B.08.03 - Fort McNair_Geotechnical_Report_02_08_2021.pdf

JBMHH Family Housing Fort McNair, Washington D.C.

Geotechnical Engineering Report

February 8, 2021

FOR INFORMATION ONLY

Quality information

Document name Ref Prepared for Prepared by Date Reviewed by

Geotechnical Engineering Report

Final USACE Baltimore District

Marco Gravina, PE. 02-08-2021 Victor Omelchenko, PE, DGE

Revision history

Revision Revision date Details Name Position

This document has been prepared by AECOM Limited for the sole use of our client (the “Client”) and in accordance with generally accepted consultancy principles, the budget for fees and the terms of reference agreed between AECOM Limited and the Client. Any information provided by third parties and referred to herein has not been checked or verified by AECOM Limited, unless otherwise expressly stated in the document. No third party may rely upon this document without the prior and express written agreement of AECOM Limited.

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Table of Contents

INTRODUCTION AND SCOPE OF WORK .............................................................................. iii

1 EXISTING CONDITIONS AND PROPOSED CONSTRUCTION

2 FIELD EXPLORATIONS

2.1 Subsurface Explorations

2.2 Boring Stakeout and Subsurface Utility Clearance

2.3 Drilling Methodology and Sampling

2.4 Investigative Derived Waste

3 SUBSURFACE EXPLORATION RESULTS

3.1 Subsurface Conditions

3.2 Groundwater

3.3 Soil Laboratory Testing

3.4 Seismic Design Criteria

3.5 Expected Variations in Subsurface Conditions

3.6 Previous Geotechnical Data

4 DESIGN AND CONSTRUCTION RECOMMENDATIONS

4.1 Foundation Recommendations

4.2 Floor Slab Recommendations

4.3 Basement Walls

4.4 Uplift Design Considerations

4.5 Existing Underground Utilities

5 CONSTRUCTION CONSIDERATIONS

5.1 Fill, Subgrade Preparation

5.2 Fill Placement and Compaction

5.3 Other Site Considerations

5.4 Construction Monitoring

6 LIMITATIONS

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List of Figures and Appendices

Figure 1- Site Vicinity Map

Figure 2- Soil Boring Location Plan

Figure 3- Design Earth Pressures for Basement Walls

Figure 4- Foundation Subdrainage Design Recommendations

Appendix A

Soil Boring Logs (24 Sheets)

USCS Soil Identification Sheet (2 Sheets)

Appendix B

Environmental Laboratory Test Results (38 Sheets)

Appendix C

Soil Laboratory Test Results (26 Sheets)

Appendix D

Previous Soil Boring Logs (8 Sheets)

Previous Soil Laboratory Test Results

(27 Sheets)

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INTRODUCTION AND SCOPE OF WORK

This project consists of assessing the condition of 57 historical family housing units (Quarters) at

Fort McNair and Fort Myer and providing architecture and engineering documents to bring these housing units back into good repair. The scope of this report encompasses Quarters 1 through 6, 10 through 15 (Group 1), Quarters 7, 8 and 9 (Group 2), Quarter 16 (Group 3), Quarter 19 (Group

4) and Quarters 23 through 27 (Group 5) located within Fort McNair in Washington, DC. AECOM’s geotechnical scope of work for the project included performing a subsurface investigation at Fort

McNair and preparation of this geotechnical engineering report with the following information:

A. A soil boring location plan;

B. Final soil boring logs including soil descriptions and soil laboratory test results;

C. Results of the soil laboratory testing;

D. Recommendations for foundation support of the proposed building additions;

E. Recommendations for floor slab subgrade preparation;

F. Recommendation for underpinning of distressed buildings.

G. Recommendations for the handling of groundwater in the design and construction;

H. Recommended lateral earth pressures for below grade walls and site retaining walls;

I. Recommendations for earthwork requirements, comments regarding the suitability of on-site materials for re-use as structural fill and backfill material, and removal of unsuitable materials;

J. Comments regarding geotechnical construction considerations that should be considered both in the design and in the construction plans and specifications.

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1 EXISTING CONDITIONS AND PROPOSED CONSTRUCTION

The quarters located within Fort McNair, Washington DC include single family and duplex dwellings/quarters. The buildings are spaced approximately 40 feet apart. Some of the quarters have backyards that that face the Potomac River. Quarters 23 through 27 are located along 4th

Avenue backing to 5th Avenue also within the grounds of Fort McNair. A site Vicinity Map is included as Figure 1.

The subject quarters were constructed between about 1903 and 1905 with exterior load bearing brick masonry walls, wood floor joists and bearing walls in the interior. Some of the homes have a two-level enclosed porch at the rear of the building and a basement level. The exact configuration of the structural framing is not known due to the absence of original construction documents.

Group 5 quarters are three level duplexes with full basements. The quarters were constructed with exterior load bearing brick masonry walls, wood floor joists and bearing walls in the interior. Each home has a two-level enclosed porch at the rear of the building which consists of wood framing for the floor and wall construction over a crawl space. The exact configuration of the structural framing is not known due to the absence of original construction documents.

A limited structural survey was conducted by AECOM in beginning in October and November

2019, and February 2020 to observe the building conditions and deficiencies identified in the

Facilities Condition Assessment (FCA). The structural survey for some of the structures is still ongoing. The FCA was based on findings from surveys conducted by others in early 2018. The

FCA and Course of Action (COA) documents outlined the deficiencies in each building and the remediation requirements. Some quarters have signs of distress possibly due to larger than normal building settlements. It is understood that the structural scope includes repairs to the deficiencies identified during the AECOM site survey along with new design elements related to the renovation of the quarters. Remediation of the foundation will be coordinated with architecture to include masonry repairs and waterproofing of the exterior basement walls. The basement slab will be remediated to repair slab cracks and slab-on-grade removal and replacement. Some of the rear enclosed porches have deficiencies including uneven floors and deterioration of the first level concrete slab. In Group 1 where the Level 1 porch concrete framing was exposed during the structural survey to view cracks, spalls, splits in the concrete, and corroded reinforcement. These observations were common throughout the Quarters. Cracks and out of plane movement were observed in the deterioration of the brick masonry foundation wall and piers supporting the porch framing. Conditions of the second-floor porch framing included unevenness and sloped framing. The rear porches were enclosed after the original construction.

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The maximum estimated existing and new building loads are as follow:

Building Number Maximum Estimated

Wall Loads (kips/lf)

Maximum Estimated

Column Loads (kips)

Quarters 1 through 15 11.5 25

Quarter 19 9 19

Quarters 16, 23 through 27 10.7 20

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2 FIELD EXPLORATIONS

2.1 Subsurface Explorations

AECOM conducted a subsurface investigation program in the vicinity of the existing quarters. A total of 12 soil borings, labeled FMc-B-1, FMc-B3, FMc-B4, and FMc-B8 to FMc-B16 were drilled to investigate the subsoil conditions. The approximate boring locations are illustrated on the Soil

Boring Location Plans included as Figures 2 and 3. It is noted that soil borings FMc-B2, FMc-B5 and FMc-B7 were not drilled due to potential conflicts with existing underground utility lines. The soil boring logs are included in Appendix A.

2.2 Boring Stakeout and Subsurface Utility Clearance

The boring locations and elevations were field located by AECOM with a hand-held GPS prior to drilling the borings to clear the staked boring locations. A “DPW Excavation Permit” was obtained from the Joint Base Myer-Henderson Hall (FBM-HH) DPW prior to drilling the borings to mark the private existing underground utilities around the staked boring locations. A District of Columbia

Department of Consumer and Regulatory Affairs (DCRA) soil boring drilling permit was also obtained to satisfy certain local requirements. “Miss Utility” was contacted by our drilling subcontractor, Connelly and Associates, Inc., to mark the existing underground utilities around the staked boring locations. Additionally, the AECOM geophysics group cleared the boring locations and marked the private underground utility lines. The approximate ground surface elevations at the soil boring locations are shown on the boring logs included in Appendix A. The approximate boring locations are illustrated on the Soil Boring Location Plans included as Figures

2 and 3. The soil boring elevations were not surveyed by a professional surveyor and should be considered approximate.

2.3 Drilling Methodology and Sampling

Connelly and Associates, Inc. of Frederick, Maryland drilled the soil test borings between

January 9th and January 17th, 2020 and between August 12th and August 17th, 2020. The borings were drilled with a track mounted Diedrich D-50 drill rig and a CME-55 using 3-1/4 inch diameter continuous flight hollow stem augers to advance the borings. Representative soil samples were obtained using a two-inch outside diameter split-barrel spoon sampler in general accordance with ASTM D1586 standards. Standard penetration tests (SPTs) were performed by driving the split-spoon sampler into the soil a distance of 18 or 24 inches over three or four six-inch intervals, respectively, by means of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler through the second and third six-inch intervals (i.e., the N-values) for each sample are indicated on the soil test boring logs included in Appendix A. Soil samples were obtained continuously and every 2.5 feet in the borings in the upper 10 feet of soil overburden and every five feet below the upper 10 feet. The N-values provide an indication of the in-place density (granular materials) and consistency (cohesive materials) of the soils. The borings were backfilled with cement/bentonite grout after the groundwater measurements were obtained.

After recovery, the soil samples were removed from the sampler and visually classified by a geotechnical engineer from our office. Representative portions of the soil samples were sealed

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in glass jars and retained for further review. The visual classifications were based on texture and plasticity, in accordance with the Unified Soil Classification System (USCS). A brief description of the USCS is also included in Appendix A.

2.4 Investigative Derived Waste

In order to meet certain DCRA drilling permit requirements, all investigative derived waste (IDW) from the soil borings was stored in US Department of Transportation (USDOT) approved drums.

Each drum was sealed, labeled and stored at a selected place on site. Two combined samples of the soil spoils were obtained from the drums for environmental testing. Based on the environmental laboratory test results, the soil cuttings were removed from the site and were disposed by our drilling subcontractor, A2Z Environmental Group, LLC, as non-impacted soils.

The environmental laboratory test results are included in Appendix B.

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3 SUBSURFACE EXPLORATION RESULTS

3.1 Subsurface Conditions

The materials encountered during the subsurface exploration are described further below for the purposes of our discussions in this report. It should be noted that these descriptions do not imply the continuity of the materials encountered in the borings. The descriptions of the materials have been established to characterize similar subsurface conditions based on material gradations. The subsurface materials encountered in the test borings, along with the range of Standard Penetration Test (SPT) N-Values are described in the following paragraphs.

Up to 12 inches of topsoil was encountered at the soil boring locations. This depth should not be considered as striping depth since the topsoil may be deeper at other areas of the sites.

Stratum A

(Existing Fill)

Encountered below the ground surface in all borings to approximate depths between 4 feet and 19.7 feet below grade; Silty Sand (SM), Poorly Graded Sand (SP-SM) with silt, Poorly Graded Sand (SP-SM) with clay, Clayey

Sand (SC), Silt (ML), Sandy Lean Clay (CL), Lean Clay

(CL) with various amounts of organic matter, brick fragments and other deleterious matter; N-Values range:

2 blows per foot (bpf) and 20 bpf.

Stratum B

(Alluvial Soils)

Encountered below the Stratum A soils to approximate depths between 38.5 feet and 48.5 feet; Silty Sand

(SM), Silty Sand (SM) with gravel, Clayey Sand (SC), and Poorly Graded Sand with silt and gavel (SP-SM), Poorly Graded Sand with silt (SP-SM), Poorly Graded

Sand (SP) with Gravel, Poorly Graded Sand (SP), Poorly

Graded Sand (SP-SC) with clay, Poorly Graded Gravel

(GP), Well Graded Gravel (GW) with gravel, Clayey

Gravel (GC), Well Graded Sand (SW), Well Graded

Sand (SW-SM) with silt and gravel, Well Graded Sand

(SW-SC) with clay, Sandy Lean (CL), Lean Clay (CL) with sand, Lean Clay (CL), Sandy Organic Soil (OL/OH), Organic Soil (OL/OH) with sand, Elastic Silt (MH), Elastic

Silt (MH) with sand, Fat Clay (CH) with sand, Fat Clay

(CH); N values range: Weight of Hammer (WOH)/24 inches to 85 bpf.

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Stratum C

(Potomac Soils)

Encountered below Stratum B soils to the maximum depths investigated by the borings of 48.8 and 50 feet;

Poorly Graded Sand (SP), Poorly Graded Sand (SP-SC) with clay, Clayey Sand (SC), Sandy Fat Clay (CH), Lean

Clay (CL) with sand; N values range: 17 bpf to 47 bpf.

3.2 Groundwater

Groundwater measurements were obtained during the drilling operations, upon completion of the borings and up to about 24 hours after drilling. A 1-inch diameter temporary PVC standpipe was installed in borings FMc-B1, FMc-B10, FMc-B12 and FMc-B14 through FMc-B16 to prevent the boring sidewalls from caving in. The standpipes were removed after the 24 hour groundwater measurements were obtained. The groundwater observations made in the borings are included in the soil boring logs included in Appendix A and are summarized below:

Groundwater Observations Summary

Soil Boring

Number

Approximate

Groundwater Depth (feet)

Approximate

Groundwater Elevation

(feet)

FMc-B1 10* +2

FMc-B3 8 +2

FMc-B4 17 -3

FMc-B8 6 +5

FMc-B9 16.2 -4.2

FMc-B10 7.2* +4.8

FMc-B11 9.2 -0.2

FMc-B12 15.3* -1.3

FMc-B13 9.5 +0.5

FMc-B14 13.3* +1.7

FMc-B15 10.3* _1.7

FMc-B16 13.2* -3.2

*Installed a 1-inch diameter temporary PVC standpipe

Perched water conditions may be encountered during construction due to the presence of fine-grained soils interbedded with free-draining sandy soils. It is possible that stabilized groundwater levels are higher than those encountered during drilling. It should be noted that fluctuations in groundwater levels may occur as a result of seasonal variations in rainfall, proximity of the site to the Potomac River, evaporation, construction activity, surface runoff, and other site-specific factors.

3.3 Soil Laboratory Testing

Soil samples were transported to AECOM’s Germantown, Maryland, office for further observation before samples were selected to undergo soil laboratory testing. Selected split-spoon soil samples were tested by Jay Kay Testing, Inc to determine the physical and engineering properties of the on-site soils. The soil laboratory tests were conducted in accordance with applicable ASTM standards and specifications. The testing included moisture

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content determinations (ASTM D2216), Atterberg Limits tests (ASTM D4318), and mechanical gradation analyses (ASTM D422/C136). The soil laboratory testing results are presented in

Appendix C and some of the results are incorporated in the boring logs included in Appendix A.

3.4 Seismic Design Criteria

The seismic site classification was analyzed in accordance with Section 1613.3.2 of the 2018

International Building Code (IBC) which in turn refers to the American Society of Civil Engineers

(ASCE) 7 standard, chapter 20. We used the SPT N-value method for classification based on the upper 100 feet of the site soil profile. The soil profile as disclosed by the soil borings consists of alluvial clayey soils and sandy soils. The calculated weighted N-value is 23. According to the IBC

2018 and the ASCE 7 standard, Table 20.3-1, the site can be classified as Site Class D.

3.5 Expected Variations in Subsurface Conditions

Interpretation of general subsurface soil conditions presented herein is based on the soil and groundwater conditions encountered in the soil borings drilled at the site. Although representative portions of the samples taken were tested, subsurface conditions may vary between exploration locations. If conditions are found to be different from those observed in the borings, recommendations contained in this report should be re-evaluated by AECOM and confirmed in writing. Since the groundwater levels are expected to fluctuate with rainfall, season, temperature, climate, proximity of the site to the Potomac River, etc., groundwater conditions at the time of construction may be different from those found during the time of the exploration.

3.6 Previous Geotechnical Data

A geotechnical investigation was conducted by the USACE, Baltimore District, in November 2018.

Previous soil borings and soil laboratory test results were used in our analysis and were obtained from a geotechnical engineering report prepared by the USACE dated February 2019. Relevant soil borings, labeled as B-2, B-3, B-4 and B-5, were considered in our analysis. AECOM has assumed that the existing borings and soil laboratory tests were performed in accordance with

ASTM criteria and that they are complete and accurate. It should be noted that AECOM assumes no responsibility to the accuracy or completeness of data obtained from the previous soil borings drilled at the site and the soil laboratory test results, as we were not present during the field investigation. The approximate soil boring locations are illustrated on the Soil Boring Location

Plans, Figures 2 and 3. The soil boring logs and the soil laboratory test results are included in

Appendix D.

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4 DESIGN AND CONSTRUCTION RECOMMENDATIONS

4.1 Foundation Recommendations

Up to 19.7 feet of existing fill material designated as Stratum A soils was encountered in the soil borings. It is believed that the existing fill of Stratum A is associated with previous grading of the site and previous utility installation. It is likely that the existing fill material was not placed in a controlled manner and no documentation was available to confirm that the fill had been placed in a controlled manner. The Stratum B soils present below the existing fill soils of

Stratum A consist of alluvial sandy and clayey soils extending to depths between about 38.5 feet and 48.5 feet below existing grades.

The Stratum A soils are soft and contain various amounts of deleterious matter. The clayey soils of Stratum B soils are also considered soft and highly compressible and were encountered at relatively shallow depths in some of the borings. Additionally, based on the

SPT N values, the upper layers of sandy soils of Stratum B are considered to be loose. It is understood that some quarters have experienced some structural distress possibly due to large building settlements, which we believe has occurred over a long period of time. It is our opinion that building distress is due to excessive settlement of the existing foundations that are founded on the soft strata A and/or B soils.

The project consists of the rehabilitation of the existing quarters. The rehabilitation includes providing remediation of the existing foundations of some quarters which have experienced large building settlements and the construction of new building additions to the quarters such as new exterior stairs (stoops) and back porches. The onsite soils of Strata A and B are not considered suitable for direct foundation support, and it is our opinion that the foundations needing repairs can best be supported on a system of helical piles. Other underpinning options were considered such as the open pit underpinning pits but are not considered suitable for foundation repairs due to the high groundwater and the deep depths required to reach suitable bearing soils.

Based on several conference calls with the US Army Corps of Engineers (USACE) and their response to AECOM’s RFI No. 026, for the FY-2020 work, Quarters 6, 23 and 24 will be supported on helical piles to mitigate the existing building settlement issues. The back porches of some of the quarters have also experienced some building distress due to the large settlements. The porches for these quarters are recommended to be supported on helical piles to mitigate the existing building settlement issues. Additionally, all new foundations, where replacement porches are considered, are also recommended to be supported on helical piles.

This is applicable to the proposed front porches proposed for some of the quarters and any new load bearing foundations.

All stoops and any lightly loaded structures can be supported on shallow foundations after partial undercut and replacement of unsuitable existing fill soils of Stratum A. The undercuts should extend a minimum of two times the width of the footing or to natural soils, whichever comes first. Crushed stone such as AASHTO No. 57 stone may be used to bring the undercut subgrades to planned grades. All undercuts should be approved and performed under the observation of the “Third-Party Testing Agency” geotechnical engineer. It is noted that there is a risk of excessive settlement with the partial undercut option, particularly if unsuitable soils

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remain undetected under the new footings. These lightly loaded structures can be supported on helical piles if the risk of future settlement is not acceptable.

Helical piles are foundation elements consisting of a steel round or square shaft with at least one helix plate located on the shaft with its axis positioned parallel to the shaft. The helical piles are installed by “screwing” them into the ground to a specified torque. The helical piles are expected to extend approximately 40 to 50 feet below existing grades to achieve a design capacity of up to about 60 kips. For this project we anticipate that a helical pile would have at least three helix plates, one 10” in diameter at the bottom, with a 12-inch helix plate above and with a 14-inch helix plate above the second plate with a 2-inch square shaft. The shafts may need to be grouted to prevent buckling of the shafts due to the deep soft and loose soils present at the site. Once the helical piles are installed the new or existing foundations can then be attached to the helical piles with steel brackets. The helical piles can generally be installed with a spacing of approximately 3 to 5 feet depending on the structural loads. It is noted that interior helical piles, if required, may need to be designed for a reduced capacity due to equipment limitations in order to install the helical piles inside the existing basements.

The specialty contractor’s licensed professional engineer is required to design the helical piles for the site-specific soil conditions based on the intent of the design including this report.

Based on historical photographs, it appears that some of the existing quarters are founded on what appears to be concrete deep foundations. The depth, diameter and spacing of these existing foundation systems are not known. It is recommended to perform exploratory test pits to expose the existing foundations, verify their conditions and to determine the proper steel bracket required to attach the foundations to the helical piles.

4.2 Floor Slab Recommendations

It is understood that some residences have experienced floor slab settlement and that the basement slabs will be completely removed and replaced. The soils expected to be present below the existing and new floor slabs are soils of Strata A and B. These soils are generally soft. Therefore, the approach with the smallest amount of risk would be to structurally support new floor slabs on helical piles. However, based on the USACE response to AECOM’s RFI

No. 017, the decision has been made to support new quarter’s floor slabs on the existing soils after completely replacing the existing slabs with conventional 4-inch thick concrete slabs.

Due to the nature of the soils expected to be present at the floor slab subgrades, some undercut, and replacement of soft and unsuitable soils may be necessary. If necessary, the undercut subgrades should be backfilled with crushed stone such as AASHTO No. 57 stone.

All undercuts, if necessary, should be approved and performed under the observation of the

“Third-Party Testing Agency” geotechnical engineer.

Some water issues inside the basement levels were observed during the structural survey. We understand that the basement levels of the existing quarters are about 5 feet to 6 feet below the existing grades. Based on the long-term groundwater observations made in the soil borings the groundwater level was observed between about El -4.2 feet and El +4.8 feet. Considering the groundwater elevations and the proximity of the Quarters to the Potomac River, it is recommended to install an inside perimeter foundation subdrainage system under the floor slabs. The subdrainage should consist of an interior collector line installed around the inside

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perimeter of the basement walls. The collector line should consist of 4-inch diameter slotted, corrugated polyethylene tubing per ASTM F405 surrounded by at least 6 inches of crushed stone such as AASHTO No. 57 stone. Geotextile consisting of Mirafi 140N or equivalent should wrap the No. 57 stone. The subdrainage pipe should outlet to an interior sump pump. The final layout should be designed to avoid structural and mechanical elements. One or two cleanouts should be incorporated into the system after a second right angle bend in the subdrainage pipe to facilitate flushing of the system

A 4-inch minimum thickness of washed gravel or crushed stone meeting the requirements of

AASHTO No. 57 crushed stone should be placed below floor slabs on-grade to serve as a capillary break. A vapor retarder consisting of a minimum six-mil polyethylene sheeting meeting ASTM E1745 standards should be placed on top of the granular layer before the placement of concrete to prevent intrusion of the concrete into the granular base and to provide an additional barrier against moisture migration. Special attention should be given to the surface curing of the slab in order to minimize uneven drying of the slab and associated cracking.

4.3 Basement Walls

All new basement walls, if any, should be designed for at-rest earth pressures to resist backfill and surcharge loads. Assuming the new backfill consists of granular soils meeting the backfill material requirements included in this report, restrained walls should be designed using an equivalent fluid pressure of 60H (psf), where H is the total wall height. For surcharge loads, 50 percent of any uniform area surcharge placed at the top of the wall may be assumed to act as a uniform horizontal pressure over the entire height of the wall. Below-grade wall design recommendations are included in Figure 3 included in this report. The recommended values do not include lateral pressures due to hydrostatic water pressures generated by infiltrating surface water that may accumulate behind the walls. Therefore, wall backfill materials should be free-draining, and provisions should be made to remove excess water that may accumulate behind the below grade walls. Backfill requirements are included in Section 5 of this report.

A perforated 4-inch diameter drainage pipe should be placed at the bases of the outside basement walls and should be surrounded by at least 6 inches of AASHTO No. 57 crushed stone and wrapped with geotextile filter cloth. Foundation wall drainage pipes should be directed to flow by gravity to the sump pit inside the basement, where water can be pumped away. Typical foundation subdrainage details are presented in Figure 4. Alternatively, weep holes may be installed through the foundation walls to collect water from the outside perimeter foundation drainage pipe to discharge into the inside perimeter drainage pipe. Weep holes should be installed at the base of the basement walls, should be spaced at about 8 feet on center and should be at least 3 inches in diameter. The weep holes should be covered on the backfill side of the retaining wall with a permeable geotextile filter cloth to prevent the migration of fines through the weep holes.

It is understood that the USACE has decided to add a foundation perimeter drain behind the existing quarter’s basement walls to prevent water build up behind the existing basement

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walls. Additionally, the walls will be waterproofed to reduce the potential for water intrusion through the basement walls.

4.4 Uplift Design Considerations

The existing quarters are located within the flood zone of the Potomac River. Therefore, it is recommended that hydrostatic uplift pressures should be considered in the rehabilitation of the quarters. For uplift design considerations, a hydrostatic groundwater elevation of El +10.6 which, corresponds to the FEMA 100-year flood elevation in the vicinity of the project site is recommended. Based on several conference calls with the USACE and their response to

AECOM’s RFI No. 017, the remediation of the quarters will not include designing for the effects of hydrostatic uplift pressures at the direction of the USACE.

4.5 Existing Underground Utilities

Several underground utility lines are present within the front and back yards. It is recommended that re-routing or abandonment of any utility line(s) present within the new building addition footprints be performed. If removed, the excavations can be backfilled with new compacted structural fill. If the utilities are abandoned, the pipes should be grouted-in-place.

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5 CONSTRUCTION CONSIDERATIONS

5.1 Fill, Subgrade Preparation

The site may require minimal cut and fill operations to reach final site grades around the Quarters.

The entire fill areas, if any, should be stripped of vegetation, asphalt, roots, topsoil, construction debris, and any deleterious materials. Following the removal of any unsuitable material, areas designated for site fill, floor or pavement subgrades should be proof-rolled with a 10-ton loaded dump truck or construction equipment of equal weight. The “Third-Party Testing Agency” representative should be present to verify the suitability of the subgrades to receive new fill material or base course material.

Fill subgrades consisting of Stratum A soils may be soft and yielding in some areas. Where moisture conditioning and re-compaction do not create stable subgrades, undercutting of these soils may be necessary to stabilize the subgrades to achieve the structural fill compaction requirements. The depth of undercutting, if necessary, will vary depending on the actual soil conditions encountered and should be determined in the field. We recommend establishing a budget for the undercutting of soft and yielding existing fill soils. All undercuts, if necessary, should be approved and performed under the observation of the “Third-Party Testing Agency” geotechnical engineer.

5.2 Fill Placement and Compaction

All new compacted structural fill and backfill should be placed in loose lifts not exceeding 8 inches in thickness and should be compacted to at least 95% of the maximum dry density, in accordance with ASTM D698. In general, the moisture content of the fill materials should be maintained within 2% of the optimum moisture content per ASTM D698. Materials to be used as compacted fill in the building and pavement areas should be classified as ML, SM, SC or more granular although backfill behind walls should classify as SM or more granular. Also, soils should have a Liquid Limit (LL) and Plastic limit (PI) of less than 40 and 20, respectively. Backfill material to be used behind basement walls should be classified as SM or more granular and should have a LL and PI less than 40 and 15, respectively.

Off-site borrow material will be required to be used as compacted fill and backfill material.

Portions of the onsite soils encountered that classify as ML, SC, ML, SM, or more granular may be suitable for reuse as compacted structural fill, provided they meet the above requirements and are free of organic matter and other deleterious matter. Some moisture conditioning of these soils will be required to achieve the compaction requirements. Soils classified CL, CH, and MH are not considered suitable for reuse as compacted fill or backfill. The suitability of the onsite soils for reuse as fill and backfill should be determined by the “Third-Party Testing

Agency” during construction.

5.3 Other Site Considerations

Proper design, drainage, construction and maintenance of the areas between individual buildings are critical to the satisfactory performance of the project. Sidewalks, entranceway slabs and roofs, fountains, raised planters and other highly visible improvements commonly are installed within these zones, and distress in or near these improvements is common. Commonly, proper soil

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preparation in these areas receive little attention during construction because they fall between the building which typically are built with heavy equipment. Subsequent landscaping and hardscape installation often is performed by multiple sub-contractors with light or hand equipment, and necessary over-excavation and soil processing is not performed. Consequently, subgrade soil conditions commonly deviate significantly from specified ranges. Therefore, the contractor should take particular care regarding proper subgrade preparation in the immediate building exteriors.

The collection and diversion of surface drainage away from the building foundation walls is extremely important to the satisfactory performance of the walls and to prevent water intrusion.

The grading around the quarters should slope away from the buildings. Final site grading should include sloping grades and piping of downspouts away from the building structures.

5.4 Construction Monitoring

Monitoring of the construction of the project is strongly recommended to address quality control/quality assurance issues and to promptly address non-conforming construction. Full-time construction monitoring should be provided during all aspects of the earthwork, excavation and construction by a “Third Party Testing Agency” that is familiar with the design and construction criteria for the project. The monitoring should include documentation of all aspects of the excavation, subgrade conditions, subgrade preparation, placement and compaction of fill and backfill, helical piles installation monitoring and other relevant construction issues.

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6 LIMITATIONS

Interpretation of general subsurface soil conditions presented herein is based on the soil and groundwater conditions encountered in the limited number of recent and existing soil borings.

Although representative portions of the samples taken were tested, subsurface conditions may vary outside of exploration locations. This report does not reflect any variations that may occur outside of boring locations or across the site in areas not sampled. The nature and extent of such variations may not become evident until construction. Groundwater conditions during construction may be different from the observations made in the borings.

This report has been prepared for the specific application to the project discussed and in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is provided. In the event that any changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report will not be considered valid unless the changes are reviewed, and the conclusions of this report are modified or verified in writing by AECOM.

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Figure 1- Site Vicinity Map

Figure 2- Soil Boring Location Plan

Figure 3- Design Earth Pressures for Basement Walls

Figure 4- Foundation Subdrainage Design Recommendations

Appendix A

Soil Boring Logs (24 Sheets)

USCS Soil Identification Sheet (2 Sheets)

0.0 - 0.5 ft: Top soil (0.0-0.5')

0.5 - 4.5 ft: (FILL) Moist, loose, reddish brown, low plasticity, Sandy Lean Clay, contains fine gravel, contains organics as root fragments

4.0 ft: changes to contains a 6 inch layer of gray, Fat Clay with Sand

4.5 - 8.0 ft: Moist, loose, dark brown, fine to coarse, CLAYEY SAND, contains fine gravel, contains organics as root fragments

6.0 ft: changes to medium dense, reddish brown

8.0 - 9.1 ft: Moist, very soft, dark brown, medium plasticity, ORGANIC SOIL WITH SAND, fine to medium sand, contains fine to coarse gravel, numerous organics

9.1 - 13.5 ft: Moist, medium dense, reddish brown, fine to coarse, SILTY SAND WITH GRAVEL, contains fines, contains fine gravel

13.5 - 23.5 ft: Moist, medium dense, reddish brown, fine to coarse, POORLY GRADED SAND WITH GRAVEL, fine gravel, contains fines

14.0 ft: changes to Wet

23.5 - 28.5 ft: Wet, medium dense, reddish brown, fine to coarse, WELL GRADED

GRAVEL WITH SAND

Top-soil

CL

SC

OL/OH

SM

SP

GW

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

22.0ft: Heavy rig catter to 23.0'

8.7

8.1

(79%)

(75%)

(33%)

(63%)

(54%)

(67%)

(100%)

(83%)

1- 2- 3- 3 (N=5)

3- 5- 5- 6 (N=10)

5- 4- 6- 8 (N=10)

8- 9- 11- 11 (N=20)

6- 7- 9- 8 (N=16)

7- 10- 15 (N=25)

4- 7- 7 (N=14)

8- 15- 14 (N=29)

A

B

HAMMER TYPE/WEIGHT: Auto Hammer/140lbs

01-17-2020

Date

17.0 DRILL RIG: Diedrich D-50 (ATV)

24-hour

BIT TYPE/SIZE: NA/NA

CHECKED BY: Kevin Bell

Date Time Groundwater Observations

14.001-16-2020Encountered

DRILL METHOD: 3-1/4" I.D. Hollow Stem Auger

Completion

Event

LOGGED BY: Jocelyn Kaselow

10.0

01-16-2020

DRILLER: Garrett Davis

DATE STARTED: 1/16/2020

DATE COMPLETED: 1/16/2020

DRILLING CONTRACTOR: Connelly & Asso

CASING TYPE: HSA

CASING SIZE: 3-1/4"

Depth (ft)

BOREHOLE DEPTH: 50.0 FT

SURFACE ELEVATION: 12 FT

Cave in Depth (ft)

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B1

U S

C S

N U

M B

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SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

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F T

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T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

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S T

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23.5 - 28.5 ft: Wet, medium dense, reddish brown, fine to coarse, WELL GRADED GRAVEL WITH SAND(continued)

28.5 - 48.5 ft: Wet, dense, reddish brown, fine to coarse, POORLY GRADED SAND WITH SILT AND GRAVEL, contains fines

29.9 ft:

48.5 - 50.0 ft: Wet, very stiff, bluish gray, high plasticity, SANDY FAT CLAY, fine to medium sand

Boring completed at 50.0 FT on 1/16/2020.

A 1-inch Dia. temporary PVC standpipe was installed. The pipe was removed and the boring was backfilled with cement/bentonite grout after the 24-hour groundwater level was obtained.

GW

SP-

SM

CH

S-9

S-10

S-11

S-12

S-13 4.00

30.0ft: Heavy rig catter to 36.0'

(67%)

(56%)

(50%)

(33%)

(100%)

4- 21- 23 (N=44)

1- 5- 18 (N=23)

13- 14- 16 (N=30)

14- 21- 21 (N=42)

6- 10- 10 (N=20)

B

C

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

SHEET 2 of 2

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B1

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

H

IC

T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

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V

F T

-15

-20

-25

-30

-35

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IN

BLOWS

S T

R A

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M

0.0 - 0.5 ft: Top soil (0.0-0.5')

0.5 - 2.0 ft: (FILL) Moist, very loose, brown, fine to coarse, Poorly Graded Sand With Clay, contains organics as root fragments

2.0 - 4.0 ft: (FILL) Moist, medium stiff, reddish brown, low plasticity, Sandy Lean Clay, contains organics as root fragments

4.0 - 5.0 ft: Moist, soft, brown, low plasticity, SANDY ORGANIC SOIL, fine to medium sand

5.0 - 14.5 ft: Moist, loose, reddish brown, fine to coarse, CLAYEY SAND, contains organics

8.0 ft: changes to Wet, very loose

13.5 ft: changes to medium dense

14.5 - 29.5 ft: Wet, very dense, brown, fine to coarse, POORLY GRADED SAND WITH GRAVEL, fine gravel, contains fines

Top-soil

SP-

SC

CL

OL/OH

SC

SP

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

18.5ft: Moderate rig chatter

21.0ft: Heavy rig /bit chatter

(71%)

(88%)

(75%)

(67%)

(NR)

(100%)

(56%)

(100%)

2- 1- 2- 2 (N=3)

2- 2- 3- 4 (N=5)

1- 2- 3- 3 (N=5)

4- 4- 3- 4 (N=7)

1- 1/18" (N=1/18")

6- 5- 1 (N=6)

7- 37- 19 (N=56)

3- 3- 6 (N=9)

A

B

HAMMER TYPE/WEIGHT: Auto Hammer/140lbs Date

17.0 DRILL RIG: Diedrich D-50 (ATV)

BIT TYPE/SIZE: NA/NA

CHECKED BY: Kevin Bell

Date Time Groundwater Observations

8.001-15-2020Encountered

DRILL METHOD: 3-1/4" I.D. Hollow Stem Auger

Completion

Event

LOGGED BY: Jocelyn Kaselow

01-15-2020

DRILLER: Garrett Davis

DATE STARTED: 1/15/2020

DATE COMPLETED: 1/15/2020

DRILLING CONTRACTOR: Connelly & Asso

CASING TYPE: HSA

CASING SIZE: 3-1/4"

Depth (ft)

BOREHOLE DEPTH: 50.0 FT

SURFACE ELEVATION: 10 FT

Cave in Depth (ft)

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B3

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

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T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

E

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V

F T

-5

-10

-15

R E

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IN

BLOWS

S T

R A

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14.5 - 29.5 ft: Wet, very dense, brown, fine to coarse, POORLY GRADED SAND WITH GRAVEL, fine gravel, contains fines(continued)

28.5 ft: changes to brownish gray

29.5 - 33.5 ft: Wet, medium stiff, dark gray, low plasticity, LEAN CLAY, contains fine to medium sand

33.5 - 43.5 ft: Wet, medium dense, brown, fine to coarse, WELL GRADED SAND, contains fines

43.5 - 50.0 ft: Wet, very stiff, bluish gray, high plasticity, SANDY FAT CLAY, fine to medium sand

Boring completed at 50.0 FT on 1/15/2020.

The boring was backfilled with cement/bentonite grout upon completion.

SP

CL

SW

CH

S-9

S-10

S-11

S-12

S-13

2.50

38.5ft: Encountered running sand, sand heaved estimated 3.0' into augers. Driller cleaned hole to depth and collected sample S-12.

(100%)

(67%)

(NR)

(100%)

(NR)

2- 3- 3 (N=6)

7- 9- 11 (N=20)

11- 19- 25 (N=44)

2- 7- 11 (N=18)

4- 4- 15 (N=19)

B

C

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B3

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

H

IC

T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

E

LE

V

F T

-20

-25

-30

-35

-40

R E

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IN

BLOWS

S T

R A

T U

M

0.0 - 1.0 ft: Top soil (0.0-1.0')

1.0 - 4.0 ft: (FILL) Moist, very loose, brown, low plasticity, Lean Clay, contains fine gravel, contains organics

2.0 ft: changes to loose

4.0 - 5.0 ft: (FILL) Moist, loose, reddish brown, fine to coarse, Poorly Graded Sand With Clay, contains fine gravel, contains organics

5.0 - 13.5 ft: Moist, stiff, reddish brown, low plasticity, SANDY LEAN CLAY, fine to medium sand, contains fine gravel, contains organics

6.0 ft: changes to medium stiff

8.0 ft: changes to stiff

13.5 - 18.5 ft: Moist, medium dense, brown, fine to coarse, CLAYEY SAND, contains fine gravel

17.0 ft: changes to Wet

18.5 - 39.5 ft: Wet, medium dense, reddish brown, fine to coarse, SILTY SAND, contains fine to coarse gravel

23.5 ft: changes to very dense

Top-soil

CL

SP-

SC

CL

SC

SM

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

7.0ft: Slight rig chatter to 8.0'

23.5ft: Driller stated possible cobble21.5

(67%)

(83%)

(100%)

(88%)

(54%)

(67%)

(78%)

(83%)

1- 2- 2- 3 (N=4)

3- 6- 4- 4 (N=10)

4- 4- 4- 5 (N=8)

4- 3- 4- 7 (N=7)

7- 5- 9- 15 (N=14)

6- 6- 7 (N=13)

7- 13- 13 (N=26)

29- 47- 38 (N=85)

A

B

HAMMER TYPE/WEIGHT: Auto Hammer/140lbs Date

DRILL RIG: Diedrich D-50 (ATV)

BIT TYPE/SIZE: NA/NA

CHECKED BY: Kevin Bell

Date Time Groundwater Observations

17.001-17-2020Encountered

DRILL METHOD: 3-1/4" I.D. Hollow Stem Auger

Event

LOGGED BY: Jocelyn Kaselow

DRILLER: Garrett Davis

DATE STARTED: 1/17/2020

DATE COMPLETED: 1/17/2020

DRILLING CONTRACTOR: Connelly & Asso

CASING TYPE: HSA

CASING SIZE: 3-1/4"

Depth (ft)

BOREHOLE DEPTH: 50.0 FT

SURFACE ELEVATION: 14 FT

Cave in Depth (ft)

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

SHEET 1 of 2

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B4

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

H

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T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

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-5

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BLOWS

S T

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18.5 - 39.5 ft: Wet, medium dense, reddish brown, fine to coarse, SILTY SAND, contains fine to coarse gravel(continued)

28.5 ft: changes to medium dense

33.5 ft: changes to dense

39.5 - 48.5 ft: Wet, dense, reddish brown, fine to coarse, CLAYEY SAND, contains fine gravel, contains organics

48.5 - 50.0 ft: Moist, very stiff, bluish gray, high plasticity, SANDY FAT CLAY, fine to medium sand

Boring completed at 50.0 FT on 1/17/2020.

The boring was backfilled with cement/bentonite grout upon completion.

SM

SC

CH

S-9

S-10

S-11

S-12

S-13

2.75

2.50

31.0ft: Moderate rig chatter to 32.0'

(72%)

(56%)

(83%)

(100%)

(94%)

7- 14- 15 (N=29)

21- 22- 16 (N=38)

10- 21- 16 (N=37)

8- 13- 11 (N=24)

4- 7- 10 (N=17)

B

C

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

SHEET 2 of 2

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B4

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

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T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

E

LE

V

F T

-15

-20

-25

-30

-35

R E

C

IN

BLOWS

S T

R A

T U

M

0.0 - 0.2 ft: Top soil (0.0-0.2')

0.2 - 2.0 ft: (FILL) Moist, loose, brown, fine to coarse, Silty Sand, contains fine gravel, contains root and brick fragments

2.0 - 6.0 ft: (FILL) Moist, very loose, light brown and brown, fine to coarse, Poorly Graded Sand With Silt, contains fine gravel, contains brick fragments

6.0 - 8.0 ft: Wet, loose, light brown and gray, fine to coarse, POORLY GRADED SAND WITH SILT, contains mica

8.0 - 13.5 ft: Moist, soft, gray, high plasticity, FAT CLAY WITH SAND, fine sand, scattered organics

13.5 - 18.5 ft: Wet, very loose, gray and dark brown, fine to coarse, CLAYEY SAND, contains fine gravel, scattered organics

18.5 - 28.5 ft: Moist, soft, dark gray, medium plasticity, ORGANIC SOIL WITH SAND, fine sand, numerous organics

23.5 ft: changes to dark brownish gray and dark grayish brown

Top-soil

SM

SP-

SM

SP-

SM

CH

SC

OL/OH

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

0.75

(100%)

(100%)

(75%)

(100%)

(100%)

(100%)

(67%)

(100%)

1- 3- 3- 3 (N=6)

2- 2- 2- 3 (N=4)

2- 2- 2- 1 (N=4)

3- 4- 3- 3 (N=7)

1- 1/12"- 1 (N=1/12")

WOH/12"- 3

(N=3+)

2- 1- 1 (N=2)

1- 1- 2 (N=3)

A

B

HAMMER TYPE/WEIGHT: Auto Hammer/140lbs Date

DRILL RIG: Diedrich D-50 (ATV)

BIT TYPE/SIZE: NA/NA

CHECKED BY: Jocelyn Kaselow

Date Time Groundwater Observations

6.001-14-2020Encountered

DRILL METHOD: 3-1/4" I.D. Hollow Stem Auger

Event

LOGGED BY: Kevin Bell

DRILLER: Garrett Davis

DATE STARTED: 1/14/2020

DATE COMPLETED: 1/14/2020

DRILLING CONTRACTOR: Connelly & Asso

CASING TYPE: HSA

CASING SIZE: 3-1/4"

Depth (ft)

BOREHOLE DEPTH: 50.0 FT

SURFACE ELEVATION: 11 FT

Cave in Depth (ft)

AECOM TECHNICAL SERVICES, INC.

PROJECT: USACE JBMHH

PROJECT LOCATION: Fort McNair, Washington, DC

PROJECT NUMBER: 60615576

RC = Rock Core

B = Bulk Sample

T = Shelby Tube SampleG = Geoprobe

S = Split Spoon Sample

12420 Milestone Center Drive, Suite 150 Germantown, MD 20876 Phone: 301.820.3000 Fax: 301.820.3009

SHEET 1 of 2

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SC = Sonic CorePS = Piston Sample

P = Pitcher Sample

H = Hand Auger Sample

DESCRIPTION

Log of Boring FMc-B8

U S

C S

N U

M B

E R

SAMPLES

Li qu id L im it

P la st ic

L im it

P oc ke t P en ts f)

D E

P T

H

F T

G R

A P

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IC

T Y

P E

T or va ne ts f)

REMARKS

AND TESTS

M oi st ur e C on te nt

E

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V

F T

-5

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R E

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IN

BLOWS

S T

R A

T U

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18.5 - 28.5 ft: Moist, soft, dark gray, medium plasticity, ORGANIC SOIL WITH SAND, fine sand, numerous…