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Home My WebLink AboutCP1320 Final Geotech Report (March 2014)Geotechnical Subgrade Evaluation Auburn M &O Facility Stormwater Improvements 1905 C Street SW, Auburn, Washington March 19, 2014 Terracon Project No. 62135014 Prepared for: City of Auburn Public Works Department Auburn, Washington Prepared by: Terracon Consultants, Inc. Tacoma, Washington IIEMI 1 1 U� March 19, 2014 City of Auburn Public Works Department 25 W. Main St. Auburn, WA 98001 Attn: Mr. Seth Wickstrom Re: Geotechnical Subgrade Evaluation Auburn M&O Facility Stormwater Improvements 1305 C Street SW Auburn, Washington Terracon Project Number: B2135014 Dear Mr. Wickstrom: Terracon Consultants, Inc. (Terracon) has completed the geotechnical engineering services for the above referenced project. These services were performed in general accordance with the Scope and Fee Proposal, P81130336, dated November 22, 2013 This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning infiltration, structural fill, compaction and temporary and permanent slopes. We appreciate the opportunity to be of service to YOU on this project. If you have any questions concerning this report, or if we may be of further service, please contact us. Sincerely, Terracon Consultants, Inc. Paul D. Davis, P.E. Office Manager cc: 1 — Client (via e-mail) �01'11 David A. Baska, Ph, D., P.E. Principal Terracon Consultants, Inc. 3006 S. 96th Street Lakewood, WA 98499 P [2531573-9939 F [253] 573-9959 terracon.com TABLE OF CONTENTS APPENDIX A — FIELD EXPLORATION Exhibit A -1 Vicinity Map Exhibit A -2 Site and Exploration Plan Exhibit A -3 Field Exploration Description Test Pit Logs A -4 through A -9 APPENDIX B — LABORATORY TESTING Laboratory Testing Sieve Analyses Exhibits B -1 through B -7 APPENDIX C — SUPPORTING DOCUMENTS Exhibit C -1 General Notes Exhibit C -2 Unified Soil Classification System APPENDIX D — MOUNDING ANALYSIS " ?' .III ofRIII vc, uJJ: 111111111 III" :,.wwmu III « 6 :! ^IR!!!II 111111111 III!' Ilii,,If`µlll�u Page EXECUTIVE SUMMARY .............................................................................. ............................... i 1.0 INTRODUCTION .............................................................................. ..............................1 2.0 PROJECT INFORMATION ............................................................... ..............................1 2.1 Project Description ............................................................... ............................... 1 2.2 Site Location and Description ............................................... ............................... 2 3.0 SUBSURFACE CONDITIONS .......................................................... ..............................2 3.1 Published Geologic Conditions .............................................. ..............................2 3.2 Subsurface Conditions .......................................................... ............................... 2 3.3 Groundwater .......................................................................... ..............................2 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ........ ..............................3 4.1 Infiltration Rates ..................................................................... ..............................3 4.2 Groundwater Considerations ................................................ ............................... 3 4.3 Construction Considerations ................................................. ............................... 3 4.4 Structural Fill Requirements .................................................. ..............................4 4.5 Compaction Requirements ................................................... ............................... 5 4.6 Temporary /Permanent Slopes .............................................. ............................... 5 5.0 GENERAL COMMENTS ................................................................... ..............................6 APPENDIX A — FIELD EXPLORATION Exhibit A -1 Vicinity Map Exhibit A -2 Site and Exploration Plan Exhibit A -3 Field Exploration Description Test Pit Logs A -4 through A -9 APPENDIX B — LABORATORY TESTING Laboratory Testing Sieve Analyses Exhibits B -1 through B -7 APPENDIX C — SUPPORTING DOCUMENTS Exhibit C -1 General Notes Exhibit C -2 Unified Soil Classification System APPENDIX D — MOUNDING ANALYSIS " ?' .III ofRIII vc, uJJ: 111111111 III" :,.wwmu III « 6 :! ^IR!!!II 111111111 III!' Ilii,,If`µlll�u Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 EXECUTIVE SUMMARY A Geotechnical Subgrade Evaluation has been performed for the Auburn M &O Facility located at 1305 C Street SW in Auburn, Washington. Terracon's geotechnical scope of work included the advancement of 6 test pits to depths ranging from approximately 3 to 8 feet below existing site grades and performing 5 infiltration tests. Based on the information obtained from our subsurface exploration, the following geotechnical considerations were identified: Soils encountered generally consisted of silt, sandy silt, gravelly silt, organic silt, sand and silty sand. Unfactored infiltration rates were on the order of 0.5 to 5.3 inches per hour. The results of our mounding analysis indicate that the trenches and ponds will have standing water during a peak modeling event with a recovery time of about 30 hours (from beginning of event). This geotechnical executive summary should be used in conjunction with the entire report for design and /or construction purposes. It should be recognized that specific details were not included or fully developed in this summary, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled General Comments should be read for an understanding of the report limitations. I "µ .;7°Ill µw w III m u J 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u GEOTECHNICAL SUBGRADE EVALUATION AUBURN M &O FACILITY STORMWATER IMPROVEMENTS 1305 C STREET SW AUBURN, WASHINGTON Terracon Project No. 82135014 March 19, 2014 1.0 INTRODUCTION A geotechnical subgrade evaluation has been completed for the Auburn M &O Facility located at 1305 C Street SW in Auburn, Washington. The purpose of our evaluation is to provide geotechnical recommendations and considerations for the following: Stormwater infiltration rates Temporary/permanent slopes Mounding analysis Structural fill requirements Compaction requirements Our geotechnical engineering scope of work for this project included the advancement of 6 test pits to depths of approximately 3 to 8 feet below existing site grades and performing 5 small scale infiltration tests. The project will include a future structure and site infrastructure, which was not a part of this current study. However, soil use, placement and slope recommendations are included, as requested. 2.0 PROJECT INFORMATION 2.1 Project Description ITEM DESCRIPTION Site layout See Appendix A, Exhibit A -2: Site and Exploration Plan Structures Single story decant building and infiltration ponds and trenches. Grading Cuts and fills of 1 to 2 feet (assumed). Infiltration depths are on the order of 4 to 6 feet below existing site grades. I "µ .;"Iµw w III m u J 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 2.2 Site Location and Description ITEM DESCRIPTION Location See Appendix A, Exhibit A -1 Existing Site Features Multiple facility buildings and vehicle and equipment storage. Current ground cover Grass, gravel and asphalt drive and parking areas. Existing topography Relatively flat 3.0 SUBSURFACE CONDITIONS 3.1 Published Geologic Conditions According to the Geologic Map of the Auburn Quadrangle, King and Pierce Counties, Washington, prepared by D.R. Mullineaux, dated 1965, the site is classified as Qaw. It describes the site as mostly gravel and sand deposited by White River. Bouldery cobble and pebble - cobble gravel and sand in White River valley. Pebble- cobble gravel overlaiain by thin sand in Duwamish Valley at mouth of White River valley, grades outward to thick coarse and medium sand overlain by thin silt, clay, and peat. 3.2 Subsurface Conditions Based on the results of the explorations, subsurface conditions on the project site consisted of silt, sandy silt, gravelly silt, organic silt, sand and silty sand. Conditions encountered at each exploration location are indicated on the individual test pit logs found in Appendix A of this report. Conditions encountered in the explorations were generally consistent with the thin silt, clay, and peat materials identified as the near - surface soil layers on the published geologic map. Stratification boundaries on the logs represent the approximate location of changes in soil types; in -situ, the transition between materials may be gradual. 3.3 Groundwater Groundwater was not encountered in the test pits at the time of the excavations, with the exception of TP -3, which encountered water at a depth of approximately 5'/2 feet below the existing site grade. Please note that groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the explorations were completed. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project and is discussed further in this report. 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u 2 Geotechnical Subgrade Evaluation Auburn M &O Facility Auburn, Washington March 19, 2014 11111111, Terracon Project No. B2135014 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION 4.1 Infiltration Rates The City of Auburn Surface Water Management Manual, Volume IV, November 2009, was used as a guide for performing the infiltration testing. As described in Section 5.4.2.1, Method 3 type testing was performed. In this case, the in -situ testing consisted of constant and falling head infiltration tests. Pilot Infiltration Tests (PIT) were not performed, but will likely be performed as a part of a future study. The following table presents unfactored infiltration rates determined during our field investigation. Location Test Depth (feet)/ Test Elevation (feet) Infiltration Rate (in /hour) TP -1 2.5/84 0.5 TP -2A 3/82.5 5.3 TP -3 3.5/80.5 1.7 TP -4 4/80.5 1.3 TP -5 3/82.5 2.9 4.2 Groundwater Considerations The estimated infiltration depth is indicated to be at an elevation of approximately 78 feet, based on information provided by the project Civil Engineer. We assume that this elevation is based on the same datum utilized to prepare the City of Auburn Topographic Survey, prepared by Parametrix, dated November 18, 2013. Based on an April, 2013 on -site monitoring well reading, groundwater was at about 76 feet. This information, along with other input data was used to perform a mounding analysis. MODRET software, by Scientific Software Group, was used to characterize mounding at this site. The results indicate that the trenches and ponds will have standing water during a peak modeling event with a recovery time of about 30 hours (from beginning of event). More detailed information on this analysis is presented in Appendix D. 4.3 Construction Considerations It is our understanding that a future study will include structure and infrastructure recommendations. In addition, Pilot Infiltration Tests (PIT) will be performed to better quantify the receptor soil infiltration rates /capacities. Variations in subsurface conditions can affect the infiltration rate of the receptor soils. We recommend that Terracon be provided the opportunity to observe conditions at the proposed infiltration locations at the time of excavation. 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u 3 Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 The infiltration rate of the receptor soils will be reduced in the event that fine sediment or organic materials are allowed to accumulate on the exposed receptor soil surfaces during construction. The use of an infiltration pond or trench as a temporary sedimentation control pond during construction has the potential to substantially alter the infiltration rate of the soils. Use of a storm chamber excavation as a temporary construction phase sedimentation pond is not recommended. Operation of heavy equipment may densify the reception soils below the infiltration facilities. The soils exposed in the bottom of the infiltration facilities should not be compacted. It may be necessary to scarify the infiltration facilities subgrade to facilitate infiltration. 4.4 Structural Fill Requirements All fill material placed in structure and non - landscaped areas should be placed in accordance with the recommendations for structural fill. Prior to placement, the surfaces to receive structural fill should be prepared as will be presented in the Final Geotechnical Evaluation. All structural fill should be free of organic material, debris, or other deleterious material. Individual particle sizes should be less than 3 inches in maximum dimension. 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 amount of fines (that soil fraction passing the U.S. No. 200 sieve) increases, soil becomes increasingly sensitive to small changes in moisture content, and adequate compaction becomes more difficult, or impossible, to achieve. Generally, soils containing more than about 5 percent fines by weight (based on that soil fraction passing the U.S. No. 4 sieve) cannot be compacted to a firm, non - yielding condition when the moisture content is more than a few percent from optimum. The optimum moisture content is that which yields the greatest soil density under a given compactive effort. It is our opinion that the existing granular soils encountered (upper 1 to to feet) on the site are suitable for reuse as structural fill from a compositional standpoint provided that organic material is not present. However, depending on the time of year that earthwork is completed; drying or wetting of these soils may be required prior to compaction. Larger particles should be screened out prior to use as structural fill. Screening of particles larger than 3 inches should be completed prior to using the sand and gravel soils for structural fill. Selective drying of over - optimum moisture soils may be achieved by scarifying or windrowing surficial materials during periods of dry weather. Soils which are dry of optimum may be moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. Imported soils for use as structural fill should consist of granular (sand and gravel) material. Structural fill should meet the general requirements of Section 9- 03.14(1), Gravel Borrow, as 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u 4 Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 presented in the Washington State Department of Transportation (WSDOT) Standard Specifications for Road, Bridge, and Municipal Construction. For wet site conditions or placement of fill during inclement weather the percent passing the US No. 200 mesh sieve should be modified to less than 5 percent by weight. The use of other fill types should be reviewed and approved by the engineer. Structural fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture content and densities throughout the fill. Fill lifts should not exceed 8 inches in loose thickness. 4.5 Compaction Requirements Excessive compaction directly above utility elements should be avoided to reduce the risk of damage. 4.6 Temporary /Permanent Slopes The contractor is responsible for designing and constructing stable, temporary excavations (including utility trenches) as required to maintain stability of both the excavation sides and bottom. Excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. 1111 III w 4 u« 6:!D III u1111 III "" IIIu mlllµlllµu 5 Per the Modified Proctor Test (ASTM D 1557) Material Type and Location Minimum Range of Moisture Contents for Compaction Compaction Requirement ( %) Minimum Maximum On -site granular or approved imported fill soils 0 0 Beneath foundations and concrete slabs: 95 0 0 -2% +2% Utility trench backfill (upper 2 feet): 95 e e -2% +2% Utility trench backfill (below 2 feet): 92 0 0 -2% +2% Foundation backfill: 92 0 0 -2% +2% Miscellaneous backfill (non - structural): 90 -2% +2% Excessive compaction directly above utility elements should be avoided to reduce the risk of damage. 4.6 Temporary /Permanent Slopes The contractor is responsible for designing and constructing stable, temporary excavations (including utility trenches) as required to maintain stability of both the excavation sides and bottom. Excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. 1111 III w 4 u« 6:!D III u1111 III "" IIIu mlllµlllµu 5 Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 We recommend maximum permanent slope configurations for sand and gravel materials as follows: Maximum Slope Configuration Soil Type Horizontal:Vertical (H:V) Native soil 2H:1 V Structural fill 2H:1 V If steeper slopes are required for site development, stability analyses should be completed to design the grading plan. 5.0 GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth- related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the explorations performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between test pits, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. This report has been prepared for the exclusive use of City of Auburn Public Works Department for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. 111111111 III w 4 u « 6:!D III 111111111 III "" IIIu mlllµlllµ u 6 APPENDIX A FIELD EXPLORATION 17N Z c 0 1 , I M: V! CIA kif St sw 3f(i 54 1 WIN 41ti St ��W �0 11 11711 .... ...... st st �'Nv 8111 $1 sit L III SIP SE tinIN eel � l Sup�l n W WI st sw I Sol st sw; II 16th sk ISE Bourv.,lao (vPV,1J 4111?t Ave, 1,1114 1f, ^5 I r ry 2obbfeet 20114 Microsoft ICor poIr,ation C 2013 PI DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS AERIAL PHOTOGRAPHY PROVIDED NOT INTENDED FOR CONSTRUCTION PURPOSES BY MICROSOFT BING MAPS Project Manager: Project No. VICINITY MAP Exhibit PDD B2135014 Drawn by: PDD Scale: AS SHOWN Irerracon Auburn M & 0 Facility Checked by: PDD File Name: VIM 3006 S. 96th St. 1305 C Street SW A-1 Approved by: PDDII Date: 3/19/14 Lakewood, WA Auburn, WA LEGEND 1W APPROXIMATE TP -3 TEST PIT LOCATIONS Basemap PDF provided by Google and modified by TERRACON. ERPDD w a" ezlseola SITE AND EXPLORATION PLAN Fll, ri; EMG AS SHOWN Con sWbn9En9ineersana Scienir6 AUBURN M &O FACILITY FUUM Ztlwg � AUBURN, WASHINGTON /� A -2 vim.q ,s„ Prepared for CITY OF AUBURN FE& 2014 Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 Field Exploration Description Our field exploration for this project included 6 test pits completed on December 18, 2013 and February 5, 2014. TP -2 was the first excavation performed as a part of our exploration. As such, it was excavated to full depth to determine the general soil profile. TP -2A was excavated approximately 5 -10 feet east of TP -2 in order to run the infiltration test. The approximate exploration locations are shown on the Site and Exploration Plan, Figure A -2. The exploration locations were determined by measuring distances from existing site features. The locations of the test pits should be considered accurate only to the degree implied by the means and methods used to define them. An independent contractor working under subcontract to Terracon performed the test pits. An engineer from our firm continuously observed the explorations, logged the subsurface conditions, and obtained representative soil samples. The samples were stored in moisture tight containers and transported to our laboratory for further visual classification and testing. After we logged each exploration, the subcontractor backfilled the explorations per Washington Department of Ecology standards. The enclosed test pit logs indicate the vertical sequence of soils and materials encountered in each test pit, based primarily on our field classifications and supported by our subsequent laboratory testing. Where a soil contact was observed to be gradational or undulating, our logs indicate the average contact depth. Our logs also indicate the approximate depths of groundwater seepage observed in the test pits, as well as sample numbers and sampling locations. Exhibit A -3 J J W O Z C7 O J H Q U) O W TEST PIT LOG NO. TP -1 Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J Q ai u. Q d W� J d E m Z W Approximate Surface Elev. 86.5 (Ft.) +/- o Q m Q w DEPTH ELEVATION Ft. O a 0 ' `` 4" - 8" GRASS AND TOPSOIL 0 ' 0.5 86 +/- SANDY SILT WITH GRAVEL, dark brown 1.5 85 +/- ® POORLY GRADED SAND WITH GRAVEL ISPI, with cobbles, dark black -brown 11ti1, S 1 ® 2.5 84 +/- CLAYEY SANDY SILT (CL-MU, trace gravel, orangish grayish brown S -2 61 grades to silty fine sand with gravel (probable slough included in sample) " ti S -3 29 4.5 82 +/- Test Pit Terminated at 4.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 2/5 /2014 Test Pit Completed: 2/5 /2014 No groundwater observed Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington IProject No.: B2135014 Exhibit: A-4 J J W 0 z 0 0 J a U) O W cD TEST PIT LOG NO. TP -2 Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J a ai u. Q d W� J d E m z W Approximate Surface Elev. 85.5 (Ft.) +/- o Q m Q w DEPTH ELEVATION Ft. O a 0.2 1/2" ASPHALT over 2" crushed base course 85.5+/ - POORLY GRADED SAND WITH SILT AND GRAVEL (SP-SMI, dark grayish brown, moist S -1 1.0 84.5+/ - SILT WITH SAND AND GRAVEL (MU, dark purplish gray, moist Nb(. I S -2 57 3.0 82.5+/ - SILT IMLI, trace sand, moist S -3 92 4.0 81.5+/ - ORGANIC SILT IOU, some interbedded sand layers, black, moist 4.5 81 +/- ORGANIC SILT WITH SAND to SILTY SAND IOU, fine grained, brownish gray, moist 5 S -4 7.0 78.5+/ - `VI POORLY GRADED SAND WITH SILT to SILTY SAND (SP-SMI, fine grained, brown -gray S-5 7.5 78 +/- ORGANIC SILT IOU, reddish brown 8.0 77.5+/ - Test Pit Terminated at 8 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 12/18/2013 Test Pit Completed: 12/18/2013 No groundwater observed Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington IProject No.: B2135014 Exhibit: A -5 J J W O Z C7 O J H Q U) O W TEST PIT LOG NO. TP -2A Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J Q ai u. Q d W� J d E m Z W Approximate Surface Elev. 85.5 (Ft.) +/- o Q m Q w DEPTH ELEVATION Ft. O a 0.3 1/2" ASPHALT over 3" crushed base course 85 +/- ® POORLY GRADED SAND WITH SILT AND GRAVEL (SP-SMI, light brown, moist 1.3 84 +/- SILT WITH SAND (MU,, dark brown, moist grades to poorly graded fine sand, trace silt, moist 3.0 82.5+/ - Test Pit Terminated at 3 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 12/18/2013 Test Pit Completed: 12/18/2013 No groundwater observed Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington Project No.: B2135014 Exhibit: A -6 J J W O Z C7 O J H Q U) O W TEST PIT LOG NO. TP -3 Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J Q ai u. Q (D d o W� J d E m Z W C7 Approximate Surface Elev 84 (Ft.) +/- m Q w DEPTH ELEVATION Ft. O a ORGANIC SILT IOU, dark reddish brown, moist 0.3 83.5+/- SILT IMU, trace fine sand, tan and gray, damp S -1 ddY(' grades to silt with sand, light gray with orange mottling `ytif S-2 grades to clayey silt, trace sand, with distinct mottling grades to silty sand S -3 37 grades to silt, trace sand " ti S -4 l , 5 S -5 grades to light gray and wet 6.0 78 +/- Test Pit Terminated at 6 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 12/18/2013 Test Pit Completed: 12/18/2013 While sampling Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington Project No.: B2135014 Exhibit: A -7 J Lu O z C7 0 J H Q U) O W TEST PIT LOG NO. TP -4 Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J Q ai u. Q d W� J d E m z W Approximate Surface Elev. 84.5 (Ft.) +/- o Q m Q w DEPTH ELEVATION Ft. O a_ FILL - POORLY GRADED GRAVEL IGPI m 0.3 +/ SANDY SILT [MU,, with gravel, brown with gray, moist S -1 1.0 83.5+/ - GRAVELLY SANDY SILT [MU, trace clay, brown with gray, moist (gravel was subrounded, with approximate 4" top size) cddY(' S -2 l , 2.0 82.5+/ - SILT IMLI, trace sand, gray with heavy rust mottling to stained orange, moist db(„ S -3 3.0 81.5+/ - SANDY SILT [MU, trace gravel, tan to grayish brown, wet S -4 50 5 grades to silt with clay, dark grayish brown " ti > S -5 l , 6.5 78 +/- 11ti1, SILT WITH SAND AND CLAY [MU, with organics (log), wet S-6 7.0 77.5+/ - Test Pit Terminated at 7 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 12/18/2013 Test Pit Completed: 12/18/2013 No groundwater observed Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington IProject No.: B2135014 Exhibit: A -8 J J W 0 Z C7 O J H Q U) 0 W TEST PIT LOG NO. TP -5 Page 1 of 1 PROJECT: Auburn M&O CLIENT: City of Auburn SITE: 1305 C Street SW Auburn, WA 00 LOCATION See Exhibit A -2 w Z d w � H O W J Q ai u. Q d W� J d E m Z W Approximate Surface Elev 85.5 (Ft.) +/- o Q m Q w ELEVATION Ft. O a_ 2" mulch (FILL) TDEPT..H ILS T IMLI, dark gray, moist POORLY GRADED SAND ISPI, trace to with organic silt, fine grained, light gray to tan, moist S -1 1 2.5 83 +/- ORGANIC SILT WITH SAND IOLI, gray with orange mottling, moist to wet, strong organic odor S -2 dVti I S -3 88 3.5 82 +/- ORGANIC SILT IOLI, trace sand, wet (roots) 5 S -4 5.5 8o +/- Test Pit Terminated at 5.5 Feet Stratification lines are approximate. In -situ, the transition may be gradual. Advancement Method: See Exhibit A -3 for description of field procedures. Notes: See Appendix B for description of laboratory procedures and additional data (if any). See Appendix C for explanation of symbols and Abandonment Method: Backf Iled with soil cuttings upon completion. abbreviations. Estimated from topographic map WATER LEVEL OBSERVATIONS Test Pit Started: 12/18/2013 Test Pit Completed: 12/18/2013 No groundwater observed Ifierracon Excavator: Operator: NW Excavating 2115 S. 56th St., Suite 405 Tacoma, Washington Project No.: B2135014 Exhibit: A -9 APPENDIX B LABORATORY TESTING Geotechnical Subgrade Evaluation, Auburn M &O Facility Auburn, Washington Irerracali March 19, 2014 11111111, Terracon Project No. B2135014 Laboratory Testing Descriptive classifications of the soils indicated on the boring logs are in accordance with the enclosed General Notes and the Unified Soil Classification System. Also shown are estimated Unified Soil Classification Symbols. A brief description of this classification system is attached to this report. All classification was by visual manual procedures. Laboratory tests were conducted on selected soil samples and the test results are presented in this appendix and /or on the exploration logs. The laboratory test results were used for the development of the recommendations. Laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. Selected soil samples obtained from the site were tested for the following engineering properties: iiiiiiiiii Sieve Analysis Graphical results of the sieve analyses are included in this appendix N U W N U z c� 95 90 85 80 75 70 65 x LD 60 w >- 55 m ry Z 50 U- 1-- 45 w ry 40 w CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER 6 4 3 1.5 ' 3/4 "'3/8 s 4 n 8 I 14 "n 20 s� 40 5V 60 1VV140'VV 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 I COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -1 2.5 CL -ML - Clayey sandy silt Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay W TP -1 2.5 25 9.0 30.1 61.0 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 12135014 Irerracon CLIENT: City of Auburn 2115 S. 56th St., Suite 405 Tacoma, Washington EXHIBIT: B -1 N U W N U z cD 95 90 85 80 75 70 65 x LD 60 W >- 55 m ry Z 50 U- 1-- 45 W ry 40 W CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER 6 4 3 3/4 "'3/8 s 4 n 8 I 14 "n 20 s� 40 5V 60 1VV140'VV 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 I COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -1 4.0 SM - Silty fine sand with gravel Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay W TP -1 4.0 37.5 0.306 0.076 28.8 41.8 29.4 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 12135014 Irerracon CLIENT: City of Auburn 2115 S. 56th St., Suite 405 Tacoma, Washington EXHIBIT: B -2 N U W N U z cD 95 90 85 80 75 70 65 x LD 60 W >- 55 m ry Z 50 U- 1-- 45 W ry 40 W CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER 6 4 3 3/4 "'3/8 s 4 n 8 I 14 "n 20 s� 40 5V 60 1VV140'VV 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 I COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -2 1.0 ML - Silt with sand and gravel Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay 1 TP -2 1.0 37.5 0.09 24.5 18.8 56.7 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 12135014 Irerracon CLIENT: City of Auburn 2115 S. 56th St., Suite 405 Tacoma, Washington EXHIBIT: B -3 N U W N U z c� Ivv 95 90 85 80 75 70 r 65 x LD 60 w >- 55 Co ry Z 50 U- 1-- 45 w ry 40 w CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS 4 3 ' 1.5 1 3/4 u'3/8 s n 8 IV 14 m 20 sv 40 5v 60 1 vv 140 wv 100 HYDROMETER 10 1 0.1 0.01 0.001 I GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depthl USCS Classification LL PL PI Cc Cu 1* TP -2 3.5 ML - Silt Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay 1* TP -2 3.5 6.35 0.1 8.0 91.9 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 82135014 CLIENT: City of Auburn EXHIBIT: B -4 N U W N U z c� 95 90 85 80 75 70 65 x LD 60 w >- 55 m ry Z 50 U- 1-- 45 w ry 40 w CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER 8. . 1 ■ ■■■ 111111■■■ IYIIYI�■■ i�11Y111� ■i�■■IIIIII ■ ■ ■IIIII� ■ ■■ 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 I COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -3 3.5 SM - Silty sand Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay 1 TP -3 3.5 4.75 0.101 0.0 62.9 37.1 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 12135014 Irerracon CLIENT: City of Auburn 2115 S. 56th St., Suite 405 Tacoma, Washington EXHIBIT: B -5 N U W N U z c� 95 90 85 80 75 70 65 x LD 60 w >- 55 m ry Z 50 U- 1-- 45 w ry 40 w CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER 1 ■ ■■■ 111111 ■ ■■IYli�i� ■ICi�11�1111■ ■■■1111111 ■■ ■111111 ■ ■■ 100 10 1 0.1 GRAIN SIZE IN MILLIMETERS 0.01 0.001 I COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -4 3.5 ML - Sandy silt Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay TP -4 3.5 9.5 0.123 1.4 48.3 50.3 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 12135014 Irerracon CLIENT: City of Auburn 2115 S. 56th St., Suite 405 Tacoma, Washington EXHIBIT: B -6 N U W N U z cD Ivv 95 90 85 80 75 70 r 65 x LD 60 W >- 55 Co ry Z 50 U- 1-- 45 W ry 40 W CL 35 30 25 20 15 10 5 0 GRAIN SIZE DISTRIBUTION ASTM D422 U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS 4 3 ' 1.5 1 3/4 �3/8 s 4 0 8 IV 14 "D 20 sv 40 ov 60 'VV 140 wv 100 HYDROMETER 10 1 0.1 0.01 0.001 I GRAIN SIZE IN MILLIMETERS COBBLES GRAVEL SAND SILT OR CLAY coarse I fine coarse I medium I fine Boring ID Depth USCS Classification LL PL PI Cc Cu TP -5 3.0 OL - Organic silt with sand Boring ID Depthl Dj, D, D, D,o %Gravel %Sand %Silt I %Clay 1 TP -5 3.0 12.5 0.4 12.0 87.5 PROJECT: Auburn M &O SITE: 1305 C Street SW Auburn, WA PROJECT NUMBER: 82135014 CLIENT: City of Auburn EXHIBIT: B -7 APPENDIX C SUPPORTING DOCUMENTS GENERAL NOTES DESCRIPTION OF SYMBOLS AND ABBREVIATIONS E H DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non - plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse - grained soils are defined on the basis of their in -place relative density and fine - grained soils on the basis of their consistency. LOCATION AND ELEVATION NOTES Unless otherwise noted, Latitude and Longitude are approximately determined using a hand -held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY Descriptive Term(s) Percent of Maior Component Particle Size of other constituents Dry Weiaht of Sample Trace < 15 Boulders Over 12 in. (300 mm) With 15-29 Cobbles 12 in. to 3 in. (300mm to 75mm) Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) Sand #4 to #200 sieve (4.75mm to 0.075mm Silt or Clay Passing #200 sieve (0.075mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Term(s) Percent of Term Plasticity Index of other constituents Dry Weiaht Non - plastic 0 Trace < 5 Low 1 -10 With 5-12 Medium 11 - 30 Modifier > 12 High > 30 Irerracon Exhibit C -1 Water Initially (HP) Hand Penetrometer Encountered Auger Split Spoon � Water Level After a (T) Torvane Specified Period of Time ' � J � Water Level After rn � b/ Standard Penetration W a Specified Period of Time I- > Test (blows per foot) Z Shelby Tube Macro Core W J J Water levels indicated on the soil boring � (PID) Photo - Ionization Detector IL � logs are the levels measured in the � � W borehole at the times indicated. J � Q Groundwater level variations will occur � (OVA) Organic Vapor Analyzer Ring Sampler Rock Core � over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. Grab Sample No Recovery RELATIVE DENSITY OF COARSE - GRAINED SOILS CONSISTENCY OF FINE - GRAINED SOILS (More than 50% retained on No. 200 sieve.) (50% or more passing the No. 200 sieve.) Density determined by Standard Penetration Resistance Consistency determined by laboratory shear strength testing, field Includes gravels, sands and silts. visual- manual procedures or standard penetration resistance � Descriptive Term Standard Penetration or Ring Sampler Descriptive Term Unconfined Compressive Standard Penetration or Ring Sampler � (Density) N -Value glows /Ft. (Consistency) Strength, Qu, tsf N -Value glows /Ft. Q' Blows /Ft. Blows /Ft. W F Very Loose 0-3 0 - 6 Very Soft less than 0.25 0-1 < 3 2 ~ Loose 4 -9 7 -18 Soft 0.25 to 0.50 2 -4 3 -4 Z W Q' Medium Dense 10-29 19-58 Medium -Stiff 0.50 to 1.00 4-8 5 - 9 F RELATIVE DENSITY OF COARSE - GRAINED SOILS CONSISTENCY OF FINE - GRAINED SOILS (More than 50% retained on No. 200 sieve.) (50% or more passing the No. 200 sieve.) Density determined by Standard Penetration Resistance Consistency determined by laboratory shear strength testing, field Includes gravels, sands and silts. visual- manual procedures or standard penetration resistance � Descriptive Term Standard Penetration or Ring Sampler Descriptive Term Unconfined Compressive Standard Penetration or Ring Sampler � (Density) N -Value glows /Ft. (Consistency) Strength, Qu, tsf N -Value glows /Ft. Q' Blows /Ft. Blows /Ft. W F Very Loose 0-3 0 - 6 Very Soft less than 0.25 0-1 < 3 2 ~ Loose 4 -9 7 -18 Soft 0.25 to 0.50 2 -4 3 -4 Z W Q' Medium Dense 10-29 19-58 Medium -Stiff 0.50 to 1.00 4-8 5 - 9 F � Dense 30-50 59-98 Stiff 1.00 to 2.00 8-15 10 - 18 Very Dense > 50 > 99 Very Stiff 2.00 to 4.00 15-30 19-42 Hard > 4.00 > 30 > 42 UNIFIED SOIL CLASSIFICATION SYSTEM A Based on the material passing the 3 -inch (75 -mm) sieve B If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. ° Gravels with 5 to 12% fines require dual symbols: GW -GM well - graded gravel with silt, GW -GC well - graded gravel with clay, GP -GM poorly graded gravel with silt, GP -GC poorly graded gravel with clay. ° Sands with 5 to 12% fines require dual symbols: SW -SM well - graded sand with silt, SW -SC well - graded sand with clay, SP -SM poorly graded sand with silt, SP -SC p(Ds,,) orly graded sand with clay E Cu = D60 /D10 Cc= z " If fines are organic, add "with organic fines" to group name. ' If soil contains >_ 15% gravel, add "with gravel" to group name. j If Atterberg limits plot in shaded area, soil is a CL -ML, silty clay. " If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel," whichever is predominant. L If soil contains >_ 30% plus No. 200 predominantly sand, add "sandy" to group name. M If soil contains >_ 30% plus No. 200, predominantly gravel, add "gravelly" to group name. " PI >_ 4 and plots on or above "A" line. ° PI < 4 or plots below "A" line. D10 x D60 P PI plots on or above "A" line. F If soil contains >_ 15% sand, add "with sand" to group name. o PI plots below "A" line. G If fines classify as CL -ML, use dual symbol GC -GM, or SC -SM. 60 For classification of fine- grained Soil Classification Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Group Group B 50 of coarse - grained soils V Symbol Equation of "A" - line Gravels: Clean Gravels: Cu >_ 4 and 1 < Cc < 3 E... GW Well- graded gravel F .... More than 50% of Less than 5% fines ° Cu < 4 and /or 1 > Cc > 3 E GP Poorly graded gravel F Z Vertical at LL =16 to P1 =7, ,/' coarse fraction retained Gravels with Fines: Fines classify as ML or MH GM Silty gravel F.G." Coarse Grained Soils: on No. 4 sieve More than 12% fines ° Fines classify as CL or CH GC Clayey gravel F,G.H More than 50% retained on No. 200 sieve Sands: Clean Sands: Cu >_ 6 and 1 <_ Cc <_ 3 E SW Well- graded sand' 50% or more of coarse Less than 5% fines ° Cu < 6 and /or 1 > Cc > 3 E SP Poorly graded sand' CL r fraction passes No. 4 Sands with Fines: Fines classify as ML or MH SM Silty sand G' "' sieve More than 12% fines ° Fines classify as CL or CH SC Clayey sand G' "' o ' PI > 7 and plots on or above "A" line CL Lean clay" `" 90 100 Silts and Clays: Inorganic: PI < 4 or plots below "A" line j ML Silt K M Liquid limit less than 50 Liquid limit - oven dried Organic clay K.F,M N Fine - Grained Soils: Organic: < 0.75 Liquid limit -not dried OL K,�.nn.o Organic sLl� 50% or more passes the No. 200 sieve PI plots on or above "A" line CH Fat clay Silts and Clays: Inorganic: PI plots below "A" line MH Elastic Silt K,L.n Liquid limit 50 or more Liquid limit - oven dried Organic clay K.F,M P Organic: < 0.75 Liquid limit - not dried OH Organic silt K,L.n,.o Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3 -inch (75 -mm) sieve B If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. ° Gravels with 5 to 12% fines require dual symbols: GW -GM well - graded gravel with silt, GW -GC well - graded gravel with clay, GP -GM poorly graded gravel with silt, GP -GC poorly graded gravel with clay. ° Sands with 5 to 12% fines require dual symbols: SW -SM well - graded sand with silt, SW -SC well - graded sand with clay, SP -SM poorly graded sand with silt, SP -SC p(Ds,,) orly graded sand with clay E Cu = D60 /D10 Cc= z " If fines are organic, add "with organic fines" to group name. ' If soil contains >_ 15% gravel, add "with gravel" to group name. j If Atterberg limits plot in shaded area, soil is a CL -ML, silty clay. " If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel," whichever is predominant. L If soil contains >_ 30% plus No. 200 predominantly sand, add "sandy" to group name. M If soil contains >_ 30% plus No. 200, predominantly gravel, add "gravelly" to group name. " PI >_ 4 and plots on or above "A" line. ° PI < 4 or plots below "A" line. D10 x D60 P PI plots on or above "A" line. F If soil contains >_ 15% sand, add "with sand" to group name. o PI plots below "A" line. G If fines classify as CL -ML, use dual symbol GC -GM, or SC -SM. 60 For classification of fine- grained soils and fine - grained fraction z' 50 of coarse - grained soils V Equation of "A" - line J CL Horizontal at PI =4 to LL =25.5. X - then PI =0.73 (LL -20) 10\ 40 Wp Equation of "U" - line ,' �at Z Vertical at LL =16 to P1 =7, ,/' G >- 30 then PI =0.9 (LL -8) ' 0 00 20 ........... ............................... ........... 0r ......................... . MH or OH CL r 10 r 7 _ L - ML ML or OIL o ' 0 10 16 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT (LL) Irerracon Exhibit C-2 APPENDIX D MOUNDING ANALYSIS Auburn M &O M()w::„ P I B2135014 m, u� :r January 25, 2013 G OBJECTIVE Perform mounding analysis for infiltration trench. Trerracon p: �o 1 1 I� . „ ,tl RTS i N 11 w � II N 11 1 ',' GIVENS • Two ponds, with total dimensions: 20'x 820'x 6' deep (45 maximum design depth) *This maybe unconservative if less than 20% of the water is routed to Pond 4. • Impervious surfaces draining to ponds: 5.20 acres ASSUMPTIONS • Low - permeability stratum is sufficiently low so as not to affect mounding • Elevation conversion: NAVD 1988 Elevation = NGVD 1929 Elevation + 3.527 feet • Long -term saturated drainage: 0.112 ft/hr (from infiltration test at TP -4) • Top elevation of trench: 84' to 84.5' (use 84.2') • Design high water level: 82.7' • Bottom elevation of trench: 78' to 78.5' (78.2') • Groundwater elevation: 76.25 ft (4/26/12) • Directly Connected Impervious Area: 100% (all pervious surfaces ignored in this analysis) • 10:1 horizontal /vertical conductivity ratio • Design event: 1.44 " /24 hr • Rainfall distribution: SCS Type IA • Kvu Factor of Safety: 2.0 CALCULATIONS Time of concentration Time of concentration can be calculated using the following formula: L T, = 60V Where T, is the time of concentration (min), L is the longest flow length to the trench (ft), and V is the average velocity (ft) along that travel path. From "Technical Release 55: Urban Hydrology for Small Watersheds ", for a paved travel path, at an estimated slope of 1.6% over 210 horizontal feet (from the provided topographical map), V = 2.6 ft /sec. 210 T — = 1.35 minutes 60(2.6) The software MODRET, by Scientific Software Group, was used to characterize mounding at this site. Inputs are shown on the following pages. Average effective storage coefficient of soil for unsaturated and saturated analyses comes from Table A -1 in the MODRET manual. text] MODRET HYDROGRAPH DATA INPUT - SCS UNIT METHOD Project Name: AuburnSCS Rainfall Distribution : SCS Type IA (24 hrs) Contributing Basin Area 5.20 ac. SCS Curve Number 92.00 Time of Concentration 1.35 min. Rainfall Depth 1.44 in. Shape Factor 256 Percent DCIA 100.00 % Analysis Date: 1/26/2014 MODRET SUMMARY OF UNSATURATED & SATURATED INPUT PARAMETERS PROJECT NAME: Auburn012614 HYDROGRAPH RUNOFF DATA USED UNSATURATED ANALYSIS INCLUDED Pond Bottom Area Pond Volume between Bottom & DHWL Pond Length to Width Ratio (L /W) Elevation of Effective Aquifer Base Elevation of Seasonal High Groundwater Table Elevation of Starting Water Level Elevation of Pond Bottom Design High Water Level Elevation Avg. Effective Storage Coefficient of Soil for Unsaturated Analysis Unsaturated Vertical Hydraulic Conductivity Factor of Safety Saturated Horizontal Hydraulic Conductivity Avg. Effective Storage Coefficient of Soil for Saturated Analysis Avg. Effective Storage Coefficient of Pond /Exfiltration Trench Time Increment During Storm Event Time Increment After Storm Event Total Number of Increments After Storm Event Runoff Hydrograph File Name: aubscs.scs Time of Peak Runoff: 7.70 hrs Rate of Peak Runoff: 1.78 cfs Hydraulic Control Features: Groundwater Control Features - Y/N Distance to Edge of Pond Elevation of Water Level Impervious Barrier - Y/N Elevation of Barrier Bottom Analysis Date: 1/26/2014 16,400.00 ftz 73,800.00 ft3 41.00 58.93 ft 76.25 ft 78.20 ft 78.20 ft 82.70 ft 0.11 2.69 ft/d 2.00 26.90 ft/d 0.11 1.00 1.00 hrs 10.00 hrs 6.00 Top Bottom Left Right N N N N 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 N N N N 0.00 0.00 0.00 0.00 MODRET SUMMARY OF RESULTS PROJECT NAME: Auburn012614 CUMULATIVE TIME (hrs) WATER ELEVATION (feet) INSTANTANEOUS INFILTRATION RATE (ds) AVERAGE INFILTRATION RATE (ds) CUMULATIVE OVERFLOW (ft3) 00.00-0.01 76.250 0.000 0.00000 0.01 76.250 0.25530 0.25530 5.47 78.200 0.25530 0.00 0.25530 6.47 78.230 0.25530 0.00 0.25530 7.47 78.295 0.25530 0.00 0.25530 8.47 78.516 0.25530 0.00 0.25530 9.47 78.580 0.25530 0.00 0.25530 10.47 78.608 0.25530 0.00 0.25530 11.47 78.624 0.25530 0.00 0.25530 12.47 78.632 0.25530 0.00 0.25530 13.47 78.635 0.25530 0.00 0.25530 14.47 78.635 0.25530 0.00 0.25530 15.47 78.631 0.25530 0.00 0.25530 16.48 78.624 0.25530 0.00 0.25530 17.48 78.616 0.25530 0.00 Analysis Date: 1/26/2014 MODRET SUMMARY OF RESULTS PROJECT NAME: Auburn012614 CUMULATIVE TIME (hrs) WATER ELEVATION (feet) INSTANTANEOUS INFILTRATION RATE (ds) AVERAGE INFILTRATION RATE (ds) CUMULATIVE OVERFLOW (ft3) 0.25530 18.48 78.604 0.25530 0.00 0.25530 19.48 78.589 0.25530 0.00 0.25530 20.48 78.573 0.25530 0.00 0.25530 21.48 78.556 0.25530 0.00 0.25530 22.48 78.537 0.25530 0.00 0.25530 23.48 78.518 0.25258 0.00 0.21992 30.06 78.200 0.14479 0.00 0.06967 47.48 77.755 0.06106 0.00 0.05246 59.48 77.617 0.00 Maximum Water Elevation: 78.635 feet @ 14.47 hours Recovery @ 30.064 hours * Time increment when there is no runoff Maximum Infiltration Rate: 1.345 ft /day Analysis Date: 1/26/2014 C O N W N (6 INFILTRATION: AUBURN012614 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Time (hrs) Max Water Elevation = 78.64 ft 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 6 hrs 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 8 hrs 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 12 hrs 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 18 hrs 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 23 hrs 7£ 7£ 7£ 7£ ►I c 0 7 0 w 7 ►ri 7£ 7£ 7£ 7£ CROSS SECTION : Auburn012614 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 DISTANCE ALONG X AXIS (ft) CROSS SECTION ALONG X AXIS AT Y AXIS = 0.00 ft @ 25 hrs