B08_-_Solicitation_Attachment_-_(2303568_FINAL_MNWR_Geotech_Report_R1-Nov2024)_0001.pdf

Geotechnical Recommendations Report

USFWS Multi-Purpose Facility Montezuma National Wildlife Refuge, Seneca Falls, NY

Submitted to:

Jared Heinl Beardsley Architects and Engineers 64 South Street Auburn, NY 13021

Submitted by:

GEI Consultants Engineering, Geology, Architecture & Landscape Architecture 950 Danby Road, Suite 201-F Ithaca, NY 4850 607-216-8968

November 6, 2024 Project 2303568

P.J. Snyder, P.E.

Vice President

Colby Jesset, P.E.

Project Engineer

Consulting

Engineers and

Scientists

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture ii

Table of Contents

Executive Summary iv

1. Introduction 1

1.1 Purpose 1

1.2 Scope 1

1.3 Authorization 1

1.4 Elevation Datum 2

2. Site and Project Description 3

2.1 Site Description 3

2.2 Project Description 3

3. Subsurface Explorations 5

3.1 Exploration Program 5

3.1.1 Previous Explorations by Others 5

3.2 Geotechnical Borings 5

3.3 Test Pit Explorations 6

3.4 Percolation Testing 6

3.5 Laboratory Testing 6

4. Subsurface Conditions 7

4.1 Subsurface Soils 7

4.2 Infiltration Test Results 8

4.3 Groundwater Conditions 9

4.4 Corrosivity of Soil Samples 9

4.5 Sample Storage and Disposition 10

5. Foundation Design Recommendations 11

5.1 General Suitability 11

5.2 Foundation Design 11

5.2.1 Down Drag 12

5.2.2 Lateral Pile Capacity 13

5.3 Frost Depth 13

5.4 Seismic Design and Liquefaction Evaluation 13

5.5 Pavement Design 14

Table 1. Recommended Pavement Section (New) 14

6. Construction Recommendations 16

6.1 Subgrade Preparation 16

6.1.1 Removal of Surface Materials 16

6.2 Excavation and Dewatering 17

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GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture iii

6.3 Horizontal Directional Drilling 17

6.4 Freezing Conditions 18

6.5 Backfilling and Compaction 18

6.6 Freezing Conditions 18

6.7 Cuts and Fills 19

6.8 Site Disturbance 20

7. Limitations 21

7.1 Future Work and Limitations 21

8. Recommended Material Specification 22

Figures

1. Site Location Map

2. Site and Subsurface Exploration Plan

3. Infiltration Test Location Plan

Appendices A. Borings Logs B. Test Pit Logs C. Percolation Test Results D. Laboratory Testing Results E. Equivalent SPT N Values F. Geotechnical Design Parameters Table

JRP/PJS:tc

B:\Working\BEARDSLEY A&E\2303568 Montezuma NWR Geotechnical Engineering\08_REPORT\2303568_FINAL_MNWR_Geotech_Report_R1-Nov2024.docx

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture iv

Executive Summary

This report presents the results of a subsurface exploration program and geotechnical recommendations for the proposed new construction of a multipurpose facility and water service extension at the U.S. Fish and Wildlife Services (FWS) Montezuma National Wildlife Refuge (NWR) in Seneca Falls, New York. The proposed two-story building will be located adjacent to the existing one-story visitor center building.

The geotechnical exploration program consisted of 6 borings and 4 test pits. One boring was completed at the proposed building location and remainder were completed along the proposed water main alignment. Test borings were advanced between 16 to 45 feet below ground level along the water main alignment and up to 100 feet at the proposed building location. Percolation testing was performed at the proposed septic field location.

Subsurface conditions were generally fill that consists of granular soils (SP, SW, GW), previously dredged from Cayuga Seneca canal, over organic (OL, ML) deposits, over lacustrine deposits (CL, CH, ML), overlying glacial till (SP-SM, CL, ML). Bedrock was not encountered during the investigation. Groundwater readings observed during drilling and test pit excavations ranged between approximately 3 to 5 feet below ground surface.

The project site is overlain with soft cohesive soils up to 60 feet in depth. We recommend that the proposed structure be supported on deep foundations bearing on glacial till. We understand driven, steel H piles are the preferred foundation type due to the straightforward installation and absence of adjacent structures. The soft cohesive soils overlying the glacial till will apply down drag forces onto the pile foundation, in addition to the loads applied by the proposed structures.

Driven piles are recommended for the relatively quick and straightforward installation methods and are familiar to many contractors. Using a single-pile analysis, we calculate that a 100-foot-long pile has an allowable capacity of about 44 tons using a factor of safety of 2, including an allowance of 44 tons for negative skin friction (down drag caused by settlement of the thick deposits of fill, organic soil and lacustrine deposits around the piles). Pile capacity can be increased with depth. However, significant penetration into the dense glacial till soils may be difficult.

Regardless of the type of deep foundation chosen, a site-specific load test on a sacrificial pile should be performed to verify vertical (compressive) capacity using a minimum factor of safety of 2. If lateral or tension capacity is required, additional load tests will be required for loading in those directions.

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GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

1. Introduction

1.1 Purpose

This report presents the results of a subsurface exploration program and foundation recommendations for the proposed water service extension and multipurpose facility at the Montezuma National Wildlife Refuge (NWR) in Seneca Falls, Seneca County, New York.

Beardsley A/E (Beardsley) engaged GEI to provide geotechnical engineering services for this project.

1.2 Scope

GEI scope consisted of the following:

• Performed exploration mark outs at the site.

• Prepared a site-specific Health and Safety Plan (HASP).

• Engaged drilling subcontractor, coordinated and observed the subsurface exploration program consisting of seven test borings and four test pits.

• Coordinated and observed septic field feasibility tests by performing four percolation tests.

• Engaged a geotechnical and analytical testing laboratory to perform testing on soil samples from the test borings and pits.

• Developed recommendations for foundation design and construction.

• Prepared this letter report presenting the results of the subsurface explorations and our recommendations.

We performed these services in general accordance with the 2018 edition of the International Building Code (IBC).

1.3 Authorization

Beardsley’s Agreement for Professional Consultant Services was signed by Jared Heinl on June 29, 2023, authorizing the scope of work detailed in GEI’s proposal dated March 28, 2023.

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1.4 Elevation Datum

Elevations provided in this report are in feet and are referenced from the site plan provided by Beardsley. The vertical datum is the North American Vertical Datum of 1988 (NAVD 88). Elevations provided on test boring logs were approximated by interpolation from provided topographical data and/or hand-held GPS readings and should be considered approximate.

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2. Site and Project Description

2.1 Site Description

The site is located on the north side of Route 20 between Route 89 and Route 90 in Seneca Falls, New York, as shown in Figures 1 and 2. Subsurface explorations for the proposed water service extension were conducted south of Route 20 on River Road and on the road shoulders on the south side of New York State Route 20 (Fig. 2).

The project site is currently occupied by existing visitor center, which is a single-story wood-frame building with a foundation system reported to consist of a post-tensioned mat slab with integral concrete piers and a steel beam and girder support frame atop the piers (Colliers, 2021).

The topography of the proposed facility area is currently gently sloped, increasing from west to east. Ground surface elevations vary from a low of El. 382 closest to the wetland, to a high of El. 386 at the edge of the existing parking lot.

The surface topography along the proposed water service extension along River Road ranges from El. 389 at the junction with the existing water main to El. 403 on Route 20. The ground elevation slopes back down to El. 385 at the location of the directional drill receiving pit near the Cayuga Seneca Canal.

The ground surface on the Eastern bank near the canal slopes from El. 385 to El. 373. The surveyed canal bed elevation is El. 356. The ground surface on the western bank near the canal slopes from El. 383 at the location of the directional drill launching pit, up to El. 385, and back to El. 373 at the edge of the canal. The surface topography along the proposed water service extension on the NWR property is generally flat. The surface elevation at the directional drill launching pit and the proposed building differ by approximately one foot.

2.2 Project Description

The proposed multi-purpose building is located at 3395 US Route 20 East, Seneca Falls, New York, as shown on Figure 1. A plan of the proposed building is shown on Figure 2. The proposed two-story building will be located adjacent to the existing one-story visitor center building.

The proposed facility will consist of an approximately 11,240 gross square foot, two-story building and associated parking area, and other amenities such as bicycle racks and electric vehicle charging stations.

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The proposed water service extension involves installing a new water main which will extend from the existing Aurelius Water District main, approximately 825 feet north along River Road, 1,350 linear feet west along US Route 20 (includes crossing the Seneca River), and 1,750 linear feet north on the NWR property.

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3. Subsurface Explorations

3.1 Exploration Program

GEI personnel visited the site to stake/mark out the exploration locations based on the proposed building locations provided in RFP documents and to coordinate with our subcontractor regarding the location of existing utilities and explorations. Dig Safely, New York (811), was contacted prior to starting intrusive work to mark subsurface utilities near the proposed exploration locations.

GEI engaged the services of a subcontractor, Nothnagle Drilling, LLC (Nothnagle), of Scottsville, New York, to perform the geotechnical borings and test pits, and excavate the holes used for permeability testing. Nothnagle provided traffic control, coordination, planning, and permitting for borings along the water service alignment in or near roadways.

GEI field engineers were on site between March 11 and 15, and April 10 to 11, 2024 to observe and document the subsurface explorations performed by Nothnagle. Due to traffic safety and NYSDOT permitting challenges, boring B5 has not been installed.

3.1.1 Previous Explorations by Others

A preliminary geotechnical exploration report was prepared by Colliers Engineering and Design for McMillen Jacobs Associates in September 2021. During the preliminary design, eight borings were advanced near the existing visitors center. Borings were terminated at depths of approximately 60 feet or shallower.

3.2 Geotechnical Borings

Nothnagle drilled one boring (B1) at the site of the proposed multi-purpose building and five borings (B2, B3, B4, B6 and B7) along the proposed water line during two mobilizations.

The first mobilization, from March 11 to 15, 2024 included drilling borings B1, B2, B6, and B7. Borings B3 and B4 were performed on the second mobilization, from April 10 to 11, 2024. The borings were advanced with a CME-85 truck mounted drill rig using hollow-stem augers. Standard Penetration Testing (SPT) and split-spoon sampling were performed continuously to either 16 or 20 feet, and at generally 5-foot intervals thereafter, to the termination depth using an automatic hammer in all borings.

Boring B1 was drilled to a total depth of 100 feet, borings B2, B3, B6, and B7 were drilled to 16 feet deep, and boring B4 was drilled to 60 feet deep. The boring logs are provided in Appendix A.

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Soil was visually classified in the field using GEI’s visual manual soil description guide, which is based on the Unified Soil Classification System (USCS) ASTM D2487. The boring logs and GEI’s visual-manual soil description guide are included in Appendix A.2.

Approximate exploration locations are shown in Figure 2.

3.3 Test Pit Explorations

Nothnagle excavated four test pits (TP1 through TP4) within the proposed location of a new septic field (Fig. 2) on April 10, 2024, using a track-mounted hydraulic excavator. Test pits were excavated to a depth of approximately eight feet. A GEI field engineer observed the test pit excavation and document subsurface conditions. Spoils were placed back in each test pit in the order it was removed and compacted with the bucket of the excavator. Test pit logs are included in Appendix B.

3.4 Percolation Testing

Percolation tests were performed in the proposed septic field, in accordance with the New York State Design Standards for Intermediate Sized Wastewater Treatment Systems, dated March 4, 2014, Section B.4 – Soil Evaluation for Subsurface Discharge. Percolation testing was performed in accordance with Section B.4.b of the same standard.

On April 11, 2024, Nothnagle drilled four pilot holes, and on April 17, 2024, the remaining soil was excavated by hand to reach the desired depth and diameter. Four holes (P1 through P4) were excavated to a depth of approximately two feet and approximately 12-inches in diameter. Percolation tests were conducted by a GEI field engineer on April 17. However, in the days prior to the percolation testing, the area experienced heavy precipitation, and therefore, the in-situ soils were moist to saturated prior to the tests being performed.

Percolation tests P3 and P4 could not be performed due to high groundwater levels.

Percolation test locations and results are included in Figure 3 and Appendix C, respectively.

3.5 Laboratory Testing

Soil samples were sent to GEI’s soil testing laboratory in Woburn, Massachusetts where the following tests were performed.

• 5 Sieve Analyses w/Hydrometer [D6913]

• 2 Atterberg Limits [D4318]

GeoTesting Express, Inc of Acton, Massachusetts, under subcontract to GEI, performed corrosivity and electrical resistivity testing [ASTM G51 and G57], on a composite sample.

The laboratory test results are provided in Appendix D and are incorporated into the soil descriptions on the boring logs.

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4. Subsurface Conditions

4.1 Subsurface Soils

In the deeper borings, four soil strata were encountered in the borings and are described below, in order of increasing depth. Subsurface profiles at the building locations are provided on Figures 3 through 6.

As discussed above, standard penetration testing (SPT) was performed using an automatic hammer. We corrected the SPT N-values for hammer energy (N60) based on energy measurements of the automatic hammer system. Corrected SPT N-values (N60) are tabulated in the Appendix E and are used in the discussion of subsurface conditions below. Field (uncorrected) SPT N-values are shown on the boring logs.

The soil conditions are known only at the exploration locations. Conditions between exploration locations may vary significantly from the descriptions given below.

• Stratum I: Fill

• Stratum II: Organics

• Stratum III: Lacustrine Deposits

• Stratum IV: Glacial Till

Surface Material, Asphalt & Topsoil: Asphalt and subbase up to 9-inches thick was encountered at test borings B6 and B7; topsoil with thickness of up to 9-inches was encountered in the remaining borings and test pits.

Stratum I: Fill: Fill was encountered in each boring up to a depth of 9 feet but averaged between 5 to 6 feet. The fill generally consists of brown to light brown, narrowly graded sand with varying amount of silt and gravel (SP, SP-SM), and/or silty sand (SM), with up to 20 percent fines and up to 40 percent gravel. In some areas, fill may consist of dredge spoils from previous dredging activities of the adjacent Cayuga Seneca canal.

The lower fill likely consists of spoils from dredging the adjacent waterway and channelizing it when it was formerly made part of the canal system, which occurred sometime between 1825 and 1828. At B-1, the layer of highly organic soil at about 6.5 feet would likely mark the original wetland/marshland surface before filling.

The more recent development of the site, including the existing visitors center would account for the upper fill in the top four feet of the fill stratum B-1. The upper fill generally has a higher gravel content than the lower fill.

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SPT N values ranged from 3 to 39 blows per foot (bpf), and averaged 13 bpf, indicating medium dense soil.

Stratum II: Organics: Organic soils were encountered between 7 and 22 feet deep, and Borings B2, B3, B6, and B7 terminated in this stratum. The organic soils generally consist of brown to gray, low to medium plasticity fines (i.e. CL, ML, OL) with layers of loose narrowly graded sand (SP-SM) to silty sand (SM). Trace amounts of shells and wood fragments were observed in this stratum.

SPT N-values ranged from weight of hammer (WOH) to 15 bpf, and averaged 2 bpf, indicating very loose soil.

Stratum III: Lacustrine Deposits: Lacustrine deposits were encountered from 16 to 54 feet deep, and Boring B4 terminated in this stratum. The lacustrine deposits generally consist of stratified clays and silts and were brown, non-plastic to medium plasticity fines (CH, ML) with up to 10 percent gravel.

SPT N-values ranged from weight of hammer (WOH) to 3 bpf, indicating very loose soil.

Stratum IV: Glacial Till: Glacial till was encountered at approximately 59 feet deep in Boring B1. The depth of the stratum is indeterminate as we did not reach the bottom of the layer in B1. However, geologic maps published by the New York State Museum (https://www.nysm.nysed.gov/publications/map-chart-series) indicate glacial drift thickness (i.e. top of bedrock) is approximately 250- to 300-feet-deep in this area. The glacial till soils generally consist of brown, low to medium plasticity fines (CH/ML) with layering of narrowly graded sand with up to 15 percent fines and 5 percent gravel (SP, SP-SC).

From 70 to 83 feet deep, a zone of narrowly graded sand was encountered. The presence of narrowly graded sand below the water table and the inability to keep a head of water on the drill tooling likely caused some of the sand to “run” into the drill tooling. This may have also caused the low SPT N-values reported in this zone during the drilling process, as the groundwater may have loosened the sands as the confining pressure above was removed.

SPT N-values ranged from 22 bpf to sampler refusal, defined as greater than 50 blows per 6-inch interval, and averaged 55 bpf, indicating dense to very dense soil.

4.2 Infiltration Test Results

The infiltration rates computed during the percolation tests at locations P1 and P2 were measured to be approximately 26.0 and 38.0 minutes per inch (mpi), respectively using the methodology provided in Section B.4 of the NYSDEC Onsite Wastewater Treatment Design Guidance. Tests were performed in hand-dug holes to a depth of approximately 2 feet.

Infiltration test results are located in Appendix C.

https://www.nysm.nysed.gov/publications/map-chart-series

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Infiltration tests could not be conducted at locations P3 and P4 due to high water levels. The boreholes filled with water almost immediately upon removal of soil and drill tooling. Both boreholes remained filled with water when the GEI field engineer returned to conduct the infiltration tests. The recent higher than average precipitation, coupled with the fact that test locations P3 and P4 were located at a lower elevation relative to the immediate surroundings, likely accounted for the increased saturation of the soils and higher water levels observed during the tests.

4.3 Groundwater Conditions

Groundwater levels are subject to seasonal and weather-related variations. Groundwater measurements made at different times and different locations may be significantly different than the measurements taken during our exploration program.

A distinct groundwater table was not observed in the test pits. Perched groundwater was observed in test pits TP1 and TP2, at depths of approximately 7 to 7.5 feet. TP-3 and TP-4 were located in a low area of standing water from precipitation and poor drainage.

Groundwater was observed in borings B1, B2, B3, B4 and B7 at 4 feet, 2 feet, 3 feet, 6 feet, and 7 feet, respectively. Groundwater was not measured in the other borings.

4.4 Corrosivity of Soil Samples

Electrical resistivity is a broad indicator of soil corrosivity because corrosion reactions are electrochemical in nature and proceed most rapidly when resistivity (i.e. resistance to the flow of ions and electrical current) is low. Specifically, resistivity is a measure of how strongly a given material opposes the flow of electrical current.

The sample tested had an electrical resistivity reading of 960 Ω cm at the received water content, indicating a severely corrosive environment. We recommend using Type II cement for concrete installed below grade concrete and providing corrosion protection measures or sacrificial steel thickness for exposed steel elements.

Sulfates in soil and groundwater in concentrations greater than 1,000 mg/kg are generally considered to be corrosive to structural elements. The sample test results indicate sulfates concentrations of <10 mg/kg, respectively.

Chloride concentrations above 500 mg/kg are generally considered to be corrosive to structural elements. The sample test results indicate chloride concentrations of <10 mg/kg, respectively.

We summarized our evaluation of the soil corrosivity to structural elements shown in the table below by comparing the laboratory test results to some available corrosivity references.

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Test Laboratory

Results Reference

Corrosivity to Structural Elements pH 7.2 Caltrans - Corrosion Guidelines January 2015 Not corrosive

Electrical Resistivity 960 Ω-cm

EPRI - Environmental Factors Governing Corrosion Rates, Report 1021854

December 2011

Severely Corrosive

Chloride <10 ppm Caltrans - Corrosion Guidelines January 2015 Not corrosive

Sulfate <10 ppm Caltrans - Corrosion Guidelines January 2015 Not corrosive

The proposed facility is being installed where road salt may exist during the winter months.

Due to the possible presence of soluble salts or other corrosive agents, we recommend concrete made with Type II cement be specified for concrete installed below grade.

4.5 Sample Storage and Disposition

The soil samples collected from our explorations are being stored at our offices in Woburn, Massachusetts. The soil samples will be held for 6 months after the issuance of this report.

We will discard the samples approximately 6 months after the final report has been issued unless other arrangements are made by Beardsley.

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5. Foundation Design Recommendations

5.1 General Suitability

In general, the site faces challenges with the presence of soft soils but is suitable for the proposed construction with the use of deep foundations. The following sections of this report present the preliminary recommendations for the design of the foundations for the proposed structure and utility construction.

5.2 Foundation Design

The proposed building site is underlain by approximately 60 feet of soft/loose material, including weight of hammer (WOH) organic soils and lacustrine silts and clays, overlying glacial deposits that contain medium dense to dense granular material and stiff clay. The fill, organic soil and lacustrine deposits are not suitable to support the proposed building, as consolidation of these soils would result in unacceptable total and differential settlements.

However, the deeper glacial deposits are suitable bearing layers for the proposed building to be supported by deep foundations.

Driven piles are recommended for the relatively quick and straightforward installation methods and are familiar to many contractors. Additionally, given new technologies with variable moment hammers and the rural location of the building, potential impacts to adjacent structures or other stakeholders from vibrations are low. However, the soft cohesive soils overlying the glacial till will apply down drag forces on the foundations. The down drag will apply additional loads to the foundation elements, in additional to the loads applied by the proposed structures. Therefore, pile lengths of 100 feet or more may be required to resist the applied loads.

Precast pre-stressed concrete piles, steel H-piles, and concrete-filled pipe piles are all appropriate for this project. However, the use of precast concrete piles may be challenging due to the long pile lengths. The final selection of pile type should be based on cost and availability. We recommend that only one pile type and size be used for the entire project.

Steel H-piles may penetrate deeper into the till to achieve the same capacity as pipe piles.

Alternatively, drilled micropiles can be used to bypass the cohesive soils. The drilled piles can use steel isolation casing that separates the elements from unsuitable material, and the isolation casing helps to mitigate the down drag forces. With reduced lengths, piles of around 80 feet or more may be suitable for the foundation loads. However, while material is saved, drilling these piles, especially with the use of isolation casing, will likely be a more costly and slower installation process in comparison to driven piles.

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Additionally, if steel piles are used, the steel should have a minimum yield strength of 50 kips per square inch (ksi), and the piles should be designed for a minimum corrosion rate of

0.0015 inches/year [AASHTO, Section 10.7.5]. If driven H-pile sections are used, we recommend using a HP 14x89 section or larger. If pipe piles are used, we recommend using concrete-filled pipe piles with a minimum diameter of 14-inches with a 0.375-inch wall thickness. Steel pipe piles should be filled with conventional concrete having a 28-day compressive strength of 5,000 pounds per square inch (psi) or greater.

Depending on the embedment length and end bearing capacity, our experience in similar soil conditions is that an H-pile or pipe pile section can provide allowable capacities ranging from 60 to 90 tons. Using a single-pile analysis, we calculate that a 100-foot-long pile has an allowable capacity of approximately 44 tons using a factor of safety of 2. This design capacity includes an allowance of 46 tons for down drag (negative skin friction). In our calculations, the estimated down drag load has been subtracted from the allowable pile capacity. Pile capacity can be increased with depth. However, significant penetration into the dense glacial till soils may be difficult.

The piles should be designed and constructed in accordance with Section 1808 of the 2018 International Building Code (IBC). Cobbles and boulders were not encountered above the till stratum in the borings. However, due to the potential for cobbles and boulders to exist in the till, and the observed density of the till stratum, we recommend that a driving shoe or conical pile point/end cap be installed on each pile.

Regardless of the deep foundation elements chosen, a site-specific load test on a sacrificial pile should be performed to verify capacity using a minimum factor of safety of 2. The pile load test should be performed in accordance with ASTM D1143 Standard Test Methods for Deep Foundation Elements Under Static Axial Compressive Load as indicated in IBC18 Section 1810.3. ASTM D1143 Procedure A (Quick Test Method) provides ample information to verify estimates of pile capacity and the distribution along the pile length. If lateral or tension capacity is required, additional load tests will be required for loading in those directions.

5.2.1 Down Drag

Increased loads on the fill and organics, or a decrease in groundwater level can cause settlement in the soft and compressible soil layers. This settlement could result in down drag, or negative skin friction, that can exert an additional vertical load on the piles. Due to the substantial thickness of the soft organic soil and clay layers, the down drag load is a significant component of the overall pile design load. As described above, an estimated down drag force of 46 tons was calculated using the subsurface profile of boring B1.

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5.2.2 Lateral Pile Capacity

We developed a model to estimate lateral pile capacity, with the software program Lpile. We used the input properties provided in Appendix F and the subsurface profile from boring B1, to aid in the development of the model. We evaluated a HP14x89 and a 14-inch-diameter steel pipe pile, in a free-head condition. The allowable lateral capacity per pile was calculated to be approximately 2.5 kips, in the weak axis, with a minimum safety factor of 2. Lateral load capacity should be verified in the field with lateral load testing on a pre-production test pile, performed per ASTM D3966.

5.3 Frost Depth

We recommend using a minimum frost depth of 48 inches below final grade for the site, or deeper, if required by the local building official for shallow foundations bearing directly on soil.

5.4 Seismic Design and Liquefaction Evaluation

We recommend using Site Class E (Soft Soil Profile) for seismic design of the proposed structures at the site, in accordance with IBC Section 1613.2.2 and ASCE 7-16. Borings less than 20 feet in depth are not included in the seismic classification as the limited depth is not considered representative of the soil column to a depth of 100 feet. Corresponding spectral response design parameters are as follows:

Seismic Design Values

Site Class E Risk Category TBD

SS 0.139 g S1 0.048 g Fa 2.4 Fv 4.2

SDS 0.222 g SD1 0.136 g

PGAM 0.169 g Seismic Design Category TBD

We calculated the spectral response parameters for the Site using the procedures outlined in IBC18 Section 1613. Peak ground acceleration (PGAM) was calculated per the ASCE 7 Hazard Tool. The appropriate Risk Category and Seismic Design Category should be selected by the project architect or structural engineer using the seismic design values and in accordance with Building Code Tables 1613.2.5(1) and (2).

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For structures assigned to Seismic Design Category C, D, E or F, Section 1810.3..6.1 of the Building Code requires that splices of deep foundation elements shall develop the lesser of the following:

• The nominal strength of the deep foundation element.

• The axial and shear forces and moments from the seismic load effects including overstrength factor in accordance with Section 2.3.6 or 2.4.5 of ASCE 7.

Section 1810.3.13 of the Building Code requires that the pile caps be tied together for seismic design, if the structure is assigned to Seismic Design Category C, D, E, or F. This can be accomplished with grade beams or an appropriately designed floor slab.

This can also be achieved by using oversized pile caps that can develop the required restraint by passive pressure against the soil.

We evaluated the potential for liquefaction based on the results of the subsurface investigation and in our opinion, the site is not susceptible to liquefaction. Plastic silts and clays are not expected to be liquefiable but may be subjected to cyclic softening or deformations as a result of earthquake ground motions.

5.5 Pavement Design

Most of the traffic for the development is anticipated to consist of passenger vehicles or small trucks. We expect that pavements can be designed using a standard duty section with consideration that heavier loads such as delivery trucks and garbage trucks will pass over the site in certain areas. For areas that may be subject to repeated, heavy traffic loads, we recommend a heavy-duty asphaltic pavement or rigid concrete sections. Dumpster pads are subjected to relatively heavy loads during pickups and are generally built as a rigid, wire fabric reinforced concrete section. Areas without heavy truck loads may be designed as a standard-duty asphaltic pavement. We recommend the following pavement sections for these areas:

Table 1. Recommended Pavement Section (New)

Layer Material Standard-Duty Section (in.)

Heavy-Duty Section (in.)

Bituminous Wearing Course

NYSDOT

Type 7 Top

1.5 2.0

Bituminous Binder Course

NYSDOT

Type 3 Binder

2.5 3.0

Base Course Processed Aggregate Base 9.0 9.0

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

The subgrade soils for paved areas should be evenly graded to provide suitable drainage and should be compacted with at least four complete coverages of a vibratory roller compactor weighing at least 10 tons and imparting a dynamic force of at least 20 tons. Any soft materials in the roadbed where deflections are observed under the compactor or other traffic should be over-excavated and replaced with compacted Ordinary Fill. All subgrades should be free of frost before the start of compaction through placement of the pavement.

The recommended Rigid Pavement section is a minimum of 6 inches of welded wire fabric reinforced concrete (4,000-psi min.) over a minimum of 6 inches of processed aggregate base.

Imported materials should be placed and compacted in accordance with New York State Department of Transportation (NYSDOT) Standard Specifications. A tack coat should be applied to the binder course prior to placement of the surface course.

Although these pavement sections are typical for a 20-year design life, maintenance such as sealing of cracks and localized patching due to normal weathering should be expected within the first 5 to 10 years of life.

We do not anticipate that the site grading will be deep enough to expose the underlying organics. However, if the organic soils are exposed, we recommend that a biaxial geogrid be placed on top of the organic soil prior to placing fill or subbase. If the site grading results in raising the ground surface elevation by more than 1 foot from its current elevation, we recommend that the grade be raised by 1.2 times the designed grade change with this additional fill or subbase material being left in place for a minimum of 3 months before final grading and paving takes place. This will allow for compression of the organic layer and will minimize long-term settlements of the pavement.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

6. Construction Recommendations

6.1 Subgrade Preparation

If the exposed subgrade is granular (primarily sand and gravel), then any loose or disturbed soil should be removed from the bottom of the excavation, and the subgrade should be compacted with at least three coverages of a vibratory compactor weighing at least 200 pounds and imparting an impact load of at least 2.5 tons.

Any observed soft or ‘pumping’ zones in the subgrades should be over-excavated and replaced with either compacted Structural Fill or with ¾-inch crushed stone wrapped in filter fabric. Areas of the subgrade disturbed by traffic or surface water should be re-compacted.

We recommend that a GEI engineer observe the final preparation of subgrades prior to footing construction.

6.1.1 Removal of Surface Materials

Site preparation should include the removal of all unsuitable surface materials within the footprint of the structure foundations, including trash refuse and construction debris.

6.1.2 Removal and Reuse of Excavated Soils

Existing topsoil and root mat is not expected to be suitable for direct support of the new structure or roadway. However, excavated materials may be suitable for as fill in non-structural and landscaped areas. Excavated material should be closely evaluated during construction by an experienced geotechnical engineer to determine its suitability for reuse. Excess material should be disposed of off-site in accordance with the applicable regulations.

6.1.3 Foundations and Slab on Grade

We recommend the following for preparing subgrades below the proposed structures:

Bearing surfaces should be free of standing water, frost, loose soil, and soil softened by water intrusion before placement of reinforcing steel and concrete. Areas of the subgrade disturbed by traffic or surface water should be re-compacted.

For concrete slabs-on-grade, the subgrade should be proof rolled with a 10-ton vibratory roller. Soft zones should be over excavated, a geotextile separation layer installed on the native subgrade, and excavated material replaced with compacted Structural Fill.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

If water is present, or if precipitation is forecasted, the subgrade be covered with a minimum 3-inch-thick, plain concrete mud slab to protect the subgrade from disturbance during foundation construction.

6.2 Excavation and Dewatering

All excavations should be made in accordance with the applicable state and federal (e.g. OSHA) regulations pertaining to the protection of property and worker safety. Any excavation greater than 4 feet in depth should be sloped or benched unless shoring is used. A track-mounted hydraulic excavator or similar mechanical equipment will be suitable for the excavations of this project. We expect temporary slopes with a maximum slope of 2H:1V will be suitable to install shallow foundation elements and subsurface utilities. If necessary, temporary shoring systems or other excavation support methods shall be designed by a licensed professional engineer registered in New York State.

Standard trenching methods and pipe bedding details are suitable for the observed subsurface conditions. However, due to the presence of shallow fine-grained soils and the potential for shallow groundwater or poor drainage of precipitation or surface water, proper water management and subgrade preparation is critical to avoid softening/loosening of the trench subgrade.

Fill soils and newly placed structural fill will be suitable for support of subsurface utilities. If soft, wet, or loose soils are encountered in trench subgrades and/or at utility invert levels, the subgrade should be over excavated to a minimum depth of 6 inches, a geotextile separation layer installed, and backfilled with crushed stone or compacted structural fill. A smooth bladed bucket is recommended to excavate unstable soils and minimize disturbances to suitable subgrade. If over excavation of unsuitable soils is greater than 2 feet, granular fill wrapped in a geotextile filter fabric should be used to provide a firm base for utility bedding fill and to prevent particle migration. Any soft, wet, or deleterious soils that are left in place may result in greater than typical settlement. Plain concrete mud mats may also be used to provide stable subgrades.

Site runoff may infiltrate the excavations during construction. Removal of runoff and other water may be accomplished with filtered sumps and pumps. The sumps should consist of a perforated pipe wrapped in filter fabric and surrounded by pea stone. The site should be graded to route stormwater runoff away from excavations.

6.3 Horizontal Directional Drilling

Horizontal Directional Drilling (HDD) is expected to be the most cost effective and least intrusive method for installation of the proposed water main at the Seneca River crossing. To ensure success of the HDD installation it is crucial to follow best practices and recommendations.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

The proposed drill path should be designed to provide sufficient cover to mitigate the risk of experiencing inadvertent returns (IR) of drilling fluid to the surface. During the design phase an IR risk assessment and supporting calculations should be developed. The IR risk assessment should at a minimum consider site specific geology, drill hole diameter, drilling fluid, bathymetry of the river, pumping rates, and intended drill path.

Special consideration should be given for the use of conductor casing at the launching and receiving pits due to the weight of hammer material encountered in the borings. In addition to an increased risk of experiencing inadvertent returns, the weight of hammer material can result in difficulty in maintaining the intended drill path, both during opening of the initial pilot hole and subsequent reaming and swab passes.

6.4 Freezing Conditions

The soils above the frost line depth at the site are susceptible to frost action. Therefore, if construction is performed during freezing weather, special precautions will be required to prevent the subgrade soils from freezing. Freezing of the soil beneath the foundation during construction may result in subsequent settlement of the structure.

All subgrades should be free of frost before placement of concrete. Frost-susceptible soils that have frozen should be removed and replaced with compacted Structural Fill.

The footing and the soil adjacent to the footing should be insulated until they are backfilled.

Soil placed as fill should be free of frost, as should the ground on which it is placed.

If slabs-on-grade or footings are built and left exposed during the winter, precautions should be taken to prevent freezing of the underlying soil.

6.5 Backfilling and Compaction

If filling is required, structural fill may be used adjacent to and beneath the foundation footprint. Soils to be used as fill imported from off-site sources should also meet the Recommended Material Specifications provided herein. Reuse of in situ soil is not recommended for backfill.

6.6 Freezing Conditions

The soils at the site are frost susceptible. Therefore, if construction is performed during freezing weather, special precautions will be required to prevent the subgrade soils from freezing. Freezing of the soil beneath the foundation during construction may result in subsequent settlement of the structure.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

All subgrades should be free of frost before placement of concrete. Frost-susceptible soils that have frozen should be removed and replaced with compacted Structural Fill. The footing and the soil adjacent to the footing should be insulated until they are backfilled.

Soil placed as fill should be free of frost, as should the ground on which it is placed.

If slabs-on-grade or footings are built and left exposed during the winter, precautions should be taken to prevent freezing of the underlying soil.

6.7 Cuts and Fills

Based on our understanding of the project, minor cuts and fills may be required to facilitate the proposed site improvements. If cuts and fills are needed, we recommend that final cut and fill slopes be no steeper than 3H:1V to allow for the planting and maintenance of grass cover. Slopes as steep as 2H:1V will be stable but should be covered with a suitable type of erosion control.

We recommend removing sod, topsoil, organics, roots, debris, and surface obstructions, such as cobbles or boulders from the site before placing fill. Where filling is required to achieve the desired grades, on-site fill should be free of organic matter, surface coatings, frozen material, boulders, debris, and other deleterious materials. If off-site fill is required, we recommend using either Structural Fill below structures or Ordinary Fill in landscaped areas.

On-site fill should be compacted in 12-inch-thick loose lifts with a vibratory roller (static roller if cohesive) compacted to at least 92 percent of their maximum dry density calculated in accordance with ASTM D1557. Ordinary Fill should be compacted in 12-inch-thick loose lifts with a vibratory roller or plate compactor to the recommended degree of compaction as specified in the Recommended Material Specifications section.

Structural Fill and other materials used below foundation elements should be placed and compacted in 9-inch-thick loose lifts with a vibratory roller or plate compactor to the recommended degree of compaction as specified in the Recommended Material Specifications section.

On-site soils contain moderate to high percentages of fines and therefore will be sensitive to moisture content during placement and compaction. Proper moisture control is important to achieve adequate compaction. In addition, the on-site soils, either in situ or if reused as fill, will be easily disturbed if they become wet or saturated. Protection of exposed soil will be required.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

6.8 Site Disturbance

Project specifications should require the contractor to always maintain stable site conditions.

Specific measures to stabilize equipment traffic areas could include compacted aggregate placed over a geotextile, temporary drainage, or other appropriate measures.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

7. Limitations

7.1 Future Work and Limitations

This report was prepared for the exclusive use of Beardsley A/E. Our recommendations are based on the project information provided to us at the time of this report and may require modification if there are any changes in the nature, design, or location of the proposed structure. We cannot accept responsibility for designs based on our recommendations unless we are engaged to review the final plans and specifications to assess whether any changes in the project affect the validity of our recommendations and whether our recommendations have been properly implemented in the design.

The recommendations in this report are based in part on the data obtained from the subsurface explorations. The nature and extent of variations between explorations may not become evident until construction. If variations from the anticipated conditions are encountered, it may be necessary to revise the recommendations in this report. We, therefore, recommend that GEI be engaged to make site visits during construction to a.) check that the subsurface conditions exposed during construction are in general conformance with our design assumptions, and b.) ascertain that, in general, the work is being performed in compliance with the contract documents.

Our professional services for this project have been performed in accordance with generally accepted engineering practices; no warranty, express or implied, is made.

Montezuma National Wildlife Refuge, Seneca Falls, NY November 2024

GEI Consultants, Inc. DBA GEI Consultants Engineering, Geology, Architecture & Landscape Architecture

8. Recommended Material Specification

Structural Fill shall consist of hard, durable sand and gravel, free of clay, organic matter, surface coatings, and other deleterious materials. Soil finer than the No. 200 sieve (the “fines”) should be non-plastic. Soils to be used as fill imported from off site should also meet the gradation requirements given below.

Structural Fill [GEI]

Structural Fill shall meet the following gradation requirements:

Table 7-1. Structural Fill Gradation Requirements

Sieve Size Percent Passing by Weight

3 inches 100

0.5 inch 50 to 100

No. 4 35 to 85

No. 16 20 to 65

No. 50 5 to 40

No. 200 (fines) 0 to 8

Structural Fill shall be compacted in maximum 9-inch-thick, loose lifts to at least 95 percent of the maximum dry density determined in accordance with ASTM D1557 (Modified AASHTO Compaction).