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HomeMy WebLinkAboutSWP272160(2) 1 1 2 1 i 1 1 1 1 1 1 1 1 1 1 1 1 NELSON-COUVRETTE & ASSOCIATES, INC. 1 CONSULTING GEOTECHNICAL ENGINEERS, GEOLOGISTS AND ENVIRONMENTAL SCIENTISTS ' GEOTECHNICAL EVALUATION REPORT FOR TWO DETENTION PONDS RENTON, WASHINGTON FOR ' LAI{ERIDGE DEVELOPMENT NELSON-COUVRETTE & ASSOCIATES, INC. CONSULTING GEOTECHNICAL ENGINEERS, GEOLOGISTS \`��..... AND ENVIRONMENTAL SCIENTISTS ' 17311-135th Ave.NE,A-500 Snohomish County(206)794-4332 Woodinville,WA 98072 (206)486-1669•FAX 481-2510 Wenatchee/Chelan(509)784-2756 ' August 4, 1994 Mr. Wayne Jones ' Lakeridge Development P.O. Box 146 Renton,Washington 98057 ' Geotechnical Evaluation Report for Two Detention Ponds Honey Creek Ridge Renton,Washington NCA File No. 10921394 Dear Wayne: INTRODUCTION ' This report presents the results of our gcotechnical investigation for the two detention ponds of your Honey Creek Ridge development. The site is located south and west of the intersection of S.E. 100th Street and ' 124th Avenue S.E., in the City of Renton, as shown on the Site Vicinity Map in Figure 1. You have retained us to perform a subsurface investigation to locate a less permeable soil that could be used as a pond liner and to provide additional comments on pond construction and stabilization of an erosion feature located south of the project site. We, as David L. Nelson and Associates, Inc., have previously prepared Geotechnical Evaluation Reports, dated July 7, 1989, May 17, 1991 and January 11, 1993. We have recently been provided plans for the Basin A and B detention ponds showing the topography and planned locations, prepared by City of Renton, dated February 20 &25, 1994, for our use in preparing this report. PROJECT DESCRIPTION ' Basin A Basin A detention pond is located in the northwest corner of the site. The pond facility will consist of a water quality swale, detention pond and bioswale. The bottom of the water quality swale will be at an elevation of 313.27 feet, with a maximum water level of 315.4 feet. The bottom of the pond will be at an elevation of 308.77 feet, with a maximum water level of 314.87 feet. A gabion wall will be used to divide ' the pond into two cells. A gabion wall will also be constructed on the dowi-d-ull side of the biofiltration Swale in order to prevent overtopping of water onto the slope below. The bioswale will have side slopes of ' Geoteclvlical Evaluation Report for Two Detention Ponds Honey Creek Ridge ' NCA File No. 1092B94 August 4, 1994 Page 2 ' 3 Horizontal to 1 Vertical (H:V). A rockery 4 to 5 feet high is planned on the north and east sides of the ' detention facility. The rockery will be used to face cuts in this area. You have indicated that a gabion wall may be substituted for the rockery in this area. Basin B Basin B detention pond is located in the west central portion of the site. The pond facility will consist of a ' detention pond with three cells and a biofiltration swale. The bottom of the pond will be at an elevation of 328.75 feet, with a maximum water elevation of 342.09 and a top of berm of 350. The pond is to be located in an existing swale type feature.. A berm will be built across the swale forming the pond. The ' downstream face of the berm will have a total height of about 40 feet. Gabion walls are planned between the cells of the pond. The elevation of the top of the gabion walls will be 340.0 feet. The bioswale will be ' located downslope of the berm in the center of the natural swale. The bioswale starts on one side of the natural Swale, nuns roughly parallel to the contours, drops in elevation then turns in the upstream direction, ' then crosses the centerline and turns again toward the doN nstrcam direction. In order to make the required grades, rockeries or gabion walls will be required for most of the length of the swale. It appears that the ' maximum exposed height of the rockery or gabion will be about 4 feet with a 3:1 (H:V) slope away from the base of the rockery, according to the cross-section shown on the plans. The plan view of the bioswale suggests that the exposed heights will be on the order of 3 feet or less. The bioswale will have side slopes ' of 3 Horizontal to 1 Vertical (H:V). ' Erosion Features A large erosion feature is located at the south end of the project, south of SE 104th Court, between lots 25 ' and 26. We understand that it was formed by concentrated storm runoff from adjacent development and that it lies entirely in the City of Renton property. The city has asked for a review with respect to its encroachment onto the planned SE 104th Court. You have indicated that you would like to place broken ' concrete on the lower portion of the feature and then wood waste to fill the bulk of it. The surface would be capped with additional concrete pieces and topsoil to match adjacent grade. Your plan is to fill another erosion feature located to the west in a similar manner. This feature was formed in a telephone cable easement. It appears to have been created by soil eroding from around the telephone cable. ' SCOPE The purpose of this study is to explore and characterize the subsurface conditions in the pond and around ' the site, and present recommendations for construction of the detention ponds, rockeries and restoration of the two erosion features. The exploration program was designed to supplement the original data and to NELSON-COUVRETTE & ASSOCIATES, INC. Geoteclmical Evaluation Report for Two Detention Ponds Honey Creek Ridge ' NCA File No. 1092B94 August 4, 1994 Page 3 ' n h i which could be used as and liner material. Specifically, evaluate if a less permeable soil exists o the site p p y, our scope of services include the following: 1. Explore the subsurface conditions at the site with test pits excavated with a backhoe. ' 2. Perform laboratory analysis of the soil to identify typical permeability rates. 3. Provide recommendations for the detention ponds; such as pond liner and construction. ' 4. Provide our opinions regarding restoration of the large and small erosion features. ' 5. Provide recommendations for rockery construction. 6. Prepare a written report to document our findings and recommendations. ' SITE CONDITIONS Surface ' General: The site consists of 50 acres and is located west of 124th Avenue SE and between the alignments of SE 104th Street and SE 98th Street. The topography consists of an upland area with moderate to steep ' slopes along the west side of the site. The development will be confined mostly to the upland portion with the detention pond facilities located adjacent to the steep slope (Pond A) or at the base of the slope (Pond B) Pond A: Pond A is located in the northwest corner of the site. The ground surface in the area slopes ' gently to moderately down to the west and northwest in this area. Below the area of the proposed pond,the ground surface slopes steeply done to a road located below. The area is vegetated with brush with large ' trees located on the slope. Pond B: Bond B is located in the west central portion of the site. The area is in a natural occurring bowl ' shaped drainage feature. The feature was formed some time ago, in a geologic sense, as evidence of significant flow (active stream channel) at the pond location was not observed. The ground surface slopes ' up steeply to the upper portion of the site to the east, north and south of this area. The vegetation consists of mixed trees and underbrush. Downstream of the pond area, a defined drainage chamlel exists. This is ' where the bioswale will be constructed and the pipe that exits the storm system will be routed. This channel continues down gradient and empties into Honey Creek. The lower reaches of this channel has incised and shows signs of fairly recent downcutting. NELSON-COUVRETTE & ASSOCIATES, INC. Geotecluiical Evaluation Report for Two Detention Ponds Honey Creek Ridge t NCA File No. 10921394 August 4, 1994 Page 4 Geology ' Most of the Puget Sound region was affected by past intrusion of continental glaciation. The last period of glaciation, the Vashon Stade, ended approximately 10,000 years ago. Many of the geographic features seen today are a result of scouring and overriding by glacial ice. During the Vashon Stade, the Puget ' Sound region was overridden by over 3,000 feet of ice. Soil layers overridden by the ice sheet were compacted to a much greater extent than those that were not. A typical sequence includes glacial till (Qvt) ' mantling advance outwash sand (Qva). Glacial till is an unsorted mixture of sand, silt and gravel that is deposited at the bottom of the glacier. The advance outwash sand is a water-sorted fine to coarse sand with varying gravel content. It may contain finer-grained layers. Both the advance outwash and the till have been overridden by the continental glaciers. The glacial till exhibits both high strength and low ' permeability. The advance sand, where confined, also has fairly high strengths and is moderately to highly permeable. Our explorations encountered glacial till mantling advance outwash sands. ' Subsurface We explored subsurface conditions in specific areas of the site by excavating 12 test pits using a rubber- tired tractor-mounted backhoe. The main reason for the explorations was to identify location and quantities of less permeable soils that could be used in the pond construction. The test pits were located in the field ' by our geologists who maintained logs of the conditions encountered. The location of the test pits excavated are shown on the Site Plan in Figure 2. The specific test pit locations are in the areas of planned cuts and the ponds. The soils were classified in general accordance to the Unified Soil Classification system, a copy of which is presented in Figure 3. The test pit logs are presented in Figures 4 through 7. ' Soil samples were obtained to conduct laboratory permeability tests and grain size analysis. The gradation curve is presented as Figure 8. In general, the site was found to be primarily underlain by dense glacial deposits; glacial till within the upland portion, and glacial outwash within the lower elevation areas. The till, which is a conmionly less ' permeable soil, consists of a gray to brown, dense, silty fine to medium sand with coarse sand and gravel. Large quantities of the till did not exist where cuts are planned. The till is underlain by advance outwash. The outwash consists of gray, medium dense to dense, fine to medium sand with trace amounts of silt. The advance outwash sands were found in the vicinity of the two detention ponds and in the road cut areas in the northwest portion of the site (122nd Avenue NE and SE 97th Court). The area of the deepest roadcut, ' at Test Pits 1, 3, 4, and 5, was found mostly to be underlain by outwash. Till was only found in this area in the upper test pits located in this area, Test Pits 4 and 5. Till was found to the depths explored in the test NELSON-COUVRETTE & ASSOCIATES, INC. ' Geotechnical Evaluation Report for Two Detention Ponds Honey Creek Ridge NCA File No. 10921394 August 4, 1994 Page 5 i pits located in the upper central portion of the site, Test Pits 8, 9, 10, 11, and 12. The data from Test Pits ' 4 and 5 suggest a till/outwash contact at approximately at elevation 360 to 370 feet. For the purposes of detennining material quantities of till, we would not extrapolate this elevation over the entire site. Laboratory Testing Soil samples from the bottom of Detention Pond B and from road cut areas were returned to our laboratory ' for permeability testing. Since insufficient quantities of till were found, permeability tests were only run on the material at the base of Detention Pond B. A constant head permeability test was nm on the advance ' outwash sand in general accordance with ASTM D 2434. Constant head tests were run on samples compacted to a dry density of 113.8 pounds per cubic foot (PCF) and 112.2 PCP (Modified and Standard Proctors respectively). Permeability values (k) of 1.3 X 10 -3 and 2.7 X 10 -3 centimeters per second ' (cm/sec) were calculated for the modified and standard proctor samples respectively. A grain size analysis was performed on the same sample and is presented as Figure 8. ' CONCLUSIONS AND RECOMMENDATIONS ' General Our explorations encountered advance outwash sands in.the area of the planned detention ponds. The advance outwash sand in the pond area is uniformed grained, moderately to highly permeable and would be ' susceptible to piping if an unlined detention pond were constructed on it. Piping occurs when the water flow through the soil mass has a high enough velocity that it carries soil particles away from the point ' where the seepage exits the ground surface. As soils is carried away from the exit location, it starts to form a "pipe" under the embankment which could lead to ultimate failure of the embankment. It is our opinion ' that the detention ponds should be lined to prevent excessive seepage and possibly this type of failure. We have discussed various options for lining of the two detention ponds. Our subsurface investigation has ' indicated that not enough low permeability soil (glacial till, etc.) exists on the site. Rather than importing additional soil liner material you have chosen to line both ponds and the bioswales with a synthetic liner. The previous report presents specific recommendations for design and construction of the pond. The pond should be constructed by stripping off of the existing fill down to native bearing soils in the area of the planned berms. The berms should then be constructed with a suitable material by compacting to the appropriate density. The till or outwash could be used as suitable material provided the appropriate moisture can be obtained. The pond slope angles and construction method should be performed as outline ' in the Detention Pond sub-section of this report. NELSON-COUVRETTE & ASSOCIATES, INC. ' Geotechnical Evaluation Report for Two Detention Ponds Honey Creek Ridge NCA File No. 10921394 August 4, 1994 Page 6 The spillway for Pond B will be approximately 40 feet long and located on a 2:1 (H:V) slope. Control of erosion and seepage into the embanlumcnt will be critical. We have discussed various options for the spillway design. The option chosen would be to construct the dowi-lbill face of the embankment such that there is a minimum of 3 feet of low permeable soils below the spillway. We recommend that these soils have a maximum permeability of 1xl0-5 cnVsec. The glacial till found in the upland portions of the site should be suitable for this use. The spillway itself should be lined with geoweb filled with soil and seeded. ' It is our opinion that this type of erosion protection would be better suited for the spillway than rock spalls. ' Detention Ponds General: The ponds are both located in areas underlain by sand and should be lined to prevent excess seepage. The soil placed in the berms should be compacted as outlined in our May 17, 1991 report. Recommendations for liner placement are included in this report. We also recommend that liner manufacturers recommendations be followed. Where there is a discrepancy, we should be contacted to ' review the discrepancy and provide recommendations as appropriate. Wet Pond and Berm Design: We recommend that a 20 mil liner be used for this project. Since the ' environment is not considered chemically hostile, it is our opinion that any liner made to be placed in soil and not degrade could be used. Typically, a 20 mil un-reinforced PVC material is appropriate. The liner should have a minimum of 1 foot of cover. Additional cover may be desired for sustaining plant life. This should be determined by a landscape type designer. The liner should have a maximum slope angle of 3:1 (H:V). Steeper slopes would most likely require a geotextile to be placed over the liner to increase soil friction. The liner should be anchored at the top of the berm by placing it into a trench. The trench should ' have a minimum depth and width of 18 inches and 12 inches respectively. The liner should be placed on the slope, and be continued to line the trench. The trench should then be filled and the fill compacted to meet the berm compaction specifications. Piping will be placed in the pond that will cross through the ' liner. Where ever this occurs, the liner should be scaled to the pipe using appropriate methods as reconunendcd by the manufacturer. ' The liner should prevent water from the pond seeping into the subsoils and impacting downslope ' conditions. Even with small leaks in the liner, enough water to cause significant impacts arc not expected. Natural occurring ground water was not observed in the area of the pond. Therefore, it is our opinion that the lined pond should not have downstream stability problems. NELSON-CO UVRETTE & ASSOCIATES, INC. ' Gcoteclmical Evaluation Report for Two Detention Ponds Honey Creek Ridge NCA File No. 10921394 August 4, 1994 Page 7 Filling of Erosion Feature A description and restoration of the large erosion feature has been described in our geotechnical engineering report dated January 11, 1993 (DLN Job No. 0193). It is our opinion that the use of crushed concrete placed in the bottom and on the sides of the washout followed by tree stumps and capped with additional ' crushed concrete, would be a suitable solution with the following addition. The intent of the fill would be to protect the existing up hill face from further erosion and provide some lateral confinement. The fill placed as described should be expected to settle with time. We reconunend that the upper portion of the feature have additional material placed above the existing ground surface in order to offset the fixture ' settlement at this location. This would take the form of a 2 to 3 foot high mound. The materials described as fill planned for this area will have significant voids. We reconunend that the walls of the upper portion of the feature be lined with a suitable filter fabric in order to help prevent soil from washing or migrating into the new fill. The fabric should extend a minimum distance of 30 feet onto the bottom of the feature. We recommend that the final slope be graded to a 1.5 H to 1V inclination or flatter. This method may also ' be used to repair the telephone easement erosion feature. However, we recommend that the cable be rebedded and compacted fill placed around it to protect it from abrasion by the cement pieces. It may be prudent to have slack in the cable to allow for some differential settlement of the fill without stretching the cable. We recommend that the owners of the cable be contacted and the plamied discussed. Settlement of ' the fill around their cable may not be an acceptable solution. Rockeries ' Rockeries are plarined for facing the road cuts on 122nd Avenue SE, SE 97th Court and on the north and cast sides of Detention Pond A. You have indicted that rockery heights will range from 4 to 8 feet in the roadway cuts and 4 to 6 feet around the detention pond. Most of the planned rockeries will face advance outwash with a 2:1 (H:V) backslope. For rockeries supporting this slope inclination, we reconunend that the base rock extend into the face of the cut a minimum distance of one-half the wall height. This means that for an 8 foot high wall, the base rock should extend 4 feet into the cut. An alternative to using the ' larger rocks would be to reinforce the fill behind the rockery with a suitable fabric or geogrid. We can provide recommendations and designs for reinforced fills if desired. To prevent migration of the native soils through the rockeries or gabions, we recommend that a filter of 2 inch minus crushed rock be ' substituted for rock spalls as back fill behind the wall. We reconunend that rockeries be constructed in accordance with Associated Rockeries Contractors (ARC)guidelines. NELSON-COUVRETTE & ASSOCIATES, INC. ' Gcoteclulical Evaluation Report for Two Detention Ponds Honey Creek Ridge NCA File No. 1092B94 August 4, 1994 Page 8 Gabions As an alternative to rockeries you are considering using gabions around the detention pond and bioswales. Gabions are wire baskets filled with rock spalls. We reconunend that a filter consisting of 2 inch minus ' crushed rock be used behind the gabion walls to prevent the migration of the fine sands through the wall. As an alternative an appropriate geotextile fabric may be used as a filter. We recommend that the gabion walls be designed as gravity strictures using standard stability calculations. For gabions supporting a 2:1 (H:V) backslope, we recorrunend that the wall be designed to resist an active equivalent fluid pressure of 50 pounds per cubic foot. For gabions supporting a level backslope an active equivalent fluid pressure of 35 pounds per cubic foot may be used for design. A base friction of 0.5 may be used for design. The actual design of gabion walls,rockery walls or reinforced soil walls is beyond the scope of this report. We are available to provide a design at your request. 1 USE OF THIS REPORT AND WARRANTY We have prepared this report for Mr. Wayne Jones of Lakeridge Development, and his agents use in plamning and design of this project. The data and report should be provided to prospective contractors for their bidding and estimating purposes, but our report conclusions and interpretations should not be construed as a warranty of subgrade conditions. 1 The scope of our work does not include services related to construction safety precautions, and our ' reconunendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. There are possible variations in subsurface conditions. We recommend that project planning include contingencies in budget and schedule, should areas be found with conditions that vary from those described in this report. Within the limitations of scope, schedule and budget for our services, we have strived to take care to complete our services in 1 accordance with generally accepted practices followed in this area at the time this report was prepared. No other conditions, expressed or implied, should be understood. i 1 1 1 NELSON-CO UVRETTE & ASSOCIATES, INC. Geotechnical Evaluation Report for Two Detention Ponds Honey Creek Ridge NCA File No. 10921394 August 4, 1994 Page 9 We appreciate the opportunity to be of service to you. If there are any questions concerning this report or Pp pp if we can provide additional services, please call. Sincerely, ' NELSON-COUVRETTE & ASSOCIATES, INTC. 1I �// Bill Benzer ' Project Manager S P. CO& ' d , 2as p ww� 4Ig4 ' Charles P. 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DATE U N E 1994 1092B94 SITE PLAN T _ -� Tr-11 ^� .'T TP-12 5 51 J7 33 ?9 ?8 I 56 �� 1 30 32 I r 38� j/ i� ?7 I \+co 57 79 r5B ^.3 4 41 26 0 I ,50 42 1 / 49 TP-9 4J J TP-1 TEST PIT NUMBER AND 60 47 46 45 17 2/ ✓' T .B 16 /� - ' APPROXIMATE LOCATION 61 TP-g 22 / I 15.:0 23 - 24 25 4 'Fo o U 2 6 J .O $.�. 1 7 +., 3J0 1 „o '00 .w 25 24 2J IW 3,0 0 26 B ,+° 2a0 - 10 2,0 ? 30 � Tr-6 \ 29 10 rA 2 � 9° ?7 28 - ,. J2 ?0 I J4 i I 17 TP-1 TP-3TP-4TP-5 t 1130 °a U �0 1 c 14 7 76 B z 1 , Oi \i9'0110 CEO I 9 I 12 W 7 \ 40 50 Tr-2 .� po may, 0 50 100 scale: 1" =50' FIGURE - NELSON-COUVRETTE&ASSOCIATES,INC. HONEY CREEK RIDGE 2 CONSULTING GEOTECHNICAL ENGINEERS,GEOLOGISTS AND ENVIRONMENTAL SCIENTISTS FILE NO. DATE 10921394 JUNE 1994 SOIL CLASSIFICATION SYSTEM GROUP GROUP NAME MAJOR DIVISIONS SYME30L WELL-GRADED GRAVEL, FINE TO GRAVEL CLEAN GRAVEL aw COARBE GRAVEL COARSE ' GRAINED Gp POOFILY-GRADCD GRAVEL SOILS MORE THAN 150% GRAVEL GM SILTY GRAVEL OF COAROC FRACTION WITH FINES ' RETAINED CLAYEY GRAVEL ON NO. 4 OICVE aC MO`tC THAN 60X R�TAINCD ON CLEAN SAND 3W WCLL-GRADED BAND, FINE TO Nc. 200 BIEVE SAND COARBE BAND ' 313 POORLY-GRADED BAND MORE THAN 00'% SAND 3M BILTY BAND OF COARBC FRACTION WITH FINES PABBEO NO, 4 BIEVE SC CLAYEY BAND ' SILT AND CLAY ML SILT FINE INORGANIC DRAINED CL CLAY SOILS LFOUID LIMIT LEBO THAN 50 ORGANIC OL ORGANIC SILT, OR CLAY SILT AND CLAY MH GILT OF HIGH PLAOTICITY, CLAOTIC SILT ' MO AC THAN 50% INORGANIC PA116E0 NO, 200 CH CLAY OF HIGH PLAOTICITY, FAT CLAY BICvE LIQUID LIMIT 60 OR MORE ORGANIC OH ORGANIC CLAY, ORGANIC GILT ' PT FEAT HIGHLY ORGANIC SOILS 1 , r NOTES: SOIL MOISTURE MODIFIERS: ' 1. Field classification le based on Dry - Absence of moisture, dusty, dry visual examination of soil In general to the touch accordance with A3TM D2400-03. Molt - Damp, but no visible water 2. Sell clasalflcallon using laboratory loata Is based on ASTM D2407-03. Wot - Visible free water .or saturated, usually aoil Is obtained from ' 3. Doacrlptiona of soll density or below water table conalstoncy are based on Interpretation of bfowcount data, ' visual appearance of soils, and/or lost data. NELSON-COUVRETTE & ASSOCIATES,INC. SOIL CLASSIFICATION SYSTEM CONSULTING GEOTECHNICAL ENGINEERS,GEOLOGISTS AND ENVIRONMENTAL SCIENTISTS FIGURE 3 LOG OF EXPLORATION ' DEPTH USC SOIL DESCRIPTION TEST PIT ONE 0.0-0.5 DARK BROWN TOP SOIL ' 0.5-3.0 SP-SM MEDIUM REDDISH BROWN FINE TO MEDIUM SAND WITH SILT AND OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST)ROOTS TO 1.0 FEET 3.0-6.0 SP MEDIUM GRAY FINE TO MEDIUM SAND WITH TRACE SILT (MEDIUM DENSE TO DENSE,MOIST)(OUTWASH) A SAMPLE WAS COLLECTED AT 2.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED ' TEST PIT WAS COMPLETED AT 6.0 FEET ON 4113194 TEST PIT TWO 0.0-0.5 DARK BROWN TOP SOIL ' 0.5-1.5 SP-SM MEDIUM REDDISH BROWN FINE TO MEDIUM SAND WITH SILT(MEDIUM DENSE, MOIST)ROOTS TO 1.0 FEET 1 1.5-4.0 SP MEDIUM GRAY FINE TO MEDIUM SAND WITH TRACE SILT (MEDIUM DENSE TO DENSE,MOIST)(OUTWASH) GROUND WATER SEEPAGE WAS NOT ENCOUNTERED ' SLIGHT TEST PIT CAVING WAS ENCOUNTERED BETWEEN 0.0-1.5 FEET TEST PIT WAS COMPLETED AT 4.0 FEET ON 4113/94 TEST PIT THREE 0.0-0.5 DARK BROWN TOPSOIL WITH LEAVES AND ORGANIC MATERIAL 0.5-1.5 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST) 1.5-5.0 SP MEDIUM GRAY FINE SAND WITH TRACE SILT AND OCCASIONAL SANDSTONE GRAVEL AND COBBLES(MEDIUM DENSE TO DENSE,MOIST)(OUTWASH) ROOTS TO 2.5 FEET A SAMPLE WAS COLLECTED AT 3.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 5.0 FEET ON 4/13/94 TEST PIT FOUR 0.0-0.5 DARK BROWN TOP SOIL WITH ROOTS AND LEAVES ' 0.5-2.0 SM MEDIUM TO DARK REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL AND ROOTS(MEDIUM DENSE,MOIST) ' 2.0-4.0 SM MEDIUM GRAY AND BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL AND OCCASIONAL ROOTS (DENSE, MOIST) (WEATHERED TILL) 4.0-12.0 SM MEDIUM GRAY SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL ' AND OCCASIONAL COBBLES(DENSE,MOIST)(TILL) 12.0-12.5 SP-SM MEDIUM GRAY FINE TO MEDIUM SAND WITH SILT AND OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE TO DENSE,MOIST)(OUTWASH) ' SAMPLES WERE COLLECTED AT 7.0 AND 12.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED ' TEST PIT WAS COMPLETED AT 12.5 FEET ON 4113/94 NELSON-COUVRETTE& ASSOCIATES, INC. FILE NO.10921393 ' FIGURE 4 ' LOG OF EXPLORATION ' DEPTH USC SOIL DESCRIPTION TEST PIT FIVE 0.0-0.5 DARK BROWN TOP SOIL WITH LEAVES,ROOTS AND ORGANIC MATERIAL ' 0.5-2.0 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH OCCASIONAL COARSE SAND,GRAVEL AND ROOTS(MEDIUM DENSE,MOIST) 2.0-4.0 SM MEDIUM GRAY AND BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND, GRAVEL AND ROOTS (MEDIUM DENSE TO DENSE, MOIST) (WEATHERED TILL) 4.0-9.0 SM MEDIUM GRAY SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL ' AND OCCASIONAL ROOTS TO 5.0 FEET(DENSE,MOIST)(TILL) SAMPLES WERE COLLECTED AT 1.5 AND 7.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 9.0 FEET ON 4/13/94 TEST PIT SIX 1 0.0-4.0 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH OCCASIONAL COARSE SAND, GRAVEL, ROOTS, SMALL PIECES OF WOOD AND SMALL ZONES OF ORGANIC MATERIAL(LOOSE TO MEDIUM DENSE,MOIST) 4.0-7.0 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH OCCASIONAL COARSE SAND, GRAVEL, ROOTS AND CHARRED WOOD (MEDIUM DENSE, MOIST) 7.0-10.0 SP MEDIUM GRAY FINE TO MEDIUM SAND WITH TRACE SILT AND OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST)(OUTWASH) SAMPLES WERE COLLECTED AT 4.0 AND BETWEEN 7.0 AND 10.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 10.0 FEET ON 4/13/94 TEST PIT SEVEN ' 0.0-3.0 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH OCCASIONAL COARSE SAND AND ROOTS(LOOSE TO MEDIUM DENSE,MOIST) 1 3.0-6.5 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST) 6.5-9.0 SP-SM MEDIUM GRAY FINE TO MEDIUM SAND WITH SILT AND OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST)(OUTWASH) ' SAMPLES WERE COLLECTED AT 1.0,4.0 AND 8.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED ' TEST PIT WAS COMPLETED AT 9.0 FEET ON 4/13/94 NELSON-COUVRETTE& ASSOCIATES, INC. FILE NO.10921393 ' FIGURE 5 LOG OF EXPLORATION DEPTH USC SOIL DESCRIPTION TEST PIT EIGHT ' 0.0-0.5 DARK BROWN TOP SOIL WITH ROOTS 0.5-2.0 SM MEDIUM BROWN SILTY FINE TO MEDIUM SAND WITH ROOTS AND OCCASIONAL COARSE SAND AND GRAVEL(MEDIUM DENSE,MOIST) ' 2.0-4.0 SM MEDIUM GRAY AND BROWN SLIGHTLY MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL(DENSE,MOIST)(WEATHERED TILL) SAMPLES WERE COLLECTED AT 1.0 AND 4.0 FEET ' SLIGHT TO MODERATE GROUND WATER SEEPAGE WAS ENCOUNTERED AT 2.0 FEET SLIGHT TEST PIT CAVING WAS ENCOUNTERED BELOW 2.0 FEET TEST PIT WAS COMPLETED AT 4.0 FEET ON 4113/94 TEST PIT NINE 0.0-2.5 SM MEDIUM GRAY AND BROWN SLIGHTLY MOTTLED (UPPER 1.0 FEET) SILTY FINE TO MEDIUM SAND WITH COARSE SAND, GRAVEL, OCCASIONAL COBBLES AND ' OCCASIONAL ROOTS BETWEEN 0.0 AND 1.0 FEET(DENSE,MOIST)(WEATHERED TILL) A SAMPLE WAS COLLECTED AT 2.0 FEET ' VERY SLIGHT GROUND WATER SEEPAGE WAS ENCOUNTERED BETWEEN 0.5 AND 1.0 FEET TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 2.5 FEET ON 4/13/94 ' TEST PIT TEN 0.0-3.0 SM MEDIUM TO DARK REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH COARSE SAND,GRAVEL AND ROOTS(LOOSE TO MEDIUM DENSE,MOIST) ' 3.0-5.0 SM MEDIUM GRAY AND BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL(DENSE,MOIST)(WEATHERED TILL) ' SAMPLES WERE ENCOUNTERED AT 1.0 AND BETWEEN 4.0 AND 5.0 FEET HEAVY GROUND WATER SEEPAGE WAS ENCOUNTERED AT 3.0 FEET SLIGHT TEST PIT CAVING WAS ENCOUNTERED BETWEEN 2.5 AND 3.0 FEET TEST PIT WAS COMPLETED AT 5.0 FEET ON 4113/94 TEST PIT 11 0.0-0.5 DARK BROWN TOP SOIL WITH ROOTS ' 0.5-1.5 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH COARSE SAND, ROOTS AND OCCASIONAL GRAVEL(MEDIUM DENSE TO DENSE,MOIST) 1.5-2.0 SM MEDIUM GRAY AND BROWN MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL(DENSE,MOIST)(WEATHERED TILL) 2.0-8.0 SM MEDIUM GRAY SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL (DENSE,MOIST)(TILL) ' SAMPLES WERE COLLECTED AT 1.0,2.0 AND 4.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 8.0 FEET ON 4/13/94 NELSON-COUVRETTE&ASSOCIATES, INC. FILE NO.10921393 FIGURE 6 LOG OF EXPLORATION DEPTH USC SOIL DESCRIPTION TEST PIT 12 ' 0.0-1.5 SM DARK BROWN SILTY FINE TO MEDIUM SAND WITH ROOTS AND OCCASIONAL COARSE SAND AND GRAVEL(LOOSE,MOIST)TOP SOIL 1.5-3.0 SM MEDIUM REDDISH BROWN SILTY FINE TO MEDIUM SAND WITH COARSE SAND, ROOTS AND OCCASIONAL GRAVEL AND SANDY ZONES (MEDIUM DENSE TO DENSE,MOIST) 3.0-4.0 SM MEDIUM GRAY AND BROWN SLIGHTLY MOTTLED SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL AND OCCASIONAL ROOTS (DENSE, MOIST) (WEATHERED TILL) 4.0-7.0 SM MEDIUM GRAY SILTY FINE TO MEDIUM SAND WITH COARSE SAND AND GRAVEL AND OCCASIONAL COBBLES(DENSE,MOIST)(TILL) SAMPLES WERE COLLECTED BETWEEN 3.0-4.0 AND 4.0-6.0 FEET GROUND WATER SEEPAGE WAS NOT ENCOUNTERED TEST PIT CAVING WAS NOT ENCOUNTERED TEST PIT WAS COMPLETED AT 7.0 FEET ON 4/13/94 I ' NELSON-COUVRETTE& ASSOCIATES, INC. FILE NO.10921393 FIGURE 7 il' Z U. S . STANDARD SIEVE SI7E 1711 O \ IIn 100 g C) �I nm 9 0 sidVE S ZE ASS �tl o F- 8 0 3 n �11 z' w 70 rn Z � O ' 60 I� I I I 10 7 3m n n , 1 1#1,iol .o ~ y Li q N Li I IW y 50I I k I I kI ' im( Z.9 m � y� Z 40 z Li 30 i w z = 20 jE zz 10 0 _< �l I - 1+ 1 E I m 1000 100 10 1 . 0 0 . 1 0 . 01 0 . 001 c° m T� GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY pa G) COARSE FINE COARSE MEDIUM FINE q m m EXPLORATION SAX,PLE m SY,^'B0L NUMBER DEPTH SOIL DESCRIPTION 'Brown med;v m -sand wi fh trace Silt and grave z m m CO