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HomeMy WebLinkAboutWPO201500005 Study 2015-05-27 �Irlll. Niwir REPORT OF SUBSURFACE EXPLORATION AND SLOPE STABILITY 5TH STREET STATION LANDFILL POND ALBEMARLE COUNTY, VIRGINIA ECS PROJECT NO. 28:1810 FOR: S.J. COLLINS ENTERPRISES 5 SW BROAD STREET, SUITE B FAIRBURN, GEORGIA 30213 ATTN: MR. JAMES P. DISCORDIA FEBRUARY 3, 2015 REVISED: MAY 27, 2015 • ECS MID-ATLANTIC, LLC 'Setting the Standard for Service" Geotechnical • Construction Materials • Environmental • Facilities February 3,2015 Revised: May 27, 2015 Mr. James P. Discordia Senior Project Director S.J. Collins Enterprises 5 SW Broad Street, Suite B Fairbum, Georgia 30213 ECS Project No.: 28:1810 Reference: Report of Subsurface Exploration and Geotechnical Engineering Services, 5th Street Station Landfill Pond Stability—Albemarle County, Virginia Dear Mr. Discordia: ECS Mid-Atlantic, LLC(ECS)is pleased to present the following report for the above-referenced project. Our services were provided in general accordance with ECS Proposal No. 28:1199-GP dated November 10, 2014 and authorized by your office on December 5, 2014. In addition to our original scope, we have addressed follow-on concerns regarding fill areas near Avon Street on the east side of the site. This report describes our understanding of the project information, presents the findings of our field and laboratory testing program, and provides geotechnical recommendations pertaining to the global stability and the construction of the above-referenced pond, as well as fill areas along and adjacent to the Bent Creek Parkway road alignment. We appreciate the opportunity to be of service to S.J. Collins Enterprises on this project. If you have any questions concerning the information and recommendations contained in the accompanying report, or if we may be of further assistance to you in planning and/or construction phases, please do not hesitate to contact us. MIN Respectfully, j, • r' Cir? ECS MID-ATLANTIC, I6,4e„A„ R zIgraf 031.119 Grant E.Walker, P.E. z . re ' Alexander Sarant, P.E. , Principal Engineer ,. 2��j Principal Engineer Senior Vice President � , r l:tGeotechnicaiiProJects1180011818-5th Street Station Landfill Pond Slope Stabfity.doc 4004 Hunterstand Court,Suite 102, Charlottesville,Virginia 22911 • T:434-973-3232 • F:434-973-3238 • www.ecsiimited.com ECS Capitol Services,PLLC•ECS Carolinas,LLP•ECS Central,PLLC•ECS Florida,LLC•ECS Mid-Atlantic,LLC•ECS Midwest,LLC•ECS Southeast,LLC•ECS Texas,LLP REPORT SUBSURFACE EXPLORATION AND GEOTECHNICAL ENGINEERING ANALYSIS PROJECT 5th Street Station Landfill SWM Pond Stability Albemarle County, Virginia CLIENT S.J. Collins Enterprises 5 SW Broad Street, Suite B Fairbum, Georgia 30213 PROJECT 28:1810 DATE February 3,2015 Revised: May 27, 2015 TABLE OF CONTENTS PAGE INTRODUCTION Project Description 1 Purpose and Scope of Services 2 EXPLORATION PROCEDURES Subsurface Exploration Procedures 3 Soil Borings 3 Laboratory Testing Program 3 EXPLORATION RESULTS Site Conditions 4 Site Geology 4 Soil Conditions 5 Groundwater Observations 6 ANALYSIS AND RECOMMENDATIONS Global Stability Analysis 7 Stripping Operations and Subgrade Preparation 8 Fill Placement 9 Embankment Fill Placement 10 Potentially Expansive Soils 11 Construction Groundwater Control 11 Pond Liner 12 Natural Clay Liner 12 Geosynthetic Liner 12 Seepage Analysis 13 Fill Zones-Avon Street Extended 13 Construction Considerations 13 Landscaping&Aesthetics 14 Closing 14 APPENDIX INTRODUCTION Project Description We understand that this project will consist of the construction of a permanent stormwater management (SWM) pond on the Avon Street Extended side of the project development site. Based on the parcel's former use as a landfill, only limited disturbance has been authorized within this area. This SWM pond will generally be constructed to maximize the use of existing topography, while augmenting its natural contour with a constructed dam approximately 6-8 ft. high on the east side of the pond and a fill slope adjacent to the road alignment on the west side of the pond. Please note that the specifics of the SWM pond are based on Sheet 16 of Bohier Engineering's WPO Plan — E&S Phase II and SWM/BMP Design entitled "Landfill Pond — Design Information" revised October 23, 2014. From our review of Cross Section C-C it appears the dam will be constructed to a width of about 50 ft. at its base and 8 ft. at its highest elevation. A maximum fill of about 22 ft. of engineered fill is proposed in the vicinity of STM C-3 near the proposed road, with the 10-year high water mark corresponding to EL *417 ft. MSL. This elevation equates to a maximum water depth of about 17 ft. near STA 11+00 of Section C- C shown on Sheet 16 of the aforementioned plan set. We understand that the pond bottom elevation may be raised at the time of construction dependent on the thickness requirement for the pond stabllzation base. The following table presents proposed design parameters which will be utilized for construction of this pond. SWM Pond Design Parameter *ELEV(ft) Pond Bottom 410.0 Top of Dam 419.0 Top of Fill Slope 422.0 2-Year Water Surface 415.90 10-Year Water Surface 416.99 Based on a concern for stability of the constructed pond berm and the fills along the road, soil test borings, laboratory testing and global stability analyses were performed along two cross sections in order to evaluate the stability of the fill soils on the existing landfill material, as well as confirm the suitability of the previously specified stabilization base for the pond and roadway bed subgrades. We understand that the timeline for this project is aggressive and the requirements for design revisions are dynamic. If any of this information presented above is inaccurate, either due to our misunderstanding of project details or due to design changes that may occur during the ECS Project No.28:1810 -2- February 3,2015(Revised: May 27, 2015) construction phase, we recommend that we be contacted as soon as possible in order to provide any additional or alternate recommendations that may be warranted. Purpose and Scope of Services The purposes of this exploration were to explore the soil, rock and groundwater(if encountered within the depths explored), conditions at the site and to develop engineering recommendations to guide design and construction of the project. Since future construction will occur over a former landfill, the general composition of waste cells within the areas of deep fills and constructed embankments was also deemed a critical requirement. We accomplished these purposes by: 1. Drilling soil borings, including Standard Penetration Tests (SPT), to explore the subsurface soil and groundwater conditions; 2. Reviewing soil test borings and test pit data conducted by others in areas where information was not available or immediately accessible; 3. Performing laboratory tests on selected representative soil samples from soil borings within the confines of the development to determine and evaluate pertinent engineering properties; 4. Conduct a Global Stability Analysis with GSTABL7; 5. Analyzing the field, laboratory and computer model data to develop appropriate engineering recommendations for inclusion into this geotechnical report. The conclusions and recommendations presented in this report are based on our subsurface field exploration, laboratory testing, and a review of the available geologic data. A total of six borings, B-2 through B-7, were drilled for this study. Laboratory tests were performed on selected soil samples within the vicinity of the site to identify the soil types and to assist in evaluation of the properties of the soil. in addition to the borings advanced by drilling crews under our direct supervision, we have reviewed boring logs by Schnabel Engineering and test pit data collected by Draper Aden Associates in the early stages of this project. The results of our subsurface exploration, along with a Boring Location Diagram, are included within the Appendix of this report. The results of subsurface exploration conducted by others may be found within the bodies of their specific reports. The number and general locations of the borings drilled for the subsurface exploration were selected and located on document plans for drilling purposes by representatives of ECS. The locations were selected to support the cross section information requested by the Virginia DEQ. The borings were located in the field by a Kirk Hughes&Associates surveying crews. ECS Project No.28:1810 -3- February 3,2015(Revised: May 27,2015) EXPLORATION PROCEDURES Subsurface Exploration Procedures Our scope of subsurface exploration included a total of seven (7) soil test in order to support stability analyses of critical areas within the pond and road alignment. Of the seven proposed, six borings were advanced based on access issues. The procedures for each method of subsurface exploration are discussed in the following sections. Soil Borings The soil borings were performed with an ATV-mounted auger drill rig, which utilized continuous flight, hollow stem augers to advance the boreholes. Representative soil samples were obtained by means of the split-barrel sampling procedure in general accordance with ASTM Specification D-1586. In this procedure, a 2-X-inch Q.D., split-barrel sampler is driven into the soil a distance of 18 inches or 24 inches by a 140-pound hammer falling 30 inches. The number of blows required to drive the sampler through a 12-inch interval is termed the Standard Penetration Test(SPT)N-value and is indicated for each sample on the boring logs. This value can be used as a qualitative indication of the in-place relative density of cohesionless soils. In a less reliable way, it also indicates the consistency of cohesive soils. This indication is qualitative, since many factors can significantly affect the standard penetration resistance value and prevent a direct correlation between drill crews, drill rigs, drilling procedures, and hammer- rod-sampler assemblies. Field logs of the soils encountered in the borings were maintained by an Engineering Geologist. After recovery, each sample was removed from the sampler and visually classified. Representative portions of each sample were then sealed and brought to our laboratory in Charlottesville, Virginia for further visual examination and laboratory testing, if deemed appropriate. Laboratory Testing Program Representative soil samples were selected and tested in our laboratory to check field classifications and to evaluate pertinent engineering properties. The laboratory testing program included visual classifications, moisture content tests, washed sieve grain size analyses, and Atterberg Limits tests. Data obtained from the laboratory tests are included on the respective boring logs or on separate sheets in the Appendix. Each soil sample was visually classified based on texture and plasticity in accordance with the Unified Soil Classification System (USCS). The group symbols for each soil type are indicated in ECS Project No. 28:1810 -4- February 3,2016(Revised: May 27,2015) parentheses following the soil descriptions on the boring logs. A brief explanation of the USCS is included with this report. The various soil types were grouped into the major zones noted on the boring logs. The stratification lines designating the interfaces between earth materials on the boring logs are approximate; in situ,the transitions may be gradual. The soil samples will be retained in our laboratory for a period of 60 days, after which they will be discarded unless other instructions are received as to their disposition. EXPLORATION RESULTS Site Conditions During our site reconnaissance, the majority of the site was observed to be wooded and heavily overgrown with smaller vegetation and scrub brush. There were some cleared areas , to include the near vicinity of Avon Road Extended in the eastern side of the site, as well as in the tow-lying areas adjacent to Moores Creek on the western side of the parcel. The site is bounded by Interstate 64 on the south and smaller residential and commercial structures within wooded areas on the north. Avon Street Extended delineates the site's eastern boundary, with Moores creek and the future commercial development area abutting the western side of the parcel. Existing site grades range from EL±500 ft. MSL near Avon Street Extended to EL±375 • ft. MSL near Moores Creek to the west. Site Geoloav The site is located within the Blue Ridge Physiographic Province and is underlain by metamorphic rocks of the Catoctin Formation. The Catoctin Formation is composed grayish green fine grained metabasalt, containing schistose chlorite and actinolite. In the southeastern outcrop belt, amygdaloidal metabasalts are common as are volcanoclastic rocks interbedded with basaltic flows. This formation was originally a series of lava flows separated by layers of sediments. According to the Soil Survey of Albemarle County, Virginia there are two types of soils within the site, Udorthents and the Wehadkee. Both of these soils were encountered during drilling, with the majority being of the Udorthents. The Udorthents is made up of areas that have been used for cutting or filling during the grading of roads, housing developments, recreational areas, quarries and other similar uses. Permeability ranges from moderately rapid to slow, and the water capacity is low to moderate. Included within these soils are areas of soils that have not been appreciably altered by cutting and filling and areas where bed rock is exposed. Surface runoff is moderate to very rapid and the hazard of erosion is severe. The soil is medium acid to very strongly acid throughout. The Udorthents encountered on the site consists primarily of landfill deposits that contain garbage consisting of glass, metal, wood, paper and plastic. ECS Project No.28:1810 -5- February 3,2015(Revised: May 27,2015) The Wehadkee series Is generally found floodplains along streams that drain from the mountains and the piedmont. It is poorly drained with moderate permeability. Surface runoff is very slow and the hazard of erosion is low. The soil is very strongly acid to neutral throughout. Soil Conditions The natural, near surface soil deposits that were encountered by our field exploration program were generally consistent with the regional geology and soils information described above. Five of the six soil test borings advanced were located in areas that required the construction of a work platform to gain drill rig access. As such, topsoil was not apparent within the split spoon samples obtained. Based on previous studies, topsoil depths range from about 3 inches to 12 inches. Based on the borings, the subsurface conditions within the first 10 feet below existing grades generally consist of sandy, low plasticity CLAY (CL) and sandy SILT (ML) FILL materials, with trace amounts of material consistent with municipal solid waste(glass, wood, plastic, paper and similar materials). One boring, Boring B-5, encountered very soft high-plasticity CLAY(CH) material exhibiting low blow-count material (Weight-of-Hammer — WHO) at a depths between 5 ft. and 10 ft. below existing grades. Boring 8-5 was located near Moores Creek, with the low densities apparent within alluvial Fat CLAY(CH)just above the observed groundwater table. Alluvial sediments deposited in floodplain areas frequently have properties similar to fill soils. Therefore, It is possible some of the materials identified on our boring logs, specifically within Borings B-5, B-6 and B-7, and described as FILL may actually be more representative of alluvium or floodplain sediments. With the exception of Boring B-5, Standard Penetration Test (SPT) N-values in this soil layer generally ranged from 3 blows per foot(bpf)to 21 bpf,with an average value of about 9 bpf. Atterberg Limits testing completed on soil samples previously obtained in this portion of the site indicated that the soils encountered were generally consistent with the silts and clays of the geology, with Liquid Limit values of ranging from 30 to 33 with corresponding Plasticity Indices ranging from 9 to 10. Weathered rock, which for engineering purposes is defined as any residual material exhibiting a relict rock structure with SPT N-values greater than 100 bpf, was encountered in 2 of the 6 borings advanced, at depths of approximately 15 feet and 19 feet below existing grades. Hard rock, as defined by the depth of auger refusal, was encountered in four of the borings at depths ranging from 17.2 feet to 25 feet below existing grades. Weathered rock may be encountered .reit► ECS Protect No.28:1810 -6- February 3,2015(Revised: May 27,2015) during shallow excavations. Based on the limited disturbance permitted in this area of the site, we do not anticipate rock impacting construction. Boring logs describing the soil conditions encountered in the soil borings are included in the Appendix of this report. Groundwater Observations In drilling operations, water is not introduced into the boreholes and the groundwater position can often be evaluated by observing water flowing into the boreholes. Furthermore, visual observation of the soil samples retrieved during the drilling operations can often be used in evaluating the groundwater conditions. Groundwater was encountered during drilling in Borings B-5 and B-7 at depths of 9 feet and 18.5 below the ground surface. Groundwater was re- measured upon completion of drilling, both before and after removal of the augers, and was only encountered in Boring B-5 (after removal of augers) at a depth of 16 feet below the ground surface. Groundwater was also measured approximately 24 hours after completion of the borings and was not encountered within any of the borings. Cave-in depths in the borings ranged from approximately 3 feet to 16.4 feet below the existing ground surface. Groundwater encountered on sites with a shallow rock surface is generally perched. Specifically, rainfall that enters the site, either directly from overland flow or from adjacent properties, begins to percolate through low to moderately permeable, surficial soils and fill materials. Once the water percolation reaches the bedrock, which is relatively impermeable, it begins to flow at the interface of the rock and the soil. Only in the lowest lying areas and adjacent to existing creeks is a shallow groundwater table in a continuous condition. The groundwater conditions at this site are expected to be significantly influenced by surface water runoff and rainfall. The highest groundwater observations are normally encountered in late winter and early spring. Variations in the location of the long-term water table may occur as a result of changes in precipitation, evaporation, surface water runoff, and other factors not immediately apparent at the time of this exploration. ANALYSIS AND RECOMMENDATIONS Based on our subsurface exploration and geotechnical engineering analysis, along with the proposed construction information provided to us, the site appears to be suitable for the proposed SWM pond, providing an adequate stabilization mat is constructed to reduce the overburden pressures associated with the embankments and deep fills proposed. Although the magnitude, locations and specific composition/performance of waste cells cannot be accurately determined, the medium dense material encountered, combined with the observed cover depths at the locations explored, are conducive to construction of the nature proposed. The following ECS Project No.28:1810 -7- • February 3,2015(Revised: May 27,2015) sections present our analysis of the proposed design based upon the results of our subsurface exploration and geotechnical recommendations pertaining to construction of the pond. Global Stability Analysis The proposed dam embankment and road alignment slope were analyzed for global stability along two cross sections, designated as A-A and B-B, respectively. The general locations of Cross Sections A-A and B-B correspond with the alignments of Borings B-5, B-6, and B7 (Section A-A) and Borings B-1, B-2, and B-4 (Section B-B), which are shown on the Boring Location Diagram included in the Appendix of this report. Note that Boring B-1, although depicted on the diagram, was not drilled due to access constraints. The soil profiles were developed utilizing the information obtained from our subsurface exploration program, with topography based on the survey information provided to us. Soil strength parameters were estimated using conventional industry correlations based on soil type, index properties, and N-values as noted on the boring logs. Based on our experience, the strength parameters used in the analyses are conservative and have accounted for the presence of non-soil materials within the existing fill. The analytical soil properties and parameters are depicted on the output for each section and are provided in the Appendix. The slope stability analyses were performed using a two-dimensional computerized slope stability method based on a limit equilibrium analysis. The SLIDE computer program was utilized to perform these computations. The factor of safety against slope instability computed by the program is defined as the ratio of the sum of the moments (or forces) resisting failure divided by the sum of the moments (or forces) causing failure along a specified potential failure surface. Hence, a factor of safety greater than 1.0 indicates a marginally stable slope, while a factor of safety less than 1.0 indicates a potentially unstable or failed slope. Because of the uncertainty regarding in-situ soil parameters (and considering the uncertainty associated with the sporadic and heterogeneous composition of the waste cells), and the current estimated values assumed for the soil parameters, a factor of safety of 1.50 is considered to be the minimum adequate factor of safety for analyses performed without laboratory soil strength test results. Within SLIDE, we analyzed each cross section using both circular and block failure mechanisms. The analysis also included surcharge loading conditions, as follows. • Pond Section (A A): two-foot-thick compacted clay liner(250 psf) and 5 feet of water in pond (310 psf). Note that the clay surcharge does not plot on the figure, but is embedded in the design. • Road Section(B-B): 250 psf for traffic loading ECS Protect No.28:1810 -$- February 3,2015(Revised: May 27,2015) Note that the pond section does not pass through the dam embankment as it is approximately parallel to and offset from the profile line analyzed. On this section, existing topography retains the water, as shown in the figure. The cross section of the road alignment includes the distributed surface loading forces imposed by the constructed embankment. As part of the analysis for the roadway profile, the initiation/termination limits of the analysis were extended to the toe of the slope, but resulted in a higher factor of safety than that stated below. Based on our analysis, both cross sections (pond and roadway) meet generally accepted factors of safety for slope stability. The critical failure surface for the pond is circular with a FOS of 1.79, whereas that for the roadway section is a block failure with a minimum FOS of 1.61. Strippino Operations and Suborade Preparation The existing ground surface in the area of the proposed dam embankment, abutments, and spillway structures should be stripped of vegetation, rootmat, topsoil, any soft or unsuitable materials, to the extent that that land disturbance permit will allow. The stripping operations should be extended at least 10 feet, where possible, beyond the planned limits. Once prepared for construction, the stability of the subgrade shall be evaluated by a proofroll conducted by a loaded,tandem-axle on-road dump truck with an axle weight of at least 10 tons. This evaluation should be made by the Geotechnical Engineer; any soft or unsuitable materials encountered during this proofrolling should be removed and replaced with an approved backfill compacted to the criteria presented in the section entitled Fill Placement. If an extremely unstable subgrade is encountered, soft or unsuitable areas should be remediated by a large stone, reverse-graded base PRIOR to the installation of the 5-layer stone-geogrid stabilization mat specified previously and included within the Appendix of this Report. As mentioned previously, it is possible some of the material identified as undocumented fill actually represents unconsolidated floodplain alluvium, particularly at lower elevations closest to the drainage swaie. These materials are frequently difficult to distinguish when both are present in floodplain areas. However, these materials are not expected to perform under loading and pore pressure conditions consistent with areas in the near vicinity of the embankment dam subgrades. Therefore, for the purposes of this report, recommendations presented in the preceding paragraph pertaining to soft, unsuitable fill areas are also applicable to floodplain alluvium that cannot meet the requirements of a proofroll. The preparation of fill subgrades, as well as proposed roadway subgrades should be observed on a full-time basis. These observations should be performed by the Geotechnical Engineer, or his representative, in an effort to ensure that unsuitable materials have been removed and that ECS Project No.28:1810 _g- • February 3,2015(Revised: May 27,2015) the subgrade is consistent with the results of our soil borings and is suitable for support of the proposed construction and/or fills. Fill Placement Upon achieving competent subgrade materials and after the installation of the stabilization mats specified in the Appendix, controlled engineered fill should be placed, where appropriate, to planned subgrade elevations. Fill and backfill placed within proposed structural areas should be placed in lifts not exceeding 8-inches in loose thickness and moisture conditioned to within 2 percentage points of the optimum moisture content. We recommend that the lifts be compacted to at least 95 percent of the maximum dry density, as determined by ASTM D 1557A, Modified Proctor Test Method A (or 98 percent of the maximum dry density as determined by ASTM D 698, Standard Proctor Method),for the full depth of the fill. It should be noted that prior to the commencement of fill operations and/or utilization of any off- site borrow materials, the Geotechnical Engineer should be provided with representative samples in order to evaluate the material's suitability for use in a controlled compacted fill and to develop moisture-density relationships. Non-select type soils to be used as controlled fill should be approved inorganic materials, free of debris, and have a liquid limit and plasticity index less than 40 and 15, respectively. In order to expedite the earthwork operations, we recommend that where off-site borrow materials are required, they be comprised of select granular materials which will provide suitable support, and be easily compacted and be free draining. The footprint of the proposed embankment and roadway areas should be well defined, including the limits of the fill zones at the time of fill placement. Grade controls should be maintained throughout the filling operations. Filling operations should be observed on a full-time basis by a qualified soils technician to determine that minimum compaction requirements are being achieved. A minimum of one compaction test per 2,500 square foot area should be made for each lift. The elevation and location of the tests should be clearly identified at the time of fill placement. Compaction equipment suitable to the soil type used as fill should be selected to compact the fill. Theoretically, any equipment type can be used as long as the required density is achieved. Ideally, a steel drum roller would be most efficient for compacting and sealing the surface soil. A sheepsfoot roller should be utilized for compaction of the cohesive soils. Areas receiving fill should be graded to facilitate positive drainage away from pavement areas of any free water associated with precipitation and surface run-off. Fill materials should not be placed on frozen soils or frost-heaved soils and/or soils, which have been recently subjected to precipitation. Frozen soils should be removed prior to continuation of fill operations. Borrow fill materials, if required, should not contain frozen materials at the time a. 1 ECS Project No.28:1810 -10- February 3,2015(Revised: May 27,2015) of placement. Frost-heaved soils should be removed prior to placement of controlled, compacted fill. If any problems are encountered during the earthwork operations, or if site conditions deviate from those encountered during our subsurface exploration, the Geotechnical Engineer should be notified immediately. Embankment Fill Placement The soils encountered within the borings conducted in the vicinity of the stormwater management pond consisted primarily of Sandy SILT (ML) and sandy CLAY (CL) with varying amounts of fines. Much of the on-site silt and clay materials would normally be suitable for use as compacted structural fill, for either the pond dam or the road alignment, however; due to the waste material and trash debris encountered in this FILL material, these soils, as a whole, are not suitable for use as engineered fill for either the dam, pond embankment or structural embankment supporting the road alignment. We recommend select material be imported, from either offsite or of the western side of the development, to ensure project earthwork specifications are achieved. Highly plastic or potentially plastic CLAY(CH)soils, if encountered, should not be utilized as structural fill, or within the proposed stormwater management facilities unless utilized in the area adjacent to the proposed pond liner or within a constructed embankment of the pond requiring low-permeability soils. Acceptable soil types for construction of the embankment include soils having a USCS designation of ML or CL; and SM or SC having a minimum of 25% passing No. 200 sieve. Soils classified as SM in accordance with ASTM D 2487 may also be used as embankment fill which should be confined to fill areas downstream of the embankment crest. These fill materials are to be placed in lifts not exceeding 8 inches in loose thickness, moisture-conditioned to within 2% on the wet side of the optimum moisture content, and compacted with a sheepsfoot or tamperfoot roller to a minimum of 95% of the maximum dry density determined in accordance with ASTM D 1557A. Free draining materials should not be utilized in the construction of the embankment. It is recommended that new fill soils be benched into the existing soils, where possible, to verify adequate soil bonding of these materials. If the top of an exposed layer is too smooth, it should be rerolled with a sheepsfoot roller, or scarified prior to the placement of the next lift of fill. Although it is desirable to seal off fill surfaces on a daily basis using a steel drum or rubber tired roller, these surfaces should be scarified the following day prior to fill activities to reduce the creation of planes of seepage within the embankment structure. The preparation of fill subgrades and the operations of fill placement should be observed on a full-time basis by an authorized representative of the geotechnical engineer to verify that unsuitable materials are removed and fill is constructed in compliance with the recommendations presented within this report. ECS Project No.28.1810 -11- • February 11- February 3,2015(Revised: May 27,2015) Potentially Expansive Soils High plasticity soils, defined as soils with USCS symbols of MR and/or CH, were not encountered to a great degree within the borings, but are known to be present within the general vicinity and local geology. Due to their potential for shrink-swell with moisture fluctuations (expansive properties), such soils pose severe restrictions with respect to their use/reuse and generally require moisture adjustment for fill placement. We recommend that the high plasticity soils not be utilized as engineered fill, irrespective of the total depth of fill. During construction operations, it is important that every effort be made to identify the location and extent of high plasticity soils. An experienced geotechnical technician should be utilized to identify high plasticity soils, which require undercutting and/or replacement. Construction Groundwater Control Groundwater was encountered at two of the borings drilled as part of our recent subsurface exploration. However, groundwater conditions encountered at the site are likely to be influenced by surface water flow and infiltration. Specifically, water that enters the site migrates downward to the interface of the soil and rock. Once the water reaches the relatively impermeable rock, the water travels laterally, often over large distances. Such perched groundwater conditions will likely be encountered during construction operations. Also, the degree of fracturing within the rock materials can be increased and altered significantly by blasting operations. Therefore, it is common to have "springs" develop in areas that were previously dry once initial grading operations have commenced. Excavations performed at this site, especially those in or near existing drainage swales, generally encounter water flowing at the interface of the rock and the soil. These conditions should be anticipated and can be handled using French drains installed on the uphill side of any excavations performed on site. In addition, French drains may need to be installed in areas where springs develop. A typical French Drain Installation Procedure is included in the Appendix of this report. The perched groundwater conditions are seasonal in nature. While perched groundwater conditions may not be encountered during the summer months, such conditions can occur in the winter and late spring months. Specific recommendations regarding building design relative to these perched groundwater conditions are presented in subsequent sections of this report. The surface of the site should be kept properly graded in order to enhance drainage of the surface water away from the proposed areas of development during the construction phase. We recommend that an attempt be made to enhance the natural drainage without interrupting its pattern. MOW ECS Project No.28:1810 -12- February 3,2015(Revised: May 27,2015) Pond Liner A geosynthetic liner has been specified due to the requirement to limit the infiltration of water into the former landfill subgrade. We recommend that the liner be installed to at least the elevation of the 10 year storm water surface elevation. The liner should be installed along the embankment and extend a minimum distance of 100 feet upstream of the embankment. Either a natural clay liner or a geosynthetic liner should be feasible for use in the proposed pond, provided the recommendations presented herein are followed. The following text presents recommendations both for a natural clay liner and for a geosynthetic liner. Natural Clay Liner If a geosynthetic liner is not utilized, the installation of a compacted natural CLAY (CL or CH) liner at least two feet thick and having permeability properties of 104 cm/sec or less should remedy potential water infiltration through the soil. The existing vegetation and topsoil should be stripped prior to liner undercut and installation. The clay should be moisture conditioned to 2% points wet of optimum and compacted as previously stated. Geosvnthetic Liner A geosynthetic liner is an acceptable alternative to a natural clay liner and would require less undercut for installation. We recommend the use of Cetco Akwaseal® or other equivalent approved by the Geotechnical Engineer of Record for a geosynthetic liner. If a geosynthetic liner is utilized, it should be installed in accordance with the manufacturer's recommendations. These recommendations typically address proper installation equipment, shipping and unloading, storage, subgrade preparation, installation procedures, anchorage, sealing around penetrations, repair to damaged sections and liner cover. Proper subgrade preparation is critical for the proper installation of a geosynthetic liner. Prior to installation, the subgrade should be observed for soft spots, protrusions, and uneven surfaces such as ruts. Any such areas which are identified should be repaired prior to placement of the liner. Subgrades should be firm, stable under proofroll, and free of abrupt elevation changes, voids, cracks, ice or standing water. In addition, the subgrade surface should be smooth and free of vegetation, sharp-edged rocks, stones, sticks, construction debris, and other foreign objects that may contact the liner, as these have the potential to puncture the liner. Due to the amount of rock excavation which will likely be required for establishment of the pond invert elevation, and the potential for sharp-edged rocks to remain as a result of blasting, we recommend a six-inch layer of cover soil be placed prior to installation of the pond liner. The subgrade should be rolled with a smooth-drum vibratory roller to remove any significant wheel ECS Project No.28:1810 -13- • February 3,2015(Revised:: May 27,2015) ruts, footprints, or other abrupt grade changes. Protrusions extending more than one half inch from the subgrade surface should be manually removed or pushed into and flush with the surface. Prior to the placement of cover soils, the liner itself should be inspected to confirm that it has not been damaged. Liner overlaps should be checked for adequate length and penetrations should be checked for proper construction. The placement of cover soils should be monitored to help ensure the liner is not damaged by equipment or rocks in the cover soil. The thickness of the cover soils should be checked periodically to ensure the minimum specified cover depth is achieved. In our experience, the cover soils above the liner should generally be about one foot in thickness. However, we recommend that the thickness of this layer be in accordance with the manufacturer's installation procedures. Seepage Analysis Since we have recommended that dental concrete and a clay or geosynthetic liner be utilized within the pond area to the height of the 10-year storm elevation, we have not performed seepage analysis as part of the preparation of this report. If any changes to the design of the pond are made such that the pond basin will not consist of weathered rock material, and the liner or dental concrete are eliminated from the design, ECS should be contacted immediately to perform a seepage analysis of the proposed dams which might be affected. Fill Zones—Avon Street Extended As shown on Bohler Engineering's plan set entitled "WPO Plan—Landfill Capping for 5th Street Station" and dated December 23, 2014, substantial fill volumes are planned to be placed on either side of Bent Creek Parkway at the entrance from Avon Street Extended. We have reviewed boring logs provided by Schnabel Engineering in this area, and evaluated initial and final grade changes proposed. Based on the roadway and pond stabilization mats proposed, and the conditions given in the borings, we do not anticipate stability issues in this area of site provided the 3H:1V slopes are constructed per specification. Construction Considerations Proper compaction and control of fill is an important aspect of this project. We recommend that all fill operations be observed by a qualified soil technician under the direction of the Geotechnical Engineer to determine if minimum compaction requirements are being met. The Contractor should provide and maintain good site drainage during earthwork operations to help maintain the integrity of the surficial soils. All erosion and sedimentation shall be controlled in accordance with sound engineering practice and current jurisdictional requirements. ECS Project No.28:1810 -14- February 14February 3,2015(Revised: May 27, 2015) Landscaping&Aesthetics We understand the dam embankments are often constructed with landscaping and/or water features constructed in tandem with the principal spillway structure. Dam appurtenances should generally be constructed such that they would not cause debris to collect, or otherwise obstruct the flow of water over the dam embankment during overtopping events. DCR requirements do not allow the planting of trees or other woody vegetation on the embankments, abutments, or within a buffer zone extending 25 feet beyond the abutments and 15 feet beyond the toe of the dam. Protective vegetative grass cover contributes to embankment stability by helping to stabilize embankment soils and therefore is generally a requirement for embankment dams. Grass cover should be maintained with a length of 4 to 12 inches. Bare spots in the grass cover, if they occur, should be re-seeded and stabilized to help restore protective vegetative cover. If vegetation other than grass cover is landscaped into the embankments of the dam, this vegetation should be limited to non-woody vegetation such as annuals, ornamental grasses and perennials which would not be expected to grow roots in excess of a quarter inch in diameter. Closing This report has been prepared in order to aid in the evaluation of this site and for use by SJ Collins and the design and construction team. The scope Is limited to the specific project and location described herein, and the project description represents our understanding of the significant aspects relevant to soil and foundation characteristics. In the event that changes in the development are planned, ECS should be contacted so the changes can be reviewed and the conclusions of this report modified or approved in writing by ECS. It will also be necessary for the GER to review the design plans and prepare or review the Geotechnical Specifications for submission with the site plan. Without this review, we will not be responsible for misinterpretation of our data, our analysis, and/or our recommendations, nor how these are incorporated into the final design. This report does not reflect any variations that may occur between the test locations. In the performance of the subsurface exploration, specific information is obtained at specific locations at specific times. However, it is a well known fact that variations in soils and rock conditions exist on most sites between boring locations and also such situations as groundwater levels vary from time to time. The nature and extent of variations may not become evident until the course of construction. If variations then appear evident, it will become necessary for a reevaluation of the recommendations for this report after performing onsite observations during the construction period and noting the characteristics and variations. i ECS Project No.28:1810 -15- • February 3,2015(Revised: May 27,2015) This report was prepared for the sole use of SJ Collins and its consultants, the only Intended beneficiaries of our work. The scope is limited to this specific project and locations described herein and our description of the project represents our understanding of the significant aspects relative to it. In the event that any change in the nature or location of the proposed construction outlined in this report or the accompanying plans and specifications, we should be informed so that the changes can be reviewed and the conclusion of this report modified or approved in writing by the Design Engineer. No other party should rely on the information contained herein without prior written consent of ECS Mid-Atlantic, LLC. APPENDIX Boring Location Diagram Unified Soil Classification System (USCS) Reference Notes for Boring Logs Boring Logs (B-2 through B-7) Global Stability Analysis Outputs Roadway and Pond Subgrade Stabilization Mats Summary of Laboratory Test Data r 1.- •\:-.. . . /// ' / / • / I a I 1 t .71 htfir491-1 ie•Et - .10 z.• . ' 4 1 . • .,2'. , /I/1 . /it // .4 t . -4 • , ' ' ,zef / 0 ' I .1.. .' fijiwilmik-'1111.-_ 4 3:4? ---4.. :7 11'. '. '‘s\x '\\'' ,,, ••• •/ ,lie- / I 7 7 . / 7 7 ilit .7, ''4* '• •• •-* 44" • // I, / It, ii d, .;:„..1 , H '1.74ZWIt li'\ ' • I 1 / I ALIII4t#4.1 _ V / 1 i / 1 ' litt‘j, s\ i . L 11,k i\ i • ,•:•:s...,,,, I ,tiii gill. 1 . i \se\•\\ \\\ ........... ‘ \\--.... .. • •• , x •..\ 7 7 °'110Ats Xi .P., IPA 7 , \ \ , ' *'•• . ,.. AlillueL\N \ , tt , , -....‘ .k::\..,..:,..., , , ..,.... .,......... .. '''' '''''''''' , N•,,N.%*'‘*:.*' ,..,..`,..... ..... 7.' * , ' .:\** ' *'':*:''' ,T, :' '**,•.,,7,,,N''''\'''\.,:Kl.'''.'N*".‘'' . - -- N._..,,,k,...,„ , 1., ."::-.,, 'N.::-...,\:,,s..,,- ...... ,..-.=,....,,,,,,,. -- - --•, ' '• ! . . ...,1 ,,,,,*,-... ....L-.. •),... i _ --INI:41°4: .'`..b7''',2Nt .• \ ''' ..-,s ''. • l i R . \ „s \ \ Vex , '..•'''''''s \'"`--ZZ-<,..„,... ..,`^ 1 RJR. ' 113 R.1...4 5, , \ \ \\ .- •'' -"s444,...... '..,‘••-•::••.'..,,,, .•, 2. N',14:4.Plr4. '' . , \ N 0° l!ie°L,4;,4b..4> 1 \ \ g- '--'1 ..1.4„: ' .,• 4. 4 1 ...A \ 1 ST •..'i , . _ s -•.. '..-;,'-i..%,ie, 1, . 'k u' : ‘* ' • - "--... -;•".,,,....-`1, ' I 1 41t5' t et 1 1 sN•,... 'i'''' 4 ' ."i Ecc ' ' t ' I •• -. A. • _.' 4rt„ ../. I I .1. ' 1 1 i 1/ii ,-.--- •:........N.........,....... —.."---...„4.......j.. 1/ ....,,. v., rni , s.. • - ••• ''''N...i. .., , .,,,,,, to „ -•,'•>•_•,, • '''...„.2. 1 -,, '--- ,-----, 5th Street Station 71. , 2&-1810 Proposed Landfill Pond Boring ECS Mid-Atientic,LLG Charlottesville, Virginia 4004 Huntarstand Court,Suite 102 Location Diagram Charlottesville,Virginia 22911 / CLIENT JOB BORING# SHEET taiii;;;11 S.J.Collins Enterprises 28:1810 B-2 1 OF 1 PROJECT NAME ARCHITECT-ENGINEER 5th Street Station Landfill Pond Slope Stability SITE LOCATION -0-CALIBRATED PENETROMETER TONS/FT= Avon Street Exteded,Charlottesv'Ne Virginia NORTHING LASTING 1sikriow ROCK QUALITY DESIGNATION a RECOVERY ROD% -—- REC% g DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER LIQUID = LI>IT% CONT: LIMITS, E Z E i 1 BOTTOM OF CASING: LOSS OF CIRCULATION ZO I � SURFACE ELEVATION 420 ft, 0 F ®STANDARD TION D (CL FILL)SANDY LEAN CLAY,Reddish Brown, %//// 420 1z _ S-1 SS 18 6 Moist, Stiff to Very Stiff,Contains Rock '//^ s 1 C. Fragments and Roots 4 - S-2 SS 18 2 // 11 ` a 21 - / 13 5 - (CL FILL)SANDY LEAN CLAY,Contains Rock 415 5 _ S-3 SS 18 6 4 6 C. Fragments and Roots,Reddish Brown,Moist, 4 — \Medilnrl Stiff,Contains Glass (CL FILL)SANDY LEAN CLAY,Black,Moist,j ✓ Stiff to Medium Stiff,Contains Rock Fragments, ,./"... Roots,Glass,Wood And Metal S-4 SS 18 3 6 11 ,_ 10 410 5 — !1 - S-5 SS ie 5 /72.-- a 15— 405 3 — 5-6 SS 6 4 Highly Weathered Moderately Hard,Greenish _ Drone =' - Gray.Meta-Slitstone - 50/6 20—_ 400 — AUGER REFUSAL n 20.50' ._ 25— —395 30— --390 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES.IN-SITU THE TRANSITION MAYBE GRADUAL. 4 WI Dry Ws0 WOO BORING STARTED 11/18/14 WLoBCR) T, WL(ACR) BORING COMPLETED 11/18/14 CAVE IN DEPTH ©9.00' 31 WL RIG D-50 FOREMAN Howie DRILLING METHOD HSA CLIENT JOB# I BORING# SHEET S.J.Collins Enterprises 28:1810 B-3 I 1 OF 1 PROJECT NAME ARCHITECT-ENGINEER ril 5th Street Station Landfill Pond Slope Stability SITE LOCATION -0-Avon Street Extended'Charlottesville.Virginia BR'�D�N�ROM TONS/FT' NORTHING I EASING I STATION ROCK QUALITY DESIGNATION&RECOVERY RQD% -—- REC% ' DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER G UQUID UMC1% CONTENT% LIMrr% E Q t_ 1 o BOTTOM OF CASING a LOSS OF CIRCULATION g X +♦ Q 1 1 I i SURFACE ELEVATION 4.70 ft. ce < 3 i 2 SLO®STANDARD PENETRATION W 1 U – (ML FILL)SANDY SILT,Orangish Brown, _ 470 1 =S-1 SS 18 8 Moist,Soft 2 ;•3 —. 1 ` S-2 SS 18 12 (CL FILL)SANDY LEAN CLAY,Greenish ;/ 4 C.- Brown,Moist,Very Stiff,Contains Rock /�� 8 17 5 Fragments And Glass S-3 SS 18 6 /�% 465 $ — ...";/: .////f;._ 9 12 21 .� - -S-4 SS 18 4 (ML FILL)SANDY SILT,Brown,Moist,Stiff, f11 Plastic And Paper s ' + Contains Rock Fragments, 10 _ -460 4 .--S-5 SS 18 8 (CL FILL)SANDY LEAN CLAY,Greenish %/ 4 TS Brown,Moist,Stiff,Contains Rock Fragments, 4 •• Glass And Wood r-455 5 SB SS 18 0 7 20 _ - B t4:• 450 B — i.fr:/' S-7 SS 18 2 to 25 i�//� 5 11 .., - END OF BORING Q 25.00' 30— — —440 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES.IN-SITU THE TRANSITION MAY BE GRADUAL. SZ wL Dry ws❑ WDC BORINGSTARTED 11/18/14 f WL(BCR) T WL(ACR) BORING COMPLETED 11/18/14 CAVEINDEPTH @ 15.40' 32 WL RIG 0.50 FOREMAN Howie DRILLING METHOD HSA CLIENT JOB II BORING rf SHEET l,,` .,1 S.J.Collins Enterprises 28:1810 B-4 1 OF 1 PROJECT NAME ARCHITECT-ENGINEER aigi 5th Street Station Landfill Pond Slope Stability ,. SITE LOCATION -a-CALIBRATED PENETROMETER TONS/FT2 Avon Street Extended,Charlottesville.Virginia NORTHING EASTING STATION ROCK QUALITY DESIGNATION&RECOVERY ROD% -—- REC% g DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER LIQUID • 9LIMIT% CONTENT% LIMIT% Y g Es t BOTTOM OF CASING II LOSS OF CIRCULATION Z X IN / I i g SURFACE ELEVATION 484 ft. fq 1 .q 0 STANDARD PENETRATION BLOWS/FT 0 _ (ML FILL)SANDY SILT,Brown,Moist,Medium 3 — SA SS 18 10Stiff to Soft,Contains Organics,Plastic And ,— b 8 Glass — 2 S2 SS 18 6 _ 1 3 2 —480 5 a 2 _ S3 SS 18 2 _ 1 3 2 (CL FILL)SANDY LEAN CLAY,Black,Moist, ////,._415 3 _ S 4 SS 18 12 Stiff to Hard,Contains Rock Fragments,Wood, i% 3 10Glass And Metal — 6 - S-5 SS 18 6 r, ..._470 10 3 15— cf—z,„_ _ /,'/://:.- - AUGER REFUSAL @ 17.20' — — —485 20— — a --460 25— — —455 30— — THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES.IN-SITU THE TRANSmON MAY aE GRADUAL. 4 WL 12.00 WS❑ w00 BORING STARTED 11/18/14 g WL(BCR) T WL(ACR) BORING COMPLETED 11/18/14 CAVE IN DEPTH @7.20' WL RIG D-50 FOREMAN Howie DRILLING METHOD HSA CLIENT JOB# I BORING# SHEET S.J.Collins Enterprises 28:1810 &5 I 1 OF 1 PROJECT NAME ARCHITECT-ENGINEERWI 5th Street Station Landfill Pond Slope Stability SITE LOCATION -0- Avon Street Extened Charlottesville,Virainia cALIaRATED PENETROMETER TONS/Fr NORTHING STING I STATION ROCK QUALITY DESIGNATION 8 RECOVERY ROD% -—- REC% DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER LIQUID if o £ E LIMIT% CONTENT% LIMIT% E 2 6 BOTTOM OF CASING* LOSS OF CIRCULATION g$ 1 1 SURFACE ELEVATION 367 ft, 4 STANDARD PENETRATION 0 - (SM)ALLUVIAL SILTY SAND,Brown,Moist, __ 1 __ 51 SS 18 18 Very Loose 1 , — Iqat x L 385 S-2 SS 18 18 �-- 1 (CL)ALLUVIAL LEAN CLAY,Trace Sand, a 5 - Brown,Moist,Medium Stiff _ 5-3- SS 18 10 (CH)ALLUVIAL SANDY FAT CLAY,Gray, — woh Moist,Very Soft _ wd� 380 — (SM)ALLUVIAL SILTY SAND,GraMoist, ' • 1 S-4 SS 18 6 VeryLoose w� ` 10 r I 1 - II 355l •.^S-5 SS 8 8 l B Highly Weathered,Moderately Hard,Greenish T say • 15-- Gray,Meta-Siitstone �• Wiart- _- 5.z,'. 350 - AUGER REFUSAL @ 18.20' 20-- — —345 25- _ — _- —340 3D-^ THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES.IN-SITU THE TRANSITION MAY BE GRADUAL. V. WL 9.00 WS❑ WOO BORING STARTED 11/17/14 WL(BCR) f M4(ACR) 16.00 BORING COMPLETED 11/17/14 CAVE IN DEPTH @ 4.00' wt. RIG 0-50 FOREMAN Howie DRILLING METHOD HSA 3 CUENT JOB# BORING# SHEET S.J.Collins Enterprises 28:1810 8-6 1 OF 1Ers PROJECT NAME ARCHITECT-ENGINEER 5th Street Station Landfill Pond Slope Stability _ - SITE LOCATION -0-CAUBRATED PENETROMETER TONS/FT2 Avo Street Extended Charlottesville Virginia NORTHING EASTII�iG STATION ROCK QUALITY DESIGNATION&RECOVERY RQD% -—- REC% g DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER UOUID LIMIT% CONTENT% LIMIT% E 2 a BOTTOM OF CASING: LOSS OF CIRCULATION p X F SURFACE ELEVATION 402 ft. j ®STANDARD PENETRATION linW BLOWS/FT U _ (ML FILL)SANDY SILT,Brown,Moist,Soft, - 2 — S-1 SS 18 16 Contains Glass,Coal,And Rock Fragments — 1 3 —. `--400 - 2 S•• 2 SS 18 16 2 : .: 4 5 _ (CL FILL)SANDY LEAN CLAY,Reddish Brown, /' 3 — S-3 ' 16 16 Moist,Medium Stiff,Contains Rock Fragments /� 3 8 �' — And Glass '� 5 385 I S-4 SS 18 s (CH FILL)SANDY FAT CLAY,Grayish Black, - i 0 3 10— Moist,Soft to Hard,Contains Rock Fragments, 2 Glass,UVaod,Plastic And Metal /,/ 390 - S• -5 SS 18 821 E 2 co,3 15 _ 2 — �f 385 s-8 SS 18 8 3 5 27 •:0 20 .°-,7"..— , 22 — 380 33 25 S-• 7 SS 18 6 i":/- 21 48 0- END OF BORING(4)25.00' ' /_ — —375 30— — THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY UNES BETWEEN SOIL TYPES.IN-SITU THE TRANSmON MAY BE GRADUAL. V. WL Dry ws❑ wo❑ BORING STARTED 11/17/14 * WL(BCR) 3.1. WL(ACR) BORING COMPLtI tL) 11/17/14 CAVE IN DEPTH©3.0D' f WL RIG D-50 FOREMAN Howie DRILLING METHOD HSA CLIENT JOB (BORING# SHEET jJj „'Eliffill4f- w"- S.J.Collins Enterprises 28:1810 B-7 1 OF 1 PROJECT NAME ARCHITECT-ENGINEER 5th Street Station Landfill Pond Slope Stability SITE LOCATION Avon Street Extended,Charlottesville, -0-CJWBRATED PENETROMETERTONSIFTZ NORTHING JEAS11IG ION ROCK QUALIY DESIGNATION 3 RECOVERY RQD% -—- REC% g DESCRIPTION OF MATERIAL ENGLISH UNITS PLASTIC WATER LIQUID g• UMIT'16 CONTENT% LIMMIIT% B BOTTOM OF CASING' r)LOSS OF CIRCULATION 2 X • 1 I I i 1 SURFACE ELEVATION 415 ft. r4 [ 0 STANDARD PENETRATION (CL FILL) BLOWS/FT Y LEAN ®©ma AY,Brown,Moist, Pr 3 SUIT to Medium Stitt ConlainAs Rock Fragment s, 4 4 ■■■■ Wood,And Glass s ®En® 43 11 .. 5 EMI= 7 mom 410 3 7 G ,,,1 4 Trash,Paper,Glass,Metal,Concrete And Rock T 101111®�� Fragments,Molst,Medium Stitt To Hard 'I 7 C. 405 9 15 1111:111111119 7 1 e 4009 1111 ley :Mae 7 385 4 20 III" w/ ® %%% 21 25 ©�� '/ 390 16 34 D END OF BORING @ 25.00' 30 385 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES.IN-SITU THE TRANSr110N MAY BE GRADUAL, 4 WL 18.50 ws❑ WOO BORING STARTED 11/17/14 Z WL(BCR) * WL(ACR) BORING COMPLETED 11/17/14 CAVE IN DEPTH @ 5.00' I. RIG D-50 FOREMAN Howie DRILLING METHOD HSA UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D 2487) Major Divisions Group Typical Names Laboratory Classification Criteria Symbols Well-graded gravels, gravel- y) sand mixtures, little or no nC„=Daa&D,a greater than 4 > cc GWfines c C,=(D30)2/(D,oxDeo)between 1 and 3 E 15 N a — m� Poorly graded gravels,a) 0 °a tj. GP gravel-sand mixtures, little or LO Not meeting all gradation requirements far GW no fines 9 2 m a N a0 N a5 $"a 8 a 2"6 2 a C It m c7 w c c 'o Silty gravels, gravel-sand a Atterberg limits below"A"line o =2 s m mixtures am'� or P.I.less than 4 Above "A" line with P.1. o m �, between 4 and 7 are N -t.. m 3 m m n Es =.c) ab n a borderline cases requiring Z o=a >a N o use of dual symbols a C a o. a 6 . GC Clayey gravels, gravel-sand- N Atterberg limits below"A"line aclay mixtures me o or P.I.less than 7 �C la to a m C o •o o SW Well-graded sands, gravelly IF IS 2 E a' C„ =Dr,o/D,a greater than 6 m c c sands,little or no fines m C.=(1330)/(13,axO60)between 1 and 3 Um aaa to0a, >O CI)E od m_� mu m a 2 Poorly graded sands,gravelly V N m ,, Not meeting all gradation requirements for SW m 0— SP sands,little or no fines aro a rj C E n c.`-� C7 ar a p v a o ,t, m 0t7m W oZ ° d wi main w a c m 8 Siltysands,sand-silt mixtures Q)c c...= Atterberglimits above"A"line s E "4c .° m or P.I.less than 4 Limits plotting in CL-ML m `m rasa v .re d a» zone with P.1. between 4 m 3.a c u al c v n.N and 7 are borderline E E a m e IS C c m cases requiring use of U) O. g c m$ Ndual symbols a SC Clayey sands,sand-clay a, a u Atterberg limits above"K line mixtures a3 m I° 2o~ with P.I.greater than 7 OD m_.12an Inorganic silts and very fine :- ______. E ML sands, rock flour, silty or Plasticity Chart a c clayey fine sands, or clayey m= silts with slight plasticity > u g Inorganic clays of low to 60 .. _._.._..., d c d medium plasticity, gravelly oto E CL clays,sandy clays,silty clays, , i "A"line N 0-3 a lean clays i 50 L----- • a Q Organic silts and organic silty Z = OL clays of low plasticity i i CH a se 40 I- la" Inorganic silts, micaceous or a CL Ti m c diatomaceous fine sandy or d E c MH silty soils,elastic silts I 30 `�- — - I. C a a m , _ , ----T--- E°� a m c? CH Inorganic clays of high 20 ��1� MI-I un OH )i ,-1 ai a a CA plasticity,fat clays r E 2 E [0 r I Csrii ' OH Organic clays of medium to MI!l.d�ML anif OL ' a high plasticity,organic silts i 0 -- - -- _.:..�. E 0 10 20 30 40 50 60 70 80 90 100 0 a-`2 Liquid Limit C m o Pt Peat and other highly organic j I O a soils L— _....__.._ ---......__ _l Division of GM and SM groups into subdivisions of d and u are for roads and airfields only. Subdivision is based on Atterberg limits;suffix d used when L.L.is 28 or less and the P.1.is 6 or less;the suffix u used when L.L.is greater than 28. °Borderline classifications, used for soils possessing characteristics of two groups,are designated by combinations of group symbols. For example: GW-GC,well-graded gravel-sand mixture with clay binder. (From Table 2.16-Winterkom and Fang,1975) REFERENCE NOTES FOR BORING LOGS I. Drilling Sampling Symbols SS Split Spoon Sampler ST Shelby Tube Sampler RC Rock Core, NX, BX,AX PM Pressuremeter DC Dutch Cone Penetrometer RD Rock Bit Drilling BS Bulk Sample of Cuttings PA Power Auger(no sample) HSA Hollow Stem Auger WS Wash sample REC Rock Sample Recovery% RQD Rock Quality Designation II. Correlation of Penetration Resistances to Soil Properties Standard Penetration (blows/ft) refers to the blows per foot of a 140 lb. hammer falling 30 inches on a 2-inch OD split-spoon sampler,as specified in ASTM D 1586. The blow count is commonly referred to as the N-value. A. Non-Cohesive Soils(Silt,Sand, Gravel and Combinations) Density Relative Properties Under 4 blows/ft Very Loose Adjective Form 12%to 49% 5 to 10 blows/ft Loose With 5%to 12% 11 to 30 blows/ft Medium Dense 31 to 50 blows/ft Dense Over 51 blows/ft Very Dense Particle Size Identification Boulders 8 inches or larger Cobbles 3 to 8 inches Gravel Coarse 1 to 3 inches Medium 1/2 to 1 inch Fine 1/4 to'/inch Sand Coarse 2.00 mm to%inch (dia.of lead pencil) Medium 0.42 to 2.00 mm(dia.of broom straw) Fine 0.074 to 0.42 mm (dia. of human hair) Silt and Clay 0.0 to 0.074 mm (particles cannot be seen) B. Cohesive Soils(Clay,Silt,and Combinations) Unconfined Degree of Plasticity Blows/ft Consistency Comp. Strength Plasticity Index Under 2 Very Soft U dertst)0.25 None to slight 0—4 3 to 4 Soft 0.25-0.49 Slight 5—7 5 to 8 Medium Stiff 0.50-0.99 Medium 8—22 9 to 15 Stiff 1.00-1.99 High to Very High Over 22 16 to 30 Very Stiff 2.00-3.00 31 to 50 Hard 4.00-8.00 Over 51 Very Hard Over 8.00 Ill. Water Level Measurement Symbols WL Water Level BCR Before Casing Removal DCI Dry Cave-In WS While Sampling ACR After Casing Removal WCI Wet Cave-In WD While Drilling 0 Est. Groundwater Level V Est. Seasonal High GWT The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering,without adding fluids,in a granular soil. In clay and plastic silts, the accurate determination of water levels may require several days for the water level to stabilize. In such cases,additional methods of measurement are generally applied. .g E E1o &r, to v c i g o o $ g -r 0 8 ,. 1\ , V lick 0 0 0 0 0 z • cr' in ) II .0 L Z 80 p� N C i ►f1In Y1 Ih K1 Q _ - C it el N N a ,.... VI rl ri N jji} N [—I I] ❑ I... to to rS O E 0 so Z a 8, c �� 2 2 Di to H ait -o V Z in vi o N - {f O1 - tti . o E - C3 . L8 1 a�9 . . . 1 . . . ,069 . . , ' . , . 099 . . . 1 . . . ,OOS , . , ' . . . a . . . ' . , . .0 . . . . ' . . . (4E . . . ' . -A 0. 8 11 !1 " 8 el Si>,ill 8 ei IN Z ' L g fq 8 in g \Ill,. o IL Oa. ti N in N in to 0 j 1 a s p p g I g g O N § O 1.i 1 0 0 0 0 0 0 E 0 to° o u° a u° o ° 2 a, N 0 0 0 0 0 0 2 2 2 2 2 2 Vt 011 ... 8 1 i I I • G +.. E C s EEEfEE cam. Gm) ;_ tu Lu 2 ..., ''' NN z m a Z a G ' obi , . ' , . ' 069 . . . , . . . , . oar , . . . . .� 0617 ECS MID-ATLANTIC, LLC "Setting the Standard for Service" Geotechnical•Construction Materials•Environmental•Facilities February 14,2013 Via email:danasicoliinsent.com Mr.Daniel Tucker 5 SW Broad Street,Suite B P.O.Box 214 Fairbum,Georgia 30213 • ECS Project No.:28:1552 Reference: Bent Creek Road Subgrade Stabilization- 5th Street Station Development located in Albemarle County,Virginia Dear Mr.Tucker. ECS Mid-Atlantic, LLC (ECS) Is pleased to present recommendations for ground improvement and subgrade stabilization along the Bent Creek Road alignment for the referenced project. Due to the fast track nature for this phase of construction these recommendations have been incorporated into an abridged, letter report. The contents of this letter will be finalized and incorporated into our final geotechnical study for this project. Jiacktround The road alignment is proposed along an area north of Interstate 64 that was formally utilized as a municipal landfill. Based on State requirements to minimize disturbance in this area the options to improve and stabilize the subgrade are somewhat limited. Although the location of the waste cells are generally known, the thickness of the cells likely varies considerably throughout the site, and the composition of the landfill contents are heterogeneous. From our review of the road profile developed by Bohier Engineering, the elevation changes between existing grades and bottom of road section subbase vary as much as 30 feet. Additionally,changes at existing grades from one side of the road bed to the other vary as much as 5 feet. ;roil Conditions Three geotechnical borings (8-667 through B-69) were advanced to depths of 15 feet along the road alignment. Nine environmental borings(probes only,E-1 through E-9)were advanced to depths of up to 5 feet along the road alignment to facilitate gas monitoring in this area of the site. 11 of the 12 total borings encountered trash and debris at shallow depths (in most cases less than one foot beneath existing grades),which is consistent with earlier studies that confirm the existence of a former municipal landfill in this vicinity. Boring B-67,located nearest Avon Street Extended,encountered orange brown sandy CLAY(CL)to a depth of 7.5 feet below the existing grade. Auger refusal,indicating rock,occurred 1601 Airport Road,Charlottesville,VA 22911 • T:434-973-3232 • F:434-973-3238 • wwwecslimited.com ECS Carolinas,LLP • ECS Florida,LLC • ECS Midwest,LLC • ECS Mid-Atlantic,LLC • ECS Southeast,LIC • ECS Texas,LLP Bent Creek Rood Stabilization 5th Street Station ECS Project No.28:1552 February14,2013 Page 2 at a depth of 7.5 feet below the existing grade. Additional hand augers are currently being advanced near borings proposed (Borings B-70 and 8-71) but not drilled due to access issues in the field, along with additional hand augers proposed near the bottom of the creek bed in locations that can only be accessed by foot traffic. Based on our knowledge of the geology of the site and recent subsurface exploration at locations to the north and west of this vicinity,the near-surface soils in the majority of this area of the site likely consist of sandy CLAY(CL)or sandy SILT(ML)material. Geotechnical Recommendations in order to provide adequate support for the road surface and mitigate the differential settlements that are expected as loads are applied over the landfill, the following recommendations for ground improvement and subgrade stabilization are made: - The area proposed for the construction road (future Bent Creek Road) shall be cleared and grubbed to the greatest extent possible within the confines of the project's permit and minimum disturbance requirements. Larger root balls and root masses should be removed and disposed of in order to reduce the volume of organics left in place beneath structural fill areas. - Where necessary and required to align grades along the road cross-section, minimum lifts of engineered fill shall be placed and compacted in accordance with the geotechnical requirements for this project. Briefly, the fill should be placed in lifts not exceeding eight inches in loose thickness, moisture conditioned to within +1- 2% of the optimum moisture content and compacted to at least 95% of the maximum dry density obtained in accordance with ASTM Specification D-698, Standard Proctor Method. Engineered fill is defined as on-site soils classified as SP,SM,SC,CL, ML,GM,GP,or GC which are free of organics and other deleterious, non-soil materials. This material has been identified and is available on the development portion of this project. Imported material should classify as CL, ML, SM, SC, SP, or better. Suitable imported material should have a maximum Liquid Limit of SO and maximum Plasticity Index of 25. Maximum aggregate size for all materials should be limited to four inches. - At the greatest depth possible(i.e.prior to placing fill required to achieve final design grades for Bent Creek Road)a stone/geogrid system shall be initlled to limit differential settlements and stabilize the subsurface near the waste cells. The system should be installed along the entire road alignment where construction is located on the former land fill, and the system should extend a minimum of 5 feet out from the outer most edge of the loaded pavement section. The system shall be constructed of the following components,installed in the order given below: 1. GRID 1-Tenser TriAx TX1901 Geogrid or equivalent installed on cleared existing grades or minimum lifts of compacted engineered fill. Minimum laps shall be three feet. Bent Creek Road Stabilization Sth Street Station PruettNo.28.15.52 February24,2013 Pape 3 1 STONE 1 - 18 inches of VDOT Grade No. 3 stone installed over the top of GRID 1. Alternatively, crushed stone from onsite rock or crushed concrete may be utilized, subject to review and approval of material submittals. 3. FABRIC 1 — Mirafi 180N needlepunched nonwoven geotextile or equivalent installed over STONE 1 to prevent the migration of fines into open graded stone. Minimum laps shall be three feet. 4. GRID 2- Tenser TriAx TX160 Geogrid or equivalent installed on FABRIC 1. Minimum laps shall be three feet. 5. STONE 2 — 12 inches of VDOT Grade No. 21-A stone placed in two lifts, moisture conditioned to within 4/- 2% of the optimum moisture content and compacted to at least 95%of the maximum dry density obtained in accordance with ASTM Specification D-698,Standard Proctor Method. Please see Enclosure(1)for product specification sheets to compare alternate manufacturer mechanical properties. Substitutions shall be reviewed to ensure performance requirements are met. If the road is to be utilized for heavy equipment during the construction phase of the project,It is recommended that only GRID 1 and STONE 1 be installed to prevent damage to subsequent component layers. When final grades are required to construct Bent Creek Road, engineered fill, as defined above, may be placed in compacted lifts above SCONE 2. We have appreciated the opportunity to be of service to you. The Information presented herein will be finalized and included with our final geotechnical report for this project. If we can be of further assistance to you during the early construction phases of this project,please do not hesitate to contact us. F,ALTJi *4 $ER SARANT Sk LiC.No.042553 a A�� Z itrAo13 „t7 Steven Crouch Alexander Sarant,P.E. Engineering Geologist Principal Engineer End: (1)Product Specification Sheets Tei sar i : i,... V',hi'r 91 H••I Product Specification-Tr1A00TX1901.Geofiridl TeeeahalersitleW CogamIlin roma Ike Apt uchange Its want eMd atlandiff a.nkiMsMMaagwyalike pains spedgd lrraeerlli udeleutildiunkrrmrtlat MwMtigr tleu ll*an lit deskierposswirad papists am moat s dlrtlisreadi skablebriblotenisi mu sidtbilme. GeneralTensor TriPat®Gs/grI 1. Mt geogtid is maimfactamd hem apunched petypropyhmesheet,*Molt is then minted WON.l ally ♦'��iTAt equheteral dilutions so thMUla leselUn6 sive shall have a Wish degree Mmolecular(Mutation,which tontines atleast ilput timeaptthe num otthe Mai"nada. Al2. Tee amnesties a:Mutingto the performance eta mechanically stabilized layer include the following V���YAY kW=Praeetiks Limgibukal Diagonal Mineral • R ' l 0a) 60 DAM 60(2.40) m rRecbutedar Amami shape Manipur StamtwalIntern?, • Jumilan officiancym,7,% • teoImplc Stiffness MOM93 0.0 • Radial stiffness atiowetrahl l,IIJ/m6+0.5%sdrada 380Mine O.5%dada) (23.988) DIffability • Reatstaaee to chemical degradation's) nosh • Resistance toaitravioletlight and w$ut.rh►6m 705( Rwandan and Delhaey 11m1x&Maid"di bedilirsredtotbaj Modtwatsd8rtachle6ledbdllallyidsetl6odendammbelymessark43.0meterst9.6fat) andrn4 mesa(sa.lbea)in*Mb ami 80 mdaa(164 lea)In twgh. Notes I. Wks indicatedeWnttte,values:bawnammYhdewmavengemilrakesdebmminedinaasmiace:aAMR075942.add es oftest madam angina kr the Maytag atm. 2. naminaldimessiems. 6. Laid tmnsktcipabi rdaenMfinedInaeeaMmoewithAS7MD6687-SBaadA611107737 uaaderpresadasap at*afultimatawadi: a 1, 4. Mendip betweasthe minima and m dnwmMmenadmines Mradial diffams MOM stein,aaessteedondband midwayboon Mt directions. S. Radial Witlessisdetamhadfrom bindle stiffness maasucdhlora Midas*ads tew Wangli acconiaaawith AS1$0N87.10. B. Resistance sleu ofload camdrasbmcanaiintspitr when=WNWrchamtediraggoimdmimnirsaments in accoodanse Mat EPA 9090baaaslaltastM6. 7. itesiet ease to less of load capacityasamurai iMmdtywhen:wi ad le 500 betas M oltravielstaght and aggressivewadabgila ewhitASIM 048564. 6. Maim*Maass tab and WWI stifibessvalves st0.5%istrain ambler pn6Mdnewmantes madam sifted tochew" 'hour littsmethatal Comeadiso womemommopsuaserommedurromeaminrammanem~mmensamtemenenwomaw astam arse 0 " wir tunaantoram estutewmeass arrerm up+lc a n.er.rrinesorww.maearearnermer n.�a. 1mMewem aaM•WwMM�mMIrMi ala mtka.MUM rriebwtMrtslMulYmdaaMiMarmrKt.rNW A Genii tr ets ikeismartrrrrmilwerwemlirYmamiespeiK,mlisswerdesemareemb•yelr4ey PhoneLTi iJSAR�l ereneemakdanagarlaewassAi ed ,yyeraemea merb ostensewet www.teasamantmete Mair(i•tam•1nnmarrYpeani wmYaatYeaeyrpla�e,epge�eeyyrraeMrr.bsasaim Num INensar IIATIO 1 Product Specification - TriAxe TXI66 Geogrid Tenor h,ler-WaeatCerpetetion moves the npht to change Ar endue rpedt aetar s atter dm b b the nupenslintretthe prier spedyley the use ofthb piadosIand of the pwWser Si mane that peeled s pecaradmu reed upon fordo/pa orpeortern ear purposes are team:anti On the pronto nto b sulabk Au kr Mteneled use In each 1111171101. Tenser TriAx'Geogrld 1. The 1. The geogrid is manufactured from a punched polypropylene sheet,which is then AVA oriented in three substantially equilateral directions so that the resulting ribs shall �.�T��. have a high degree of molecular orientation,which continues at least in part through the mass of the integral node. IF IF 2. The properties contributing to the performance of a mechanically stabilized layer Tj�.T include the following: index Properties Longitudinal Diagonal Transverse General • Rib pitch's),mm(in) 40(1.60) 40(1.60) - • Mid-rib depthal,mm(in) - 1.6(0.06) 1.4(0.06) • Mid-rib width's),mm(in) - 1.0(0.04) 1.2(0.05) • Rib shape rectangular • Aperture shape triangular Structural integrity • Junction efflciency0),% 93 • Aperture stability's),kg-cm/deg 5.0kg-cm a) 3.6 • Radial stiffness at low strain'si,kN/m!0.5%strain 300 (Ib/ft 0.5%strain) (20,580) Durability • Resistance to chemical degradation%) 100% • Resistance to ultra-violet light and weatheringm 100% Dimensions and Davey The TX geogrld shall be delivered to the jobsite In roll form with each roil individually identified and nominally measuring 3.0 meters(9.6 feat) and/or 4.0 meters(13.1 teat)In width and 75 meters(246 feet)in length. Notes 1. Unless Indicated otherwise,values shown are minimum average roll values determined in accordance with ASTM 04759-02. Brief descriptions of test procedures are given in the following notes. 2. Nominal dimensions. 3. Load transfer apabilty determined In accordance with GRi-GC2-117 and GRI-GGI-S7 and expressed as a percentage of ultimate tensile strength. 4. In-plane torsional rigidity measured by applying a moment to the central junction of a 25mm x 225mm specimen restrained at its piameter in accordance with U.S.Army Corps of Engineers Methodology for measurement of Torsional Rigidity,(Kinney,T.C.Aperture stability Modulus ref 3. 3.1.2000). 5. Radial stiffness is determined from tensile stiffness measured in any in-plane axis from testing in accordance with ASTM 06637-01. 6. Resistance to loss of load capacity or structural Integrhtywhen subjected to chemically aggressive environments In accordance with EPA 9090 immersion testing. 7. Resistance to loss of load capacity or structural Integrity when subjected to 500 hours of ultraviolet light and aggressive weathering In accordance with ASTM 04355-0S. aspeaiauasuu am/esinn and enper epeNka•m �� etersnproducteeip+• + •andlanotepieddeteeny 5 Tldpuma shipped eller lMen*name.Tenger and Wu'ant uad andaaiTeem IC petananorNs anal= Atialte.Guelph 30121-5163 7,001.I U.tsatawer POW•opklla s alga sad in deermadden.Find delervaln nen et ew sdiddntlrdow slnmm - Phew 100-1ThSAR-1 •endeeedIbaenemnamales ler tee use ooewapldsd.and ilsmanna el,wweSmsobice a ilydnnaau. www 'Tema k*emaeanCapaaesasisu osawmetaleepreea.espiedorsleWlayaanmuse.MekOnelednet%Medto. ear vnevenly el ostehenlabley et Illness far a palmist eurpone modem Olds product sr Oarmanyt°dun Me non et The Inie n den n n reined linen eneineedne advice. te Se TENCATE ■ ■ e Mirafi POO "' aE POO a aye spars .n Mirafi® 180N Mirafi® 180N is a neediepunched nonwoven geotextile composed of polypropylene fibers, which are formed into a stable network such that the fibers retain their relative position. Mirafie 180N geotextile is inert to biological degradation and resists naturally encountered chemicals, alkalis,and acids. Mechanical Properties Test Method Unit Minim Value Average D CD Grab Tensile Strength ASTM D4632 lbs(N) 205(912) 205(912) Grab Tensile Elongation ASTM 04632 % 50 50 Trapezoid Tear Strength ASTM 04533 lbs(N) 80(356) 80(358) CBR Puncture Strength ASTM 06241 lbs(N) 500(2224) Apparent Opening Size(AOS)1 ASTM D4751 U.S.Sieve(mm) 80(0.18) Permittivity ASTM D4491 sec' 1.4 Flow Rate ASTM D4491 gal/minHt (1/min/m2) 95(3870) UV Resistance(at 500 hours) ASTM 04355 %strength retained 70 'ASTM 04751:AOS is a Matdmum Opening Diameter Value Physical Properties Unit Typical Value Roll Dimensions(width x length) ¶(m) 12.5 x 360(3.8 x 110)J 15 x 300(4.5 x 91) Roll Area yd ( ) 500(418) Estimated Rot)Weight lb(kg) 265(120) Disclaimer. TenCate asscanes no liability for the accuracy or completeness of this information or for the ultimate use by the purchaser.TenCate disclaims any and all express.implied,or statutory standards,warranties or guarantees, t limitation any Implied warranty as to merhwt �a rsofdo lingng o r Y or fitness for a parthr�er purpose or eristng from a course of dosing or usage of trade as to any equipment,mater,or information furnished herewith.This document should not be construed as engineering advice. 0 2012 TenCate Geosynlhatics Americas Miratfa is a registered trademark of Nicolon Corporation folt TENCATE. Maths In USAmaterials that make a dine encs FGS000351 ETOR41 ECS Mil-ATLANTIC LLC "Setting the Standard for Service" Geotechnical • Construction Materials •Environmental •Facilities September 10,2014 Via email:danlasicolllnsent com Mr.Daniel Tucker S SW Broad Street,Suite B P.O.Box 214 Fairburn,Georgia 30213 ECS Project No.:28:1552 Reference: Landfill Pond Stabilization - Sth Street Station Development located in Albemarle County,Virginia Dear Mr.Tucker: ECS Mid-Atlantic, LLC (ECS) is pleased to present recommendations for ground improvement and subgrade stabilization for the landfill pond proposed north of the Avon Street access road alignment for the referenced project. During the course of our analysis we have reviewed the contents of the ECS and Schnabel Engineering Geotechnical Reports as well as Sheet 17 of Bohler Engineering's Plan Set entitled "WPO Plan—E&S Phase II and SWM/BMP Design"sealed May 15,2014. aackaround and General Subsurface Conditions The storm water detention pond Is proposed to be located to the north of the road alignment in an area of the project that was formally utilized as a municipal landfill. Based on State requirements to minimize disturbance in this area, ground improvement options must be limited to above the existing grades. From our review of borings in the near vicinity(specifically Schnabel Boring G-4 near the east end of the pond) the waste cells may be as great as 50 feet in depth. The composition of the waste is largely heterogeneous; the nearby boring encountered a mix of soil material, crushed stone, wood, glass, plastic,and other waste typical of a Subtitle D landfill. From our review of the aforementioned plans by Bohler Engineering,the high water mark for a 10 year storm is approximately 6 feet,with the top of the dam on the order of 10 feet above the design bottom-of-pond elevation,El.1409 ft.MSL at the deepest section of the pond. Geotechnical Recommendations In order to provide adequate stabilization and reduce differential settlements to within tolerable limits, it will be necessary to construct a working platform within the extended footprint of the pond to disperse the imposed loads. The following recommendations for ground improvement and subgrade stabilization are made: 4004 Hunterstand Court,Suite 102,Charlottesville,Virginia 22911 • T:434-973-3232 • F:434-973-3238 • www.ecsiimited.com ECS Capitol Services,PLLC•ECS Carolinas.LLP•ECS Central,PLLC•ECS Ronda,LLC•ECS LLC•ECS Midwest,LLC•ECS Southeast,LLC•ECS Texas,uP tandfllt Pond 5tabnnation 5th StreetStation ECS Project Na.28:1552 September 10,2014 Paget - The extended area (10 feet beyond the highest contour line associated with the perimeter of the pond footprint) shall be cleared and grubbed to the greatest extent possible within the confines of the project's permit and minimum disturbance requirements. Larger root balls and root masses should be removed and disposed of in order to reduce the volume of organics left in place beneath structural fill areas. - A stone/geogrid system shall be installed to limit differential settlements and stabilize the subsurface near the waste cells. The system should be installed on the entire extended area of the pond as described above. The system shall be constructed of the following components, installed in the order given below: 1. GRID 1 Tensar TriAx TX190L Geogrid or equivalent installed on cleared existing grades or minimum lifts of compacted engineered fill. Minimum laps shall be one foot. 2. STONE 1 - 18 inches of VDOT Grade No. 3 stone installed over the top of GRID 1. Alternatively, crushed stone from onsite rock or crushed concrete may be utilized, subject to review and approval of material submittals. 3. FABRIC 1 — Mirafi 180N needlepunched nonwoven geotextile or equivalent installed over STONE 1 to prevent the migration of fines into open graded stone. Minimum laps shall be three feet. 4. GRID 2- Tenser TriAx1X160 Geogrid or equivalent installed on FABRIC 1. Minimum laps shall be one foot. 5. STONE 2 — 12 inches of VDOT Grade No. 21-A stone placed in two lifts, moisture conditioned to within +/- 2% of the optimum moisture content and compacted to at least 95%of the maximum dry density obtained in accordance with ASTM Specification D-698,Standard Proctor Method. 6. SOIL 1—Final grades of the pond should be established with a 12-inch lift of approved soil. This thin lift of soil is optional, but should be utilized as required for the fine- grading required to ensure appropriate tolerances are achieved prior to the placement of the liner. Engineered fill shall be placed and compacted in accordance with the geotechnical requirements for this project. Briefly,the fill should be placed in lifts not exceeding eight inches in loose thickness, moisture conditioned to within+1-2%of the optimum moisture content and compacted to at least 98%of the maximum dry density obtained in accordance with ASTM Specification D-698, Standard Proctor Method. Engineered fill is defined as on-site soils classified as SP,SM,SC, CL, ML,GM,GP,or GC which are free of organics and other deleterious, non soil materials. This material has been identified and is available on the development portion of this project Imported Landfill Pond Stabilization 5th Street Station ECS Project No.28:1552 September 14 2014 Page 3 material should classify as CL, ML, SM, SC, SP, or better. Suitable imported material should have a maximum Liquid Limit of 50 and maximum Plasticity Index of 15. Maximum aggregate size for all materials should be limited to two inches. 7. Impermeable Geosynthetic Pond Liner—Based on our review of the liner Installation Detail provided to us, we do not consider a layer of impermeable soil (i.e. CLAY (CH) material w/permeability less than 104 cm/sec)warranted or required in this case. We consider the specified 30 mil Reinforced Polyethylene (RPE) pond liner adequate to prevent infiltration into the constructed stabilization platoform and underlying subgrade of the former landfill. We recommend the installation of and seaming procedures for the liner be reviewed to ensure the membrane and associated connections are sufficient to prevent damage due to excessive strain induced by tensile forces along the interior of the storm water structure. Please see Enclosure(1)for product specification sheets to compare alternate manufacturer mechanical properties for geofabrics and geogrids. Substitutions shall be reviewed to ensure performance requirements are met. We request that ECS be given the opportunity to review all requests for geoproduct or material substitutions,as well as product submittals prior to approving the selection and installation methods of the impermeable geosynthetic pond liner. We have appreciated the opportunity to be of service'to you. If we can be of further assistance to you during the Co 3 ction phase of this project,please do not hesitate to contact us. o��pLTH U r U ' DER SARANT Ua No.042553 4s„tONAL'16` Alexander Sarant,P.E. Principal Engineer End: (1)Product Specification Sheets • CC: Daniel R.Hines,P.E.,Bohier Engineering Stephen G.Werner,P.G.,Geo-Environmental Consulting Services,LLC Tensa®, i;. •��•� ., Product Specification-Taut TX1901.Geogridi TinatialemoilmallkosoatlesaaasaeabhtisetagseetsintepeeadlenemayVac.NieweapxtMMMelh•I imine td•Pmast.d.rwwa•uaMalumame► pauggetspodkassuitsumponeae teepavanapgreaaeeamtendtMtibMdr<thsYeYohoblotendedise emhietasse. Omani trIAxI Sse rbl 1. Da d la mmiudidivedt o podiaPidynag abed.which Ist en°dentedMnuec subsemllak A A idirectional)that the[d lag&mai dbagsadighdovealmalsielaraantaeaa,whichewdlases Khasi kipad Neigh Owmammal the bland nada. -•.Tr i 2. MaampmYa htgloth°petlaaxeaasla memanalcallyttablIked law klub Ike Mewing V VATAY index Pnpardas lanasidimdMagma' Genital • ftplat;eampe) 9D(2.4Q) BO(2.40) • Wisps Retlugubt Thangdar Inbrily • ,a.dha aflehniel,t: • Mekapla Winans Rtdaw• 93 OA • RadWM1Wnasatlow at 94,ttiim90.5%iteda MAOR.5%attdn} ) Dir • Redden*lachemical dgmdedlale 100% • Beildasee to allawiloIstaBit and wedhedgm 70% Olonanalans aidbop tkelllPOW shall lxManed Ytlit)11911a rah=weklath roeb id7kletdendexdnomladlymauuilag3Amaims(L5bat) aayar+lAwain(13.1toe)b211119 and 50m anhal)InIsaiah. liabis 1. Unless iaNtxladu1I si,eadiaahem,anmhala=amassi dvalusdeedktueWaneswokAS1 10475942.Iddetiadptbaaettossp avaOmInrxldadngnalas. 2. Nominal dhasmileas 3. LW Inankresasidmydatanelnedha naw ASF#401537-16 and 96131077A7.11a don smog man pettentagealmOlwistataadelengt. 4. The alb Won Oaminimum and madam ibsnwdulnas afradial a00eaiat0.5l4Wain,trasundeatleandaddteaybe6aaandbdeacdep, 5. bed Ohm Is lead°Minos nna In any ia•IdaxeMahon Immiegr.aaeadaaaasalt A51MDg8T10. 6. Wat ap:abe=ribrniaapae sardntAad kdspleywhonmaltjadmiltoekeiatailbr aaavha Inatxwdaaawkh EPA 9p50te liataid*. 7. ROMINSbbit dhadmadly or tbdgdlywkaa=Wastedla509Was idul alsinght admonish*alsalhehigla assaidanceillsASEN 01356.55. L beYapiaatl5aaasJab mad nulls]ellinassvalues at0.5KNob=both lxib+ktnyesdnalesmad aeesakjeettadolga. • Tula elCarmatbs Pithalluilwaponadusolasdieliimidkoirsktbepiteniripredalkeriamikutioammobripidisolinattolle 25th11ltadnabdil tivaiet «ebbndaMrakar Yds.riuiaw.arrm..agrb..aewrr.W.simale Baa• parsimminaRimammisommummaisatrommosausa Pim rrrrtgpr lwombeakemma a ons.nal Atlanta,Semile30009 rtimatraaMMaMxgMarMamordematrtgreoMMMbrearrrolvaik al baamenf rmilnal, Phan te�t815AR�1 awrywrawaa. rrwrumr�rgaraaA.,rtudn wrdr. a ,wale arttadaaNasesseemame berig••••• raritiae.eGweaeyapippNrr.}w.yyd,+roadeaa.Ma.run e.aa. Tensar INTERNATIONAL Product Specification -TriAxs TXI60 Qeogrid roararihepwh terms sum thatp n dent* ll a n es oncornettime t s er of the mason apsdlylai arse itse Ma Nava seri wit K Uapranubsate saws taerpnrhnr fA�p imam " TenserTrdAxa Geogrid General AVAYL 1. The geogtid is manufactured from a punched polypropylene sheet,which is then oriented In three substantially equilateral directions so that the resulting ribs shall `t`'�,�►` have a high degree of molecular orientation,which continues at least in part through IP' the mass of the integral node. 2. The properties contributing to the performance of a mechanically stabilized layer include the following: index proper Longitudinal Diagonal Transverse General • Rib pttchat,mm(in) 40(1.60) 40(1.60) — • Mid-rib depths,mm(In) - 1.6(0.06) 1.4(0.06) • Mid-rib widthoi.mm UN - 1.0(0.04) 1.2(0.05) • Rib shape rectangular • Aperture shape triangular Structural lntagrtty► • Junction efficiency(?).tb 93 • Aperture stability"),kg-cm/deg 6)5.0kg-cm ori 3.6 • Radial stiffness at low strains).kN/m tE 0.5%strain 300 Ob/ft 0.5%strain) (20.580) Durability • Resistance to chemical degradation(*) 100% • Resistance to ultra-violet light and weathering(?) 1 DM Obaealdwn and Daum The TX geogrid shall be delivered to the robsite In raft form with each roll lndMdutdly identified and nominsiy measuring 3.0 meters(9.6 feet) addlor 4.0 meters(13.1feet)in width and 75 meters(246 feel)In inngth. tomes 1. Unless indicated adutadsa,values shown are minimum average roil values determined In accordance with ASPM 04759-02. Oder descriptions a(test procedures are given in the Mowing notes. 2. WsenMal dimensions. 3. Lad minder qty detuaded in accordance with Geri-G(2-417 and cm-cot-N end impressed as a percentage or ultimate tensile strength. 4. let-plant unkswl rigidity/measured by applying a moment to the central junction of RAN=a 225mm specimen rstrabted at its perimeter In accordance with U.S.Army Corps or Engineers Methodology Pot measurement of Torsional Rigidity.Mosey.S.C.Aperture stability Modulus ref 3. 3.1.20001. 5. Rafal stiffness is determined from tensile stiffness measured In Ravin-plane axis from testing in accordant*with ASTM 061537-01. 5. Resistance to loss of load capadty or structural integrltywhen subjected to dcmdcaly aggressive environmenu in accordance with EPA 9090 immersion lasting. 7. Reslatentn to toss of load capacity or struatral integrity when subjected to 513)hours of Muntenia lght and aggressive weathering in accordance with AMA 04355-05. Tenser intentational Sion 'fhb spdatallea warmer e yamiesprwermor ra trouts plashedrealbwlaimsowlIspatAmaodistany Saar fieDrive.Mike 200 weeettawleeerae leitodhn.ease.TaadendMAR aseaeaedmdTour M2raNwlCemerMynrels aalNaMweWane ewe emmieet.TWO eeayddarlrrsea e afnaMro drdedhyUs.RMlb. 11111501,WM*103224353 7.Of.tt2.Nwaeerpewae/�Ersra todstb,drraaa Ips.AdaY tmIeteltaspddYW)'dep•aMm• Phone - issellassa kdemalloass pedal be es y law. tinumze iu,Mtun llo neLeom r plyi•wplCrpneadWdnmeev etieml •e�ym'p"d a dens staiatuyieremeralndidee pr MrUrtfrRedb a� soegradbrain nM mina aerrpnpeaeb, . co TENCATE ■ M Mirafi coo i PPP 111111 Asge opus Mirafi® 180N Mirafis' 180N is a neediepunched nonwoven geotextile composed of polypropylene fibers, which are formed into a stable network such that the fibers retain their relative position. Mirafl 180N geotextile is inert to biological degradation and resists naturally encountered chemicals, alkalis,and acids. IMechanical Properties Test Method Minimum Average Un(t Roll Value MD CD Grab Tensile Strength ASTM D4632 lbs(N)_ 205(912) 205(912) Grab Tensile Elongation ASTM D4632 gi, 50 50 Trapezoid Tear Strength ASTM D4533 lbs(N) 80(356) 80(356) CBR Puncture Strength ASTM D6241 lbs(N) 500(2224) Apparent Opening Size(AOS)' ASTM 1)4751 U.S.Sieve(mm) 80(0.18) Permittivity ASTM D4491 sec' 1.4 Flow Rate ASTM D4491 gal/mine(I/minima) 95(3870) UV Resistance(at 500 hours) ASTM D4355 %strength retained 70 'ASTM D4751:AOS Is a Maximum Opening Diameter Value Physical Properties Unit Typical Value Roll Dimensions x length) ft(m) 12.5 x 380(3.8 x 110) C 15 x 300(4.5 x 91) RollEstimated Roll Weight lb(kg)) 500(+418) 265(120) Disclahner: TenCate assumes no!lability for the accuracy or completeness of this information or for the ultimate use by the purchaser.TanCate disclaims any and all ewes:,implied or statutory standards,warranties or guarantees,Including without limitation any to had warranty as to merchantability or Illness for a per ar purpose or arising from a course of dealing or usage of trade as to any equipment,materials,or information furnished ished herewith.This document should not be construed as engineerkrg advice. ®2012 TenCate Geosynthatics Americas Mlmfi°is a registered trademark of Nicxlon Corporation ATE TENCATE. materiels that make a difference Mad.Ira USA FOS00 1351 ETOR41 8 i i S 0 - v Vi girh Q i Q m c+ m m e.gg _ >on 9 a n /�/� L W g e V r: -55 , 111Z g : u.1 ,-, EfiTi 1. lletv 11W11 i ill 1 1 1111 i i 1 73 S 0a 3 a r 1 ' N N 1 I- il o d O a v v $ I 3 I v z 2 r ii ; : In 2 g 1 I ii s � S s s s. $ � � � E 1.1 r 7 a ti1 r 4- -- F 8, 8, ! ! $ ! a 1 I ! 11 iiiHnii i• I fflf ii ll N I j1J I : : : m :_ _