Geotech Report 04 19 2021

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 8 West Orange, NJ of fines into the fragments. The need for the placement of a geotextile fabric should be determined in the field at the time of construction. All structural fill and backfill placed within building areas should be installed under the technical observation of a geotechnical engineer. Controlled soil fill materials should be spread in layers on the order of 12 inches in loose thickness and compacted to at least 95 percent of maximum dry density as determined by the ASTM D-1557 test procedure. Layers of rock fill may be somewhat greater than 12 inches compatible with the appropriate compaction equipment and should also be compacted to a visually dense condition. Groundwater is not anticipated to present significant problems during construction. We recommend that surface grades be maintained during construction to prevent the inundation of the subgrade soils from surface water runoff. Any water seepage that may occur should be immediately collected and removed from the construction excavations by pumping from sumps established within or adjacent to excavations. All excavations should be in accordance with OSHA requirements. For this site, the soils are considered to be Type C which limits excavation sides to 1 vertical to 1% horizontal. Steeper slopes should be adequately protected with sheeting, shoring, and bracing. Permanent embankment slopes should be no steeper than 1 vertical to 3 horizontal for erosion control and maintenance purposes. Foundation Design Criteria: The proposed buildings may be supported on conventional spread foundations. Foundations may be supported directly on the controlled backfill, competent natural soils or clean %-inch size crushed stone placed over these materials or basalt bedrock. We recommend that the foundation subgrades be observed by a qualified geotechnical engineering firm to ensure that competent bearing soils are present and the subgrade should be recompacted or undercut as directed. The exposed foundation subgrade soils will likely consist of sandy silt/clayey silt, silty gravelly sand, or basalt bedrock. These sandy silt or clayey silt soils were in a soft condition and are susceptible to further disturbance during construction activities, especially in the presence of excess water. Care should be

ck. These sandy silt or clayey silt soils were in a soft condition and are susceptible to further disturbance during construction activities, especially in the presence of excess water. Care should be exercised during foundation excavation and construction to limit disturbance of the subgrade sails. If the exposed

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 9 West Orange, NJ foundation subgrade is soft or becomes wet, it should be over-excavated by 6 inches or more and replaced with compacted %-inch crushed stone. Layer of clean %-inch size crushed stone over the foundation subgrade soils would provide a stable working surface during foundation construction and limit the potential for soil disturbance and resulting loss of soil strength. Foundations established on the competent bearing controlled fill, natural sandy silt/clayey silt or silty gravelly sand or clean %-inch size crushed stone placed over these soils may be proportioned to impose a maximum allowable net bearing pressure of up to 4000 pounds per square foot. However, wall foundations should be at least 24 inches in width and column foundations at least 3 feet by 3 feet in plan dimensions. The bottoms of all exterior or exposed foundations should be established at least 3 feet below the adjacent exterior grades to provide protection from frost penetration. Interior foundations in permanently heated portions of the buildings may be established at convenient depths beneath the floor slab provided they reach the intended bearing stratum. Foundations deriving their support from the competent basalt bedrock may be proportioned to impose a maximum allowable net bearing pressure of up to 8 tons per square foot. Footings deriving their support directly on basalt bedrock may be established at convenient depths beneath the ground level slab. We estimate that differential settlements between foundations deriving their support from the undisturbed natural soil, compacted fill and basalt bedrock would be approximately % of 1 inch. Post-construction settlements of foundations established on bedrock would be negligible. In the event the foundation will be established partially on bedrock and partially on soil, we recommend either over-excavating the bedrock a depth of 12 inches and replacement with controlled compacted fill or providing a construction joint. Slab-On-Grade Design Criteria: We recommend that immediately prior to slab construction, the exposed subgrade soils be recompacted and proofrolled to a dense and unyielding condition by multiple passes of a vibratory steel-drum compactor. Any localized areas that cannot be recompacted to a dense and

subgrade soils be recompacted and proofrolled to a dense and unyielding condition by multiple passes of a vibratory steel-drum compactor. Any localized areas that cannot be recompacted to a dense and unyielding condition should be removed to expose suitable subsoils and the excavations backfilled with controlled compacted backfill or clean %-inch size crushed stone. Following the recompaction and in)

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 10 West Orange, NJ proofrolling operations, slabs may be designed using a vertical modulus of subgrade reaction of 200 pounds per cubic inch. We recommend that slabs be underlain by a minimum 4-inch thick layer of clean %-inch size crushed stone to provide a capillary break as well as a porous drainage layer beneath the slab. We estimate that post-construction settlements of slabs designed and supported on material prepared in accordance with our recommendations would be negligible. Retaining Walls: Any below grade walls required to accommodate grade changes should include provisions for full drainage. Provided the walls are fully drained and backfilled with controlled compacted fill in accordance with previous sections of this report, the following soil parameters are recommended for wall design: Maximum Allowable Soil Bearing Pressure 4000 psf Angle of Internal Friction (@) 30 degrees Total Unit Weight of Soil 125 pef Active Earth Pressure Coefficient (Ka) 0.30 Passive Earth Pressure Coefficient (Kp) 3.25 Friction Factor — Concrete on Soil 0.40 Pavement Design Criteria: Site preparation procedures within proposed pavement areas should consist of stripping the surficial topsoil, vegetation, and all debris from within and to a distance of 5 feet beyond the pavement limits. Following general grading, but prior to placing any fill in areas to be raised, the surface should be thoroughly proofrolled and compacted to a dense and unyielding condition by numerous passes of a heavy vibratory compactor. Localized areas that cannot be compacted to a dense and unyielding condition should be removed to expose suitable subsoils and the excavations backfilled with controlled granular fill in accordance with the recommendations presented in previous sections of this report. Assuming that the pavement subgrade soils are compacted to a dense and unyielding condition immediately prior to construction, pavements may be designed using an estimated California Bearing Ratio (CBR) value of 6 percent. Based on this value, we recommend the following minimum pavement design sections for flexible pavements:

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 11 West Orange, NJ Access Roads Automobile Parking | Bituminous Concrete Surface Course 2 inches 2 inches Bituminous Concrete Base Course 4 inches 2 inches Dense Graded Aggregate Subbase 6 inches 6 inches Total Section Thickness 12 inches 10 inches For a rigid pavement, a modulus of subgrade reaction of 200 pounds per cubic inch may be used. Proposed Detention Basins: An exploration program consisting of six backhoe excavated test pits was performed at the site. Four test pits were performed in the proposed basin area. The area of basin is currently grass/vegetation covered. The existing ground surface elevation is approximately +538 to +546 feet. The area of second infiltration area is at TP-14 and 15 locations and is currently grass/vegetation covered or wooded. The existing ground surface elevation is approximately +594 to +598 feet. The test pits, TP-24, 25, 26 and 27 performed at basin area encountered 8 inches of topsoil. Light brown silt loam to clay loam was encountered beneath the topsoil at test pits and extended to depths of 3 to 5.5 feet below surface. Loam was encountered beneath the silt or clay loam and extended to maximum depths explored, 6 to 13 feet. At TP-25 bedrock was encountered at a depth of 6 feet. Groundwater or seasonal high groundwater was not encountered to the maximum depths explored. The test pits, TP-14 and 15, performed at the infiltration area encountered 8 to 12 inches of topsoil. Brown loam material was encountered beneath the topsoil and extended to depths of 10 to 11 feet below surface where bedrock was encountered. Water seepage was encountered at a depth of 9 feet in TP-15 location. The tube samples collected during the field investigation were returned to our soil mechanics laboratory. Five mechanical grain-size analyses and falling head tube permeability tests were performed on the samples. The test results are included with this report. The falling head permeability test results for the basin indicate that the loam has a permeability rate ranging from 0.81 to 1.58 in/hr (K2 soils). Test results on silt loam (TP-25) has a permeability rate of 0.18 in/hr (KO soils) which is hydraulically restrictive.

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 12 West Orange, NJ The falling head permeability test results at the infiltration area (TP-14, TP-15) indicate that the loam material has a permeability rate ranging from 0.79 to 1.5 in/hr (K2 soils). Based on our evaluation of the subsurface conditions encountered in the test pits as well as the results of the laboratory test results, it is our opinion that the loam material encountered beneath the silt/clay loam is favorable for the construction of the detention basins or infiltration systems. The basins or infiltration systems should be designed based on the measured permeability rates for the subsoils encountered at these locations. Seismic Design Considerations: Structures must be designed in conformance with the applicable seismic design criteria of the New Jersey Edition of the 2015 International Building Code. In accordance with the Code, the subsurface information obtained from the borings and the known geologic conditions in this area, the site is considered to have a rock profile which corresponds to a site class “B”. Based on our analysis of the subsurface conditions, the field and laboratory test results and the known geology of this area, the on-site soils are not susceptible to liquefaction in a seismic event and the underlying bedrock is not considered susceptible to solutioning or the formation of sinkholes. RECOMMENDED SERVICES It is recommended that Sor Consulting Engineers be provided the opportunity for a general review of the final design and specifications to assure that the foundation and earthwork recommendations are properly interpreted and implemented in the construction documents. We also recommend that controlled compacted fill and backfill operations as well as foundation and floor slab subgrades be observed by a geotechnical engineer from our firm. This is to ensure compliance with the recommendations contained herein and to address any changes in the subsurface conditions that were not disclosed by the borings and test pits. Sor Consulting Engineers appreciates the opportunity to be of assistance with this project. Should there be any questions concerning the information provided herein,

SOR CONSULTING ENGINEERS, INC. Garden Homes Report No. 21-C-12 Proposed Residential Development Page 13 West Orange, NJ please do not hesitate to contact us. The following appendices are attached and complete this report: Appendix |: Exploration Location Plan Subsurface Profiles AA, BB and CC Appendix II: Boring Logs 1 through 15 Test Pit Logs 1 through 27 Burmeister and USDA Soil Classification Systems Appendix Ill: Laboratory Soil Test Results Appendix IV: Limitations Very truly yours, SOR CONSULTING ENGINEERS, INC Atilla Sencar, P.E. Senior Engineer AS/gs cc: Anderson Consulting Services, LLC Attn: Paul Anderson, P.E., P.E., CME E-Mail: pandersonpe@gmail.com

APPENDIX | EXPLORATION LOCATION PLAN SUBSURFACE PROFILES AA, BB AND CC

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