17_CEEC-MOD_RFP_Attachment L_GeotechnicalReport.pdf

J0859-49-01 April 13, 2026

Ms. Aelan Tierney, AIA, LEED AP, NCARB Kuhn Riddle Architects, Inc.

28 Amity Street, Suite 2B Amherst, Massachusetts 01002

Re: Geotechnical Engineering Recommendations UMass CEEC – North Pleasant Street Amherst, Massachusetts

Dear Ms. Tierney:

O’Reilly, Talbot & Okun Associates, Inc. (OTO) is pleased to provide this letter report summarizing our geotechnical engineering recommendations for the proposed University of Massachusetts Amherst Center for Early Education and Care (UMass CEEC) to be located at 972-990 North Pleasant Street in Amherst, Massachusetts. A Site Locus is provided as Figure 1. A Site Plan is provided as Figure 2.

Our geotechnical recommendations are based upon subsurface conditions observed in four soil borings and nine test pits. Our services consisted of the full-time observation of the borings and test pits, review of the logs and soil samples, review of historic logs, engineering analyses, and preparation of this report. This report is subject to the attached limitations.

1.0 PROJECT DESCRIPTION

The Site is located within two property parcels within the residential neighborhood of north Amherst: 972 North Pleasant Street (northern portion of Site) and 990 North Pleasant Street (southern portion of Site). The property line between the two parcels approximately bisects the proposed development. The location of the Site is shown on Figure 1.

The Site is bounded to the east by North Pleasant Street. An existing house and detached garage surrounded by grassy areas are located within the eastern portion of the 972 North Pleasant Street parcel. The western portion of this parcel consists of wooded areas. The 990 North Pleasant Street parcel consists of a large grass covered area with trees to the east. A fence separates the two parcels. The North Village Apartments complex and associated driveways are located further to the north and northwest of the Site.

We understand that the North Village complex was constructed in early 2020’s, after demolition of the former complex. The former complex footprint overlaps with the northern portion of the proposed building, including former building footprint(s) and former paved areas.

ATTACHMENT L

Geotechnical Engineering Recommendations UMass CEEC – North Pleasant Street

Amherst, Massachusetts April 13, 2026

Topography generally slopes downward from the east/southeast (approximate elevation 179 feet at North Pleasant Street) to the west (approximate elevation 165.5 feet at the western boundary of the woods). The existing ground surface within the vicinity of the proposed building area is generally flat, between an approximate elevation of 172 to 170 feet. The ground surface in the proposed parking lot area varies between elevation 170 and 166 feet.

Project plans call for the construction of an approximately 13,000 square foot (footprint) one-story building, located between the two parcels. We understand that the structure will be slab on grade, with a finish floor slab at elevation 173. Due to the topography within the existing building, we expect one to three feet of fill will be placed to form the building pad. Therefore, we expect cuts and fills to be four feet or less to construct the building.

The proposed building location and paved vehicular parking areas are shown on Figure 2.

We expect structural loads to be supported on both isolated column and continuous strip footings. Structural loads are unknown at this time. However, it is expected that maximum column loads will be on the order of 50 kips or less. We anticipate bearing walls will carry a load of approximately two kips per linear foot. These assumptions should be confirmed by the design team.

2.0 SUBSURFACE EXPLORATIONS

Subsurface investigations and testing consisted of soil borings, backhoe test pits, in-situ permeability testing, and environmental field screening. Soil boring logs and test pit logs are attached. The locations of subsurface explorations are shown on Figure 2.

Historic Soil Borings and Test Pits

OTO reviewed soil borings and test pits from the report “Geotechnical Engineering Report UMA UG/G Housing Project – North Village Site” dated May 20, 2021, Revised September 17, 2021, prepared by GZA. This project is located immediately north of the proposed UMASS CEEC. GZA borings GZ-114 and GZA test pits TP-101 and TP-102 were extended to depths between 8 and 10 feet below ground surface. GZ-117 extended to a depth of 16 feet. Boring GZ-115 was performed using a B-53 mobile drill rig using case and wash drilling techniques, to a depth of 51 feet below ground surface. Historic logs are attached to this report.

Soil Borings

Four soil borings (PS-1 through PS-4) were performed near the footprint of the proposed building on March 16 and 17, 2026 by Seaboard Drilling of Springfield, Massachusetts.

Borings were performed using a B-48 track mounted drill rig using hollow stem auger drilling techniques. One boring encountered refusal in the near surface, and the remaining borings were performed to a depth of 22 to 27 feet below ground surface. Boring locations are shown on Figure 2. Boring logs are attached.

Amherst, Massachusetts April 13, 2026

Soil samples were collected using a two-inch diameter split spoon sampler, driven 24 inches with a 140-pound automatic hammer falling 30 inches (American Society for Testing and Materials Test Method D1586 “Standard Test Method for Penetration Test and Split-Barrel Sampling of Soils”). The number of blows required to drive the sampler each six inches was recorded. The standard penetration resistance, or N-value, is the number of blows required to drive the sampler the middle 12 inches. Soil properties, such as strength and density, are related to the N-value. The field N-values are corrected to a standard 60% hammer efficiency, known as N60, to account for differing hammer efficiencies for each hammer type, borehole diameter, sampler type, and sample depth.

The N-values presented on the boring logs are field values, which are not adjusted for hammer efficiency. However, the adjusted N60 values were used in our engineering calculations and analysis.

An O’Reilly, Talbot & Okun Associates, Inc. (OTO) representative observed and logged each of the soil borings. Soils were described according to a modified version of the Burmister Soil Classification System. Upon completion, bore holes and test pits were backfilled with soil cuttings.

The headspace of soil samples collected from the borings was screened in the field using a MiniRAE Lite Photo Ionization Detector. PID screening provides an assessment of volatile organic content of the samples.

Test Pits

Test pits TP-1 through TP-9 were performed by Hatfield Construction of North Hatfield, Massachusetts on March 20, 2026. The test pits were performed using a CAT 308 CR mini excavator, equipped with an approximate 0.3 cubic yard bucket. Test pit logs and photographs are attached.

Test pits TP-1 and TP-2 were performed to observe near subsurface conditions and to identify indications of Estimated Seasonal High Ground Water Table (ESHGWT) for the design of stormwater management systems. In addition, hydraulic conductivity (permeability) tests were conducted at these test pits. Test pits TP-3 through TP-9 were performed near the footprint of the proposed building to observe the nature of surface fill soils.

An O’Reilly, Talbot & Okun Associates, Inc. (OTO) representative logged each of the test pits. The test pits performed in proposed stormwater control areas were observed by a Massachusetts licensed soil evaluator. Upon completion, test pits were backfilled with soil cuttings.

3.0 SUBSURFACE CONDITIONS

This discussion of subsurface conditions at the Site is based upon published geologic information, general knowledge of the Site location and nearby vicinity, and the soil investigations performed during this study. Subsurface conditions generally consisted of the following, in order of increasing depth: a surface layer of topsoil; fill and/or reworked soils; native granular soils; and native varved silt and clay. With the exception of the near

Amherst, Massachusetts April 13, 2026 surface fill/reworked soils, the soil conditions are favorable for the proposed construction.

Boring GZ-115, completed in 2021 by others, was used to assess deep soil conditions and determine the Seismic Site Class.

Topsoil: Approximately 5 to 8 inches of topsoil was present at the ground surface of each boring and test pits north of the existing fence (PS-1 through PS-3, TP-3 through TP-9).

The topsoil in this area consisted of fine to medium sand with some silt and little to trace amounts of organics (roots).

Within the wooded area south of the existing fence, topsoil thickness was approximately 14 to 16 inches. This layer generally consisted of very loose, fine sand and silt, with trace (+) organics (roots, tree roots).

Granular Fill: The surficial topsoil was underlain by granular fill in test pits TP-3 through TP-9 and boring locations PS-1 through PS-3. This layer generally extended to 4 to 5 feet below the ground surface, except in test pit TP-3 where the fill layer extended to 2.5 feet below ground surface. This layer generally consisted of medium dense, sand and gravel or fine to medium sand with some gravel, with trace amounts of silt and debris. Wooden stakes, and pieces of pipe were encountered in test pit TP-4. Caution tapes, and wooden stakes were observed in test pit TP-5.

A 6-inch-thick layer of hardpack was encountered starting at a depth of between 6 to 24 inches in test pits TP-3 (3a through 3c), TP-4, and TP-9, which were located in the central and eastern portions of the proposed building footprint at the north side of the existing fence.

A thin concrete slab (approximately 2.5 inches thick) was observed in test pit TP-8 near a depth of 2 feet below ground surface. This slab appears to be a former equipment pad associated with the recent development of the North Village Complex. Boring PS-1 (and associated off-set borings) had terminated upon this debris; however, this area was further investigated in test pit TP-8 to expose the thin concrete layer.

Native Granular Soils: Native granular soils extended to a depth of 13 to 15 feet, and generally consisted of medium dense, fine sand with varying amounts of silt and medium sand. OTO test pits TP-1 through TP-9, and GZA boring GZ-114 terminated in this layer at depths of 5 to 10 feet.

Varved Silt and Clay: The granular soils were underlain by a very soft to medium stiff, varved silt and clay. This layer consists of fine-grained, post-glacial lake deposits that were deposited within ancestral Lake Hitchcock (which filled much of the Connecticut River Valley from the retreat of the last continental glacier until approximately 15,000 years ago).

These fine-grained soils are characterized by alternating layers (or varves) of silt, sand, and clay. Published geologic maps1 indicate that the silty clay deposit is less than 50 feet thick in the site vicinity. In general, the upper two to three feet of this layer was found to

1“Map Showing Distribution and Thickness of Principal Fine Grained Deposits, Connecticut Valley Urban Area, Central New England”, Langer, USGS, 1979.

Amherst, Massachusetts April 13, 2026 be stiff to medium stiff, indicating a top, desiccated crust. The clay became soft to very soft beneath the crust, near a depth of 20 feet below ground surface. The soft clay extended to the maximum depth explored in the nearby 2021 boring, GZA-115, which was terminated at a depth of 51 feet.

The varved clay unit can be soft and compressible, which can cause building settlement under moderate to heavy loading. However, at this Site and for this project, it is unlikely that building performance would be adversely impacted based upon anticipated building loads and depth to the top of the clay surface.

Groundwater Conditions

During drilling, groundwater was observed generally at a depth of between 3 and 8 feet below ground surface, corresponding to elevation between 161 and 166.5 feet. Two borings, PS-3 and PS-4, encountered saturated soils at a higher elevation of 168 feet;

however, this may have been due to perched layers from recent heavy rains.

We anticipate that groundwater will be encountered during the service life of the structure and during construction. Groundwater recommendations are provided below. If groundwater is encountered, it appears that the contractor will be able to dewater shallow excavations using sump pumps and trenching. We note that significant flows may be encountered during periods of wet weather.

Field Testing Results

Unconfined Compressive and Shear Strength

The unconfined compressive strength of the clay stratum was estimated in the field using a pocket penetrometer and the undrained shear strength was estimated using an E-285 Pocket Vane Shear Tester. These field measurements are intended to provide a rough measure of the engineering properties of the fine-grained soils. Vane Shear measurements of shear strength ranged from approximately 100 to 500 pounds per square foot (psf) in the varved silt and clay portion. Pocket penetrometer measurements of unconfined compression strength ranged from approximately 500 to 3,000 psf. Both tests showed a relatively stiff crust at the surface of the silt and clay layer and becoming soft below. Pocket vane shear and penetrometer test results are presented in the boring logs.

Photo-Ionization Detector (PID) Screening

PID screening provides an assessment of volatile organic compounds (VOC) present in the soil sample. The PID readings were generally below instrument detection limits.

Samples S-1 (0-2’) and S-2 (2-4’) in boring PS-1, samples S-1 (0-2’), S-2 (2-4’), S-4 (7-9’) in PS-2 and sample S-7 (20-22’) read values between 0.1 and 3.3 parts per million (PPM).

These values are consistent with background levels.

Amherst, Massachusetts April 13, 2026

4.0 IN-SITU HYDRAULIC CONDUCTIVITY TESTING & RECOMMENDATIONS

To aid in the design of the storm water infiltration system, two in-situ hydraulic conductivity (or permeability) tests were performed in test pits TP-1 through TP-2 using a Guelph Permeameter to provide information for design of the stormwater management systems.

The Guelph Permeameter uses a constant head testing methodology, which allows the rate of water recharge into an unsaturated soil to be measured. The permeability tests were performed by auguring a shallow hole into the soil, adding water to the apparatus, and then recording the remaining volume of water in the device at consistent time intervals.

Calculations are then made to estimate the saturated coefficient of permeability (K-value) of the soil based upon these measurements.

Hydraulic conductivity (or permeability) testing was performed within test pits TP-1 and TP-2 at depths of 3.0 and 2.0 feet below ground surface, respectively, within the unsaturated natural fine sand layer present at the test depth. The saturated hydraulic conductivity (K-value) determined from these tests were approximately 0.23 (TP-2) and

5.3 (TP-1) feet per day. A summary of the conditions and results for each test location is presented in Table 1 below.

We recommend that the field conditions be verified during installation of the stormwater structures to ensure that actual conditions are similar to those observed during these investigations and that the values assumed for design are appropriate. Furthermore, we recommend that any pockets and/or layers of silty soils near the base of the structures (if encountered) be removed and replaced with permeable sand.

Table 1 Hydraulic Conductivity Testing Results

Infiltration Test Location

Test Depth Soil Conditions K Value

(feet/day) TP-1 3.0 Brown to grayish brown, fine sand, little silt 5.3 TP-2 2.0 Brown, fine sand, some to little clayey silt 0.23

Notes:

1. In situ hydraulic conductivity tests were performed immediately adjacent to test pits using a Guelph Permeameter.

5.0 SIGNIFICANT GEOTECHNICAL ISSUES

The significant geotechnical issues for the proposed construction addressed in this report include the following: the presence of fill; foundation bearing capacity and settlement;

stormwater control; groundwater control; seismic design considerations; and the suitability of on-Site materials for use as engineered fill.

6.0 DESIGN RECOMMENDATIONS

The following recommendations are provided for the construction assumed in this report and refer to the 10th Edition of the Massachusetts State Building Code (MSBC), which

Amherst, Massachusetts April 13, 2026 includes amendments to the 2021 International Building Code (IBC) and became effective on October 11, 2024.

Existing Structures and Utilities

We understand that former buildings and associated roadways and parking areas were located within the northern portion of the site. OTO did not encounter any significant debris within the investigations; however minor debris were encountered in the near surface. If encountered, any remaining foundation walls or slabs, basements, or utilities that are located within the footprint of the proposed building should be removed in their entirety.

These excavations may extend below the planned slab and footing levels. Any excavations resulting from the removal of remaining foundations and/or slabs, should be backfilled with compacted engineered fill, consistent with the recommendations provided below and in the Earthwork Considerations section.

Buried utilities containing asbestos (such as electrical conduit insulation or transite pipe) are commonly found during construction excavations. In case asbestos is encountered, such materials should be handled in accordance with MassDEP’s asbestos regulations (310 CMR 7.15). We recommend that suspect materials be managed appropriately and tested by a Department of Labor Standards (DLS) certified asbestos inspector prior to disturbances.

Any debris, loose or non-engineered fill should be removed and replaced with engineered fill.

Foundation Recommendations

The proposed building can be founded on normal spread footing foundations bearing on compacted, native sandy soils or engineered fill. We note that minor amounts of debris and a hardpack soil layer were encountered within the building footprint. In general, the granular fill was observed to be dense; however, localized loose layers may be present.

Therefore, we recommend that debris layers be removed from beneath footings and that the entire building footprint be proof compacted. Deleterious materials (wood, trash) should be removed from beneath the slab subgrade. The resulting excavation should be backfilled with compacted Sand and Gravel or Crushed Stone fill, as recommended below.

Given the presence of elevated groundwater conditions or perched groundwater layers, it appears that some of the footings may extend into the groundwater table, particularly in the southern portion of the Site. Therefore, in areas where subgrades extend into the groundwater table or where soft soils are present, we recommend that footing subgrades be over excavated by a minimum of 6 inches and replaced with Crushed Stone. The Crushed Stone will provide for a firm bearing surface and facilitate dewatering and compaction in wet conditions. A non-woven geotextile separation fabric should be placed between the natural soil and crushed stone. Provided the recommendations within this section are followed, we recommend that the spread footing foundations bearing on 6 inches of Crushed Stone or compacted native soils be designed for a maximum allowable bearing pressure of 3,000 pounds per square foot. If any soft, wet, or disturbed soil or any

Amherst, Massachusetts April 13, 2026 deleterious or debris fill is encountered at the subgrade, these materials should also be removed and replaced with Sand and Gravel or Crushed Stone fill.

Exterior footings should be embedded a minimum of 48 inches below the lowest adjacent grade for frost protection. Any Interior footings should bear at least two feet below the surrounding floor slab. The perimeter strip footings, beneath the load bearing walls, should be at least 18 inches wide. Isolated column footings (if present) should be at least 24 inches wide. All other applicable requirements of the Massachusetts State Building Code (MSBC) should be followed.

Footings should not be placed on frozen soils. Footing excavations should be free of loose or disturbed materials. Any boulders or cobbles larger than four inches in diameter should be removed from within one foot of the bottom of the footings and replaced with Crushed Stone or compacted Sand and Gravel fill. The footing subgrades should be densified immediately prior to placement of footing concrete with at least three passes with a vibrating plate compactor. If loose materials are present in the excavations, they shall be recompacted to form a firm, dense bearing surface.

Settlement

The compression of the clay layer which underlies the site is a geotechnical consideration for this project. This concern is partially reduced due to the relatively light building and fill loads, depth to the top of the soft clay layer, and relative thickness of the upper crust.

However, we have estimated that fill placed to establish final building slab grades will vary from approximately one to three feet in height. It is anticipated that fills (if used) to grade around the building will be similar in height. The fill loads may compress the underlying clay, and due to the variable constancy of the clay and thickness of the fill across the building footprint, differential settlement may occur.

We anticipate that settlement will be largely elastic in nature and should occur relatively quickly after load application (during construction). The magnitude of consolidation and settlement of the varved silt and clay soils is dependent on the anticipated load, the stiffness of the underlying soils, the maximum pressure that the soil has experienced in the past, and the presence of sand lenses in the fine grained soil matrix. Therefore, since the anticipated loads due to fill placement will vary, we recommend that the site be filled to final subgrade elevations/preliminary grades early on in the construction sequence, to allow settlement due to the weight of fill to occur prior to construction of the building. This early sequencing of fill placement will limit post-construction total and differential settlement of the clay layer.

Provided that the preliminary grading is preformed early on in the construction sequence, we anticipate that maximum post construction total settlement would be on the order of 1 inch and differential settlement on the order of ½ inch. This estimate assumes that approximately one to three feet of fill will be placed to form the building pad. As described above, we recommend that the placement of the fill should occur early on in the construction sequence. Furthermore, if more fill than estimated is needed or if the building

Amherst, Massachusetts April 13, 2026 conditions differ from the light weight, wood-framed, one-story structure presently anticipated, settlement estimates should be re-evaluated.

If preliminary grading (including fill placement of one foot or greater) occurs within one month of footing construction, we recommend that the contractor monitor the settlement throughout the construction process to mitigate potential concerns due to differential settlement. The total amount and rate of settlement should be reviewed prior to framing and roofing and again, prior to construction of building finishes. We recommend that settlement points be installed on the building foundation and monitored on a weekly basis to confirm/refine post-construction settlement estimates.

Concrete Slabs

We recommend that the concrete floor slab bear on at least 12 inches of compacted Sand and Gravel fill or Crushed Stone to provide uniform support and a capillary moisture break.

The subgrade should also be free of large boulders or cobbles, if encountered. The Sand and Gravel fill beneath the concrete slabs should meet the grain size distribution characteristics outlined in Table 3.

The subgrade within the footprint of the proposed addition should be stripped of topsoil, concrete, and any non-engineered fill (if present). Prior to the placement of any engineered fill, we recommend that the footprint of the new structure be thoroughly densified to treat any loose areas present. If non-engineered fill, soft, or disturbed areas are present, these materials should be removed and recompacted or replaced with compacted, Sand and Gravel or Crushed Stone. Fill supporting slabs should be placed in accordance with the recommendations presented on Sheet 1.

Groundwater and Surface Water Control

Wet soils were observed in borings PS-2 through PS-4 and water seepage was observed in test pits TP-1 through TP-6 at a depth of between 2 and 8 feet below ground surface, corresponding to elevations between 161.2 and 168. The shallowest depths were observed in the southern portion of the Site. In addition, perched groundwater may be present during periods of wet weather. Therefore, we recommend perimeter drainage be included around the proposed building to control groundwater and surface water infiltration. The perimeter drainage system can consist of perforated PVC pipe, installed in a Crushed Stone trench, and wrapped in a non-woven geotextile fabric. The perimeter drain should be sloped to allow the water to flow away from the foundation via gravity. A typical detail of the underdrain system is shown on Sheet 2. Clean-outs should be provided in the perimeter drainage system as needed to allow for future maintenance.

If groundwater is encountered during excavations for footings and utilities, it should be possible to dewater these excavations by trenching or using sump pumps. We note that significant flows may be present during periods of wet weather or high groundwater.

Furthermore, the contractor should establish and maintain proper drainage of soils during construction.

Amherst, Massachusetts April 13, 2026

Seismic Considerations

Earthquake loadings must be considered under requirements in Section 1613 and 1806 of the 10th Edition (October 2024) of the Massachusetts State Building Code (MSBC), which is based upon the International Building Code 2021 (IBC) with Massachusetts amendments. Note that the IBC refers to ASCE-7, Minimum Design Loads for Buildings and Other Structures.

Section 1613 of the IBC covers lateral forces imposed on structures from earthquake shaking and requires that every structure be designed and constructed to resist the effects of earthquake motions in accordance with ASCE-7. Lateral forces are dependent on the type and properties of soils present beneath the Site, along with the geographic location.

Per Table 1604.11, the maximum considered earthquake spectral response acceleration at short periods (Ss) and at 1-sec (S1) was determined for Amherst, Massachusetts.

Soil properties are represented through Site Classification. Procedures for the Site-specific determination of Site Classification are provided in Chapter 20 of ASCE-7. At this Site, we evaluated Site Classification using one of the parameters allowed, Standard Penetration Resistance (N-value), based upon soil data collected. Furthermore, the Site coefficients Fa and Fv were determined according to Tables 1613.3.3(1) and 1613.3.3(2) of the IBC (2021), using both the Ss and S1 values and the Site Class. Parameters are provided in Table 2.

Table 2 Seismic Design Parameters

Parameter Value Ss 0.172 S1 0.057

Site Class E Fa 2.4 Fv 4.2

Section 1806.4 relates to the liquefaction potential of the underlying soils. The liquefaction potential was evaluated for saturated Site soils, using Figure 1806.4 of the MSBC. Based upon the observed density and fine grained nature of soils below a depth of 15 feet, liquefaction should not occur under the design earthquake.

Exterior Slabs and Pavements

This section provides recommendations for exterior entryways, slabs, and sidewalks, as well as flexible and rigid pavements.

Sidewalks and Concrete Slabs

Exterior concrete slabs, such as those at entryways and sidewalks adjacent to the building should be designed to mitigate differential frost movement between adjacent slabs, Amherst, Massachusetts April 13, 2026 doorways, and pavements. To address this concern, we recommend that concrete slabs at entryways be underlain by four feet of non-frost susceptible Sand and Gravel fill or consist of a structural slab connected to a perimeter frost wall foundation, so it cannot move vertically as a result of frost. Where exterior slabs butt against hard surfaces, we recommend that for the area beyond the edges of the slab, the bottom of Sand and Gravel fill should transition gradually upward at a slope of 3H:1V or flatter (zone of influence).

We recommend that concrete sidewalks and slabs that are outside the zone of influence of the building and entryways, as well as areas where differential frost movement would not cause a tripping hazard, bear on at least 12 inches of imported, compacted Sand and Gravel to provide uniform support and a capillary moisture break. Depending on proposed final grades of pavements and sidewalks, an underdrain system should be considered in wet areas to help remove water from within the subgrade. Fill should be placed in accordance with the recommendations for compaction provided on Sheet 1. Subgrades should also be free of large boulders. We recommend that the entire subgrade of the sidewalk and slabs be proof compacted with a heavy vibrating roller to treat any loose areas. The Sand and Gravel fill beneath the concrete slabs and sidewalks should meet the grain size distribution characteristics described in Table 3.

Pavement Design

We understand that pavements will be designed by others. We recommend that the pavement subgrade be proof compacted prior to placement of any engineered fills. In addition, we note that the depth to groundwater was relatively shallow in proposed pavement areas to the south and west. Depending on final grades of the pavement surface, we recommend that the project team consider including drainage beneath pavements to allow the base course and subbase materials to drain. Pavements placed near a high groundwater table will be more susceptible to frost movement and future damage.

Earthwork Considerations

We anticipate that earthwork for this project will include the following: excavations for footings; placement of engineered fill beneath the building, floor slab and exterior slabs and sidewalks (as needed); and the treatment of the existing soils to address any localized loose areas that may be present.

Engineered Fill Recommendations

Three engineered fill types are recommended:

Sand and Gravel for use immediately below slabs and sidewalks Crushed Stone for use below footings and in place of Sand and Gravel fill (as needed) Granular Fill use as miscellaneous fill and to form the building pads at depths greater than 12 inches beneath floor slabs and footings

Amherst, Massachusetts April 13, 2026

Table 3 Grain Size Distribution Requirements

Size Sand and

Gravel Granular Fill Crushed

Stone Percent Finer by Weight

3 inch 100 100 --- 1 inch --- --- 100 ¾ inch --- --- 90-100 ½ inch 50-85 --- 10-50 ⅜ inch --- --- 0-20 No. 4 40-75 --- 0-5 No. 10 --- 30-90 --- No. 40 10-35 10-70 ---

No. 200 0-10 0-15 ---

Grain size distribution requirements are presented in Table 3. At this time, it does not appear that significant quantities of on-Site soils will meet requirements for use as engineered fill. Please note that the Sand and Gravel specification is approximately that for Mass Highway M1.03.0, Type B Gravel Borrow.

Compaction Recommendations

Fill, debris, and topsoil should be removed from beneath the building footprint. Debris and topsoil should not be reused as fill beneath structures. The existing fill may be reused, provided it is free of trash and organic material, and meets project grain size and compaction requirements. To avoid point loads, any cobbles or boulders larger than four inches in diameter encountered at the subgrade should also be removed.

We recommend that the entire building footprint be thoroughly proof compacted prior to the placement of any engineered fill. Proof compaction should be accomplished by a minimum of six passes with a 6,000-pound vibratory roller, or a walk-behind vibratory roller. If proof compaction of the silty soils causes pumping to occur, the contractor should consider compaction by static methods (without vibration) utilizing a large roller. To facilitate compaction, the moisture content of the on-Site material should be maintained at or near the optimum moisture content as determined by ASTM D1557.

The resulting excavations should be backfilled with compacted Sand and Gravel or Crushed Stone fill. Compacted fill should be placed in lifts ranging in thickness between 6 and 12 inches depending on the size and type of equipment. Recommended degrees of compaction and compaction means and methods are presented on Sheet 1.

Weather Considerations

The contractor should note that the natural soils within the near surface may vary and contain increased amounts of fines. These types of soils are poorly draining and

Amherst, Massachusetts April 13, 2026

O:\Job Files\J0800\859 Kuhn Riddle Architects\49-01 UMASS CEEC North Pleasant St Amherst MA\Report\OTO Geotech Report UMass CEEC - April 2026.docx susceptible to disturbance when wet due to its high fines content. If these soils become wet during construction, they will become soft and easily disturbed. During periods of precipitation, the silty soils will tend to remain wet and cannot be easily dried or stabilized.

It may be necessary to remove the disturbed soils and replace the materials with compacted sand and gravel or crushed stone. To avoid this potential issue, the contractor should establish and maintain proper drainage and protection of soil surfaces during construction, including immediately covering subgrades after preparation.

7.0 FINAL DESIGN AND CONSTRUCTION PHASE SERVICES

We recommend that O’Reilly, Talbot & Okun Associates, Inc. (OTO) be retained during final design to prepare and/or review appropriate specification sections and drawings, if necessary. During construction phases, we recommend that OTO be retained to provide engineering support and to document subgrade conditions and preparation.

We appreciated the opportunity to be of service on this project. If you have any questions, please do not hesitate to contact the undersigned.

Sincerely yours, O'Reilly, Talbot & Okun Associates, Inc.

Stephen McLaughlin, E.I.T Ashley L. Sullivan, P.E.

Sr. Project Manager Principal

Attachments: Limitations, Site Locus, Site Plan, Sheet 1, Sheet 2, OTO Boring Logs, OTO Test Pit Logs, GZA Logs (2021)

LIMITATIONS

1. The observations presented in this report were made under the conditions described herein. The conclusions presented in this report were based solely upon the services described in the report and not on scientific tasks or procedures beyond the scope of the project or the time and budgetary constraints imposed by the client. The work described in this report was carried out in accordance with the Statement of Terms and Conditions attached to our proposal.

2. The analysis and recommendations submitted in this report are based in part upon the data obtained from widely spaced subsurface explorations. The nature and extent of variations between these explorations may not become evident until construction. If variations then appear evident, it may be necessary to reevaluate the recommendations of this report.

3. The generalized soil profile described in the text is intended to convey trends in subsurface conditions. The boundaries between strata are approximate and idealized and have been developed by interpretations of widely spaced explorations and samples; actual soil transitions are probably more erratic. For specific information, refer to the boring logs.

4. In the event that any changes in the nature, design or location of the proposed structures are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report modified or verified in writing by O'Reilly, Talbot & Okun Associates Inc. It is recommended that we be retained to provide a general review of final plans and specifications.

5. Our report was prepared for the exclusive benefit of our client. Reliance upon the report and its conclusions is not made to third parties or future property owners.

PROJECT No.

FIGURE No.

276 Bridge Street, Suite 302 Springfield, MA 01103 413.788.6222

O'Reilly, Talbot & Okun E N G I N E E R I N G A S S O C I A T E S www.OTO-ENV.com

UMASS CEEC

972-990 NORTH PLEASANT STREET

AMHERST, MASSACHUSETTS

SITE LOCUS

O

J o b F ile s \J

\8

K u h n R id d le A rc h it e c ts

\4

-0

U M

A S

S C

E E

C N o rt h P le a s a n t

S t

A m h e rs t

M A

\F ig u re s

J0859-49-01

Topographic Map Quadrants:

WILLIAMSBURG, MA

Map Version: 1990

Current As Of: 1997

Date: FEBRUARY 2026

SITE

1:25,000 SCALE NATIONAL GEODETIC VERTICAL DATUM 1929 10 FOOT CONTOUR INTERVAL

0 1000

FEET

0 0.5 1.0

MILES

0 0.5 1

KILOMETERS

PROJECT NO.

FIGURE NO.

Br id ge S tr ee t, Sp rin gf ie ld , M

A

3.

8.

O 'R ei lly

, T al bo t &

O ku n E

N G

I N

E E

R I

N G

A

S S

O C

I A

T E

S w w w .O

TO

-E

N V.

co m

U M

A S

S C

E E

C

-9

N O

R T

H P

L E

A S

A N

T S

T R

E E

T A

M H

E R

S T

M

A S

S A

C H

U S

E T

T S

S

IT

E P

L A

N

O J o b F ile s \J

\8

K u h n R id d le A rc h it e c ts

\4

-0

U M

A S

S C

E E

C N o rt h P le a s a n t S t A m h e rs t M

A \F ig u re s

J0859-49-01

DESIGNED BY: CYI

DRAWN BY: CYI

CHECKED BY:

DATE: 3/2/2026

REV. DATE:

NOTES:

1. BASE MAP PROVIDED TO OTO IN ELECTRONIC FORMAT. ORIGINAL DRAWING BY PRECISION

LAND SURVEYING TITLED "EXISTING CONDITIONS PLAN" DATED APRIL 30, 2026

2. SAMPLE LOCATIONS ARE SHOWN ACCORDING TO TAPED MEASUREMENT TAKEN FROM

EXISTING SITE FEATURES

3. ALL DATA IS TO BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHODS

USED IN THE DEVELOPMENT OF THIS PLAN

SCALE IN FEET

1" = 60'

0' 30' 60' 120'

LEGEND:

EXISTING BUILDING FOOTPRINT

APPROXIMATE FOOTPRINT OF PREVIOUSLY

DEMOLISHED BUILDINGS

PROPOSED BUILDING FOOTPRINT

PROPOSED VEHICULAR PAVED AREAS

APPROXIMATE SOIL BORING LOCATION

PERFORMED BY OTHERS

APPROXIMATE TEST PIT LOCATION

PERFORMED BY OTHERS

APPROXIMATE SOIL BORING LOCATION

PERFORMED BY SEABOARD DRILLING ON

3/16 & 3/17/2026, OBSERVED BY OTO

APPROXIMATE TEST PIT LOCATION

PERFORMED BY HATFIELD CONSTRUCTION

ON 3/20/2026, OBSERVED BY OTO

TP-101

GZ-114

TP-102

GZ-117

TP-3

TP-6 TP-4

TP-9

TP-5

TP-1 TP-2

TP-3b TP-3c

TP-5a

PS-3

PS-1/

TP-8

PS-4

TP-3a

PS-2/

TP-7

X

SHEET No.

276 Bridge Street, Suite 302 Springfield, MA 01103 413.788.6222

O'Reilly, Talbot & Okun E N G I N E E R I N G A S S O C I A T E S www.OTO-ENV.com

UMASS CEEC

972-990 NORTH PLEASANT STREET

AMHERST, MASSACHUSETTS

GENERAL COMPACTION GUIDELINES

O

J o b F ile s \J

\8

K u h n R id d le A rc h it e c ts

\4

-0

U M

A S

S C

E E

C N o rt h P le a s a n t

S t

A m h e rs t

M A

\F ig u re s

DESIGNED BY: ALS

DRAWN BY: CYI

CHECKED BY:

DATE: 4/6/2026

REV. DATE:

J0859-49-01

Table 1-1 Degree of Compaction Recommendations

Location Minimum

Compaction* Below Structures (Foundations and Slabs) 95% Below Pavements/Sidewalks/Exterior Slabs 95%

Against Basement Walls/Retaining Walls 92% Utility Trenches 95%

General Landscaped Areas 90% Notes.

1. Percentage of the maximum dry density as determined by Modified Proctor ASTM D1557, Method C.

2. When location falls into two or more categories, the engineer should be notified to determine appropriate compaction efforts and/or methods.

3. Crushed stone should be compacted in lifts of 12 inches to form a dense matrix using either traditional compaction methods (vibratory plate and/or roller) or tamping with an excavator bucket in deep excavations. It is generally not necessary to perform laboratory or field density testing on crushed stone.

Table 1-2 General Guidelines for Compaction Means and Methods

Compaction Method Maximum Stone Size

Maximum Lift Thickness Minimum Number of

Passes

Below Structures & Pavement

(Critical Areas)

Less Critical Areas

Below Structures & Pavement

(Critical Areas)

Less Critical Areas

Hand-operated Vibratory Plate and confined spaces 3 inches 6 inches 8 inches 6 4

Hand-operated vibratory drum roller

(less than 1000 pounds) 3 inches 6 inches 8 inches 6 4

Hand-operated vibratory drum roller

(at least 1,000 pounds) 4 inches 8 inches 10 inches 6 4

Light vibratory drum roller (minimum 3000 pounds)

4 inches 10 inches 14 inches 6 4

Heavy vibratory drum roller (minimum 6000 pounds)

4 inches 12 inches 18 inches 6 4

Notes: The contractor should reduce or stop drum vibration if pumping of the subgrade is observed.

SHEET No.

276 Bridge Street, Suite 302 Springfield, MA 01103 413.788.6222

O'Reilly, Talbot & Okun E N G I N E E R I N G A S S O C I A T E S www.OTO-ENV.com

UMASS CEEC

972-990 NORTH PLEASANT STREET

AMHERST, MASSACHUSETTS

TYPICAL FOUNDATION SECTION

O

J o b F ile s \J

\8

K u h n R id d le A rc h it e c ts

\4

-0

U M

A S

S C

E E

C N o rt h P le a s a n t

S t

A m h e rs t

M A

\F ig u re s

DESIGNED BY: ALS

DRAWN BY: CYI

CHECKED BY:

DATE: 4/6/2026

REV. DATE:

J0859-49-01

NOTES:

1. NOT FOR CONSTRUCTION, FOR ILLUSTRATION PURPOSES ONLY

2. FOR ADDITIONAL INFORMATION, REFER TO OTO's GEOTECHNICAL REPORT DATED JULY 2017

3. UNPAVED AREAS SHALL INCLUDE LOAM CAP AND SHOULD BE GRADED TO DIRECT SURFACE FLOW AWAY FROM BUILDING

4. PERMEABLE BACKFILL SHALL BE USED IN AREAS WITH UNDERDRAIN SYSTEMS

BASE/SUBBASE

TYPICAL FOUNDATION SECTION

SLAB ON GRADE FOOTING WITH ENTRANCE SLAB

FLOOR SLAB

PREPARED SUBGRADE

SAND AND

GRAVEL FILL

GRANULAR

FILL

SAND AND GRAVEL

SEE NOTES 3 AND 4

PERIMETER

DRAINAGE

SYSTEM TO BE

DESIGNED BY

OTHERS

CRUSHED STONE UPON

NON-WOVEN GEOTEXTILE

FABRIC (AS NEEDED) CRUSHED STONE TRENCH

PERFORATED PIPE

4' (MIN)

NON-WOVEN

GEOTEXTILE

FABRIC

PAVEMENT SECTION

ENTRANCE SLAB

SLOPING PER

OSHA STANDARDS

BLOWS/FOOT

(SPT N-Value)

0-4 Very soft

4-10 Soft

10-30 Medium Stiff

30-50 Stiff

>50 Very stiff Hard

MATERIAL FRACTION SMALLEST

Coarse DIAMETER

Fine None SILT

Coarse 1/4" (pencil) clayey SILT

Medium 1/8" SILT & CLAY

Fine 1/16" CLAY & SILT

SILT/CLAY see adjacent table 1/32" Silty CLAY

COBBLES 1/64" CLAY

BOULDERS

TERM % OF TOTAL

and 35-50% some 20-35% little 10-20% trace 1-10%

RQD: Rock Quality Designation is determined by measuring total length of pieces of core 4" or greater and dividing by the total length of the run, expressed as %. 100-90% excellent; 90-75% good; 75-50% fair; 50-25% poor; 25-0% very poor.

PID: Soil screened for volatile organic compounds (VOCs) using a photoionization detector (PID) referenced to benzene in air. Readings in parts per million by volume.

Glacial till: Very dense/hard, heterogeneous mixture of sand, silt, clay, sub-angular gravel.

Deposited at base of glaciers, which covered all of New England.

Varved clay: Fine-grained, post-glacial lake sediments characterized by alternating layers (or varves) of silt, sand and clay.

Fill: Material used to raise ground, can be engineered or non-engineered.

COMMON FIELD MEASUREMENTS

Torvane: Undrained shear strength is estimated using an E285 Pocket Torvane (TV). Values in tons/ft2.

Penetrometer: Unconfined compressive strength is estimated using a Pocket Penetrometer (PP). Values in tons/ft2.

ADDITIONAL CONSTITUENTS COMMON TERMS

Cannot distinguish individual particles High

3" to 6" in diameter Very High

> 6" in diameter Wetted sample is rolled in hands to smallest possible diameter before breaking.Note: Boulders and cobbles are observed in test pits and/or auger cuttings.

ORGANIC SILT: Typically gray to dark gray, often has strong H2S odor. May contain shells or shell fragments. Light weight.

Fibrous PEAT: Light weight, spongy, mostly visible organic matter, water squeezed readily from sample. Typically near top of layer.

Fine grained PEAT: Light weight, spongy, little visible organic matter, water squeezed from sample. Typically below fibrous peat.

DEBRIS: Detailed contents described in parentheses (wood, glass, ash, crushed brick, metal, etc.)

BEDROCK: Underlying rock beneath loose soil, can be weathered (easily crushed) or competent (difficult to crush).

SAND

1/16" to 1/4" Slight

1/64" to 1/16" Low

Finest visible & distinguishable particles Medium

MATERIAL: (major constituent identified in CAPITAL letters)

COHESIONLESS SOILS COHESIVE SOILS

GRAIN SIZE RANGE

PLASTICITY IDENTITY

GRAVEL

3/4" to 3"

1/4" to 3/4" Non-plastic

*Based upon uncorrected field N-values >30

Method: Samples were collected in accordance with ASTM D1586, using a 2" diameter split spoon sampler driven 24 inches. If samples were collected using direct push methodology (Geoprobe), SPTs were not performed and relative density/consistency were not reported.

N-Value: The number of blows with a 140 lb.

hammer required to drive the sampler the middle 12 inches.

WOR: Weight Of Rod (depth dependent) WOH: Weight Of Hammer (140 lbs.)

RELATIVE

DENSITY

BLOWS/FOOT

Medium dense 4-8

Dense 8-15

Very dense 15-30

CONSISTENCY

(SPT N-Value)

Very loose <2

Loose 2-4

BORING LOGS

SUMMARY OF THE BURMISTER SOIL CLASSIFICATION SYSTEM (MODIFIED)

RELATIVE DENSITY (of non-plastic soils) OR CONSISTENCY (of plastic soils)

STANDARD PENETRATION TEST (SPT) COHESIONLESS SOILS COHESIVE SOILS

4.0

172.5 Kern

2 Art

0 Hollow Stem Auger (4.25" O.D.)

A (1 5/8" O.D.)

FIRST (ft) N/E 2" O.D. Split Spoon

LAST (ft) N/A Automatic

TIME (hr) N/A N/A

DEPTH (ft) ELEV.

9/27/22/17 17/24 S-1 PID 0.5 TOPSOIL 1

(0-2') FILL

9/11/9/8 15/24 S-2 PID 1.0

(2-4')

4.0 168.5

2,3

1. Soil screened in field using MiniRAE Lite photoionization detector (PID) referenced to benzene in air. Readings in parts per million by volume.

2. Auger grinding from 0 to 2'. Auger not advancing past 2-3'. No cuttings observed.

3. Offset 3' southwest. Auger not advancing past 2-3'.

PS-1

Remarks:

PROJECT NO.

0859-49-01

LOG OF BORING

25'

20'

15'

Top 5'': Dense, dark brown, fine to medium SAND, some silt, little organics (roots), moist

(TOPSOIL)

Bottom 12'': Dense, brown, fine to medium SAND, some coarse sand, little gravel, moist (2" gray layer at botom)

Top 5'': Medium dense, dark brown, fine SAND and SILT, trace medium to coarse sand, moist (piece of yellow caution tape at 4" from top) Bottom 10'': Medium dense, brown, medium SAND and GRAVEL, some fine to coarse sand, trace silt, moist

10'

5'

Auger refusal at approximately 2' to 3', sampler advanced beyond refusal

REMARKS/

WELL

CONSTRUCTION

PENETR.

RESIST.

(bl / 6 in)

REC.

(in)

TYPE/

NO.

FIELD

TEST

DATA

PROFILEDEPTH (ft)/

SAMPLES

SAMPLES

SAMPLE DESCRIPTION

(MODIFIED BURMISTER)

BORING

LOCATION

Northeast corner of proposed building footprint

SAMPLER ROCK CORING INFORMATION

HAMMER TYPE TYPE N/A

HAMMER WGT/DROP SIZE N/A

LOG OF BORING PS-1

PROJECT UMass Amherst CEEC CONTRACTOR Seaboard Environmental Drilling

N/A

FINISH DATE 3/16/2026 UNDISTURBED SAMPLES BIT TYPE HAMMER WGT N/A

ENGINEER/SCIENTIST Caren Irgang WATER LEVEL ROD TYPE HAMMER DROP

N/A

JOB NUMBER 0859-49-01 FINAL DEPTH (ft) DRILLING EQUIPMENT B-48 Track Mounted Rig

LOCATION Amherst, MA SURFACE ELEV (ft) FOREMAN CASING

START DATE 3/16/2026 DISTURBED SAMPLES HELPER CASE DIAMETER

27.0

171.0 Kern

8 Art

0 Hollow Stem Auger (4.25" O.D.)

A (1 5/8" O.D.)

FIRST (ft) 7.0 2" O.D. Split Spoon

LAST (ft) N/A Automatic

TIME (hr) N/A N/A

DEPTH (ft) ELEV.

10/10/10/8 14/24 S-1 PID 0.0 TOPSOIL 1

(0-2') FILL

9/6/5/4 16/24 S-2 PID 3.3

(2-4')

5.0 166.0

12/11/13/13 0/24 S-3 -- FINE SAND

(5-7') s 164.0

8/9/11/12 15/24 S-4 PID 0.1 ≡ 2

(7-9')

10.0 161.0

3/4/5/5 19/24 S-5 PID 0.0 VARVED SAND

(10-12')

15.0 156.0

4/5/5/6 15/24 S-6 PID 0.0 VARVED CLAY 3

(15-17') PP 1.5 AND SILT 4

TV 0.1 5

1/1/1/2 8/24 S-7 PID 0.0 6

(20-22') PP 0.75

TV 0.1

WOH for 24" 6/24 S-8 PID 0.0

(25-27') PP 0.1

TV 0.05

27.0 144.0

1. Soil screened in field using MiniRAE Lite photoionization detector (PID) referenced to benzene in air. Readings in parts per million by volume.

2. Auger grinding at ground surface and at 7'.

3. 3' blow-in observed before taking sample S-6. After re-drilling to 15', 1' blow-in observed. Driller cleared disturbed soil within auger prior to sampling.

4. Unconfined compressive strength estimated in field using Pocket Penetrometer (PP). Values in tons/ft2.

5. Undrained shear strength estimated in field using E285 Pocket Torvane (TV). Values in tons/ft2.

6. 4' blow-in observed before taking sample S-7. After re-drilling to 20', 0.5' blow-in observed. Driller cleared disturbed soil within auger prior to sampling.

15'

End of exploration at 27'

Remarks:

PROJECT NO.

Soft, gray, CLAY and SILT, trace fine sand, wet (1/16-1/8" clay and silt varves) 20'

Top 4'': Stiff, gray brown, CLAY and SILT, trace fine sand, wet (0-1/8" medium sand varves) Bottom 11'': Stiff, gray brown, CLAY and SILT, trace fine sand, wet (1/16-1/8" clay and silt varves)

0859-49-01

LOG OF BORING

PS-2

25' Very soft, gray, CLAY and SILT, trace fine sand, wet (1/16-1/2" clay and silt varves)

Loose, brown, varved fine to medium SAND, little silt, wet (1/4-2" medium sand layers, 1-3" fine sand layers, 1/4" silt layers)

10'

Medium dense, light brown, fine SAND, trace silt, wet (13" disturbed material over sample)

NO RECOVERY

5'

Top 14'': Medium dense, light brown, fine to medium SAND, little gravel, trace coarse sand, damp Bottom 2'': Medium dense, red brown, medium to coarse SAND and gravel, trace fine to coarse sand, trace silt, damp

Top 7'': Medium dense, dark brown, fine to medium SAND, some silt, little organics (roots), moist (TOPSOIL) Bottom 7'': Medium dense, brown, fine to medium SAND, some fine gravel, little silt, little coarse sand, moist

DEPTH (ft)/

SAMPLES

SAMPLES

SAMPLE DESCRIPTION

(MODIFIED BURMISTER)

REMARKS/

WELL

CONSTRUCTION

PENETR.

RESIST.

(bl / 6 in)

REC.

(in)

TYPE/

NO.

FIELD

TEST

DATA

PROFILE

BORING

LOCATION

West portion of proposed building footprint

SAMPLER ROCK CORING INFORMATION

HAMMER TYPE TYPE N/A

HAMMER WGT/DROP SIZE N/A

ENGINEER/SCIENTIST Caren Irgang WATER LEVEL ROD TYPE HAMMER DROP N/A

FINISH DATE 3/16/2026 UNDISTURBED SAMPLES BIT TYPE HAMMER WGT N/A

LOG OF BORING PS-2

PROJECT UMass Amherst CEEC CONTRACTOR Seaboard Environmental Drilling

START DATE 3/16/2026 DISTURBED SAMPLES HELPER CASE DIAMETER N/A

JOB NUMBER 0859-49-01 FINAL DEPTH (ft) DRILLING EQUIPMENT B-48 Track Mounted Rig

22.0

171.0 Kern

7 Art

0 Hollow Stem Auger (4.25" O.D.)

A (1 5/8" O.D.)

FIRST (ft) 3.0 2" O.D. Split Spoon

LAST (ft) N/A Automatic

TIME (hr) N/A N/A

DEPTH (ft) ELEV.

3/34/17/9…