Geotechnical Report.pdf

USACE

US ARMY CORPS OF ENGINEERS NY

26 FEDERAL PLAZA, RM 1843

NEW YORK, NY 10278-0090

COVERED CANOPY SOLAR ARRAY

ARMED FORCES RESERVE CENTER

25 BAITING PLACE ROAD

FARMINGDALE, NY 11735

SOLICITATION #W16R0E22576993

CONTRACT #W912DS-19-D0009

GEOTECHNICAL REPORT

28 AUGUST 2024

ARCHITECUTRAL / SITE

QPK DESIGN, LLP

ARCHITECTS/ENGINEERS

450 SOUTH SALINA ST., STE. 500

SYRACUSE, NY 13202

315-472-7806

QPK #222281.00

PURPOSE AND SCOPE

The Farmingdale Armed Forces Reserve Center serves as a multi-purpose facility for members of the

National Guard, Army Reserve, Naval Reserve and Marine Corps Reserve. The purpose of this project is to provide an open canopy structure to support a solar array system along the northern perimeter of the existing parking lot. The support structure will include steel framing and concrete piers connecting to foundations to support the solar panels.

This report documents our subsurface exploration and describes our geotechnical engineering evaluations for design and construction of the foundations for the proposed solar array structure.

We recommend constructing the proposed solar array structure on drilled shaft foundations. Details of our evaluations follow.

SITE DESCRIPTION

The solar array structure is proposed on the north side of the Farmingdale Armed Forces Reserve Center parking lot located at 25 Baiting Place Road, Farmingdale, NY. The center is located approximately a half mile southwest of the Republic Airport. As shown on Figure 1, it is bounded by Marine Street to the north and west, Farmingdale Reserve Center to the south, and Baiting Place Road to the east.

The site generally sloped gently down from the northwest towards the southeast, from Elevation 56 ft at the northwest corner of the parking lot, to a low spot at Elevation 54 ft towards the southeast boundary of the site.

The site was predominantly a bituminous asphalt parking lot with grass-covered medians and a main security gate to the north of the proposed array alignment. Figures 2 shows the existing utilities and asphalt parking lot.

Historic aerial photographs showed that the project site was once a stockpile area during construction in

2010. In 2010, an area directly west and extending south of the existing gatehouse was excavated below current grades, used as a temporary construction stormwater control pond, and subsequently backfilled.

PROJECT DESCRIPTION

Current plans, on Figure 4, indicated the proposed solar array will have concrete piers spaced at 27-feet apart and extend from the west side of the north parking lot median to the east and terminate at Baiting

Place Road.

The structural engineer identified three design load cases for the solar array foundations in Table 1.

Table 1: Load Cases for Piers

Load

Case

Min. Stanchion

Diameter (ft)

Max. Axial

Compression

(kip)

Max. Lateral

(kip)

Max. Moment

Groundline

(kip-ft)

Max Axial

Tension

(kip)

P1 5 24.0 4.8 48.3 0.0

P2 5 0.0 3.8 15.2 -10.8

P3 5 0.0 3.3 120.8 -6.7

GEOLOGY AND SEISMICITY

Geologic reports indicated that the site is within the Atlantic Coastal Plain physiographic province, within the broad, low sandy outwash plain south of the Ronkonkoma terminal moraine, along the south shore of Long

Island. Bedrock is reported to slope down towards the south, and is expected to be deeper than 300 ft.

Soils would be expected to consist of medium dense sand and gravel with moderate bearing properties.

According to ASCE 7-16, the design earthquake is characterized by mapped spectral response accelerations of Ss= 0.230g and S1=0.046g. These values must be adjusted for subsurface conditions that are reflected by the Site Class described later in this report, in accordance with UFC 3-301-01.

SUBSURFACE EXPLORATION

We directed and oversaw a subsurface exploration on August 6, 2024. It consisted of the 4 test borings drilled with Standard Penetration Test (SPT) testing per ASTM D1586, designated as Test Borings B24-1 through B24-4 as shown on Figure 2. Prior to drilling borings, utilities were cleared by Utility Detection Inc.

on August 5, 2024. The test borings were advanced to 22 ft and 25 ft depths. Borings were performed in the presence of our on-site geotechnical engineer, Mr. Edin Hurtic, EIT and under the direction of Mr. Brandon

Rhea, P.E.

The subsurface conditions were as shown on the Test Boring Logs in Appendix A. Our engineer interpreted test borings to develop the Subsurface Profile on Figure 3.

The exploration generally encountered 4 ft to 6 ft of Medium Dense to Dense, Light Brown, Silty Fine Sand with Gravel over Medium Dense, Fine to Coarse Sand with Gravel. Uncorrected SPT N-values in the Silty Fine

Sand ranged from 19 to 46 blows per foot (bpf) with an average SPT N-value of 31 bpf. Uncorrected SPT N-values in the Fine to Coarse Sand ranged from 10 to 42 blows per foot (bpf) with an average SPT N-value of

27 bpf.

Old fill was encountered in Test Boring B24-3 and extended from the ground surface to a depth of 11 feet.

The old fill consisted of a Very Loose to Medium Dense, Brown, Silty Fine Sand with Gravel. Uncorrected SPT

N-values ranged from 1 to 21 blows per foot (bpf) with an average SPT N-value of 9 bpf.

Groundwater was encountered in the explorations at depths between 14.2 and 15.1 feet (corresponding to

Elevations 40.4 to 40.9 ft). Bedrock was not encountered in any of the test borings.

GEOTECHNICAL ENGINEERING EVALUATION

Based on the results of the explorations, we determined the most suitable foundation will consist of relatively short, drilled shafts. Drilled shafts should be designed for end bearing and side resistance in the native fine to coarse sand encountered in test borings between 4 and 11 ft below ground surface (Generally below Elevation 50.0 ft). Drilled shafts bearing at least 3 ft into the native sandy soils could be proportioned for a maximum allowable end bearing pressure of 3.0 ksf and allowable side resistance may be taken as 0.3 ksf over the portion bearing in native sandy soils. Given the relatively light axial loads and the minimum shaft size required for piers, the drilled shaft length will likely be governed by the lateral loads and groundline moments. Uplift resistance derived from side friction and effective shaft weight.

Based on old fill soil encountered in Test Boring B24-3 to a depth of 11 ft (Elevation 44.0 ft) drilled shafts at

Pier Location 8-14 should be designed with old fill design parameters to Elevation 44.0 ft. Drilled shafts at remaining pier locations may be designed with the native sandy soil parameters over the full depth.

Proposed Pier locations are shown on Figure 4 and design parameters are provided in Table 3.

The sandy native soils will be sensitive to disturbance from drilled shaft construction, and presence of water may complicate inspection of the bearing surface. Nevertheless, the axial capacity of the drilled shaft will be derived mainly from side resistance, and we estimated that total settlement under the design loads would be less than 1 inch.

Drilled shafts should be constructed with temporary casing to ensure shaft wall stability. Groundwater was encountered at or below the estimated drilled shaft depth. If groundwater is encountered above the drilled shaft tip during installation and groundwater cannot be controlled then concrete should be placed by tremie methods. When concrete is placed in a dry cased hole, gravity placement methods should be acceptable.

We determined that Site Class D should be used for Seismic Design in accordance with UFC 3-301-01. The mapped accelerations given must be modified according to UFC-3-301-01. Our analyses did not indicate significant potential for liquefaction or seismically induced settlement during the design earthquake.

For the design loads in Table 1, we estimated the following drilled shaft dimensions for a maximum top lateral deflection less than 0.5 inches:

Table 2: Estimated drilled shaft dimensions to be verified by design

Drilled Shafts Diameter (ft) Estimated Length (ft)

1-7, 15-18 5 11

8-14 5 14

GEOTECHNICAL ENGINEERING RECOMMENDATIONS

Based on our evaluations, we conclude that the proposed solar array structure can be supported on drilled shafts bearing on native sandy soils. We recommend that design and construction conform to:

A. Drilled Shaft Foundation Design and Construction

1. For seismic design, use Site Class D in accordance with UFC 3-301-01.

2. Proportion drilled shafts bearing at least 3 feet into native soils according to the parameters in Table

3. If old fill is encountered at the proposed tip elevation, drilled shafts must be drilled deeper to ensure at least 3 feet of embedment into native soils.

Table 3: Parameters for drilled shaft design and lateral load analysis using program LPILE by Ensoft.

Parameter Sandy Old Fill Native Sandy Soils

Total Unit weight, γ 120 lb/ft3 (moist) 125 lb/ft3 (moist)

Friction angle, φ 28° 32°

Subgrade Modulus, K 60 lb/in3 (default) 60 lb/in3 (default)

Depth of soil below surface not contributing to support

Ignore top two (2) feet --

Allowable end bearing pressure -- 3.0 ksf

Depth of soil below surface not contributing to support

Ignore top two (2) feet Ignore top one (1) foot

3. Pile diameter and tip Elevations should be refined during final design phase.

4. Drilled shaft bearing area to be cleaned of loose material using machine equipped with special cleaning bucket.

5. Excavate and expose utilities or perform vacuum excavation procedures for any utilities within 5 feet of the proposed drilled shaft.

6. Use temporary casing to maintain hole stability during drilling and concrete placement. Set casing into native sandy soils.

7. Thoroughly machine clean bottom of drilled shaft with cleanout bucket. Engineer’s representative to inspect and approve bottom of hole before concrete is placed. Visual inspection of drilled shaft bottoms from the ground surface may be sufficient.

8. Drilled shafts spaced closer than 3 times the drilled shaft diameter center to center should be drilled to full depth with temporary casing. Contractor to either pour concrete for drilled shafts simultaneously or delay pouring of adjacent drilled shaft a minimum of 48 hours after initial drilled shaft is poured.

9. Immediately before placing concrete, pump water from casing so that concrete can be placed in the dry. No more than 2 inches of water may be left in drilled hole.

10. Place rebar cage at appropriate level.

11. Place concrete so that remining water is displaced outward, and not mixed into concrete. As concrete is placed, withdraw temporary casing. Maintain at least 5 ft of concrete above bottom of casing and above groundwater level at all times.

12. After temporary casing is removed, vibrate top 5 feet of concrete.

B. Special Inspections

In accordance with Chapter 17 of the International Building Code these Special Geotechnical Inspections should be provided:

1. Verification of structural fill and backfill materials and documentation of the degree of relative compaction.

2. Observe and document drilling operations for each drilled shaft.

3. Verify drilled shaft dimensions, lengths, and bearing stratum comply with the design requirements.

Respectfully submitted, QPK DESIGN

BRANDON RHEA, PE JASON THORPE, P.E.

Geotechnical Engineer Geotechnical Engineer

BR/JT

Attachments: Figure 1. Site Location

Figure 2. Site Layout and Test Boring Location Plan

Figure 3. Soil Profile A

Figure 4. 35 Percent Foundation Plan and Notes

Appendix A: Test Boring Logs

JOB No.: DESIGNED BY: DATE:

QPK DESIGN

SYRACUSE, N.Y. 315-472-5238

108/26/2024B.R.222281.00

PROJECT LOCATION PLAN

FIG:

ARMED FORCES RESERVE CENTER

25 BAITING PLACE ROAD, FARMINGDALE NY 11735

COVERED PARKING CANOPY SOLAR ARRAY

PROJECT LOCATION

0' 30' 60' 120'

SCALE

NOTES:

1. SUBSURFACE CONDITIONS HAVE BEEN DETERMINED AT EXPLORATION LOCATIONS ONLY.

CONDITIONS BETWEEN THESE LOCATIONS REPRESENT THE ENGINEER'S INTERPRETATION.

JOB No.: DESIGNED BY: DATE:

FIG:

LEGEND

Sheet: 1

File: ..\Plan and Survey 2-14-24.pdf

Missing or invalid reference

B-#

A A

TEST BORING LOCATION

SOIL PROFILE SECTION

A

A

APPROXIMATE AREA OF

OLD FILL

NORTH

QPK DESIGN

SYRACUSE, N.Y. 315-472-5238

08/26/2024B.R.222281.00

ARMED FORCES RESERVE CENTER

25 BAITING PLACE ROAD, FARMINGDALE NY 11735

SITE LAYOUT AND BORING LOCATION PLAN

NOTES:

1. SUBSURFACE CONDITIONS HAVE BEEN DETERMINED AT EXPLORATION LOCATIONS ONLY.

CONDITIONS BETWEEN THESE LOCATIONS REPRESENT THE ENGINEER'S INTERPRETATION.

JOB No.: DESIGNED BY: DATE:

FIG:

FILL

SM

OLD FILL

MEDIUM DENSE TO DENSE, LIGHT BROWN, SILTY FINE SAND WITH GRAVEL

SW MEDIUM DENSE TO DENSE, LIGHT BROWN, FINE TO COARSE SAND WITH GRAVEL

QPK DESIGN

SYRACUSE, N.Y. 315-472-5238

08/26/2024B.R.222281.00

ARMED FORCES RESERVE CENTER

25 BAITING PLACE ROAD, FARMINGDALE NY 11735

SOIL PROFILE A

FIGURE 4: 35 PERCENT FOUNDATION PLAN AND NOTES

PRINTED AT HALF SCALE: 1" = 40'

NTS NTS

APPENDIX A

TEST BORING LOGS

SLACKE TEST BORING, INC.

Subsurface Soils & Foundation Explorations

P.O. Box 64, Kings Park, Long Island, New York 11754 • (631) 269-7930 • info@slacketestboring.com

Date ___________ Job Number ___________ Number of Borings ___________

Job Location ________________________________________________________________

1) WATER LEVELS SHOWN ARE THOSE MEASURED ON THE DATE INDICATED AND MAY OR MAY

NOT BE REFLECTIVE OF DAILY OR SEASONAL VARIATIONS IN THE GROUNDWATER LEVEL.

2) THE BORING RESULTS REPRESENT SUB-SURFACE CONDITIONS AT THE BORING LOCATION

ONLY AND ARE NOT NECESSARILY REPRESENTATIVE OF CONDITIONS AT OTHER LOCATIONS.

Date: August 6, 2024

Client: John P. Stopen Engineering, LLP Phone: 315-472-5238 Temperature: 82°F

Job Number: 24-290 Boring Number: B24-1 Depth of Boring: 22 Feet

Job Location: 25 Baiting Place Road, Farmingdale NY 11735

Water Level: 15.1 Feet Below Ground Surface at 7:43AM

Vicinity Recorded High Tide: 12:17PM Low Tide: 7:03AM

Drilling Method: Geoprobe

Depth

From To

Classification of Soil 30” Blows Sample Spoon

Penetration of Spoon in

Inches Ground Surface

2’ Dark Brown and Pale Brown Very Fine Silty Same Size Sands with Some Organics (Roots) at Top of Spoon with Trace Fine Gravel into Mostly Fine Silty Same Size Sands with Some Fine Clean Same Size Sands Throughout with Some Fine to Small Gravel. (SM) Sample #1 @ 0’ to 2’

4-9-15-20 24”

2’ 4’ Pale Brown and Light Brown Mostly Fine Silty Same Size Sands with Some Fine Clean Same Size Sands Throughout with Some Fine Gravel into Fine Same Size Sands with Some Fine to Small Gravel. (SM/SP) Sample #2 @ 2’ to 4’

16-17-20-22 24”

4’ 6’ Light Brown Fine to Medium Mix Size Sands with Some Silts at Bottom of Spoon with Some Fine to Small Gravel. (SW) Sample #3 @ 4’ to 6’

13-18-24-25 24”

6’ 8’ Light Brown and Light Rust Brown Fine to Medium Mix Size Sands with Trace Silts Mid Spoon with Some Fine to Large Crushed Gravel with Large Crushed Rock at Bottom of Spoon.

(SW)

Sample #4 @ 6’ to 8’

21-20-24-28 24”

8’ 10’ Light Rust Brown Fine to Coarse Mix Size Sands with Some Fine to Large Crushed Gravel with Large Crushed Rock Mid Spoon.

(SW)

Sample #5 @ 8’ to 10’

12-18-24-22 24”

Elevation: 56.0 Feet +/-

10’ 12’ Light Rust Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #6 @ 10’ to 12’

11-15-16-20 24”

12’ 17’ Light Brown Fine to Coarse Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #7 @ 15’ to 17’

10-9-12-12 24”

17’ 22’ Light Brown Fine to Coarse Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #8 @ 20’ to 22’

7-8-7-8 24”

END OF BORING 22’0”

Job Number: 24-290 Boring Number: B24-2 Depth of Boring: 22 Feet

Job Location: 25 Baiting Place Road, Farmingdale NY 11735

Water Level: 14.2 Feet Below Ground Surface at 8:31AM

Vicinity Recorded High Tide: 12:17PM Low Tide: 7:03AM

Sample Spoon

Penetration of Spoon in

Inches Ground Surface

2’ 5” of Asphalt into 2” of Fine to Small RCA Stone and Fill into Dark Brown and Pale Brown Very Fine Silty Same Size Sands with Some Urban Material (Crushed Red Bricks) and Some Fine to Medium Gravel. (SM) Sample #1 @ 0’ to 2’

18-18-16-13 24”

2’ 4’ Light Rust Brown Fine to Medium Mix Size Sands with Trace Silts Throughout with Some Fine to Small Gravel. (SW) Sample #2 @ 2’ to 4’

16-10-19-20 24”

4’ 6’ Light Rust Brown Fine to Coarse Mix Size Sands with Trace Silts Throughout with Some Fine to Small Gravel. (SW) Sample #3 @ 4’ to 6’

17-14-21-20 24”

6’ 8’ Light Rust Brown Fine to Medium Mix Size Sands with Some Fine to Medium Gravel. (SW) Sample #4 @ 6’ to 8’

19-17-17-14 24”

8’ 10’ Light Rust Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #5 @ 8’ to 10’

8-10-13-13 24”

10’ 12’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #6 @ 10’ to 12’

12-10-10-12 24”

12’ 17’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #7 @ 15’ to 17’

7-9-11-10 24”

Elevation: 55.0 Feet +/-

17’ 22’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #8 @ 20’ to 22’

4-6-7-6 24”

Job Number: 24-290 Boring Number: B24-3 Depth of Boring: 22 Feet

Job Location: 25 Baiting Place Road, Farmingdale NY 11735

Water Level: 14.6 Feet Below Ground Surface at 9:10AM

Vicinity Recorded High Tide: 12:17PM Low Tide: 7:03AM

Drilling Method: Geoprobe W=WEIGHT OF HAMMER

Sample Spoon

Penetration of Spoon in

Inches Ground Surface

2’ Dark Brown and Pale Brown Very Fine Silty Same Size Sands with Some Organics (Roots) at Top of Spoon with Some Fine Clean Same Size Sands at Bottom of Spoon with Some Fine to Small Gravel. (SM) Sample #1 @ 0’ to 2’

3-9-12-13 24”

2’ 4’ Pale Brown Fine Silty Same Size Sands with Some Fine to Small Gravel. (SM) Sample #2 @ 2’ to 4’

9-7-8-5 24”

4’ 6’ Brown Moist Very Fine Silty Same Size Sands with Some Fine to Small Gravel. (SM) Sample #3 @ 4’ to 6’

5-6-2-2 24”

6’ 8’ Brown Moist Very Fine Silty Same Size Sands with Some Fine to Small Gravel. (SM) Sample #4 @ 6’ to 8’

3-3-2-1 24”

8’ 10’ Brown Moist Very Fine Silty Same Size Sands with Some Fine to Small Gravel. (SM) Sample #5 @ 8’ to 10’

1-W-1-W 24”

10’ 12’ Light Rust Brown Fine to Medium Mix Size Sands with Some Silts Throughout with Some Fine Gravel. (SW) Sample #6 @ 10’ to 12’

W-W-2-4 24”

12’ 17’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #7 @ 15’ to 17’

7-9-12-12 24”

17’ 22’ Light Brown Fine to Medium Mix Size Sands with Some Fine to

Sample #8 @ 20’ to 22’

6-5-7-7 24”

Job Number: 24-290 Boring Number: B24-4 Depth of Boring: 25 Feet

Job Location: 25 Baiting Place Road, Farmingdale NY 11735

Water Level: 14.3 Feet Below Ground Surface at 9:55AM

Vicinity Recorded High Tide: 12:17PM Low Tide: 7:03AM

Sample Spoon

Penetration of Spoon in

Inches Ground Surface

2’ Dark Brown and Brown Very Fine Silty Same Size Sands with Some Organics (Roots) at Top of Spoon with Some Fine to Large Crushed Gravel with Large Crushed Rock at Bottom of Spoon.

(SM)

Sample #1 @ 0’ to 2’

3-7-12-14 24”

2’ 4’ Pale Brown and Brown Very Fine Silty Highly Compact Same Size Sands with Some Fine to Small Gravel. (SM) Sample #2 @ 2’ to 4’

9-21-25-24 24”

4’ 6’ Pale Brown and Light Rust Brown Mostly Fine Silty Same Size Sands Mixed with Some Fine Clean Same Size Sands Throughout with Some Gravel into Fine to Medium Mix Size Sands with Some Fine Gravel. (SM/SW) Sample #3 @ 4’ to 6’

9-7-12-16 24”

6’ 8’ Light Rust Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #4 @ 6’ to 8’

17-20-22-22 24”

8’ 10’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Small Gravel. (SW) Sample #5 @ 8’ to 10’

10-13-17-16 24”

10’ 12’ Light Rust Brown Fine Same Size Sands with Some Fine to Small Gravel. (SP) Sample #6 @ 10’ to 12’

15-13-16-17 24”

12’ 17’ Light Brown Fine to Coarse Mix Size Sands with Some Fine to

Sample #7 @ 15’ to 17’

8-12-13-14 24”

17’ 22’ Light Brown Fine to Coarse Mix Size Sands with Fine to Small Gravel. (SW) Sample #8 @ 20’ to 22’

4-3-7-8 24”

22’ 25’ Light Brown Fine to Medium Mix Size Sands with Some Fine to Medium Gravel. (SW) Sample #9 @ 23’ to 25’

11-12-13-13 24”

END OF BORING 25’0”