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HomeMy WebLinkAboutSWP272340(1) ' OAGRA AGRA Earth & CITY OF FENTON Environmental. Inc. Earth & Environmental RECEIVED 11335 NE 122nd Way ' Suite 100 OCT 2 8 1996 Kirkland, Washington U.S.A. 98034-6918 ' 18 October 1996 BUILDING DIVISION Tel (206) 820-4669 6-91 M-1 1 175-00 Fax (206) 821-3914 ' St. Matthews Lutheran Church c/o Baylis, Brand, Wagner Architects 10801 Main Street ' Bellevue, Washington 98004 ' Attention: Ms. Marcie Hanna Subject: Subsurface Exploration and Geotechnical Evaluation Proposed St. Matthews Lutheran Church Addition 1700 Edmonds Avenue Northeast Renton, Washington Dear Ms. Hanna: This letter report presents the results of our subsurface exploration and geotechnical engineering evaluation for the proposed addition to St. Matthews Lutheran Church. The purpose of this evaluation was to establish general subsurface conditions at the site from which ' recommendations for foundation design and site improvements could be formulated. The scope of our services consisted of a field exploration program, visual assessment of the site conditions, geotechnical engineering analyses and preparation of this report. Authorization for ' our initial phase of services was provided via a signed copy of our proposal number 91 P-10084-00, dated 18 July 1996. A scope and cost amendment was authorized in our Project Scope/Budget Change Confirmation dated 26 August 1996. This report has been prepared for the exclusive use of the St. Matthews Lutheran Church; Baylis, Brand, Wagner Architects, and their agents for specific application to this project in accordance with generally accepted geotechnical engineering practice. The site location is resented on the Location Ma (Figure 1 , and the existing church and planned P P ( 9 ) 9 ' additions, as well as the approximate locations of the borings completed for this study, are shown on the Site and Exploration Plan (Figure 2). Boring logs with interpretive descriptions of conditions encountered at the boring locations are also enclosed. SITE AND PROJECT DESCRIPTION The subject site is that of the existing St. Matthews Lutheran Church at 1700 Edmonds Avenue ' NE in Renton, Washington. Existing site improvements include a wood-framed single-story church building, paved parking areas and access drives, buried and overhead utilities and other ancillary structures. One of the parking areas on site is currently used as a Park and Ride lot. Engineering& Environmental Services St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 2 Regional topography slopes gently downward to the southwest. The site was graded to its ' current configuration at the time the existing church facility was constructed. Topography in the area of the proposed construction slopes gently downward to the west and south, with overall relief in the proposed construction area of approximately 5 feet. The area of the proposed addition was occupied by landscaping, walkways, and paved areas at the time of our subsurface investigation program. The proposed project would include construction of a new sanctuary, narthex, and fellowship hall attached to the existing church building. We understand that the new additions would be completed in two phases, with the planned sanctuary and narthex constructed first, and the planned fellowship hall completed at a later time. The conclusions and recommendations presented in this report are based on the currently proposed building footprint and anticipated floor grade. In the event of any changes in the building location or elevation, or other changes in the nature and design of the project, the conclusions and recommendations contained in this report should be reviewed by us and ' modified as necessary to reflect those changes. SUBSURFACE EXPLORATION The subsurface exploration program completed for this project consisted of advancing three borings on 9 August 1996 at the approximate locations shown on the Site and Exploration Plan, ' Figure 2. The borings were drilled by advancing a 4% inch I.D. (inside diameter) hollow-stem auger with a truck-mounted drilling rig. Sampling was performed by the Standard Penetration Test method. This involves driving a standard 2 inch O.D. (outside diameter) sampler 18 inches into the soil at the bottom of the auger, using a 140-pound hammer free-falling a distance of 30 inches. The number of blows required to drive the sampler each 6 inch interval is recorded. The number of blows required to drive the sampler the final 12 inches is the Standard Penetration Resistance ("N") or blow count. The penetration resistance, or N-value, provides a measure of the relative density of granular soils or the relative consistency of cohesive materials. The borings were advanced to depths of approximately 16 to 21 %2 feet below the existing ground surface. The borings were continuously observed and logged in the field by an experienced engineering geologist from our firm. The soils recovered were visually classified and representative portions placed in moisture-tight containers and returned to our laboratory for further visual evaluation. Boring locations, shown on the Site and Exploration Plan, Figure 2, were obtained by hand-taping from physical features shown on the site plan provided us. The locations shown should be considered accurate to the degree implied by the method used. The exploration logs enclosed with this report are based on interpretations made in the field. The logs indicate the various types of soils and materials encountered in the borings. The 103 AG RA Earth & Environmental St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 3 relative density of the soils indicated in the logs is based on the drilling action and advancement rate of the drilling tools, as well as the driving resistance measured during sampling ("N" values). The logs also indicate the depth where the strata or characteristics of the strata changed, although changes may be gradual. If the change occurred between sample intervals, the depth to the change was interpreted. Subsurface Conditions The subsurface soil conditions were found to be variable across the site. One should refer to the enclosed boring logs for specific subsurface conditions. All three borings encountered approximately 6 inches of topsoil at the surface. Borings B-1 and B-2 encountered surficial layers of loose silty fine sand beneath the topsoil to depths of approximately 6 and 4% feet, respectively. The surficial loose soil was underlain by medium dense to dense silty sand with a varying gravel content, the lowest soil horizon encountered in boring B-1. In Boring B-2, a second layer of loose sand was encountered between approximately 13 and 18'/2 feet in depth. Boring B-2 was terminated in dense sand at a depth of approximately 21 '/2 feet. We interpret ' the loose surficial soil conditions observed in borings B-1 and B-2 to represent soils disturbed during previous grading on site. Boring B-3 encountered dense to very dense silty sand with some gravel from beneath the existing topsoil horizon to the full depth explored of approximately 16% feet. The soils observed in boring B-3 appear to represent relatively undisturbed native deposits. Groundwater was not encountered in our explorations at the time of drilling. Perched groundwater frequently develops seasonally in the project area. Perched groundwater occurs 1 where the downward infiltration of surface water is impeded by relatively lower permeability soils at depths. Groundwater conditions can be expected to vary with precipitation, season, site utilization and other on and off-site factors. CONCLUSIONS AND RECOMMENDATIONS Development plans call for construction of a new sanctuary and narthex on the south side of the existing buildings at St. Matthews Lutheran Church. A new fellowship hall is to be constructed in the same vicinity during a later phase of the project. The new building would be of single level construction, and low to moderate foundation loads are anticipated. We anticipate that the new addition will be constructed with a finished floor elevation on the order of 360 feet. Due to loose soil conditions in the vicinity of our boring locations B-1 and B-2, it will be necessary to perform some amount of remedial foundation subgrade preparation. Contingent upon adequate floor subgrade preparation, we anticipate that no remedial subgrade preparation will be required to support concrete slab-on-grade floors. 103 AG R A Earth & Environmental St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 4 Our recommendations are predicated on the anticipated finished floor elevation of approximately 360 feet. Different finished floor elevations would require additional fill placement or soil excavation, and may necessitate different foundation preparation procedures. If the currently proposed building location or elevation is changed significantly, we should be allowed to review our recommendations and modify them as needed. Site Preparation Prior to site grading, any surface water or drainage entering the work area should be intercepted and routed to a suitable discharge, and siltation control should be installed to local standards. Once surface water is controlled, all buildings, asphalt pavement, concrete sidewalks and existing buried utilities should be removed within the footprint area of the proposed building, as well as within any areas where paving or "structural fill" is planned. Existing topsoil, vegetation, organic-rich soils, and other deleterious materials should also be removed from structural areas. Excavations to complete demolition activities which extend below finished grade in areas where structures, surfacing, or other settlement sensitive improvements are planned should be backfilled with "structural fill" as outlined subsequently. Utility work should be completed in accordance with applicable regulations. Upon completion of the demolition and stripping activities, we anticipate that the site configuration will include a slightly sloping area with grades both higher and lower than the planned building subgrade. The suitability of the exposed soils for foundation and floor support should be evaluated by a representative of AEE prior to construction or "structural fill" placement. If the soils exposed by stripping and excavation are non-yielding, undisturbed, and possess a minimum density of at least 90 percent of the modified Proctor Maximum Dry Density (as determined by the ASTM:D-1557 test procedure), no further site preparation would be required in those areas. Should the site soils not meet the minimum compaction standard, we recommend that the foundation or floor subgrade areas be prerolled and compacted with a roller or other suitable heavy equipment to a firm and non-yielding condition in order to achieve the minimum compaction level. Any soft, wet, or significantly organic areas disclosed by prerolling should also be excavated as necessary to reveal non-yielding, non-organic soils and backfilled with "structural fill" as described subsequently. At the location of borings B-1 and B-2, loose soils encountered in our explorations extended below anticipated foundation elevations. We recommend that in the areas of borings B-1 and B-2 foundation subgrades be prepared by overexcavating below the footprint of the planned foundations until competent bearing soils are encountered and verified by the geotechnical engineer. This overexcavation and replacement of loose soils should be completed wherever the loose soils are encountered. For planning purposes, we anticipate that bearing soils will be encountered below approximately elevation 356 feet at the locations of borings B-1 and B-2, and below approximately elevation 361 feet at the location of boring B-3. The overexcavations could then be backfilled using Controlled Density Fill (CDF) to restore the planned foundation subgrade elevation. L, AG RA Earth & Environmental r St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 5 1 CDF is a mixture of cement, fine aggregate, and sometimes lime or fly ash that is typically delivered to the site in a concrete truck. The CDF is placed with concrete chutes or pumps, and leveled at the desired elevation. When cured, the CDF is suitably firm to provide adequate foundation support, but still allows excavation with conventional powered excavating equipment. Although the unit cost of CDF is higher than the unit cost of conventional fill soils, the overall cost, including construction time and material quantities, for remedial foundation subgrade preparation with CDF is usually lower than if fill soils are used. If soils are used to ' fill below foundations, the area of overexcavation and backfill beneath the footing elements needs to extend laterally beyond the limits of the foundations, and must be placed in compacted lifts with hand operated or limited access equipment. In contrast, overexcavations rbelow foundations need not extend laterally beyond the foundation edges if CDF backfill is used, and no compactive effort is required to place the CDF backfill. We could provide specific recommendations for remedial subgrade preparation with compacted fill, if requested. Some of the near-surface site soils are silt and consequently highly moisture-sensitive. These Y q Y 9 Y silty soils are highly prone to disturbance during wet site conditions. To reduce site ' disturbance, the contractor should minimize traffic above prepared subgrade areas, and direct site surface water and groundwater away from the work areas. In very wet conditions, the use ' of a working surface of quarry spalls or sand and gravel may be required to protect the subgrade, especially from vehicular traffic. r Structural Fill All fill placed in the building or paving areas, for the backfill of utility trenches, and in any area where settlement sensitive structures are planned should be placed in accordance with recommendations herein for structural fill. Prior to placement of structural fill, all areas to receive fill should be prepared as previously recommended. Structural fill should be placed in lifts not exceeding 8 inches in loose thickness. Individual lifts should be compacted such that a density of at least 90 percent of the modified Proctor maximum density (ASTM:D-1557) is achieved. The upper 2 feet of any fill placed below pavement should be compacted to 95 percent of the same density standard. We recommend that a representative from our firm be r present during placement of structural fill to observe the work and perform a representative number of in-place density tests. In this way, the adequacy of earthwork may be evaluated as operations proceed. Soils used for structural fill should have a maximum particle size not exceeding 6 inches and be free of organic and other deleterious materials. The suitability of soils for use as structural fill depends primarily on the gradation and moisture content of the soil when it is placed. As the fines content (that portion passing the U.S. No. 200 Sieve) increases, soils become increasingly sensitive to small changes in moisture content and adequate compaction becomes more difficult or impossible to achieve. Silty soils containing more than about 5 percent fines by weight, such as the site soils, cannot be consistently compacted to a firm, non-yielding condition when the moisture content is more than about 2 percent from optimum. The use of LS A G R A Earth & Environmental St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 6 clean, granular soils with less than 5 percent fines may be necessary for fill used to complete wet weather site work. Topsoil and stripping waste generated during site preparation is not suitable for reuse in structural fill applications, but could be stockpiled for later use in landscape areas. Based on our explorations, the site soils that would be available for fill would be primarily silty sands with a varying gravel content. Silty soils would be difficult to use as structural fill, except during dry summer months when the water content may be carefully controlled by aeration and drying. Even during the summer, delays in grading may occur when using the siltier site soils due to precipitation. If inclement weather occurs, the upper wetted portion of the silty site soils may need to be scarified and allowed to dry prior to other earthwork. If it is not practical to dry wet silty soils, it may be necessary to remove the upper silty soils and replace them with clean, granular soils to accommodate site work in wet or adverse weather conditions. ' Shallow Foundations ' The proposed new additions may be supported by conventional spread footings founded on the existing, undisturbed medium dense to very dense native soils below elevation 156 at the locations of borings B-1 and B-2 and below elevation 361 at the location of B-3, or may be supported by CDF placed as described above in the Site Preparation section of this report. A minimum embedment depth of not less than 18 inches for exterior footings, and not less than 12 inches for interior footings should be maintained for frost protection. We recommend a minimum footing width of 18 inches for continuous footings and 24 inches for isolated footings. Based on these conditions, we recommend that the footings founded on the medium dense to dense native soils or upon adequately placed CDF be designed with the a maximum allowable soil bearing pressure of 2,000 pounds per square foot (psf) for up to 1 inch of allowable total settlement and '/2 inch of allowable differential settlement. Alternatively, an allowable bearing pressure of 3,000 psf could be used if remedial subgrade preparation is completed and total and differential settlement of up to 1 % inches is tolerable. Remedial subgrade preparation could be eliminated, and conventional shallow foundations constructed with an allowable bearing pressure of 2,000 psf if up to 2 inches of allowable total and differential settlement is acceptable. Any of the allowable bearing pressures given may be increased by up to one-third ' to accommodate transient seismic and wind loads. A base friction coefficient of 0.35 may be used for foundation concrete placed neatly against undisturbed native soils or CDF. If disturbed or soft materials are left within the footing area prior to concrete placement, future settlements may be greatly increased. For this reason, the condition of the footing subgrade should be closely monitored prior to concrete placement to confirm that the condition of the bearing soils are consistent with those assumed during design. AG RA Earth & Environmental St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 7 As some of the site soils are silty, site work in the presence of water or during wet weather 1 could disturb the bearing strata. The contractor should avoid disturbance of these soils and limit traffic across the building pad or foundation area during wet weather. To minimize disturbance associated with foundation form work and reinforcement bar placement, the use 1 of a lean concrete "mud mat" may be required. Slab-On-Grade The slab-on-grade subgrade should be prepared in accordance with the previous site preparation recommendations. To limit settlement and distress, we recommend a slab-on grade floor be founded on prerolled native ground or structural fill as recommended in previous sections of this report. Floor slabs constructed above undisturbed medium dense native soils or on properly compacted structural fill placed above undisturbed native soils should experience one half inch or less of total and differential settlement. We recommend that the floor slab be underlain by a minimum of 6-inch thickness of washed pea gravel or washed drain rock to serve as a capillary break. An impervious moisture barrier should also be placed directly beneath the slab. ' Drainage Considerations Final site grades should be planned to slope away from the new additions. We recommend that all permanent structures be provided with a permanent perimeter footing drain system to collect available water. The footing drain should consist of at least a 4-inch diameter perforated pipe within an envelope of pea gravel or washed rock. The drain pipe should lead away from the buildings via gravity to a storm sewer or other suitable discharge. Roof and surface runoff should not discharge into the footing drain system. Instead, a separate tight-line drain network should be installed or splash blocks may be used. Backfilled Walls The following recommendations are provided for relatively short retaining walls. We recommend that we be allowed to provide design-specific recommendations for backfilled walls which exceed 10 feet in height. Below grade walls constructed to allow some deflection (0.001 times the wall height) during backfill placement should be designed to resist an active pressure equivalent to that developed by a fluid with a density of 35 pounds per cubic foot for a level ground surface. Walls that are ' restrained structurally from lateral movement should be designed to resist an at-rest pressure equivalent to that developed by a fluid with a density of 55 pounds per cubic foot. These lateral pressures should be increased to 65 and 100 pounds per cubic foot, respectively, for walls placed in front of slopes inclined up to 2H:1 V. A wall base friction coefficient of 0.35 may be used for foundation concrete placed neatly against undisturbed native soils or properly constructed CDF or structural fill, as described above. Footing drains, constructed the same as described previously, should be constructed at the base of any backfilled walls. A minimum width of 2 feet of free draining, clean, granular my AG RA Earth & Environmental St. Matthews Lutheran Church 6-91 M-11 175-00 18 October 1996 Page 8 backfill which can communicate freely with the footing drain should extend from the base of ' the wall to the ground surface. The wall backfill should consist of clean, free draining granular materials with less than 5 percent fines by weight passing the U.S. No. 200 Sieve based on the portion passing the U.S. No. 4 Sieve. At least 30 percent by weight should be larger than the ' U.S. No. 4 Sieve. This drainage layer is intended to preclude the buildup of hydrostatic pressures. All backfill placed behind backfilled walls should be placed as per the structural fill recommendations of this report. The previously recommended earth pressures represent equivalent fluid pressures based on the assumption of uniform level and sloped backfill, as ' noted, and no buildup of hydrostatic pressures behind the wall. Surcharges due to sloping ground, adjacent footings, vehicles, construction equipment, etc., must be added to these values. The equivalent fluid pressures presented above assume that the backfill is compacted to 90 percent of the modified Proctor maximum dry density (ASTM:D-1557). Additional compaction immediately adjacent to the wall will increase lateral pressure, while a lesser degree ' of compaction may permit post-construction settlements. Only small, hand-operated compaction equipment should be used within 3 feet of the wall. 1 Site Disturbance Some of the site soils are silty and highly susceptible to disturbance when wet. Prior to construction, any site surface water should be routed away from the construction and the building areas as much as possible. The contractor should be made aware of the fact that the silty site soils are highly susceptible to disturbance when they are only slightly wetter than optimum. Therefore the contractor would need to perform final stripping with care in order to minimize site disturbance. In addition, vehicle traffic over wet subgrades or prepared areas should be minimized. Application of these measures will reduce the likelihood of additional overexcavation of disturbed soils and associated costs for export and import will be reduced. If grading must be initiated when the silty site soils are more than about 2 percent above optimum, those areas to receive fill should be blanketed with a clean, coarse gravel, crushed rock, quarry spalls or equivalent non-moisture sensitive material. This would provide a working surface for the subsequent structural fill placement. CLOSURE ' The conclusions and recommendations presented in this letter report are based on the explorations accomplished for this study. The number, locations and depths of the explorations were completed within the site and scope constraints so as to yield the information to formulate our recommendations. The integrity of the foundations depends on proper site preparation and construction procedures. We would be available to provide geotechnical engineering services during earthwork and foundation construction phases of the project, if requested. If variations in the subsurface conditions observed at that time, we would be available to provide additional geotechnical recommendations to minimize delays as the project 1 develops. ' =YAGRA Earth & Environmental St. Matthews Lutheran Church 6-91 M-1 1 175-00 18 October 1996 Page 9 It has been a pleasure to provide you with this information. If you have any questions, or require further information, please do not hesitate to call us at your convenience. Respectfully submitted, AGRA Earth & Environmental, Inc. ruce Guenzler Project Geologist r Todd D. Wentworth, P.E. ' r•4 Senior Project Engineer ��`= � , ' David C. 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LOCATION ' EXISTING PARKING (TYP.) - \ PROPOSED ADDITION F.F. ELEV. 356.0' SANCTUARY B-2 B 3 I ERTY B PROP OUNDARY N.E. 161h STREET 0 50 100 SCALE IN FEET m W.O. 6-91M-11175-o E ST. MATHEWS LUTHERAN CHURCH PROPOSED ADDITION * AG R A DESIGN BWG RENTON, WASHINGTON Earth & Environmental DRAWN DMW SITE 8 EXPLORATION PLAN 11335 NE 122nd Way, Suite 100 DATE AUG 1996_ w Kirkland,Washington, U.S.A.98034-6918SCALE 1"=50' FIGURE 2 DRAWING BASED ON PLAN BY BAYLIS BRAND WAGNER, ARCHITECTS, DATED 3/27/96. PROJECT: St, Mathews Lutheran Church w.o. 6-97M- 7 7 775-0 BORING NO. B- 7 I SOIL DESCRIPTION G c o z PENETRATION RESISTANCE Page 1 `w _u Location: Lawn area by sanctuary - p r A of I o < . < z v 3 Standard Blows per foot Other Approximate ground surface elevation: 362 feet ;, 0 20 So ao 5o TESTING ' 0 Grass and topsoil N/E Loose to very loose,moist,orange-brown,silty, fine SAND with some gravel and trace organic bits(Fill?) - - - S-1 S-2 Grades to loose to medium dense,damp, mottled gray,silty,fine to medium SAND with some gravel - --- -- 10 Grades to dense,moist,gray,silty,gravelly,fine _ to coarse SAND - S-3 1 Grades to very dense, with some grovel 15 — — -- - - - - - --- S-4 50/5' Boring terminated at approximately 16 feet - --- - - 20 -- ------ - - - - - -- - - - -. ..- 25 — — --- --- - 1 -- 30 G 20 40 60 ac too LEGEND MOISTURE CONTENT E Plastic limit Natural Liquid limit E 2.00-inch OD split-spoon sample cc AG RA a' v/E No groundwater encountered Earth & Environmental S 11335 NE 122nd Way,Suite 100 Kirkland,Washington 98034-6918 0 a ' Drilling method: HSA Hammer type: Automatic Date drilled: 09 August 7 996 Logged by: B WG PROJECT: St. Mathews Lutheran Church w.o. 6-97M- 11 775-0 BORING NO. 8-2 ' SOIL DESCRIPTION a � o x PENETRATION RESISTANCE Page I Location: Lawn area by parking lot 2 p < of 1 < f z v 3 Standard Blows per foot Other Approximate ground surface elevation: 359 feet 0 20 so no so TESTING 1 0 Grass and topsoil N/E --- -- --- -- - - Loose,dry,light brown,silty,fine SAND with some fine gravel - -- ' 5 Medium dense,damp,mottled gray,silty, gravelly, fine to coarse SAND . S-2 -- ---------- ----------- -- ------ - - - --------- - -- ---------- --------------- Grades with some silt 10 ----- - - — S-3 1 Loose,wet,mottled gray,medium SAND with trace to some silt and trace fine gravel 15 - - — --- -- - ---- S-4 Grades to dense 20 - - ----- S-5 --------- -- -- ------------ -- -------------- -- - - Boring terminated at approximately 21.5 feet ------ ------ - ---- --- - ---- --I ----- ----- -- ---- . ...._... 25 - -- 30 0 20 40 60 a0 100 LEGEND MOISTURE CONTENT C - Plastic limit Natural Liquid limit 0 2.00-inch OD split-spoon sample iw AG RA 1 N,E No groundwater encountered Earth & Environmental W 11335 NE 122nd Way,Suite 100 ry Kirkland,Washington 98034-6918 a Drilling method: HSA Hammer type: Automatic Date drilled: 09 August 1996 Logged by: BWG r PROJECT: St, Mathews Lutheran Church w.o. 6-9 7M- 7 1175-0 BORING NO. B-3 T SOIL DESCRIPTION � m a W PENETRATION RESISTANCE Page 1 . Location: East parking lot } o ¢ A of 1 o �- Q x 3 Standard Blows per foot Other Approximate ground surface elevation: 363 feet yr Z v 0 20 so no so TESTING r 0 BeouA Bark and topsoil _ N/E Dense,damp,gray,silty,fine to coarse SAND with some gravel S-1 r5 Grades to gravelly - S-2 -- -------- - - - -- r - - - ----- ------ r 10 Grades to very dense __ — - S-3 5t7/5" 15 _ S-4 r - ------- - --- Boring terminated at approximately 165 feet - - - ------ - - 20 - r - 25 —' — -- - ------- 30 0 20 40 60 so 100 LEGEND MOISTURE CONTENT _ Plastic limit Natural Liquid limit C 2.00-inch OD split-spoon sample w AG R A ' t N/E No groundwater encountered Earth & Environmental w 11335 NE 122nd Way,Suite 100 Kirkland,Washington 98034-6918 rDrilling method: HSA Hammer type: Automatic Date drilled: 09August 7996 Logged by: BWG i