DECHANTAL, PORT TOWNSEND, WASHINGTON (JEFFERSON COUNTY DEPARTMENT OF COMMUNITY DEVELOPMENT CASE # MLA03-00212) Dear Mr. Tapper: This letter summarizes our observations, conclusions, and recommendations regarding slope stability and development of the property referenced above for a single-story office building and addition to the existing septic drain field. In a letter to you dated May 30, 2003, Jefferson County indicated that this property is located in a Landslide Hazard area and that a geotechnical report would be required to assess the stability of the site. Consequently, we have prepared this report in accordance with the Unified Development Code for Jefferson County to evaluate the potential for slope movement and provide recommendations for development of the site with respect to slope stability. Our conclusions and recommendations are based on observations made during our visit to the site on June 12, 2003, available published geologic, topographic, and soil maps, previous work by Shannon & Wilson on properties north and south of the site, and building and site plans provided by your contractor, Mr. Clint Sherman. Results of preliminary observations and conclusions were provided to Mr. Sherman orally upon completion of the site visits. SITE DESCRIPTION The site is located on Discovery Bay on the west side of the Quimper Peninsula, as shown on Figure 1. The property is approximately 770 feet long (northeast-southwest) by approximately 250 to 350 feet wide (northwest-southeast). 400 NORTH 34TH STREET · SUITE 100 P.O..BOX 300303 SEATTLE, WASH I NGTON 98103 206.632.8020 FAX 206.695.6777 TDD: 1.800.833.6388 21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 2 SHANNON ~WILSON, INC. The topography across the site rises from sea level at Discovery Bay, to about 370 feet to the northeast. Starting from the southwest and ending at the northeast, the topography includes the following. · A beach. · A steep, waterfront bluff, (approximately 100 feet high) that slopes up to the northeast at about 60 to 66 degrees (may be near vertical in local areas). · A middle slope, (approximately 100 feet high) that slopes up to the northeast at about 27 to 32 degrees. · A steep, upper bluff (approximately 60 feet high) that slopes up to the northeast at about 50 to 60 degrees (may be near vertical in local areas). · An upper slope that extends beyond the northeast property line to Cape George Road (up to about 450 feet above sea level) at about 15 degrees. An existing residence and septic drain field are located on the upper slope. The residence is located approximately 70 to 75 feet from (northeast of) the crest of the upper bluff. The existing septic drain field is approximately 450 to 500 feet from the crest of the upper bluff. Lane DeChantal crosses the northeast end of the property between the existing residence and septic drain field. Vegetation on the site typically consists of Douglas fir, cedar, and madrona trees up to 3 feet in diameter with undergrowth that includes salal and Oregon grape. The presence of madrona trees, salal, and Oregon grape is indicative of relatively well drained near surface soils. The area in the immediate vicinity of the residence has been landscaped and includes a relatively large lawn area between the crest of the upper bluff and the residence. We understand that the proposed single-story office building will be located behind (northeast of) the existing residence on the upper slope, approximately 200 feet from the crest of the upper bluff. The proposed septic drain field addition will be located adjacent to the existing drain field on the upper slope near the northeast end of the property. 21 - 1-09221-001 -Ll/wp/lkd 21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 3 SHANNON &WILSON, INC. GEOLOGIC CONDITIONS Published geologic maps of the area indicate that the site is underlain by Pleistocene-age (+17,000 years old) Vashon Advance Outwash, which is in turn underlain by older, undifferentiated, stratified pre-Vashon sediments. The undifferentiated, pre-Vashon sediments may consist of both glacial and non-glacial deposits and may include stratified sand and gravel with lesser amounts of silt, clay, and peat. The pre-Vashon sediments are not lithified (are not rock). The overlying Vashon Advance Outwash typically consists of sand with lesser amounts of silt and gravel. The advance outwash was deposited on the pre-existing land surface, in front of the continental Vashon Stade ice sheet that advanced from Canada across the Puget Sound region approximately 17,000 years ago. The Vashon Stade ice sheet that overrode the advance outwash and underlying sediments is estimated to have been on the order of 3,000 to 4,000 feet thick in this area. Consequently, the advance outwash and the underlying pre-Vashon sediments have been compacted to a very dense or hard state due to the great weight of the overriding ice. Geologic and hazard maps also indicate that below an elevation of about 200 feet, both historic and pre-historic landslides have occurred for several thousand feet up and down the beach. A relatively large landslide (180 feet wide, extending from near the crest of the upper bluff to the beach) occurred at a nearby property to-the south (191 Lane DeChantal) in February 2000. Subsurface explorations were not performed at this site for this evaluation. However, the soils observed in road cuts, septic drain field test pits, and exposures on the site and properties to the north and south of the site indicate that the site is underlain by Vashon Advance Outwash and pre-Vashon sediments. In the septic drain field test pits and in road cuts along Lane DeChantal, very dense sandy gravel and gravelly sand advance outwash was observed. On the property to the south, the upper portion of the lower bluff also appears to underlain by. advance outwash, consisting of slightly gravelly, silty sand to fine sandy silt. On properties to the north, the lower portion of the advance outwash contained scattered layers of clay and silt. The lower portion of the upper bluff, middle slope and waterfront bluff at the site are presumably underlain by undifferentiated pre-Vashon sediment. The lower portion of the upper bluff, middle slope and waterfront bluff at the site were not accessible at the time of our site visit. However, geologic reconnaissances on the bluffs and slopes on properties north and south of the site encountered 21-1-09221-001-Ll/wp/lkd 21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 4 SHANNON ~WlLSON, INC. stratified sand, silt and clay layers. A clay layer was noted below the advance outwash in the upper bluff on properties north and south of the site. The clay layer has a blocky, fractured, or sheared appearance. Slight seepage was observed on top of this layer on the property to the south; no seeps or springs were observed on the property to the north or at the site. Since the retreat of the glacier, the upper few feet of the very dense/hard soil has loosened and weathered, and topsoil, colluvium and/or slide deposits have developed at the ground surface. Colluvium is weathered material that has reached its present location due to the forces of water and gravity and is typically found on, and at the base of steep slopes. Slide deposits also likely to be present at various locations at the base of the bluffs. CONCLUSIONS AND RECOMMENDATIONS Slope Stability Geologic hazard maps indicate that the bluffs and middle Slope are unstable and the locations of historic and pre-historic landslides. Slope movements appear to be associated with the oversteepened condition of the bluffs and with perched groundwater on fractured/slickensided clay layers within the pre-Vashon sediment. The following provides a description of the processes affecting the stability of the slopes. The waterfront bluff is the result of ongoing wave erosion and oversteepening at the toe of the bluff. The dense to very dense glacially overridden soils that presumably underlie the bluff may spall from the near vertical faces caused by wave erosion. In addition, while the very dense or hard glacially overridden soils may be stable at relatively steep slopes (e.g., 40 degrees or more), the relatively loose topsoil and colluvium that weather from these soils are not as competent and are susceptible to movement on slopes on which the underlying glacial soils are relatively stable. With enough time, movement of colluvium, topsoil and/or slide debris toward the base of the bluff would result in a flatter, more stable slope. However, wave erosion at the toe of the waterfront bluff does not allow the slide deposits, colluvium, or topsoil to accumulate at the toe and maintains the bluff in an over-steepened condition. 21-1-09221-001-Ll/wpflkd -21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 5 SHANNON ~WILSON, INC. The upper bluff may be the head scarp of an ancient landslide. Similar to the waterfront bluff, the upper bluff will tend to flatten over time by spalling and movement of shallow topsoil, colluvium, and/or slide deposits to the toe of the bluff. In addition, relatively deep-seated movements may occur on or near the upper bluff and extend back into the upper slope, similar to what occurred in 1997 on the property to the south. In that instance, it appeared that instability was associated with wetting and accompanying reduction in shear strength of a fractured clay layer in the upper bluff. The clay layer appeared to have a relatively high shear strength when dry. However, when water was introduced into the fractures, the shear strength was reduced, and the clay layer was no longer capable of supporting the weight of the advance outwash in the upper portion of the bluff. The overlying advance outwash moved out over the clay and cascaded down the middle slope and waterfront bluff. We observed that the landslide extended back from the crest of upper bluff 140 feet into the upper slope. Based on the angle of the upper and middle slopes and the size of the trees on them, it appears that these slopes are relatively stable where unaffected by instabilities associated with the bluffs. The flatter upper slope appears to be more stable than the steeper middle slope. Continued slope movements should be expected in the future as the wave erosion at the toe of the waterfront bluff and flattening of the upper bluff continues over time. In this regard, there is some risk of future instability (shallow or deep-seated) present on all hillsides, which the owner must be prepared to accept. Such instability could occur because of future water line breaks/leaks, uncontrolled drainage, unwise development in adjacent areas, or other actions or events on a slope that may cause sliding. The following provides further discussion of risk reduction measures that may be effective at this site. Provided that the risk reduction measures discussed in this letter are implemented, it is our opinion that the proposed development will not adversely impact the stability of adjacent properties. Measures to Reduce the Risk Posed by Slope Movement In general, the risk of soil movement on a slope can be reduced by not over-steepening a slope (e.g., do not excavate the toe of the bluffs) and not increasing the weight on a slope (e.g., do not place yard debris or fill on or at the crest of the bluffs). The risk of soil movement on a slope can also be reduced by maintaining a slope as dry as possible (e.g., locate septic drain fields away 21-1-09221-001-Ll/wp/lkd 21 - 1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 6 SHANNON ~WILSON, !NC. from the bluffs, route roof downspouts and yard drains away from the bluffs, and minimize the amount of surface water that could flow down bluff faces), and maintaining a vegetative cover. The following provides additional recommendations to reduce the risk of soil movement. Building Setback The measures discussed above may reduce the risk of soil movement on a slope. One of the most cost-effective measures to reduce the potential impact of slope movement is to provide an adequate building setback from the top of the upper bluff so that if soil movement on the slope does occur, the hazard to the structure is minimal. An appropriate setback is a function of the rate or risk of slope movement (regression rate), the design life of the structure, and the risk the owner of the structure is willing to assume. The regression rate for the upper bluff is unknown. However, based on the size of the trees on the middle slope between the two bluffs, it is our opinion that the regression rate of the upper bluff is relatively low (e.g., on the order of a few inches per year). Please note that there may have been several years where no noticeable regression occurs, and other times where regression of several tens of feet may have occurred (e.g., 140 feet on the property to the south in 1997). In our opinion, the proposed building setback of 200 feet from the crest of the upper bluff is adequate. Septic Drain Field Location The septic drain field should be located as far as practical from the bluffs on the upper slope. By placing the septic drain field as far as practical from the bluffs, the potential for water from the drain field to find its way down onto less pervious soils at the elevations of the upper and lower bluffs is reduced. The proposed location of the septic drain field addition at the northeast end of the property is consistent with this recommendation. Drainage In general, reducing the amount of water entering and discharging onto a slope can reduce the risk of slope movement. Drains should be constructed and maintained to collect water from impermeable surfaces that may be associated with the proposed building (e.g., .roof, decks, 21-1-09221-001-Lllwp/!kd 21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 7 SHANNON EWILSON, INC. patios, and driveways) and directed in a tightline to a suitable discharge point. The building plans we reviewed with Mr. Sherman indicated that this water would be discharged into dry wells on the upper slope in the vicinity of the proposed building. We recommend that this water not be discharged into dry wells on this slope. Instead, we recommend that any water collected from impermeable surface or footing drains be connected to the existing tightline, which discharges beyond the upper bluff and apparently onto the middle slope. The condition of the existing tightline and discharge point (e.g., tight pipe connections, surface erosion protection at the discharge point) should be monitored regularly and repaired as needed. Based on our understanding of the limited development of this property, it is our opinion that the anticipated discharge of water collected from impermeable surfaces and footing drains as outlined above will not significantly affect the pre-development drainage conditions on the adjacent properties. Impermeable surface around the proposed building (e.g., paved drives) should.be minimized to reduce potential changes in the existing site drainage characteristics and impacts on adjacent sites. Erosion Hazard We note that the according to published USDA soil maps, surficial soils on the upper slope are classified as Tukey gravelly loam on 15 to 30 percent slopes; soils on the lower slope and bluffs are identified as Cassolary sandy loam on 15 to 30 percent slopes~ The USDA maps indicate that these soils have a moderate erosion hazard. To reduce the potential for soil erosion and associated hazards, the following wet weather earthwork recommendations are presented. Provided that these wet weather earthwork recommendations and prudent construction practices are used, it is anticipated that the future earthwork for the proposed development will not significantly affect soil erosion and associated hazards on the site. Wet Weather Earthwork In western Washington, wet weather generally begins about mid-October and continues through about May, although rainy periods may occur at any time of the year. Therefore, it would be advantageous to schedule earthwork during the normally dry weather months of June 21-1-09221-OOl'L1/wp/[kd 21-1-09921-001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 8 SHANNON &WILSON, INC. through mid-October. Earthwork performed during the wet winter months will generally prove more costly. The following recommendations are applicable if earthwork is to be accomplished in wet weather or in wet conditions: Fill material should consist of clean, granular soil, of which not more 'than 5 percent by dry weight passes the No. 200 mesh sieve, based on wet-sieving the minus SA-inch fraction. Any fines should be non-plastic. The ground surface in and surrounding the construction area should be sloped and sealed with a smooth-dram roller to promote runoff of precipitation away from work areas and to prevent ponding of water. Earthwork should be accomplished in small sections to reduce exposure to wet conditions. If there is to be vehicular traffic over the exposed subgrade during construction, the size or type of equipment may have to be limited to prevent soil disturbance or the subgrade may need to be protected (e.g., covered with at least 8 inches of compacted crushed rock). · No soil should be left exposed to moisture or uncompacted. A smooth dram vibratory roller, or equivalent, should be used to seal the surface. Soils that become too wet for compaction should be removed and replaced with clean crushed rock. ~, Excavation and placement of structural fill during wet weather should be observed on a full-time basis by a geotechnical engineer (or representative) experienced in wet weather earthwork, to determine that all unsuitable materials are removed and suitable compaction is achieved. Covering work areas, soil stockpiles, or slopes with plastic, sloping, ditching, installing sumps, dewatering, and other measures should be employed, as necessary, to permit proper completion of the work. Straw bales and/or geotextile silt fences should be aptly located to control soil movement and erosion. LIMITATIONS The conclusions in this letter are based on site conditions visually observed during our reconnaissances at and around the site and inferred from published geologic, soils, topographic, 21-1-09221-001-Lllwp/lkd 21 - 1-09921 ~001 Partners in Well Being Attn: Mr. Bruce Tapper June 24, 2003 Page 9 SHANNON ~WILSON, INC. and hazard maps and assume that observed conditions are representative of the subsurface conditions throughout the site; i.e., the subsurface conditions are not significantly different from those inferred from the site reconnaissances or indicated on geologic maps. If, during subsequent site activities (e.g., construction), subsurface conditions different from those inferred in this letter are observed or appear to be present, we should be advised at once so that we can review those conditions and reconsider our conclusions where necessary. Within the limitations of scope, schedule, and budget, the conclusions presented in this letter were prepared in accordance with generally accepted geologic engineering principles and practices in this area at the time this letter was prepared. We make no other warranty, either express or implied. This letter was prepared for the use of Mr. Bruce Tapper in the evaluation of the stability of this site. With respect to possible future construction, it should be made available for information on factual data only and not as a warranty of subsurface conditions, such as those interpreted from the site visits and discussion of geologic conditions included in this letter. Please note that the scope of our services did not include any environmental assessments or evaluation regarding the presence or absence of wetlands or hazardous or toxic material in the soil, surface water, groundwater, or air on, or'below, or around this site. We are able to provide these services and would be pleased to discuss these with you if the need arises. Shannon & Wilson has prepared the attached, "Important Information About Your Geotechnical Report," to assist you in understanding the use and limitations of our report. 21-1-09221-001-LI/wp/lkd 21-1-09921-001 Partners in Well Being Attn: Mr. Brace Tapper June 24, 2003 Page 10 SHANNON &WILSON, INC. We appreciate the opportunity to provide geologic services t° you, and are available to answer any questions regarding our observations, conclusions or recommendations contained in this letter. Sincerely, SHANNON & WILSON, INC. William J. Perkins, L.E.G. Senior Principal Engineering Geologist WJP:JW/wjp Enclosures: C: Figure 1 - Vicinity Map Important Information About Your Geotechnical Report Mr. Clint Sherman, Sherman Construction, IJ~C Ms. Stacie Hoskins, Jefferson County Department of Community Development 21 - 1-09221 o001 -L1/wp/lkd 21 - 1-09921-001 o * PROJECT LOCATION 0 1/2 1 Scale in Miles NOTE Map adapted from 1:24,000 USGS topographic map of Port Townsend South, WA quadrangle, dated 1953, photorevised lg81. 281 Lane DeChantal Port Townsend, Washington June 2003 VICINITY MAP 21-1-09921-001 SHANNON & WILSON, INC. Geotec~nical and Environmental Consultants FIG. -_-III SHANNON & WILSON, INC. Geotechnical and Environmental Consultants Attachment to and part of Report 21-1-09921-001 Date: June 24, 2003 To: Parmers in Well Being Attn: Mr. Bruce Tapper IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVlRONMENTAL REPORT CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC CLIENTS. Consultants prepare reports to meet the specific needs of specific individuals. Areport prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the consultant. THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. A geotechnical/environmental report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property, involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope-of-service limitations imposed by the client To help avoid costly prOblems, ask the consultant to evaluate how any factors that change subsequent to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: (1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or orientation of the proposed project is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after factors which were considered in the development of the report have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotechnical/environmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions commonly vary seasonally. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/environment~l report. The consultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those l~redicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help reduce their impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in this respect Page 1 of 2 1/2003 A REPORT'S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your consultant's report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction. THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnicaFenvironmental report. To help avoid these pkoblems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental findings, and to review the adequacy of their plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT. Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnieal/environmental reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/environmental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing coustmction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnical/environmental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses.for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identify where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland Page 2 of 2 1/2003