HCEA Geotechnical Report
Transcription
HCEA Geotechnical Report
Geotechnical Engineering Study Penn Commons Residential Development East Buffalo Township, Union County, PA HCEA Project No.: T15107 Prepared For: Mr. Bruce Quigley Union County Housing Associates, Inc. 1610 Industrial Blvd. Suite 700 Lewisburg, PA 17837 Prepared By: Hillis-Carnes Engineering Associates, Inc. 2929 Stewart Drive, Suite 302 State College, PA 16801 October 12, 2015 HILLIS-CARNES ENGINEERING ASSOCIATES, INC. State College, PA 16801 814-231-0552 www.hcea.com Mr. Bruce Quigley Union County Housing Associates, Inc. 1610 Industrial Blvd. Suite 700 Lewisburg, PA 17837 RE: Geotechnical Engineering Study Penn Commons Residential Development East Buffalo Township, Union County, PA HCEA Project No.: T15107 Dear Mr. Quigley: Hillis-Carnes Engineering Associates, Inc. (HCEA) has completed the geotechnical engineering study for the above-referenced project that is to be located in East Buffalo Township, Union County, Pennsylvania. This portion of the exploration consisted of excavating eight (8) test pits, laboratory testing, performing engineering analyses, and preparing this written report of findings and conclusions. Should you have any questions or require additional information, please contact us. Sincerely, HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Robert Etters, P.E. Branch Manager James. P. Thornton, P.E. Senior Geotechnical Engineer Corporate Headquarters - Annapolis Junction, MD Maryland Washington, DC Delaware Pennsylvania Virginia HILLIS-CARNES ENGINEERING ASSOCIATES, INC. ENGINEERING ASSOCIATES, INC. 2929 Stewart Drive, Suite 302 October 12, 2015 TABLE OF CONTENTS LETTER OF TRANSMITTAL ........................................................................................................................ i 1.0 PURPOSE AND SCOPE ...................................................................................................................... 1 2.0 PROJECT CHARACTERISTICS .......................................................................................................... 1 3.0 GEOLOGIC INFORMATION................................................................................................................. 2 4.0 FIELD EXPLORATION.......................................................................................................................... 3 5.0 LABORATORY TESTING ..................................................................................................................... 3 6.0 SUBSURFACE CONDITIONS .............................................................................................................. 4 6.1 Surficial Materials................................................................................................................ 4 6.2 Fill Materials ........................................................................................................................ 5 6.3 Natural Materials ................................................................................................................. 6 6.4 Groundwater Conditions ..................................................................................................... 6 6.5 Site Seismicity..................................................................................................................... 7 7.0 EVALUATIONS AND RECOMMENDATIONS ..................................................................................... 7 7.1 General Site Preparation .................................................................................................... 7 7.2 Fill Selection, Placement and Compaction......................................................................... 8 7.3 Cold/Wet Weather Earthmoving Considerations ............................................................... 9 7.4 Foundations ....................................................................................................................... 9 7.5 Ground-Supported Slabs .................................................................................................. 10 7.6 Groundwater and Drainage .............................................................................................. 11 7.7 Benching/Sloping Considerations .................................................................................... 11 7.8 Pavement Design Considerations .................................................................................... 12 7.9 Rock Removal Considerations ......................................................................................... 12 7.10 Lateral Earth Pressure Considerations ............................................................................ 12 8.0 RECOMMENDED ADDITIONAL SERVICES..................................................................................... 14 9.0 REMARKS ........................................................................................................................................... 14 APPENDIX: A. B. C. D. E. F. G. General Geotechnical Notes Project Location Plan USGS Geology Map Test Pit Location Plan Test Pit Logs Representative Photographs Laboratory Testing Data HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons Residential Development East Buffalo Township, Union County, Pennsylvania HCEA Project No.: T15107 1.0 PURPOSE AND SCOPE The purpose of this study was to determine the general subsurface conditions at the test pit locations and to evaluate those conditions with respect to the concept and design of a foundation system, ground-supported slabs and site work for the proposed construction. The evaluations and recommendations presented in this report were developed from an analysis of the project characteristics and an interpretation of the general subsurface conditions at the site based on test pit information. The soil descriptions shown on the test pit logs represent the approximate boundaries between underlying materials, however; these transitions may be gradual. Such variations can best be evaluated during construction and, if necessary, any minor design changes can be made at that time. An evaluation of the site with respect to potential construction problems and recommendations dealing with the earthwork and inspection during construction are also included. The inspection is considered necessary to verify the subsurface conditions and to verify that the soils-related construction phases are performed properly. The Appendix contains a summary of the field and laboratory work on which this report is based. Our services for this project were performed in accordance with HCEA Proposal No. P150186STC, dated August 5, 2015. Authorization to perform this exploration and analysis was given in the form of a signed contract agreement signed by Mr. Bruce Quigley, Union County Housing Associates on August 7, 2015. 2.0 PROJECT CHARACTERISTICS The proposed project site is located north of Wilson Alley and Rural Avenue between North 10th and North 11th Street, East Buffalo Township, Union County, PA. The site is further bounded by rails to trails along the north. The general location of the site is shown on a Project Location Plan presented in Appendix B. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 2 of 15 The precise location of the project is shown on a Site Plan prepared by Stahl – Sheaffer Engineering, LLC. (SSE) and dated July 1, 2015. This drawing was received via email from SSE’s Project Engineer Mr. Michael Maxwell, P.E. as part of the RFP. This drawing was incorporated into the Test Pit Location Plan in Appendix D. It is our understanding that the proposed construction includes the construction of seven (7), one (1) and two (2)-story wood-framed structures with concrete slabs on-grade. Finished floor elevations are expected to approximately match existing grade with maximum cuts and fills not expected to exceed one (1) foot. The investigation was performed with the initial intent of utilizing frost protected shallow foundation (FPSF) system for the perimeter foundations. Based on the results of this investigation, alternative foundation recommendations are presented in this report. At the time of the investigation the surface of the site is variable and includes grass, concrete, residential structures and asphalt pavement. Additionally, structures previously occupied portions of the site and have been razed. It is expected that the remaining structures will also be removed during the preliminary phase of upcoming construction. Maximum wall loads of 3,000 pounds per lineal foot and maximum floor loads of 50 pounds per square foot (psf) are expected. Also, we have assumed maximum tolerable total and differential settlement values of one (1) inch and one-half (1/2) of an inch, respectively. 3.0 GEOLOGIC INFORMATION According to the Department of Environmental Resources, Office of Resources Management, Bureau of Topographic and Geologic Survey (1982), rock formations at the proposed area are undivided between the Keyser and Tonoloway formations. Both formations are comprised primarily of limestone. The Keyser formation is comprised of dark gray, highly fossiliferous, crystalline to nodular limestone: shaly limestone near the top and the Tonoloway formation is comprised of medium-gray laminated limestone containing interbedded zones of medium and light gray shale and siltstone. The rock formations are moderately resistant to weathering and the surface drainage is typically good. Excavation in both formations is difficult when rock is encountered. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania 4.0 Page 3 of 15 FIELD EXPLORATION Prior to commencement of field operations, the project was registered with the Pennsylvania One-Call System, Inc. and this phase of the project was assigned Serial Number 20152192220. Utilities were identified within the proposed construction footprint, we recommend that the contractors verify the locations of any utilities prior to commencement of construction activities. It should be noted that unmarked utilities were identified in the northeastern area of the site in the vicinity of test pit location TP-8. This included storm lines and possibly fiber optics and natural gas. The field investigation consisted of eight (8) test pits excavated utilizing a rubbertracked excavator owned and operated by J-Mar Construction, Inc. These test pits were extended to depths greater than the bearing elevation at most locations. At test pit location TP-7 excavation was hindered due to the presence of a concrete slab. Test pit TP-8 was abandoned due to unmarked utilities and the possible presence of a fiber optic and natural gas utilities. These locations are shown on the Test Pit Location Plan in Appendix D of this report. Details of the subsurface conditions encountered in our field exploration program are shown on the individual Test Pit Logs included in Appendix E. Additionally, representative photographs taken prior to and upon completion of the investigation are included in Appendix F. All test pits were checked for apparent groundwater levels at the time of excavation and prior to backfilling the pits with the excavated soil. The stratifications shown on the Test Pit Logs represent the conditions only at the actual test pit locations at the time the exploration took place. Variations should be expected between the test pit locations. In addition, the Test Pit Logs show the approximate boundaries between subsurface materials. Actual transitions between subsurface materials may be gradual. Representative soil samples were collected and transported to HCEA's laboratory for additional testing. 5.0 LABORATORY TESTING In addition to the visual classification of the soil samples, moisture content determination tests were performed on representative samples. The moisture content is the ratio of the weight of the water in the sample to the dry weight of the sample. These tests were performed in general compliance with ASTM D2216. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 4 of 15 Moisture-plasticity characteristics of two (2) composite soil samples were determined by means of the Atterberg Limit test. The test determines the moisture content at which the soil begins to act as a viscous liquid (Liquid Limit LL) and the moisture content at which the soil changes from a plastic state to a semi-solid state (Plastic Limit - PL). The difference between the Liquid Limit and the Plastic Limit is the Plasticity Index - PI. The test procedure was performed in compliance with ASTM D4318. A particle-size analysis was performed on the same soil samples in compliance with ASTM D422. The procedure includes a sieve analysis for particle sizes greater than the #200 sieve and a hydrometer analysis for particle sizes smaller than the #200 sieve. Using this information, the samples were classified using the Unified Soil Classification System (USCS), ASTM D2487. The following is a summary of the soil classification results with individual results enclosed in Appendix G: 6.0 HCEA Sample Number Location Liquid Limit (LL) Plasticity Index (PI) USCS L15150 Composite Sample: TP-4, 32-99+" and TP-6, 24-43" 40 19 CL L15151 Composite Sample: TP-1, 29106+" and TP-5, 19-109+" 24 8 CL SUBSURFACE CONDITIONS Details of the subsurface conditions encountered are shown on the individual test pit logs enclosed in Appendix E of this report. A brief description of the subsurface conditions and pertinent engineering characteristics of the soils are outlined below. 6.1 Surficial Materials A surficial vegetation/topsoil layer was encountered at test pit locations TP-1, TP-2, TP-3 and TP-4 and ranged in thickness between 2 and 25 inches. Topsoil thicknesses noted on the Test Pit Logs should not be used solely to HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 5 of 15 estimate topsoil quantities at the site. In general, topsoil contains organic matter due to the decay of vegetation and natural weathering processes and should be considered highly compressible. A concrete slab was present at the surface at test pit locations TP-6 and TP7 and measured 5 inches in thickness. Limestone gravel was present at the surface at the remaining test pit locations, TP-5 and TP-8, 3 inches and 8 inches, respectively. 6.2 Fill Materials Fill materials were encountered beneath the previously described surficial layers at all test pit locations and was highly variable in composition and consistency. At test pit locations TP-1 and TP-3 the fill consisted of a mixture of clay and shale, was moderately compacted and extended to depths of 19 and 8 inches, respectively. Of special note, the shale was predominantly black and appears to representative of the Marcellus Formation which is locally present. This formation contains abundant pyrite (iron disulfide) and siderite (ferrous carbonate) concretions and nodules and is classified as potentially expansive. The fill material at test pit location TP-2 consists of a mixture of sand and gravel as well as debris comprised of bottles, metal and other glass. This stratum also appeared to contain other burnt remnants. Appendix F, Plates 2 and 3, show the in-place and excavated material encountered at this location. This fill layer extended to a depth of 78 inches with the debris extending to a more shallow depth. A mixture of black ash and cinders was encountered at test pit locations TP4 and TP-5. The material was found to be damp, loosely compacted and extended to depths ranging between 13 and 32 inches. Beneath the concrete pavement at test pit locations TP-6 and TP-7 the fill consisted primarily of sand, cinders and gravel. The material was wet and poorly compacted. This material extended to depths of 24 and 36 inches, respectively. It should be noted that an additional concrete slab was encountered at TP-7 at the 36 inch depth as well as a concrete wall along the east side of the excavation. Standing water was also present at this location (See Plate 8 in Appendix F). This water is likely a perched condition confined by the below grade concrete slab. The fill materials at test pit location TP-8 are comprised of limestone gravel. This material extended to a depth of 18 inches at which an unmarked HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 6 of 15 abandoned utility was encountered. Since no utilities were identified at this location, the test pit was terminated. 6.3 Natural Materials The natural soils were encountered beneath the fill materials at all locations which could be advanced to a depth exceeding the expected bearing elevation. HCEA Sample Numbers L15150 and L15151 are representative of these materials and were classified as CL, lean clay and sandy lean clay. These materials exhibited stiff to hard consistency with moisture contents ranging between 15 and 30 percent. This material extended to test pit termination depth at all locations with particle size increasing with depth. Although the material was generally difficult to excavate at test pit termination depth, refusal was not encountered. Refusal is the term used to describe the condition at which the material could not be further penetrated utilizing the excavation equipment used to perform the investigation. In general, as depth increased, the amount of weathered sandstone also increased. This material was found to have a stiff to hard consistency, based upon hand penetrometer values and probing. Varying amounts of mottling were observed throughout this stratum. Mottling is the term used to describe the process by which microorganisms in an anaerobic (without oxygen) environment obtain energy from nutrients in the soil. When these nutrients are depleted, the remaining soil appears gray in color. Generally, mottling is recognized as an indicator of a water table or saturated soil conditions. For this situation, the relatively impermeable clay soil layer restricts water flow. As a result, the infiltrated water is unable to percolate through to the normal freestanding groundwater table. The presence and extent of this condition are usually attributed to drainage and precipitation. 6.4 Groundwater Conditions Groundwater was not encountered within the test pit excavations. As previously described, the water encountered at test pit location TP-7 appears to be a perched condition. However, it should be noted that groundwater levels fluctuate seasonally as a function of precipitation, the permeability of the subsurface materials and proximity to nearby water bodies. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania 6.5 Page 7 of 15 Site Seismicity According to the 2012 International Building Code, Section 1613.3.2 (Chapter 20 of ASCE 7), seismic Site Class D should be specified for this project. 7.0 EVALUATIONS AND RECOMMENDATIONS The subject site is considered suitable for the proposed construction, provided the geotechnical recommendations and suggested construction guidelines presented in this report are utilized in both the design and construction phases of this project. If there are any changes to the project characteristics or if different subsurface conditions are encountered during construction, HCEA should be consulted so that the recommendations of this report can be reviewed and revised, if necessary. 7.1 General Site Preparation Site preparation should include the removal of topsoil, any unapproved manplaced materials; frozen, wet, soft or very loose soils; and any other deleterious materials. Particular attention should be given to the removal of black carbonaceous if encountered beneath ground supported structures. These operations should be performed in a manner consistent with good erosion and sediment control practices. This would include the removal of the existing structures as well as the concrete slabs present in the eastern portion of the site. Additionally, the below grade slab should be rubblized to provide for an outlet of infiltrated water. After the initial stripping process is completed, areas of the site to receive fill, should be proofrolled. Based on the moisture content of the soil at the time of topsoil removal, drying may be required prior to proofrolling or sealing of the soil surface. The proofrolling operations should be performed using a 20 ton, fully loaded dump truck or another pneumatic tire vehicle of similar size and weight. The purpose of the proofrolling will be to provide surficial densification and to locate any near surface pockets of soft or loose soils requiring undercutting or other form of modification. Proofrolling will help to reveal the presence of unstable materials and is particularly important in evaluating fill material. A Geotechnical Engineer or experienced Soils Inspector should witness the proofrolling operations and determine whether any areas require undercutting and/or stabilization. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 8 of 15 In areas where proofrolling is not practical, such as in below-grade excavations, we recommend that the project’s Geotechnical Engineer or designated representative visually inspect and manually probe the subgrade materials. Traffic from the various construction equipment may create pumping and a general deterioration of the soils. It is our recommendation that the contractor be fully advised of these potential problems. Additionally, the contractor should not permit water to pond on the site and exposed subgrades should be sloped and sealed at all times to facilitate rainfall runoff. 7.2 Fill Selection, Placement and Compaction All material to be used as fill or backfill should be inspected, tested and approved by the Geotechnical Engineer. In general, the on-site soils with a Unified Soil Classification of CL are considered suitable for reuse as structural fill beneath floor slabs, utilities, sidewalks, pavements and areas to be landscaped. Soils having moisture contents above the typical optimum percentage required for proper compaction will require drying and/or aeration prior to placement. The difficulty associated with drying is significantly affected by seasonal conditions. It should be noted that lateral confinement of poorly graded materials will be required in order to limit horizontal movement and subsequent settlement or instability of the structural fill. If imported fill material is required, those materials should have Unified Soil Classifications of CL or better, contain no rock greater than 3 inches in diameter, and should not contain more than 1 percent (by weight) of organic matter or other deleterious material. Uniformly graded materials, such as PennDOT 2B or AASHTO #57 stone, can only be utilized as structural fill with the permission of the Geotechnical Engineer. Potentially expansive materials such as mine tailings, pyritic shale and slag should not be used as structural fill. Other materials should be considered on a case-by-case basis and approved by the project’s Geotechnical Engineer. All fill should be placed in relatively horizontal 8-inch (maximum) loose lifts and should be compacted to a minimum of 100 percent of the Standard Proctor (ASTM D-698) maximum dry density. Fill materials in landscape and other non-structural areas should be compacted to at least 90 percent of the Standard Proctor maximum dry density if significant subsidence of the fill under its own weight is to be avoided. Field moisture contents should be maintained within 2 percentage points of the optimum moisture content in order to provide adequate compaction. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 9 of 15 A sufficient number of in-place density tests should be performed by an experienced Engineering Technician on a full-time basis to verify that the proper degree of compaction is being obtained. 7.3 Cold/Wet Weather Earthmoving Considerations In order to facilitate construction during late fall, winter and early spring, special considerations should be recognized. Specifically, “cold weather” and “wet weather” can significantly reduce the potential to practically lower soil moisture content to optimum compaction levels. “Cold weather” is when temperatures drop below freezing at any time or when temperatures are consistently sustained below 40º F. “Wet weather” is any period of time with increased precipitation and can occur during any time of the year. The following considerations are offered if fill operations are anticipated during the aforementioned difficult conditions: 1. The natural moisture contents of imported soils above optimum percentages will require modification. The moisture content may need to be lowered by spreading out the wet materials in thin layers and discing in order to facilitate evaporation. This methodology becomes less practical during “wet weather” and “cold weather” conditions. 2. Any compacted structural fill materials should be positively graded and sealed with a smooth-drummed roller as soon as practical after achieving finished grade or immediately prior to any anticipated precipitation event. These measures will help to reduce the potential for rutting and pumping of the subgrade and ponding of undrained water. 3. Imported granular and well-graded structural fill, along with a stabilizing geosynthetic grid, may aid in facilitating construction during difficult weather conditions. The use of properly graded crushed rock as a working surface will aid in creating a stable working pad. The geotechnical engineer should review all design and construction operations that specifically address earthwork in “cold weather” and “wet weather” conditions. 7.4 Foundations Based on the subsurface conditions encountered during our field exploration program and our understanding of the proposed project, conventional shallow foundations and installation of a slab-on-grade system will require removal of a significant amount of fill material. An alternative to this system HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 10 of 15 would be a drilled shaft foundation and a structural slab. These shafts would extend through the unsuitable fill material to the underlying stiff, residual clay soil stratum. The diameter of the shaft should be based on the design considerations mentioned previously. Reinforcing steel and concrete strength requirements should be determined by the Structural Engineer. When the drilling operations are finished, concrete should be placed inside the casing as soon as possible. If casing is required, it should be removed as the concrete is being placed. It is recommended that concrete be placed the same day that the shaft is drilled. Based on the maximum anticipated structural loads, the maximum tolerable settlement, and the general soil conditions which were encountered, it is our judgment that the in-place soils are capable of providing a net allowable bearing capacity of 2,500 pounds per square foot. Assuming the net loading on the footings does not exceed 2,500 pounds per square foot and the recommendations in this report are followed, postconstruction total and differential settlement should be less than the assumed tolerable values. If soft or loose pockets are encountered in the footing excavations, the unsuitable materials should be removed and the footings should be located at a lower elevation. If unsuitable material is encountered, an overexcavation or other modification procedure would be necessary. If during foundation excavation, soils are encountered that are not indicative of those described in this report, a geotechnical engineer should be consulted for guidance on how to proceed with the excavation. Exterior footings and footings in unheated areas should be located at depths of at least 42 inches below final exterior grades so as to provide adequate protection from frost heave. 7.5 Ground-Supported Slabs As previously described, concrete slabs-on-grade will require special attention to evaluate fill at the intended location. An overexcavation and replacement should be expected if this type of construction is utilized. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 11 of 15 Floor slabs should be supported on approved, firm natural soils or new compacted fill. The slab subgrade should be prepared in accordance with the procedures outlined in Sections 7.1 through 7.2 of this report. In particular, the slab subgrade should be heavily proofrolled to delineate any soft or loose areas requiring undercutting and/or stabilization. The natural soils are expected to provide a subgrade modulus of reaction (k) of 100 pounds per square inch per inch (psi/inch). To reduce stress concentrations on any grade slabs and to provide a uniform bearing surface that may be associated with dissimilar fill materials, we recommend a minimum of 6 inches of compacted PennDOT 2A stone be placed between all grade slabs and the underlying subgrade. The stone will also act as a drainage course for any moisture below the slabs. It is also recommended that construction joints on the slab surface and isolation joints between the slab and structural walls be provided (such that the slab would be ground-supported). 7.6 Groundwater and Drainage Due to the absence of groundwater during our field exploration, it is unlikely that a groundwater table will be encountered during excavation operations; however, wet soil conditions may be encountered near the soil/bedrock interface. If perched groundwater is encountered, every effort should be made to keep the excavations dry. An open pump, gravity drainage system or other conventional dewatering procedure should be sufficient for these temporary purposes. Any water infiltration resulting from precipitation, surface run-off, or perched water should be able to be controlled by means of sump pits and pumps, or by gravity ditching procedures. If encountered, groundwater should be maintained a minimum of 2 feet below the bottom of all excavations during construction. If conditions are encountered that cannot be handled in such a manner, the Geotechnical Engineer should be consulted. Adequate drainage should be provided at the site to minimize any increases in the moisture contents of the foundation soils. Grades should be sloped away from the structure to prevent the ponding of water. The site drainage should also be such that run-off onto adjacent properties is controlled properly. 7.7 Benching/Sloping Considerations For slopes less than 10 feet in height, maximum slopes of 1.5:1V and 2.5:1V should be utilized for temporary (less than 24 hours) and permanent fill HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 12 of 15 operations, respectively, in soil or weathered rock. All slopes should be visually inspected for stability. Erosion control will be required at the face of all permanent slopes in soil. If any slopes are proposed to be greater than the above values, or for slopes greater than 10 feet in height, an in-depth slope stability analysis will be required to ensure the integrity of the created slope. If benching or sloping of the excavations is not practical, temporary bracing/shoring will be required. Subsurface drainage must be considered in the design of temporary bracing/shoring systems. 7.8 Pavement Design Considerations A California Bearing Ratio (CBR) of 5 is typical for the natural, residual soil. Based on the presence and non-uniformity of the fill material; a more conservative value may be warranted. All pavements should contain adequate surface and subsurface drainage. The subgrade should be prepared according to Sections 7.1 and 7.2. 7.9 Rock Removal Consideration Based on the materials encountered during the subsurface exploration and our understanding of the project, it is unlikely that the removal of bedrock will be required. However, if deep excavations are planned, special excavation techniques, such as air-rotary drilling or pneumatic jack hammering may be required in order to facilitate rock removal. The method required for rock removal will depend on the weathered and intact nature of the bedrock. It is the responsibility of the Contractor to determine the rock removal method, provided that method is acceptable to the owner and in compliance with any applicable ordinances and regulations. 7.10 Lateral Earth Pressure Considerations It is expected that the planned retaining walls will be required to resist lateral earth pressures imposed by the backfill materials. The following table presents geotechnical parameters that can be utilized to design the lateral pressure distribution behind any permanent retaining structures. The parameters listed below, which may be used to compute lateral pressures on the walls, are considered to be representative of the existing soils and typical for PennDOT 2A subbase. However, actual unit weights and friction angles will vary from one material to another. It is, therefore, HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 13 of 15 recommended that appropriate soil testing be conducted on proposed fill materials to ensure that the actual soil properties do not result in higher than anticipated lateral pressures. Material γ (pcf) (degrees) c (psf) Ko Ka Kp On-Site Natural Soil 130 32 0 0.47 0.31 3.25 PennDOT 2A Stone 135 38 0 0.38 0.24 4.20 Legend: = Moist Unit Weight = Angle of Internal Friction c = Cohesion Ko = At-Rest Earth Pressure Coefficient Ka = Active Earth Pressure Coefficient Kp = Passive Earth Pressure Coefficient The geotechnical engineer should review and approve all materials to be utilized as backfill. Additional laboratory testing and evaluation will be part of this review process. Fill material around the walls should be placed as discussed in Section 7.2 of this report, with the following exceptions: 1) 2) Compaction of backfill material within ten (10) feet of the wall should be accomplished using light, hand-operated compaction equipment. The backfill material should be placed in horizontal lifts not exceeding six (6) inches in loose thickness where compactive effort application is hindered. Where practical, we recommend installation of a drainage system behind permanent retaining walls. The drainage system could consist of a perforated drain pipe at the base of the wall, surrounded by a free draining medium such as PennDOT 2B (AASTHO #57) stone. The stone should extend to approximately 12 inches above the top of the drain pipe and be wrapped in a geosynthetic fabric to prevent the migration of fine-grained particles into the stone and drain pipe. The drainage pipe should be daylighted down slope, away from the wall and any other existing or proposed structures. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania 8.0 Page 14 of 15 RECOMMENDED ADDITIONAL SERVICES Additional soil and foundation engineering, testing, and consulting services recommended for this project are summarized below: Site Preparation and Proofrolling: A Geotechnical Engineer or experienced Soils Inspector should inspect the site after it has been stripped and excavated. The inspector should determine if any undercutting or in-place densification is necessary to prepare pavement or building subgrades for fill placement. Fill Placement and Compaction: A Geotechnical Engineer or experienced Soils Inspector should witness any required filling operations and should take sufficient in-place density tests to verify that the specified degree of fill compaction is achieved. He should observe and approve borrow materials used and should determine if their existing moisture contents are suitable. Footing Excavation Inspections: A Geotechnical Engineer or experienced Soils Inspector should inspect the footing excavations for the proposed structure. He should verify that the design bearing pressure is available and that no loose pockets exist beneath the bearing surfaces of the footing excavations. Based on the inspection, the Inspector would either approve the bearing surfaces or recommend modifications to improve stability. 9.0 REMARKS This report has been prepared to aid in the evaluation of the site for the proposed construction. It is considered that adequate recommendations have been provided to serve as a basis for design. Additional recommendations can be provided as needed. These analyses and recommendations are, of necessity, based on the information made available to us at the time of the actual writing of the report and the on-site surface and subsurface conditions which existed at the time the test pits were excavated. If subsurface conditions are encountered which differ from those reported herein, this office should be notified immediately so that the analyses and recommendations can be reviewed and/or revised as necessary. It is also recommended that: 1. We are given the opportunity to review any plans and specifications in order to comment on the interaction of the soil conditions as described herein and the design requirements. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. Geotechnical Engineering Study Penn Commons East Buffalo Township, Union County, Pennsylvania Page 15 of 15 2. A Geotechnical Engineer or experienced Soils Inspector is present at the site during the construction phase to verify installation according to the approved plans and specifications. This is particularly important during excavation, placement, and compaction of fill materials. Please note that successful completion of the project is dependent on your compliance with all of the recommendations provided in this report. While represented separately, the recommendations represent work that is intertwined. Our professional services have been performed, our findings obtained, and our recommendations prepared in accordance with generally accepted engineering principles and practices. This warranty is in lieu of all other warranties either implied or expressed. HCEA assumes no responsibility for interpretations made by others based on work or recommendations by us. HILLIS-CARNES ENGINEERING ASSOCIATES, INC. APPENDIX A GENERAL GEOTECHNICAL NOTES HILLIS-CARNES ENGINEERING ASSOCIATES, Inc. 2929 Stewart Drive, Suite 302, State College, PA 16801 Phone: (814)231-0552 • Fax: (814)231-0695 Description of Soils – per ASTM D2487 Major Component Component Type Coarse-Grained Soils, More than 50% is retained on the No. 200 sieve Fine Grained Soils, More than 50% passes the No. 200 sieve Highly Organic Soils Component Description Symbol Gravels – More than 50% of the coarse fraction is retained on the No. 4 sieve. Coarse = 1” to 3” Medium = ½” to 1” Fine = ¼” to ½” Sands – More than 50% of the coarse fraction passes the No. 4 sieve. Coarse = No.10 to No.4 Medium = No. 10 to No. 40 Fine = No. 40 to No. 200 Silts and Clays Liquid Limit is less than 50 Low to medium plasticity Clean Gravels <5% Passing No. 200 sieve Gravels with fines, >12% Passing the No. 200 sieve GW GP GM GC Well Graded Gravel Poorly Graded Gravel Silty Gravel Clayey Gravel Clean Sands <5% Passing No. 200 sieve Sands with fines, >12% Passing the No. 200 sieve SW SP SM SC Well Graded Sand Poorly Graded Sand Silty Sand Clayey Sand Inorganic ML CL OL Silts and Clays Liquid Limit of 50 or greater Medium to high plasticity Inorganic Silt Lean Clay Organic silt Organic Clay Elastic Silt Fat Clay Organic Silt Organic Clay Peat Organic Description Sand, Gravel, Silt, Clay, etc. Sandy, silty, clayey, etc. Some sand, some silt, etc. Trace sand, trace mica, etc. With sand, with mica, etc. Particle Size Identification Approximate percent by weight 50% or more 35% to 49% 12% to 34% 1% to 11% Presence only Cohesive Soils Field Description Easily Molded in Hands Easily penetrated several inches by thumb Penetrated by thumb with moderate effort Penetrated by thumb with great effort Indented by thumb only with great effort MH CH OH PT Primarily Organic matter, dark color, organic odor Proportions of Soil Components Component Form Noun Adjective Some Trace With Organic Group Name Particle Size Boulder Cobble Gravel Sand Silt/Clay (fines) Particle dimension 12” diameter or more 3” to 12” diameter ¼” to 3” diameter 0.005” to ¼” diameter Cannot see particle Granular Soils Consistency Very Soft Soft Medium Stiff Hard No. of SPT Blows/ft 0–4 5 – 10 11 – 30 31 – 50 Greater than 50 Relative Density Very Loose Loose Medium Dense Dense Very Dense Other Definitions: • • • • • • • Fill: Encountered soils that were placed by man. Fill soils may be controlled (engineered structural fill) or uncontrolled fills that may contain rubble and/or debris. Saprolite: Soil material derived from the in-place chemical and physical weathering of the parent rock material. May contain relic structure. Also called residual soils. Occurs in Piedmont soils, found west of the fall line. Disintegrated Rock: Residual soil material with rock-like properties, very dense, N = 60 to 51/0”. Karst: Descriptive term which denotes the potential for solutioning of the limestone rock and the development of sinkholes. Alluvium: Recently deposited soils placed by water action, typically stream or river floodplain soils. Groundwater Level: Depth within borehole where water is encountered either during drilling, or after a set period of time to allow groundwater conditions to reach equilibrium. Caved Depth: Depth at which borehole collapsed after removal of augers/casing. Indicative of loose soils and/or groundwater conditions. APPENDIX B PROJECT LOCATION PLAN SITE TB-1 N TB-2 TB-1 PROJECT LOCATION SCALE 1:24,000 MAP SOURCE: 0 0.25 0.50 MILES 0.75 1.0 USGS 7.5 Minute Quadrangle Map, State College, PA-2013. USGS 7.5 Minute Quadrangle Map, Julian, PA-2013. HCEA Map Created: 10/02/2015. PROJECT LOCATION PLAN PENN COMMONS RESIDENTIAL DEVELOPMENT EAST BUFFALO TOWNSHIP UNION COUNTY, PENNSYLVANIA HCEA PROJECT NO: T15107 ENGINEERING ASSOCIATES, INC. 2929 Stewart Drive, Suite 302, State College, PA 16801 Local 814‐231‐0552 Fax 814‐231‐0695 www.hcea.com APPENDIX C USGS GEOLOGY MAP o oway F l o n o T an d Keyser rma o S ided (D v i d n u , ns KT) TB-1 N Hamilton Group (Dh) Onandaga and Old Port TB-2 (Doo) Forma ons, undivided TB-1 PROJECT LOCATION Keyser and Tonoloway Forma ons, undivided (DSKT) Wills Creek Forma on (Swc) Bloomsburg and Mifflintown Forma ons, undivided (Sbm) SCALE 0 0.25 0.50 MILES MAP SOURCE: 0.75 1.0 PA DCNR Map Viewer Internet Website: www.gis.dcnr.state.pa.us HCEA Map Created: 10/07/2015. USGS GEOLOGIC MAP PENN COMMONS RESIDENTIAL DEVELOPMENT EAST BUFFALO TOWNSHIP UNION COUNTY, PENNSYLVANIA HCEA PROJECT NO: T15107 ENGINEERING ASSOCIATES, INC. 2929 Stewart Drive, Suite 302, State College, PA 16801 Local 814‐231‐0552 Fax 814‐231‐0695 www.hcea.com APPENDIX D TEST PIT LOCATION PLAN N TP-8 TEST PIT LOCATION TP-5 TP-7 TP-1 TP-2 TP-4 TP-6 TP-3 SCALE 0 60 FEET 90 TEST PIT LOCATION PLAN ENGINEERING ASSOCIATES, INC. PENN COMMONS RESIDENTIAL DEVELOPMENT EAST BUFFALO TOWNSHIP UNION COUNTY, PENNSYLVANIA HCEA PROJECT NO: T15107 MAP SOURCE: Sheet No. S2-Site Plan of the Preliminary Land Development Plan for Penn Commons, East Buffalo Township, Union County, PA by Stahl Sheaffer Engineering, LLC, State College, PA dated July 1, 2015. HCEA Map Created: 10/07/2015. 2929 Stewart Drive Suite 302 State College, PA 16801 Local 814‐231‐0552 Fax 814‐231‐0695 APPENDIX E TEST PIT LOGS Test Pit Logs Project: Penn Commons Residential Development East Buffalo Twp., Union Co., PA Location: Client: Date Performed: 28-Aug-15 File Number: Union County Housing Associates, Inc. Sheet: T15107 1 of 3 Test Pit TP-1 Location: Western Building Depth (inches) Soil Description Remarks 0-2 Vegetation, Topsoil Dry. 2 - 19 Medium Brown Clay with Shale [FILL] Damp and Compact. 19 - 29 Pre-Fill Topsoil Layer Damp and Dense. Little or no organics remaining. Medium Brown Sandy Lean Clay Damp and Hard. Moisture Content: 16.7% 29 - 106+ Test Pit TP-2 Location: West Side, Middle Building Depth (inches) Soil Description Remarks 0 - 25 Vegetation, Topsoil Dry. 25 - 78 Sand and Gravel [FILL], with bottles, metals and burnt remants Dry and Compact. Light Brown Lean Clay Moist. Moisture Content: 24.7% 78 - 109+ Test Pit Logs (con't) Test Pit TP-3 Location: South Building Depth (inches) Soil Description Remarks 0-2 Vegetation, Topsoil Dry. 2-8 Medium Brown Clay with Shale [FILL] Damp and Compact. Stone foundation encountered along south side of excavation. Medium Brown Sandy Lean Clay Moist. Moisture Content: 22.8% 8 - 96+ Test Pit TP-4 Location: East Side, Middle Building Depth (inches) Soil Description Remarks 0-3 Vegetation, Topsoil Dry. 3 - 32 Black Ash and Cinder [FILL] Damp and Loosely Compacted. Light Brown Clay with Mottling Damp and Hard. Moisture Content: 15.2% 32 - 99+ Test Pit TP-5 Location: Depth (inches) North, Middle Building Soil Description Remarks 0-3 Limestone Gravel Dry. 3 - 13 Black Ash and Cinder [FILL] Damp and Loosely Compacted. Moisture Content: 10.7% Light Brown Clay with Mottling Damp and Hard. Moisture Content: 16.4% 13 - 109+ Page 2 of 3 Test Pit Logs (con't) Test Pit TP-6 Location: Southeast Building Depth (inches) Soil Description Remarks 0-5 Concrete Slab 5-8 Sand [FILL] Damp and poorly compacted. 8 - 24 Sand, Cinders and Gravel [FILL] Wet and poorly compacted. Moisture Content: 35.8% 24 - 43 Light Brown Lean Clay Moist and Stiff. Moisture Content: 29.7% 43 - 96+ Medium Brown Sandy Lean Clay Moist and Very Stiff. Moisture Content: 17.3% Test Pit TP-7 Location: East Side, Middle Building Depth (inches) Soil Description 0-5 Concrete Slab 5 - 36 Sand, cinders, brick and concrete remnants [FILL] 36+ Remarks Wet and poorly compacted. Standing water Concrete Slab Test Pit TP-8 Location: Depth (inches) 0 - 18 Northeast Building Soil Description Remarks Limestone Gravel [FILL] Damp. Test pit was terminated due to unmarked utilities and possible gas and fiber optic presence. Page 3 of 3 APPENDIX F REPRESENTATIVE PHOTOGRAPHS Plate 1 (TP-1 Excavation) Plate 2 (TP-2 Excavation) Plate 3 (73Burn Debris) Plate 4 (North Side of Site) Plate 5 (TP-4 Coal Refuse) Plate 6 (Mottled Clay) Plate 7 (Residual Soil) Plate 8 (TP-7 Standing Water) Plate 9 (Abandoned Utilities) Plate 10 (Backfilled Test Pits) APPENDIX G LABORATORY TESTING DATA #200 #140 #100 #60 #40 #30 #20 #10 #4 3/8 in. ½ in. ¾ in. 1 in. 1½ in. 2 in. 3 in. 6 in. Particle Size Distribution Report 100 90 80 PERCENT FINER 70 60 50 40 30 20 10 0 100 10 1 % Gravel Coarse Fine % +3" 0.0 0.0 0.3 Coarse 0.8 PERCENT SPEC.* PASS? SIZE FINER PERCENT (X=NO) 100.0 99.7 98.9 98.6 97.2 94.3 91.4 88.5 85.8 82.1 71.0 63.6 57.4 44.6 33.9 0.01 GRAIN SIZE - mm. SIEVE 3/8 #4 #10 #16 #30 #50 #100 #200 0.0229 mm. 0.0149 mm. 0.0093 mm. 0.0069 mm. 0.0051 mm. 0.0027 mm. 0.0012 mm. 0.1 % Sand Medium Fine 3.1 Silt 7.3 0.001 % Fines Clay 31.4 57.1 Soil Description Light Brown Lean Clay Atterberg Limits LL= 40 PL= 21 D90= 0.1100 D50= 0.0036 D10= USCS= CL Coefficients D85= 0.0195 D30= C u= Classification AASHTO= PI= 19 D60= 0.0058 D15= Cc= A-6(17) Remarks * (no specification provided) Location: Composite of Test Pit 4 (32"-99+") and Test Pit 6 (24"-43") Sample Number: L15150 Depth: n/a HILLIS-CARNES ENGINEERING ASSOCIATES STATE COLLEGE, PA Tested By: Robert Scandle Date: Client: Union County Housing Associate Project: Penn Commons Housing Project No: T15107 Figure 9/3/2015 #200 #140 #100 #60 #40 #30 #20 #10 #4 3/8 in. ½ in. ¾ in. 1 in. 1½ in. 2 in. 3 in. 6 in. Particle Size Distribution Report 100 90 80 PERCENT FINER 70 60 50 40 30 20 10 0 100 10 1 % Gravel Coarse Fine % +3" 0.0 1.9 2.2 Coarse 3.5 PERCENT SPEC.* PASS? SIZE FINER PERCENT (X=NO) 100.0 99.2 98.1 97.1 95.9 92.4 90.9 87.5 80.3 67.8 58.3 50.9 45.9 38.9 32.7 28.6 22.0 17.1 0.01 GRAIN SIZE - mm. SIEVE 1.5 1 3/4 3/8 #4 #10 #16 #30 #50 #100 #200 0.0270 mm. 0.0177 mm. 0.0107 mm. 0.0078 mm. 0.0057 mm. 0.0029 mm. 0.0013 mm. 0.1 % Sand Medium Fine 7.8 Silt 26.3 0.001 % Fines Clay 31.0 27.3 Soil Description Medium Brown Sandy Lean Clay Atterberg Limits LL= 24 PL= 16 D90= 0.9429 D50= 0.0249 D10= USCS= CL Coefficients D85= 0.4435 D30= 0.0065 C u= Classification AASHTO= PI= 8 D60= 0.0883 D15= Cc= A-4(2) Remarks * (no specification provided) Location: Composite of Test Pit1 (29"-106+) and Test Pit 5 (19-109+) Sample Number: L15151 Depth: n/a HILLIS-CARNES ENGINEERING ASSOCIATES STATE COLLEGE, PA Tested By: Robert Scandle Date: Client: Union County Housing Associate Project: Penn Commons Housing Project No: T15107 Figure 9/3/2015