B08_-_Solicitation_Attachment_-_(21003122A_-_Montezuma_NWR_-_Geotechnical_Report_Sealed)_0001.pdf

Maser Consulting is now Colliers Engineering & Design

Prepared for:

Mr. Jeff Lowy McMillen Jacobs Associates 1471 Shoreline Drive, Suite 100 Boise, ID 83702

Prepared by:

John Walton, P. E. Jacob D. Hundl New York Professional Engineer License No. 085339

18 Computer Drive East Suite 203

Albany, NY 12205 Main: 518 459 3252

Colliersengineering.com

Project No. 21003122A

September 30, 2021

Report of Preliminary Geotechnical Exploration

Proposed Multi-Purpose Facility Montezuma National Wildlife Refuge (NWR) Seneca Falls, Seneca County, New York

JHundl Stamp

Maser Consulting is now Colliers Engineering & Design

Report of Preliminary Geotechnical Exploration | September 30, 2021

Table of contents Introduction

Site Conditions Location and Surface Features Geology

Proposed Construction

Exploration Subsurface Exploration Program Subsurface Conditions Groundwater

Conclusions and Recommendations General Building Support Options Ground Improvement - Grouted Impact Piers Removal/Replacement Driven Steel Pipe or Tapertube Piles ACIP or Micropiles Lateral Pile Capacities Floor Slab Demolition Earthwork Fill and Backfill Materials Groundwater and Surface Water Control Subsurface Utilities Seismic Parameters Lateral Earth Pressure Parameters Pavements Limitations

List of Appendices

Appendix A: Figures Appendix B: Soil Boring Profiles Appendix C: Geotechnical Laboratory Test Results

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 1 | 22

Introduction This report presents the results of a geotechnical exploration program performed for a proposed multipurpose building considered for construction at the Montezuma National Wildlife Refuge (NWR) in Seneca Falls, Seneca County, New York. The subject property is located at the existing Montezuma NWR Visitor Center along Montezuma Entrance Road, approximately 1,500 feet north of US-20/NY-5/Auburn Road. Please refer to Figure 1 – Site Location Map included in Appendix A.

The following documents were provided and used as the basis for the subsurface exploration program and preparation of this report:

• A Statement of Work prepared by the U.S. Fish & Wildlife Service dated April 22, 2021.

• Grading, Electric, Water Supply, and VCS Structural plans prepared by Beardsley & Beardsley

Architects – Engineers, P.C., date illegible.

The plans indicate the property boundaries, current site layout, existing topography, and some existing utilities. Proposed grading, utility, architectural, and structural plans were not available at the time of this program.

The scope of our exploration program for this project included the following services:

• Subsurface explorations consisting of eight (8) borings.

• Laboratory testing of representative soil samples.

• Review of publicly available geologic data as it pertains to the proposed development.

• Preparation of this report, which includes our findings and recommendations regarding:

o Earthwork, including suitability of on-site materials for reuse and associated compaction requirements o Foundation and floor slab support, including bearing capacity and anticipated settlements o Surface water and groundwater control o Seismic design considerations o Lateral earth pressure parameters o Estimation of seasonal high groundwater elevations o Pavement design considerations

Site Conditions Location and Surface Features

At the time of this program, the property was developed with a single-story Visitor Center and Lodge Nature Store building with associated landscape and asphalt pavement areas. An appended observation deck is located on the east side of the building. Based on the referenced plans, we understand the building is supported with a foundation system consisting of a post-tensioned mat slab with integral concrete piers and a steel beam and girder support frame atop the piers.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 2 | 22

Existing ancillary site improvements include gravel and asphalt drive lanes and parking spaces, outbuilding structures, pathways, and greenspace. Based on the referenced plans, the ground surface generally slopes down from west to east across the property, with surface grades ranging from Elevation (EL) ±390 feet to EL ±382 feet, respectively.

Geology

According to the National Resources Conservation Service Soil Survey Map, Seneca County, New York, the site is predominantly mapped as the Made land, tillable soil series. The Made land soil group is generally characterized as moderately well drained gravelly loam to very gravelly sandy loam.

The project site is situated within the Newark Lowlands Physiographic Province. According to the Geologic Map of New York – Finger Lakes Sheet (1970), the site is underlain by the Camillus and Syracuse Formations, which are described as consisting of shale, dolostone, gypsum, and salt.

Proposed Construction Based on the referenced Statement of Work, we understand that the proposed construction will include an approximate 11,500 square feet multipurpose building in the general area of the existing visitor center with potential parking lot improvements; however, the exact location of the proposed building had not yet been established at the time of this program. It is understood that the proposed building is expected to be single-story with a slab-on-grade but we also understand a full basement is under consideration. At the time of this writing, the design of the proposed multipurpose building was not completed.

Proposed grading was not available at the time of this exploration program. For the purposes of this report, we have assumed finished grades will be established at or near existing ground surfaces.

As such, nominal mass cuts/fills on the order of ±3 feet are anticipated to achieve final site grades and finished grades at the proposed building. Deeper excavations will likely be required for installation of subsurface utilities and potentially for ground improvement as discussed herein. If a full basement is implemented at the building, excavations are expected to be on the order of ±10.0 feet, although a basement may not be feasible due to shallow groundwater and poor soil conditions as discussed herein.

Exploration Subsurface Exploration Program

The subsurface exploration program included eight (8) Standard Penetration Test (SPT) borings (TB-1 through TB-8) performed throughout accessible portions of the parcel. Borings TB-1 through TB-6were performed in potential building locations, as requested on site by Bill Stewart, Deputy Refuge Manager of the Montezuma National Wildlife Refuge, and Borings TB-7 and TB-8 were performed in the existing parking lot. The test borings were performed utilizing Diedrich D-60 truck-mounted drilling equipment and extended to depths ranging from ±6.4 feet to ±61.1 feet below the

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 3 | 22 ground surface (BGS). The locations of the test borings performed for this exploration program are shown on Figure 2 - Exploration Location Plan in Appendix A.

The exploration locations were selected by Colliers Engineering & Design (CED) and the Deputy Refuge Manager, and were field-located by measuring from existing site features using visual estimations. Test borings were performed under the full-time technical observation of CED. Soils encountered were classified in the field in accordance with the Burmister Soil Classification System.

Soil samples obtained from the explorations were returned to our laboratory for visual classification, and representative samples were subjected to limited laboratory testing.

Test borings were advanced by SoilTesting, Inc., using hollow-stem auger drilling techniques. Split spoon sampling was performed in accordance with ASTM D-1586 (Standard Method for Penetration Test and Split-Barrel Sampling of Soils). The number of blows required to drive the split spoon every six (6) inches into the soil were recorded and are shown on the logs. The sum of blows for the 6 to 18-inch interval is the N-value. The SPT N-value indicates the soil resistance encountered at each sample layer. Sampling was generally performed continuously from the ground surface to a depth of 12 feet and then at five (5) feet intervals to the completion depth of each test boring. Details pertaining to the subsurface conditions encountered are presented on the Test Boring Logs in Appendix B. The results of the laboratory testing performed on representative samples are presented on the Geotechnical Laboratory Testing Results in Appendix C.

Subsurface Conditions

Asphalt – Two of the eight borings were performed in existing pavement areas (TB-7 and TB-8), which encountered ±4.5 inches of asphalt, underlain by ±24 to ±48 inches of aggregate subbase.

Stratum S1 – Stratum S1 soils were encountered at the ground surface of six (6) borings (TB-1 through TB-6) and beneath the surficial asphalt and subbase of the remaining borings. Stratum S1 soils extended to depths ranging from ±4.0 to ±8.0 feet BGS in borings TB-1 through TB-6, and to the completion depths of borings TB-7 and TB-8. Stratum S1 soils consisted primarily of sand with variable amounts of clay, silt, and gravel. SPT N-values indicate the in-situ densities of the Stratum S1 soils ranged from ‘very loose’ to ‘dense’, averaging ‘medium dense’.

Stratum O – Stratum O organic soils were encountered in six (6) of the explorations, beneath the Stratum S1 soils in borings TB-1 through TB-4 and TB-6, and beneath Stratum CM soils in TB-5.

Stratum O soils extended to depths ranging from ±20.0 to ±25.0 feet BGS and consisted primarily of organic clay with variable amounts of sand and silt. SPT N-values indicate the in-situ consistency of the Stratum O soils ranged from ‘very soft’ to ‘stiff’, averaging ‘soft’.

Stratum CM – Stratum CM soils were encountered at six (6) of the explorations, beneath Stratum O soils in borings TB-1, TB-3, TB-4, and TB-6; beneath the Stratum O soils and beneath the Stratum S2 soils in TB-2; and beneath the Stratum S1 soils and beneath the Stratum O soils in TB-5. Stratum CM soils extended to depths ranging from ±50.0 to ±60.0 ft BGS in TB-1 and TB-2, respectively, and to the completion depths of TB-3 through TB-6. Stratum CM soils consisted primarily of clay and silt with lesser to trace amounts of sand. SPT N-values indicate the in-situ consistencies of the Stratum CM soils ranged from ‘very soft’ to ‘very stiff’, averaging ‘medium stiff’.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 4 | 22

Stratum S2 – Stratum S2 soils were encountered at two (2) of the explorations, beneath the Stratum CM soils in TB-1, and bounded by and beneath the Stratum CM soils in TB-2. Stratum S2 soils extended to the completion depths of both borings. Stratum S2 soils consisted primarily of sand with variable amounts of clay and silt. SPT N-values indicate the in-situ densities of the Stratum S2 soils ranged from ‘medium dense’ to ‘very dense’, averaging ‘dense’.

Groundwater

Evidence of groundwater was encountered in six (6) of the explorations at depths of ±25.0 feet BGS in TB-1 and ±4.0 feet BGS in TB-2 through TB-6. It should be noted that fluctuation in groundwater levels can occur due to several factors, including variations in precipitation, seasonal changes, and site development activities, which can alter surface water drainage paths.

Summary of Encountered Groundwater Levels

Boring Location Encountered Groundwater Depth (feet)

TB-1 25.0

TB-2 4.0

TB-3 4.0

TB-4 4.0

TB-5 4.0

TB-6 4.0

TB-7 Not Encountered TB-8 Not Encountered

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 5 | 22

Conclusions and Recommendations General Based on the results of this study, it is our opinion that construction of the proposed multipurpose building is feasible; however, significant costs could be associated with site development and building construction due to the encountered deleterious soils. The primary geotechnical issue identified during this study that will likely impact site development includes:

• Deep deposits of deleterious organic soils (Stratum O), which are susceptible to long term settlement, and are not suitable for support of the buildings without soil modification and/or deep foundation systems. One, or possibly a combination, of these options will be required to provide adequate support for the building structure and floor slab.

• Shallow groundwater will likely preclude a full depth basement, unless the main floor of the building is elevated above current grades.

The following sections of this report provide further discussion of these issues and present our recommendations for design and construction of the subject project.

Building Support Options

As previously indicated herein, deleterious organic soils were encountered in the borings and extend to depths ranging up to ±25.0 feet BGS, and soft silts and clays extend to depths ranging up to ±50.5 feet BGS. Due to the presence of the organic soils and soft silts/clays, support of the proposed building using conventional shallow spread footings is not recommended, as excessive settlements will likely occur. As such, we have evaluated various building support options that include removal/replacement, ground improvement with spread footings (rammed aggregate piers-RAPs and grouted impact piers-GIPs), driven piles (Timber, H-Piles, closed-end pipe), micropiles, and auger cast-in-place piles.

Based on the above considerations, it is our opinion that ground improvement via grouted impact piers may be the most cost-effective building support option that introduces the least amount of risk. A partial overexcavation and replacement program using lightweight fill is also a viable option that will allow use of conventional foundations; however, project location may add increased costs.

A driven closed-end pile is a feasible deep foundation option, provided pile driving is not prohibited.

Micropiles or auger cast-in-place piles are a viable deep foundation options; however, their associated costs could also make them less feasible.

Based on the depth to groundwater and the presence of organic soils, the removal/replacement with conventional weight backfill option was deemed generally unfeasible and/or anticipated to be cost prohibitive. RAPs were generally deemed infeasible due to the need to bridge through soft and organic soils. Timber piles were not further considered due to the depth to suitable bearing material being near the limits of typical timber pile lengths. H-piles were also not further considered

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 6 | 22 due to the end-bearing limitations in the predominantly granular Stratum S2 soils. The following sections of this report present our recommendations for each option.

Ground Improvement - Grouted Impact Piers

Ground improvement via grouted impact piers (GIPs) generally consists of drilling or driving a 2 to 3 foot diameter hole in the ground and backfilling the hole with successive lifts of gravel that are compacted with a tapered down-hole ram. This ground improvement method creates stiffened columns and improves the overall soil mass by densifying the soils surrounding the columns.

However, compacted gravel alone is not as effective in improving soft/compressible soils, such as the Stratum O and Stratum CM soils at this site. As such, by introducing grout to the gravel, the proposed building loads can be transferred more reliably to the suitable Stratum S2 bearing soils.

GIPs are generally feasible and cost effective to depths of 50 feet BGS. For this project, the GIPs should extend through Strata S1, O, and CM, with total depths estimated to range from 30 to 50 feet

BGS.

There are two methods of GIP installation, including replacement and displacement. The replacement method consists of drilling the hole with an auger and replacing the excavated soil with compacted gravel. Shallow groundwater can be problematic for the replacement method as an open hole must be maintained after removal of the auger to allow placement of the gravel backfill.

Additionally, a significant volume of spoil material can be generated depending on the total number of GIPs installed. The displacement method provides a solution for both of these issues by driving a specially designed tamper foot and mandrel into the ground using static and dynamic energy. The tamper foot used to create the hole displaces the soils down and laterally resulting in no spoils.

Gravel is then transferred to the bottom of the hole through the hollow mandrel, eliminating the need to maintain an open hole. Considering the shallow groundwater at this site and cost implications of exporting spoil materials, the displacement method is considered the most cost-effective method of GIP installation for this site.

GIPs will bring total and differential settlements within tolerable levels and will allow design of conventional shallow spread footings for bearing pressures ranging up to 5,000 to 10,000 pounds per square foot (psf), resulting in decreased footing sizes. For preliminary planning purposes, we recommend designing spread footings supported by GIPs for a maximum allowable net bearing pressure of 5,000 psf.

GIPs can also be designed to resist uplift from seismic or wind loads. Uplift resistance is achieved by installing anchors within the GIP element, which are then structurally connected to the footings. The GIP designer should establish uplift capacities for this project.

GIPs should be installed prior to installation of new subsurface utilities to prevent potential vibration induced damage from the GIP installation process.

A modulus test and uplift load test should be performed on at least one non-production GIP in general accordance with ASTM D-1143 and ASTM D-3689, respectively. Additionally, a representative

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 7 | 22 number of GIPs designated by the designer should be subjected to bottom stabilization verification testing, and dynamic cone penetrometer testing (ASTM STP-399) within the upper 1/3 of the RAP shaft length. The geotechnical engineer should provide full-time observation and quality control testing during installation and load-testing of the GIPs. The GIP system should be designed and installed by a qualified design-build contractor.

Removal/Replacement

Depending on final building loads, ground improvement via partial excavation of existing soils and replacement with lightweight fill is an option to reduce the net bearing pressures applied to the existing soils. With this option, the existing soils should be excavated to the groundwater level or ±4 feet below current grades; however, the actual depth of excavation will depend on final building loads. The excavation should extend a minimum of 4 feet beyond the perimeter of the proposed building. The excavation should then be lined with geotextile fabric and backfilled with ultra-lightweight fill, such as ultra-lightweight foamed glass aggregate (ULFGA). The building can then be constructed on conventional shallow spread footings and a concrete slab on grade. Foundations can be designed for a maximum allowable net bearing pressure of 3,000 psf. Given the lightweight fill is frost resistant, foundations can be established at more convenient depths, provided they do not interfere with floor slab or subslab utility construction.

Depending on the final design footing subgrade levels, the depth of lightweight fill below the footings may need to be increased.

Driven Steel Pipe or Tapertube Piles

Driven steel pipe and Tapertube piles should extend through Strata S1, O, and CM materials to derive bearing in the more competent underlying Stratum S2 soils. Deeper explorations will be required to facilitate design of such foundation systems. Pile lengths will be a function of the optimum pile diameters, spacing, and layout as determined by the project structural engineer.

These pile options will require the design of pile caps as well as a pile-supported structurally reinforced floor slab. Additionally, sub-slab utilities will need to be designed with hangers to suspend the utilities from the underside of the slab.

Driven steel piles, such as steel pipe piles derive support from a combination of side resistance and end bearing. The benefit of Tapertube piles is that typically less embedment and smaller diameter piles will generate higher capacities than similar length and diameter straight shaft steel pipe piles.

However, the unit cost of each pile system may be the governing factor in the final selection process.

Tapertube piles consist of a lower tapered section that is embedded in a suitable bearing stratum with an upper section of straight steel pipe to achieve the total required pile length. Advantages of Tapertube piles are that the upper pipe section can consist of a smaller diameter to reduce downdrag loads on the pile and the smaller diameter tip can more easily penetrate obstructions.

Alternative to the Tapertube piles, we recommend steel pipe piles embedded in the dense Stratum S2 soils. The pipe piles should also be fitted with a conical driving shoe to account for hard driving conditions.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 8 | 22

The Tapertube and steel pipe piles should be filled with concrete having a minimum 28-day compressive strength of 5,000 psi.

Although limited information is available from Stratum S2 due to the scope of this program, for preliminary planning purposes, 12-inch diameter piles driven a minimum of 15 feet into the Stratum S2 soils should be capable of providing up to 40 tons allowable axial capacity in compression. Should piles be chosen as an option as the project design moves forward, deeper explorations will be required to facilitate final design of pile dimensions and capacities.

We recommend a static load test be performed on a minimum of one (1) non-production pile to confirm the pile driving system, pile capacities, and final seating blows. Dynamic load testing, such as with the Pile Driving Analyzer, should be performed during installation of the test pile to provide real-time pile capacity and driving stresses as the pile is driven, as well as corroborate the results of the static load test. We recommend that dynamic testing also be performed on a minimum of 2% of the production piles to confirm pile driving conditions throughout the site.

Prior to construction and installation of the test piles, the pile driving contractor should submit to the geotechnical engineer for review the proposed pile driving hammer type, energy rating, and CAPWAP analysis to confirm the system will provide the required installed capacities without overstressing the piles. The final pile dimensions, embedment depth, and driving criteria will be established based on the results of the pile load test results.

Provided pile spacing is maintained at a minimum of three (3) times the diameter of the individual piles, the efficiency of pile groups will be equal to the sum of the individual pile capacities.

ACIP or Micropiles

ACIP piles or micropiles should extend through StrataS1, O, and CM materials to derive bearing in the more competent underlying Stratum S2 soils. Deeper explorations will be required to facilitate design of such foundation systems. Pile lengths will be a function of the optimum pile diameters, spacing, and layout as determined by the project structural engineer. These pile options will require the design of pile caps as well as a pile-supported structurally reinforced floor slab. Additionally, sub-slab utilities will need to be designed with hangers to suspend the utilities from the underside of the slab.

ACIP piles are installed using a continuous flight auger system, which is advanced to a predetermined depth or targeted bearing layer, and then grouted from the bottom up during withdrawal of the augers. No casing (temporary or permanent) is required due to the continuous flight auger system. Following excavation and grouting, the reinforcing steel cages and/or steel tendons (for uplift) are installed within the freshly placed grout. ACIP piles can develop relatively high capacities through a combination of skin friction along the sides of the pile and end bearing.

Micropiles are a drilled foundation that generally consist of a high strength steel casing, rebar, and grout. Micropiles have diameters typically between 5 and 12 inches that can be installed with smaller equipment, obstructions can be easily penetrated during installation, and drilling below the

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 9 | 22 groundwater level is easier when compared with other drilled foundation options. Micropiles can develop relatively high capacities through a combination of skin friction along the sides of the pile and end bearing.

Micropiles and ACIP piles can be design for high capacities with various diameters, lengths, and reinforcing steel parameters. For preliminary planning purposes, a 12-inch diameter micropile or ACIP pile installed 15 feet into the Stratum S2 soils can likely provide a minimum allowable axial capacity of 40 tons. Deeper explorations will be required to facilitate final design of pile dimensions and capacities.

Lateral Pile Capacities

Lateral pile capacities will be dependent on the type and dimensions of piles selected for the project.

Lateral capacities should be evaluated by the geotechnical engineer during final design using a software program such as LPILE.

Floor Slab Provided the GIP or removal/replacement options are implemented, the floor slab can be designed as a reinforced slab-on-grade. If designed as an independent slab-on-grade, the spacing of the GIPs and depth of GIPs should be verified. The project structural engineer should confirm the reinforcing requirements for the slab through close coordination with the GIP design-build contractor.

We recommend a minimum 6-inch thick bedding of well-graded free-draining granular material be placed below the floor slab to interrupt the rise of capillary moisture through the slab and allow for proper curing of the concrete. This requirement will likely be satisfied if either the GIP or removal/replacement options are selected. The floor slab may bear on footing projections; however, control joints should be provided at the slab and wall/column interfaces to reduce the potential for slab cracking, should the building settle differentially from the floor slab.

Immediately prior to placement of the granular subbase layer below the slab, the floor slab subgrade soils should be proof-rolled under the observation of the geotechnical engineer to evaluate stability. Any areas of instability should be selectively excavated and replaced with structural fill, placed and compacted in accordance with the Fill and Backfill Materials section of this report.

Demolition

Demolition and off-site disposal of the existing building and site improvements not to remain, including their below-grade components, such as foundations, utilities, and storage tanks, will be required prior to new construction activities. Should excavations to remove existing site features extend below the proposed building and pavement subgrade levels, the excavations should be backfilled with structural fill, placed and compacted in accordance with the recommendations presented in the Fill and Backfill Materials Section of this report.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 10 | 22

Existing durable below-grade structural elements, such as existing foundations, may remain in-place below proposed pavement areas only, provided the top of the elements remain at least 3 feet below the finished pavement surface, and they will not interfere with subsequent underground utility installation. Existing utilities to be abandoned below proposed pavements may also remain in-place, provided they remain at least 3 feet below the finished pavement surface and are permanently sealed or in-filled with grout or flowable fill. If existing utilities are abandoned and only sealed, they should be evaluated to determine if they are structurally sound.

Existing pavements that are not proposed to remain should be stripped from the proposed building and pavement areas; however, we recommend the existing pavements be left in place as long as possible during construction to help protect subgrade soils. Consideration could be given to on-site processing of demolished concrete and stockpiling on site for later reuse as structural fill or backfill, pending approval by the Municipality, and the project’s environmental consultant. Additionally, any demolished concrete should be subjected to Alkali-Silica Reactivity (ASR) testing and results submitted to the Geotechnical Engineer prior to authorizing its use as on-site fill. The contractor should anticipate that concrete processing will likely require the removal of reinforcing steel from large demolition fragments prior to further particle size processing. It should be noted that demolished brick, masonry block, and asphalt millings will have limited suitability for re-use as structural fill and should be discussed with the geotechnical engineer and environmental consultant prior to use.

Earthwork

Following demolition and any soil improvement methods employed, subgrade soils exposed in proposed areas to remain at grade or receive fill should be compacted by several passes of a large 10-ton roller and proof-rolled with a loaded tandem-axle dump truck under the observation of the geotechnical engineer. Other proof-rolling methods may be deemed appropriate by the geotechnical engineer depending on the weather and site conditions at the time earthwork is performed. Any subgrade areas that are observed to be soft, loose, or otherwise unstable during the proof-rolling operation should be selectively excavated as advised by the geotechnical engineer and replaced with compacted structural fill.

All construction excavations should be sloped and shored in accordance with OSHA excavation regulations or stricter local governing safety codes. The encountered site soils and new structural fill should generally be classified as “Type C” soils under OSHA excavation regulations. Excavation stability and corresponding side slopes and/or support requirements should be evaluated by a qualified professional at the time of construction and should take into consideration the adverse impacts of groundwater seepage, if encountered.

Although some of the on-site near surface soils encountered during this program are sandy, some near-surface soils have high fines content (i.e. the Stratum O soils), which combined with shallow groundwater levels and/or during periods of prolonged rainfall, the soils will be sensitive to disturbance and softening from excessive moisture content and construction equipment. The stripping and earthwork operations may result in extensive disturbance to the subgrade, particularly if the work is performed during or after wet weather. If possible, the bulk of earthwork should be

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 11 | 22 scheduled during periods of drier weather. A smooth bucket excavator may be advisable to limit disturbance while excavating wet soils. To the extent possible, construction traffic should traverse the site outside the limits of the proposed building area to prevent widespread destabilization of the subgrade soils. Use of the proposed building pad area for material staging should be avoided. A contingency should be provided in the project budget to repair destabilized subgrade soils.

Fill and Backfill Materials

The excavated Stratum S1 soils can be reused as compacted structural fill with some limitations as discussed herein. Excavated Stratum O and Stratum CM materials should not be used as structural fill; however, they can be placed in greenspace areas, which should be taken into account by the project Civil Engineer during development of a grading design for the project.

Depending on the prevailing weather conditions at the time earthwork is performed, moisture conditioning of the excavated soils may be required prior to their reuse as fill or backfill. If air drying of the soil is not possible due to precipitation, or if the project schedule cannot accommodate the time required for air-drying of the soil, it should be anticipated that unsuitable soils will need to be exported from the site and suitable structural fill materials will need to be imported. Consideration should be given to placing tarps or similar protective cover over stockpiles prior to precipitation events to help reduce the amount of moisture conditioning and/or soil amendment that may be required prior to reuse. Alternatively, if the soils are too dry, water may need to be added prior to compaction of the materials.

Off-site borrow material, if required as structural fill to achieve the proposed grading, should consist of well graded predominantly granular material and be approved by the geotechnical engineer prior to use. If clean open-graded stone is used as fill or backfill, it should be completely separated from adjacent soil with a non-woven geotextile filter fabric to prevent particle migration.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 12 | 22

Fill materials supporting loads from buildings and pavements is considered structural fill and should be installed under the observation of the geotechnical engineer. Mass structural fill consisting of predominantly granular fill materials can be placed in lifts ranging up to 12 inches in loose thickness and compacted using a smooth drum roller. Backfill placed in confined areas, such as utility and foundation excavations, should be spread in thinner layers and compacted using the largest equipment possible without damaging the utilities or compromising the subgrade soils. Backfill placed within 3 feet of below-grade walls or retaining walls should be compacted with manually operated compaction equipment. Fill and backfill should be compacted to the following minimum requirements:

Compaction Requirements

Location Percent of Maximum Dry Density

(ASTM D-1557)

Structural fill below foundations, floor slabs, and pavements 95%

Backfill for retaining walls, below-grade walls, and utility trenches

92%

General fill for landscaped and other non-structural areas

90%

Subgrades should be evaluated for stability by the geotechnical engineer prior to fill placement, and compactive effort for each lift of fill should be verified by in-place density testing prior to placement of subsequent lifts. Adjustments to the lift thickness and/or compaction equipment may be required, as directed by the geotechnical engineer, based on prevailing weather conditions at the time of fill placement and performance of the compacted soils.

Groundwater and Surface Water Control

Evidence of groundwater was generally encountered at depths of ±4.0 feet BGS during this exploration program. Evidence of groundwater was encountered at a depth of ±25 feet BGS at Boring TB-1; however, this is expected to be an anomaly, given the shallow groundwater encountered at other boring locations and is likely a result of silt/clay soils sealing the borehole during drilling operations.

Groundwater control will be a concern during excavations for soil improvement activities, as well as construction of foundations and utilities. Additionally, following periods of precipitation, it is possible that seepage of water may occur in open excavations, even those shallower than the existing groundwater level. It is expected that such seepage can be controlled by pumping from sumps located within the excavations, depending on the horizontal extents of the excavations and provided the excavations extend no deeper than 1 to 2 feet below the groundwater level.

Otherwise, well points and/or other high-capacity pumping methods may be needed depending on the depths and extent of excavations and should be designed by the contractor.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 13 | 22

Sump pits should be filled with minimum ¾-inch clean stone and lined with geotextile filter fabric to prevent soil migration. Pumped water should be discharged away from the building pad and open excavations. Where wet subgrade soils are encountered, consideration should be given to the use of a smooth bucket during excavation at or below the groundwater level to limit disturbance to the subgrade soils.

Surface grading should be maintained on a continual basis during construction to direct surface water runoff away from open excavations and prevent water from pooling on subgrade soils. The contract documents should require the contractor to provide whatever means and methods are necessary to maintain stable excavations and subgrade conditions at all times during construction.

Disturbed areas should be roller-compacted daily to seal the ground surface and inhibit infiltration of surface water.

Subsurface Utilities

The site soils and new structural fill materials will likely be suitable for support of subsurface utilities, though if deleterious soils are left in place may cause greater than typical settlement. Greater than typical maintenance issues may also be expected as a result.

Subsurface utility excavations should be sloped, benched, or shored in accordance with OSHA requirements as discussed in the Earthwork section of this report.

Should very soft, loose, or wet soils be encountered at the utility invert levels, the subgrade should be over-excavated a minimum depth of 6 inches and backfilled with suitable granular material to provide uniform support. If overexcavation of unstable wet soils is required, consideration should be given to using a smooth bucket for excavation, and placement of a granular material wrapped in a geotextile filter fabric to provide a stable base for placement of the bedding fill and prevent particle migration. Utility excavations should be backfilled using structural fill, placed and compacted in accordance with the recommendations presented in the Fill and Backfill Materials section of this report.

Seismic Parameters

Based on the SPT data collected at the site, geologic review, and our experience in the area, and provided soil improvement is performed, the project can be designed assuming a Seismic Site Class E – “Soft Clay Soil” profile. The design should be in accordance with the latest edition of the International Building Code [2018] (IBC). As such, the following design parameters are provided utilizing tables in the IBC code and United States Geological Survey (USGS) design tools for Site Class E:

From the USGS and using ASCE 7-16 information:

Short Period Spectral Acceleration (SS) 0.139g

Spectral Acceleration at 1 Second (S1) 0.048g

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 14 | 22

Since the site is a Site Class Definition of “E”, straight line interpretation of values for Fa and Fv based upon SS and S1, respectively are:

Site Coefficient, Fa 2.4

Site Coefficient, Fv 4.2

Utilizing Equations 16-36 thru 16-39 set forth in the IBC, the following design parameters were calculated:

SMS = Fa*SS = 0.334g ; SM1 = Fv*S1 = 0.204g

SDS = 2/3*SMS = 0.223g ; SD1 = 2/3*SM1 = 0.136g

Lateral Earth Pressure Parameters

Predominantly granular portions of the excavated site soils or imported well-graded granular soils will be better-suited for use as wall backfill material. We note that the Strata O and CM soils contain too much fine-grained soil (silt/clay) and/or deleterious organic material to use as wall backfill. The maximum particle size in wall backfill materials should be limited to 3 inches, and the backfill should be free of deleterious matter and debris. Retaining walls should be designed with a zone of free-draining material directly behind the back face of the wall to prevent the buildup of hydrostatic pressures, and include discharge channels, such as weep holes to direct drainage away from the wall. Walls constructed in cut areas should be designed with back drainage to intercept seepage that may occur from the excavated slope. Recommended soil parameters for design of below-grade walls and retaining walls are presented in the following table.

Lateral Earth Pressure Parameters

Soil Parameter* Strata S1 Natural

Soils

Stratum

O & CM

Natural

Soils

Stratum S2

Natural Soils

Structural Fill

In-Situ Moist Unit Weight (pcf)

110 100 115 --

Compacted Moist Unit Weight (pcf)

115 105 125 130

Angle of Internal Friction (degrees)

30 0 34 34

Coefficient of Friction at Base (concrete on soil)

0.3 0 0.5 0.5

* Values based on industry standard empirical correlations. Specific values should be confirmed via lab testing prior to final design.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 15 | 22

Walls restrained from lateral movement at the top of the wall and/or intermediate points should be designed using the at-rest earth pressure coefficient. Walls that are not restrained from lateral displacement (free to rotate) should be designed using active earth pressure coefficients. We recommend that passive earth pressures be omitted from the wall designs. Surcharge loads imposed by sloping backfill, pavements, terraced walls, material stockpiles, construction equipment, etc. must be considered in the wall designs. Retaining wall design should consider internal stability and external global stability at all critical stages during and following construction.

Although there were no planned retaining walls at the time of this exploration, it should be noted that if retaining walls are added to the proposed design to achieve site grades, the location, geometry, and type of retaining wall may require ground improvement or alternate support systems. We request to be notified if retaining walls are proposed so an appropriate wall design and support system can be evaluated.

Provided light pole bases do not penetrate deeper than the Stratum S1 soils, they can be designed assuming a coefficient of friction against sliding of 0.25 and a maximum allowable lateral soil pressure of 150 psf per foot of base depth below the ground surface. If light pole bases will penetrate the Stratum S1 soils, alternate foundation types or support systems may be required.

Design of light pole bases should account for shallow groundwater.

Pavements

The existing asphalt encountered was ±4.5 inches thick and appeared to be in relatively good condition. The asphalt was underlain by ±12 to ±24 inches of aggregate subbase. In existing pavement areas to remain, we recommend the existing pavement be proof-rolled with a loaded tandem-axle dump truck under the observation of the geotechnical engineer to evaluate stability at the time of construction. Any areas that are observed to be unstable could be considered for selective removal and replacement with full-depth pavement sections.

New pavements can be constructed on the existing site soils or new compacted structural fill.

Immediately prior to pavement construction, the exposed pavement subgrade should be compacted with a minimum 10-ton smooth-drum roller and be proof-rolled with a loaded tandem-axle dump truck under the observation of the geotechnical engineer to evaluate stability. Any subgrade areas that are observed to be unstable or contain debris/deleterious matter should be selectively excavated and replaced with compacted structural fill or granular subbase material.

As previously indicated, portions of the site soils with elevated silt/clay content will be susceptible to disturbance from excessive moisture and construction equipment. Depending on the timing between pavement subgrade preparation and pavement section construction, the contractor should anticipate that remedial work could be required to achieve a stable subgrade prior to paving, even if the subgrade soils had previously been compacted to the required densities. Prudent scheduling of pavement construction and control of construction equipment traffic will reduce the need for potential remedial work.

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 16 | 22

Provided the pavement subgrade is prepared in accordance with the recommendations contained herein, we have assumed a California Bearing Ratio (CBR) of 5 for the subgrade soils. The following tables present recommended minimum flexible and rigid pavement sections.

FLEXIBLE ASPHALT PAVEMENT

Material Standard Duty (inches)

Heavy Duty (inches)

Wearing Course 1.5 1.5 Binder Coarse 2.5 3.5

Aggregate Subbase 5.0 7.0

RIGID CONCRETE PAVEMENT

Material Heavy-Duty (inches)

4,000 psi Reinforced Concrete

6.0

Aggregate Subbase 6.0 We recommend that rigid concrete pavements be reinforced with minimum 6x6-W2.9xW2.9 welded wire mesh. These recommended pavement sections may be subject to municipal approval.

Limitations

This geotechnical exploration program has been performed in accordance with generally accepted engineering practice and any applicable design standards as referenced herein. This report and all supporting documentation have been prepared exclusively for the use of McMillen Jacobs Associates pursuant to the Agreement between Colliers Engineering & Design, CT, P.C. and McMillen Jacobs Associates dated July 21, 202. All provisions set forth in the Agreement and the General Terms and Conditions attached thereto are incorporated herein by reference. No warranty, express or implied, is made herein.

The findings, conclusions, and recommendations contained in this report are based on data revealed by limited exploration and testing of the subsurface at the referenced project site. The explorations indicate subsurface conditions at the specific locations and times explored, and only within the depths penetrated. Should deviations from the described subsurface conditions be encountered at any time prior to or during construction, Colliers Engineering & Design should be notified immediately so that modifications to our recommendations can be made, if necessary.

This report is applicable only to the contemplated site design described herein, and any changes in the design should be brought to our attention so that we may evaluate whether our recommendations will be affected. Colliers Engineering & Design is not responsible for any claims, damages, or liability associated with interpretation of subsurface data or reuse of the subsurface

Report of Preliminary Geotechnical Exploration | September 30, 2021 Page 17 | 22 data or engineering analysis without the expressed written authorization of Colliers Engineering & Design. As such, the conclusions and recommendations contained in this report are pending our review of final plans and specifications, and verification of subsurface conditions by direct observation at the time of construction.

This report and supporting documentation are instruments of service. The subject matter of this report is limited to the facts and matters stated herein.

The scope of this geotechnical program did not include investigation or evaluation of any environmental issues, such as wetlands, or hazardous or toxic materials on, below, or in the vicinity of the subject site. Any statements in this report or supporting documentation regarding odors or unusual or suspicious items or conditions observed are strictly for the information of our Client.

Appendix A

Figures

Appendix B

Soil Boring Profiles

S-1

0.0'-2.0'

S-2

2.0'-4.0'

S-3

4.0'-6.0'

S-4

6.0'-8.0'

S-5

8.0'-10.0'

S-6

10.0'-12.0'

S-7

15.0'-17.0'

S-8

20.0'-22.0'

S-9

25.0'-27.0'

S-10

30.0'-32.0'

S-11

35.0'-37.0'

S-12

40.0'-42.0'

WOH

WOH

WOH

WOH

WOH

WOH

WOH

WOH

WOH

WOH

WOH

6.0

25.0

Stratum S1

Stratum O

Stratum CM

S-1: Brown mf SAND, some Silt, little mf Gravel. (Dry)

S-2: Brown f Sand and Silt. (Moist)

S-3: Brown f SAND, trace Silt. (Moist)

S-4: Dk. Brown Peat (Moist)

S-5: Grey Organic CLAY. (Moist)

S-6: Grey Organic CLAY. (Moist)

S-7: Grey Organic CLAY. (Moist)

S-8: Grey Organic CLAY. (Moist)

S-9: Grey-Brown CLAY, trace f Sand. (Wet)

S-10: Grey-Brown CLAY, trace f Sand. (Wet)

S-11: Grey-Brown f SILT, some f Sand. (Wet)

S-12: Grey-Brown CLAY, trace f Sand. (Wet)

PROJECT: TEST BORING: TB-01

LOCATION: GROUND ELEVATION (ft): N/A

ELEV. FROM:

PROJECT NO. 21003122A GROUNDWATER ELEV. (ft):

5275 Parkway Plaza Boulevard, Suite 100, Charlotte, NC 28217

CONTRACTOR: SoilTesting, Inc. DATE STARTED 08/16/21 DRILLER: John Knepple GROUNDWATER: DEPTH (ft) DATE

FIRST ENCOUNTERED 25.0 08/16/21 DATE FINISHED 08/16/21DRILLING EQUIPMENT: Diedrich D-60 Truck-Mounted Rig

METHOD: HSA X Mud Rotary Other END OF DRILLING (0 hrs.) 25.0 08/16/21

HAMMER: CH X Safety Automatic FIELD OBSERVER: NCO

RODS: AW NW Other ASTM D-1586 CHECKED BY: JH

NOTES:

TEST BORING: TB-01

DEPTH

BELOW

SURFACE

(ft.) DEPTH (ft.)

SAMPLE

NUMBER

0-6"

BLOWS PER 6 INCHES

6-12" 12-18" 18-24" R E

C O

V E

R Y

(i n

P O

C K

ET

P E

N E

TR

O

M

(t sf

M O

IS

T

U R

E

W A

T

ER

SY

M

B O

L

DEPTH

ELEV.

PROFILE

IDENTIFICATION OF SOILS / REMARKS

R e p o rt f o rm

C E

D -T

B -S

T D

-R

.f d t

/2 /2

Montezuma National Wildlife Refuge

Montezuma National Wildlife Refuge Seneca Falls, Seneca County, NY

S-13

45.0'-47.0'

S-14

50.0'-52.0'

S-15

55.0'-57.0'

WOH

WOH

WOH

50.0

57.0

-57

Stratum CM

Stratum S2

S-13: Grey-Brown CLAY, trace f Sand. (Wet)

S-14: Brown f SAND, some Clay & Silt. (Wet)

S-15: Brown f SAND, little Silt. (Wet)

END OF TEST BORING AT 57.0 FEET

PROJECT: TEST BORING: TB-01

LOCATION: GROUND ELEVATION (ft): N/A

ELEV. FROM:

PROJECT NO. 21003122A GROUNDWATER ELEV. (ft):

5275 Parkway Plaza Boulevard, Suite 100, Charlotte, NC 28217

CONTRACTOR: SoilTesting, Inc. DATE STARTED 08/16/21 DRILLER: John Knepple GROUNDWATER: DEPTH (ft) DATE

FIRST ENCOUNTERED 25.0 08/16/21 DATE FINISHED 08/16/21DRILLING EQUIPMENT: Diedrich D-60 Truck-Mounted Rig

METHOD: HSA X Mud Rotary Other END OF DRILLING (0 hrs.) 25.0 08/16/21

HAMMER: CH X Safety Automatic FIELD OBSERVER: NCO

RODS: AW NW Other ASTM D-1586 CHECKED BY: JH

NOTES:

TEST BORING: TB-01

DEPTH

BELOW

SURFACE

(ft.) DEPTH (ft.)

SAMPLE

NUMBER

0-6"

BLOWS PER 6 INCHES

6-12" 12-18" 18-24" R E

C O

V E

R Y

(i n

P O

C K

ET

P E

N E

TR

O

M

(t sf

M O

IS

T

U R

E

W A

T

ER

SY

M

B O

L

DEPTH

ELEV.

PROFILE

IDENTIFICATION OF SOILS / REMARKS

R e p o rt f…