preliminary geotechnical engineering report hanson

Preliminary Geotechnical Engineering Report

Hanson Regional Park

Evergreen Mills Road, Aldie

Loudoun County, Virginia

April 26, 2013

19955 Highland Vista Drive, Suite 170Ashburn, VA 20147Phone 703 726 8030 ● Fax 703 726 8032

19955 Highland Vista Dr., Suite 170 Ashburn, Virginia 20147

(703) 726-8030 www.geoconcepts-eng.com

April 26, 2013 Mr. Mark Hoffman Loudoun County Department of Transportation and Capital Infrastructure 209 Gibson Street, NW Leesburg, VA 20176 Subject: Preliminary Geotechnical Engineering Report, Hanson

Regional Park, Evergreen Mills Road, Aldie, Loudoun County, Virginia (GeoConcepts Project No. 12079.05)

Dear Mr. Hoffman:

GeoConcepts Engineering, Inc. (GeoConcepts) is pleased to present the following preliminary geotechnical engineering report prepared for the Hanson Regional Park project on Evergreen Mills Road in Aldie, Virginia. We appreciate the opportunity to serve as your geotechnical consultant on this project. Please do not hesitate to contact me if you have any questions or want to meet to discuss the findings and recommendations contained in the report. Sincerely,

GEOCONCEPTS ENGINEERING, INC. Daniel F. Gradishar, PE Associate [email protected]

Table of Contents 1.0 Scope of Services ....................................................................................................................... 1 2.0 Site Description and Proposed Construction .................................................................................. 1 3.0 Subsurface Conditions ................................................................................................................ 1

3.1 Geology........................................................................................................................... 1 3.2 Published Soils ................................................................................................................. 2 3.3 Stratification .................................................................................................................... 3 3.4 Groundwater....................................................................................................................4 3.5 Soil Laboratory Test Results .............................................................................................. 5

4.0 Engineering Analysis................................................................................................................... 5 4.1 Foundations..................................................................................................................... 6 4.2 Slabs on Grade.................................................................................................................6 4.3 Subdrainage/Temporary Construction Dewatering............................................................... 6 4.4 Pavements....................................................................................................................... 7 4.5 Earthwork........................................................................................................................ 7 4.6 Rock Excavation............................................................................................................... 9 4.7 Infiltration Analysis......................................................................................................... 10

4.7.1 Infiltration Test Results ........................................................................................... 10 4.7.2 Classification Test Results ....................................................................................... 10 4.7.3 Recommended Design Infiltration Rate..................................................................... 11

5.0 Recommendations for Additional Studies .................................................................................... 11 Figure 1: Site Vicinity Map Figure 2: Compacted Structural Fill Diagram Appendix A: Subsurface Investigation Appendix B: Soil Laboratory Test Results

April 26, 2013 12079.05 Page 1

1.0 Scope of Services This preliminary geotechnical engineering report presents the results of the field investigation, soil laboratory testing, and engineering analysis of the geotechnical data. This report specifically addresses the following:

• An evaluation of subsurface conditions within the area of the proposed site development. • Preliminary foundation recommendations for support of the proposed buildings and lower floor

slabs on grade. • Comments on subdrainage recommendations for handling of groundwater during construction

and final design. • A preliminary assessment of subgrade conditions for support pavements, including an estimated

design California Bearing Ratio (CBR) value based on soil laboratory test results.

• Preliminary earthwork recommendations for construction of loadbearing fills, including an assessment of on-site soils to be excavated for re-use as fill.

• Preliminary rock excavation requirements for the site development.

• Preliminary recommendations regarding the feasibility of using stormwater management by

infiltration, including estimated infiltration rates based on field tests and published correlations with soil classifications.

Services not specifically identified in the contract for this project are not included in the scope of services.

2.0 Site Description and Proposed Construction The site is located on Evergreen Mills Road, north and east of the intersection with Founders Drive in Aldie, Virginia. A site vicinity map is presented as Figure 1 at the end of this report. The site is currently mostly undeveloped with some lightly to moderately wooded areas. Also, there are developed areas including a residential structure, associated outbuildings and gravel roadways within the portion of the site north of Evergreen Mills Road. In addition, four ponds are mapped within the site boundaries. The elevation at the site ranges from approximately EL 385 to EL 292, sloping downward towards the southwest. Based on preliminary plans, the proposed construction consists of a 17 new athletic fields, with associated roadways, parking areas and maintenance buildings. Preliminary plans do not include proposed building slab elevations.

3.0 Subsurface Conditions Subsurface conditions were investigated by drilling a total of 11 test borings in the proposed site development area. It should be noted that the relatively small number of borings drilled may not be sufficient to provide a thorough overall view of the existing subsurface conditions when considering the size of the site. Test boring and a boring location plan are presented in Appendix A of this report.

3.1 Geology The site lies within the Piedmont Physiographic Province of Virginia. More specifically, the site is located in the Culpeper Basin, a fault bounded basin, or graben, that formed as the result of tensional tectonic activity associated with continental rifting during the Triassic Geologic Period. Over time, the Culpepper Basin filled with lacustrine and alluvial fan deposits. These deposits left behind a sequence of non-

April 26, 2013 12079.05 Page 2

durable siltstones and shales in the central portion of the basin and conglomerates and sandstones along the margins. These sedimentary deposits were periodically intruded by magma forming sills, dikes, and flows of diabase granite and basalt. Surrounding these intrusions are zones of contact metamorphism, or aureoles, where the heat and pressure from the intruding igneous body recrystalized the host rock into a more durable rock. Thermally metamorphosed rocks in the Culpeper Basin are generally classified as hornfels. In general, hornfels is more durable than its parent material. The bedrock beneath the site consists of diabase, hornfels, and siltstone rock from the Triassic and early Jurassic Geologic Periods. Generally, from northwest to southeast across the site, the diabase is encountered, then a relatively narrow band of hornfels, and siltstone to the southeast. The natural soils assigned to Strata B1 and B2 are believed to be residual materials derived from the weathering of the underlying hornfels bedrock. Stratum B3 materials represent the partially weathered portion of the hornfels bedrock. The residual materials derived from the physical and chemical weathering of the hornfels bedrock generally consists of lean to fat clay and silt soils, with increasing amounts of weathered rock fragments (gravel size) with depth. Bedrock is generally shallow, with depths to bedrock ranging from about 2 to 15 feet. The natural soils assigned to Strata C1 and C2 are believed to be residual materials derived from the weathering of the underlying diabase granite bedrock. Stratum C3 represents the partially weathered portion of the diabase granite bedrock. The residual materials derived from the physical and chemical weathering of the diabase bedrock generally consists of fat clay soils overlying clayey to silty sand soils with increasing amounts of weathered rock fragments (cobble to boulder size) with depth. Bedrock occurs at depths ranging from about 2 to 13 feet. It has been our experience that there is a thin zone of enhanced weathering in the diabase near its contact with hornfels rock. Bedrock may be present at depths greater then 25 feet in this zone. The natural soils assigned to Strata D1 and D2 are believed to be residual materials derived from the weathering of the underlying siltstone bedrock. Stratum D3 materials represent the partially weathered portion of the siltstone bedrock. The residual materials derived from the physical and chemical weathering of the siltstone bedrock generally consists of lean clay and silt soils, with increasing amounts of weathered rock fragments (gravel size) with depth. Bedrock is generally shallow, with depths to bedrock ranging from about 3 to 9 feet.

3.2 Published Soils A review of the Loudoun County soils maps indicates that portions of the site development will be built on Class III and IV soils. Specifically, Soil Mapping Units 17B (Middleburg Silt Loam), 62B (Kelly-Sycoline Complex), 63A (Kelly-Sycoline Complex), 66A (Waxpool Silt Loam), 67B (Haymarket and Jackland Soils), 69A (Elbert Silty Clay Loam), 78A (Dulles Silt Loam) and 79A (Albano Silt Loam) are located on the site. According to the Loudoun County Interpretive Guide to the Use of Soils Maps, the Middleburg Silt Loam may have a short duration water table. The Kelly-Sycoline Complex, the Kelly Silt Loam, the Waxpool Silt Loam and the Haymarket and Jackland Soils may contain high shrink-swell clays and a perched water table. The Elbert Silty Clay Loam may have wetness and high shrink-swell clays. The Dulles Silt Loam may have low soil strength and a prolonged perched water table. The Albano Silt Loam may have seasonal high water tables. The Loudoun County soils mapping is shown on Figure 3 in Appendix A of this report.

Soil Type Characteristics by Mapping Unit Mapping

Unit Soil Group Typical Terrain Parent Rock Problems/Limiting

Factors Soil

Class

14B Manassas Silt Loam

Concave upland

positions

Colluvium of soils derived from siltstone

and shale

Low bearing capacity and short duration perched

water table II

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Mapping Unit Soil Group Typical

Terrain Parent Rock Problems/Limiting Factors

Soil Class

17B Middleburg Silt Loam

Concave upland

positions

Colluvium of soils

Short duration water table III

60C Sycoline-Catlett Complex

Convex side slopes Hornfels Shallow soils over rock II

62B Kelly-Sycoline Complex

Gently sloping to nearly level ridge crests

Hornfels High shrink-swell clays and moderate duration

perched water table III

63A Kelly Silt Loam

Gently sloping to nearly level uplands with

low relief

Hornfels High shrink-swell clays and prolonged perched

water table IV

64C Legore Loam Side slopes Diabase or basalt Rock outcrops II

66A Waxpool Silt Loam

Nearly level upland flats Diabase

High shrink-swell clays and prolonged perched

water table IV

67B Haymarket and Jackland Soils

Convex ridgetops and side slopes

Diabase High shrink-swell clays and seasonal perched

water table IV

69A Elbert Silty Clay Loam Drainageways Diabase and

basalt Wetness and high shrink-

swell clays IV

73B Penn Silt Loam Sloping convex

landscapes

Siltstone and shale

Good development potential I

73C Penn Silt Loam Sloping convex

landscapes

Siltstone and shale

Good development potential I

74B Ashburn Silt Loam

Level to gently sloping

landscapes Siltstone Wetness and low bearing

capacity II

77C3 Nestoria Gravelly Silt Loam

Highly dissected

terrain with gullies

Siltstone and shale

Little soil material available for grading II

78A Dulles Silt Loam Nearly level landscapes

Siltstone and shale

Low soil strength and prolonged perched water

table IV

79A Albano Silt Loam Concave

landscapes (swales)

Siltstone and shale

Seasonal perched water tables IV

3.3 Stratification The subsurface materials encountered have been stratified for purposes of our discussions herein. These stratum designations do not imply that the materials encountered are continuous across the site. Stratum designations have been established to characterize similar subsurface conditions based on material gradations and parent geology. Per GeoConcepts’ convention, Stratum A is reserved for existing fill soils. Existing fill soils were not encountered in the soil borings completed at the site. Accordingly,

April 26, 2013 12079.05 Page 4

Stratum A was not used in this report. The subsurface materials encountered in the test borings completed at the site have been assigned to the following strata:

Stratum B1 (Hornfels-Residual)

medium stiff, sandy LEAN CLAY (CL), moist, brown


very compact, clayey SAND (SC), moist, brown


very compact, DISINTEGRATED HORNFELS ROCK, moist, brown and purple

Stratum C1 (Diabase-Residual)

medium stiff to stiff, sandy LEAN CLAY (CL), and sandy SILT (ML) with gravel, moist, brown

Stratum C2 (Diabase- Residual)

compact to very compact, clayey SAND (SC) with gravel, and POORLY GRADED GRAVEL (GP-SM) moist, brown and gray

Stratum C3 (Diabase- Residual)

very compact, DISINTEGRATED DIABASE ROCK, moist, brown and gray

Stratum D1 (Balls Bluff Formation-Residual)

medium stiff to stiff, sandy LEAN CLAY (CL) with gravel, moist, brown and reddish-brown


firm, clayey SAND (SC), moist, brown


very compact, DISINTEGRATED SILTSTONE ROCK, reddish-brown and brown

The two letter designations included in the strata descriptions presented above and on the test boring logs represent the Unified Soil Classification System (USCS) group symbol and group name for the samples based on laboratory testing per ASTM D-2487 and visual classifications per ASTM D-2488. It should be noted that visual classifications per ASTM D-2488 may not match classifications determined by laboratory testing per ASTM D-2487.

3.4 Groundwater Groundwater level observations were made in the field during drilling and up to five days after the completion of the test borings. Groundwater was encountered at depths of about two to seven feet below the existing ground surface, or about EL 318 to EL 336. We have assumed that the relatively shallow depth to water in boring SB-S1 is a perched water table condition. A summary of the water level readings rounded off to the nearest 0.5 feet elevation is presented in the table below.

Test Boring No. Depth to Groundwater (feet) Approximate Groundwater Elevation (feet)

SB-B1 2.5 EL 318

SB-B2 2.0 EL 324

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Test Boring No. Depth to Groundwater (feet) Approximate Groundwater Elevation (feet)

SB-S1 3.0 EL 372

SB-S3 7.0 EL 336

SB-S5 2.0 EL 333

The groundwater observations presented herein are considered to be an indication of the groundwater levels at the dates and times indicated. Where more impervious Strata B1, C1 and D1 silt and clay soils are encountered, the amount of water seepage into the borings is limited, and it is generally not possible to establish the location of the groundwater table through short term water level observations. Accordingly, the groundwater information presented herein should be used with caution. Also, fluctuations in groundwater levels should be expected with seasons of the year, construction activity, changes to surface grades, precipitation, or other similar factors.

3.5 Soil Laboratory Test Results Selected soil samples obtained from the field investigation were tested for grain size distribution, Atterberg limits, compaction characteristics using standard effort, and natural moisture contents. A summary of soil laboratory test results is presented below, and the results of natural moisture content tests are presented on the test boring logs in Appendix A.

Sieve Results

Atterberg Limits Test

Boring No.

Depth (ft)

Sample Type Stratum

Description of Soil

Specimen Percent

Retained #4 Sieve

Percent Passing #200 Sieve

LL PL PI

Natural Moisture Content

(%)

Remarks

SB-B1 2.5-4.0 Jar D2 silty SAND with gravel 19.8 46.5 33 24 9 19.9

SB-B3 2.5-4.0 Jar C2 clayey SAND 0.2 25.0 39 25 14 17.7

SB-B4 5.0-6.5 Jar D2 clayey SAND 0.0 29.5 31 21 10 18.4

SB-B5 0.0-5.0 Bulk D1 sandy LEAN CLAY 15.4 63.4 28 20 8 8.8

SB-S1 0.0-5.0 Bulk B1 LEAN CLAY with sand 6.5 80.8 37 20 17 21.2

SB-S2 8.5-10.0 Jar B2 POORLY GRADED GRAVEL

54.6 10 28 23 5 8.0

SB-S3 5.0-6.5 Jar B2 clayey SAND with gravel 25.5 19.5 32 23 9 11.2

SB-S6 1.5-2.0 Jar D1 LEAN CLAY with sand 8.7 76.2 36 23 13 21.9

Notes: 1. Soil tests are in accordance with applicable ASTM standards 2. Soil classification symbols are in accordance with Unified Soil Classification System 3. Visual identification of samples is in accordance with ASTM D-2488 4. Key to abbreviations: LL = liquid limit; PL = plastic limit; PI = plasticity index; NP = nonplastic; N/T = not tested

4.0 Engineering Analysis Preliminary recommendations regarding foundations, lower floor slabs, subdrainage, pavements, earthwork, rock excavation, and stormwater management by infiltration are presented herein.

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4.1 Foundations We have assumed that the floor elevations for the proposed buildings will be at about existing grades and firm natural soils or new compacted fill should be encountered at normal spread footing depths. Spread footings founded in these materials are considered suitable for support of the proposed building, and may be designed with a net allowable soil bearing pressure of 2,000 to 4,000 psf. Details regarding the building loads and locations should be obtained prior to finalizing the net allowable soil bearing pressures. In order to achieve the design bearing pressure, lowering or undercutting of specific footings may be required. It is critical that all footing subgrades be observed and approved for the appropriate bearing pressure by the geotechnical engineer, prior to placement of steel reinforcement or concrete.

4.2 Slabs on Grade Slabs supported by natural soils or new compacted fill are considered feasible at the site. However, where floor subgrades consist of fat clay soils, these fat clay soils should be undercut to a depth of at least 2 feet or until the fat clay is no longer present, whichever is less, and backfilled with new compacted fill. Prior to placement of any new compacted fill, the undercut subgrade should be observed during proofrolling by the geotechnical engineer to confirm that the new subgrade is suitable to receive new compacted fill. All debris and soft soils near the final floor slab subgrade as a result of construction operations should be stripped and removed prior to placement of underfloor stone. A 4-inch minimum thickness of washed gravel or crushed stone meeting the requirement of AASHTO No. 57 should be placed below floor slabs on grade to serve as a capillary break. This gravel layer will also serve as part of the underfloor subdrainage system. An impermeable plastic membrane should be placed on top of the crushed stone layer to assist as a moisture barrier. Special attention should be given to the surface curing of the slab in order to minimize uneven drying of the slab and associated cracking. We recommend mesh (fiber or welded wire fabric) reinforcement be included in the design of the floor slab to minimize the development of any shrinkage cracks near the surface of the slab. If welded wire fabric is used, the mesh should be located in the top half of the slab.

4.3 Subdrainage/Temporary Construction Dewatering Groundwater was encountered at depths of about two to five feet below the existing ground surface, or about EL 318 to EL 336. Additionally, several soil groups mapped within the site have perched water table conditions documented as limiting factors for development. Final site grading had not been established at the time of our investigation; however, temporary construction dewatering recommendations are presented herein. In the event that groundwater is present during utility installations or excavations for foundations we recommend that the contractor be prepared to provide temporary dewatering during construction. We recommend that the dewatering consist of both an aggressive system of individual sumps and pumps during excavation. To help maintain bottom stability of excavations, groundwater levels should be drawn-down a minimum of 3 feet below the lowest portion of the excavation. The type of dewatering recommended herein is a result of the way groundwater moves through residual soils. Groundwater moves through these materials in a non-homogenous fashion. Accordingly, the presence of groundwater is dictated by the presence of relic fractures and more pervious zones within the soil profile, instead of being based on vertical depth below the ground surface. It is critical that as soon as water seepage is observed, the contractor should excavate surface trenches from the observed water seepage to a sump pit and sump pump. If the water is allowed to saturate subgrades, softening of the subgrade will occur very quickly and extra costs will be incurred. However, if the contractor can channel the water to a sump pit and keep the majority of the subgrade from getting saturated, extra costs due to water softening should be significantly reduced. The temporary dewatering

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system should remain in place until the floor slab subgrades are approved and the permanent underfloor subdrainage system is installed and operational. It should be understood that the groundwater information presented herein should be used with caution. Fluctuations in groundwater levels should be expected with seasons of the year, construction activity, changes to surface grades, precipitation, or other similar factors. Therefore, water levels presented in this report may not be representative of those encountered at the time of construction. It should be the responsibility of the contractor to verify groundwater conditions and evaluate dewatering requirements prior to bidding and/or construction. Ground subsidence may result due to temporary dewatering and cause adverse settlement of any nearby, existing structures. Therefore, possible modification to the dewatering program may be required to reduce potential adverse effects to existing structures. Further, a monitoring program should be developed to record the effect of dewatering operation on the nearby existing structures. If dewatering-induced settlements are anticipated, either modifications in the dewatering program or foundation underpinning may be required.

4.4 Pavements Pavement subgrades are expected to consist of firm existing fill, natural soils, or new compacted fill. These materials are generally considered suitable for support of the planned roadways and parking areas. However, where pavement subgrades consist of existing fill, we recommend budgeting for undercutting the existing fill to a depth of at least 2 feet and backfilling with new compacted fill. The decision to undercut the existing fill should be based on a thorough proofroll of the pavement subgrades under the observation of the geotechnical engineer. However, if encountered, fat clay soils are susceptible to softening and excessive shrink/swell. Accordingly, where fat clay soils are present at pavement subgrades, pavement underdrains should be installed to reduce the amount of moisture that collects at the pavement subgrade. In addition, the fat clay soils should be at or above its optimum moisture content for compaction purposes, prior to placement of aggregate base course. It should be expected that pavements constructed on fat clay soils may experience greater than normal damage and require subsequent maintenance. As an alternative, the fat clay soils may be removed to a depth of 2 feet below pavement subgrades and replaced with compacted fill as detailed in Section 4.5 of this report, in order to limit the amount of pavement damage and maintenance. Based on the soil laboratory test results for the materials expected at pavement subgrades, a preliminary design CBR value of 3 is recommended for pavement design purposes. If fill placed at the site is generated from off-site borrow areas, the actual CBR value for the pavement subgrades may be significantly different from the preliminary value presented herein. Therefore, CBR tests should be performed on the in-place subgrade after rough grading and installation of utilities within roadways. Final pavement sections should be based on CBR tests taken on subgrade soils at the time of construction.

4.5 Earthwork We have assumed that fill will be required for site grading in building and pavement areas. The areas to be filled should be cleared and grubbed prior to placing fill. Unsuitable existing fill, soft or loose natural soils, organic material, and rubble should be stripped to approved subgrades as determined by the geotechnical engineer. Topsoil depths presented on the boring logs should not be considered as stripping depths, as topsoil depths may vary widely across the site, particularly in wooded or previously cultivated areas. Stripping depths will probably extend to greater depths than the topsoil depths indicated herein due to the presence of minor amounts of organics, roots, and other surficial materials that will require removal as a part of the stripping operations. In addition, seasonal soil moisture variations can affect stripping depths. In general, less stripping may occur during summer months when drier weather conditions can be expected. The depth of required stripping should be determined prior to construction by the excavation contractor using test pits, probes, or other means that the contractor wishes to employ, and this determination should be the responsibility of the excavation contractor. All

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subgrades should be proofrolled with a minimum 20 ton, loaded dump truck or suitable rubber tire construction equipment approved by the geotechnical engineer, prior to the placement of new fill. There may be some areas of deeper subcutting for removal of soft wet soils, particularly along seasonal creeks or drainage channels on the site. Actual undercutting requirements may also depend on groundwater conditions in the lower elevations at the time of construction. In some cases, soil stabilization/improvement methods such as the use of geogrids/geotextiles may be an economically beneficial option to the traditional removal and replacement option. For building areas, the new fill should extend at least 10 feet outside building lines. For parking areas, the new fill should extend at least 5 feet outside pavement edges. These recommendations are illustrated by Figure 2 at the end of this report. Fill material should be placed in lifts not exceeding 8 inches loose thickness, with fill materials compacted by hand operated tampers or light compaction equipment placed in maximum 4-inch thick loose lifts. Fill should be compacted at +/- 2% of the optimum moisture content to at least 95 percent of the maximum dry density per VTM-1. The upper 6 inches of pavement subgrades should be compacted to at least 100 percent of the maximum dry density per the same standard. Fill placed along slopes steeper than 5H:1V should be benched into the existing slope. Benches should consist of minimum 8 feet wide level cut, and at least one such bench should be used for each 3 feet of vertical rise of fill placed. Materials used for compacted fill for support of footings, floor slabs, and pavements should consist of soils classifying CL, ML, SC, SM, SP, SW, GC, GM, GP, or GW per ASTM D-2487, with a maximum dry density greater than 105 pcf. It is expected that the majority of soils excavated from Strata B1, B2, C1, C2, D1 and D2 will be suitable for re-use as fill based on classification. If encountered, fat clay soils will not be suitable for re-use as fill due to its relatively high plasticity. In addition, drying of excavated soils by spreading and aerating may be necessary to obtain proper compaction. This may not be practical during the wet period of the year. Accordingly, earthwork operations should be planned for early Spring through late Fall, when drier weather conditions can be expected. Drying of fill materials by the use of lime may also be considered. However, in the event that lime is used, more specific details regarding the percentage of lime used and installation techniques should be provided. In addition, written notification must be provided to Loudoun County prior to using lime for drying operations. Individual borrow areas, both from on-site and off-site sources, should be sampled and tested to verify classification of materials prior to their use as fill. The disintegrated rock of Strata B3, C3 and D3 may also be suitable for re-use as fill. With limited exposure and manipulation, the disintegrated rock will eventually breakdown into smaller size particles. If the disintegrated rock is placed in a fill without sufficient fines to fill void spaces adjacent to larger size particles, degradation of the larger disintegrated rock particles may result in collapse of the individual void spaces, and subsequent undesirable settlement. In order to prevent the improper placement of disintegrated rock materials due to the non-durable nature of this material, we recommend that the disintegrated rock be placed as a soil fill and not as rock fill. This will require that sufficient mechanical effort be used to breakdown and crush the disintegrated rock into particles not larger than 8 inches in mean diameter, with approximately 50 percent materials passing the U.S. Standard No. 40 sieve. These criteria should be able to be met by compacting with a CAT 815 sheepsfoot roller or similar sized equipment, in lifts not exceeding 8 inches in thickness prior to compaction. Fill materials should not be placed on frozen or frost-heaved soils, and/or soils that have been recently subjected to precipitation. All frozen or frost-heaved soils should be removed prior to continuation of fill operations. Borrow fill materials should not contain frozen materials at the time of placement. Compaction equipment that is compatible with the soil type used for fill should be selected. Theoretically, any equipment type can be used as long as the required density is achieved; however,

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sheepsfoot roller equipment are best suited for fine-grained soils and vibratory smooth drum rollers are best suited for granular soils. Ideally, a smooth drum roller should be used for sealing the surface soils at the end of the day or prior to upcoming rain events. All areas receiving fill should be graded to facilitate positive drainage of any water associated with precipitation and surface run-off. For utility excavation backfill, we recommend that open graded stone be used to backfill the pipe trench to the spring line of the pipe. Backfill should be compacted in lifts not exceeding 6 inches loose thickness, to at least 95 percent of the maximum dry density per VTM-1. Hand operated compaction equipment should be used until the backfill has reached a level 1 foot above the top of the pipe to prevent damaging the pipe. Also, backfill material within 2 feet of the top of the pipe should not contain rock fragments or gravel greater than 1-inch in diameter. After completion of compacted fill operations in building or pavement areas, construction of building elements or asphalt should begin immediately, or the finished subgrade should be protected from exposure to inclement weather conditions. Exposure to precipitation and freeze/thaw cycles will cause the finished subgrade to soften and become excessively disturbed. If development plans require that finished subgrades remain exposed to weather conditions after completion of fill operations, additional fill should be placed above finished grades to protect the newly placed fill. Alternatively, a budget should be established for reworking of the upper 1 to 2 feet of previously placed compacted fill.

4.6 Rock Excavation Rock excavation methods such as hoe-ramming or blasting may be required for some of the site development. The elevations where rock excavation methods may be required for removal of bedrock at the test boring locations are estimated as follows:

The elevations given above are based upon the use of normal earth excavation equipment including up to a D-8 Caterpillar tractor, equipped with a hydraulically operated single-tooth power ripper or equivalent, for mass excavation. Project specifications should include the following as a definition of rock excavation for mass excavation: “Rock is defined as any material which cannot be dislodged by a D-8 Caterpillar tractor, or equivalent, equipped with a hydraulically operated, single-tooth power ripper without the use of hoe-ramming or blasting. This classification does not include material such as loose rock, concrete or other materials that can be removed by means other than hoe-ramming or blasting, but which for reasons of economy in excavating, the contractor chooses to remove by hoe-ramming or blasting.” For trench excavations, rock excavation should be defined in terms of a Caterpillar 330 hydraulic backhoe, or equivalent, instead of the D-8 Caterpillar tractor. Earthwork excavation should be defined as all material except rock as defined above, including material that can be ripped.

Test Boring No. Estimated Elevation Where Rock Excavation Methods May be Required

SB-B1 EL 315

SB-B5 EL 318

SB-S1 EL 373

SB-S3 EL 334

SB-S4 EL 334

SB-S5 EL 326

SB-S6 EL 323

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Any pre-blasting of utility lines should be carefully planned and executed to avoid over shooting of the rock. Over shooting may result in separation along bedding planes and uplift of the rock. Over time, the blast loosened rock may collapse resulting in possible localized settlements. Additionally, water that penetrates the overblasted zone will cause the rock to slake and degrade over time, creating the potential for additional localized settlement. All overblasted material should be completely removed. Requirements for blasting rock should be determined by a contractor with demonstrated experience in this work.

4.7 Infiltration Analysis Two methods were used to estimate infiltration capabilities on the subject site: in-situ infiltration testing and published correlations with soil classifications. Details regarding the in-situ infiltration and classification test techniques, the estimated infiltration rates from the individual methods, and the recommended design infiltration rate for the site soils are presented herein.

4.7.1 Infiltration Test Results In-situ infiltration tests are performed in the field to observe the rate at which water will permeate the soil under saturated conditions. Six test borings were drilled in the area of planned infiltration. Test borings were initially drilled to depths of at least 4 feet below the planned infiltration invert elevations, and allowed to remain open for a period of approximately 24 hours to allow any groundwater levels within the boreholes to stabilize. After 24 hours, offset infiltration test holes were drilled at the boring locations to planned infiltration invert elevations. Four-inch diameter PVC casing was set to the bottom of the test holes. The purpose of the casing is to prevent caving of test hole sidewalls. After setting the PVC casing, the borehole was filled with water to saturate the bottom subsoils. The following day, the test hole was refilled with water and the water level in each test hole was recorded every hour for a 4-hour period. Using this procedure, the last reading of the 4-hour period is considered the infiltration rate. Based on the results of the in-situ infiltration tests, estimated infiltration rates have been assigned for the site soils, as presented in the table below:

Test Boring No. Approximate Test Depth (feet) Estimated Infiltration Rate (inches/hour)

SB-S1 2.7 0

SB-S2 6.2 0

SB-S3 5.8 2.3

SB-S4 2.0 0.6

SB-S5 2.8 0

SB-S6 5.2 0

4.7.2 Classification Test Results The classification test method is performed with grain-size sieve analyses including hydrometer testing on samples obtained from corresponding proposed infiltration depths, to determine the USDA soil texture classifications. Published correlations between USDA classifications and infiltration rates were used to provide estimated hydraulic conductivity values. Since hydraulic conductivity and infiltration values are essentially equal at no head conditions, using the hydraulic conductivity values to estimate the infiltration rates provides a conservative estimate of infiltration for use in design. Estimated infiltration rates using the USDA soil texture classifications are presented below.

April 26, 2013 12079.05 Page 11

Test Boring No.

Approximate Test Depth (feet)

USDA Soil Texture Classification

Estimated Infiltration Rate (inches/hour)

SB-S1 2.7 Clay 0.02

SB-S2 6.2 Loam 0.52

SB-S3 5.8 Sandy Loam 1.02

SB-S4 2.0 Loam 0.52

SB-S5 2.8 Loam 0.52

SB-S6 5.2 Clay Loam 0.09

4.7.3 Recommended Design Infiltration Rate Based on the results of the in-situ infiltration tests and soil laboratory classification tests, we recommend that a design infiltration rate of 1.02 and 0.52 inches/hour be used for design of infiltration structures at borings SB-S3 and SB-S4, respectively. However, please note the depths where the infiltration information was obtained as the infiltration rates may vary depending upon the in-place soil conditions at various depths. Field conditions indicate that infiltration is not recommended at the remaining boring locations. It should be noted that the recommended design infiltration rate presented herein is intended for use in design. However, during construction, observations of the subgrade conditions should be made to confirm that the subgrade soils are consistent with the soils analyzed in this report.

5.0 Recommendations for Additional Studies This preliminary geotechnical engineering study is not adequate to use for final design. It will be necessary to conduct a more comprehensive geotechnical engineering analysis and reporting for this project. The field investigation for the final design phase study should consist of additional test borings to adequately define the subsurface conditions across the site. Soil laboratory tests should also be performed to determine physical and engineering properties of the bearing soils, and on-site soils for re-use as compacted fill. The comprehensive geotechnical engineering analysis and report should contain foundation recommendations for support of the building based on final building layouts, floor grades, and structural loads. This preliminary report was prepared in accordance with generally accepted geotechnical engineering practices. No warranties, expressed or implied, are made as to the professional services included in this report.

April 26, 2013 12079.05 Page 12

We appreciate the opportunity to be of service for this project. Please contact the undersigned if you require clarification of any aspect of this report. Sincerely, GEOCONCEPTS ENGINEERING, INC. Amy E. Strobel, CPG Senior Project Manager Daniel F. Gradishar, PE Associate AES/DG/clm N:\PROJECTS\Active 12 Projects\12079.05, Hanson Regional Park\Final\GER, Hanson Regional Park-.doc

Appendix A Subsurface Investigation Subsurface Investigation Procedures (1 page)

Identification of Soil (1 page)

Test Boring Notes (1 page)

Test Boring Logs (11 pages)

Boring Location Plan, Figure 3 (1 page)

Subsurface Investigation Procedures 1. Test Borings – Hollow Stem Augers The borings are advanced by turning an auger with a center opening of 2-¼ inches. A plug device blocks off the center opening while augers are advanced. Cuttings are brought to the surface by the auger flights. Sampling is performed through the center opening in the hollow stem auger, by standard methods, after removal of the plug. Usually, no water is introduced into the boring using this procedure. 2. Standard Penetration Tests Standard penetration tests are performed by driving a 2 inch O.D., 1-⅜ inch I.D. sampling spoon with a 140-pound hammer falling 30 inches, according to ASTM D-1586. After an initial 6 inches penetration to assure the sampling spoon is in undisturbed material, the number of blows required to drive the sampler an additional 12 inches is generally taken as the N value. In the event 30 or more blows are required to drive the sampling spoon the initial 6 inch interval, the sampling spoon is driven to a total penetration resistance of 100 blows or 18 inches, whichever occurs first. The sampling operation is terminated after a total of 100 hammer blows and the depth of penetration is recorded. 3. Test Boring Stakeout The test boring stakeout was provided by GeoConcepts personnel using a Trimble GPS unit and available site plans. Ground surface elevations were estimated from topographic information contained on the site plan provided to us and should be considered approximate. If the risk related to using approximate boring locations and elevations is unacceptable, we recommend an as-drilled survey of boring locations and elevations be completed by a licensed surveyor.

Identification of Soil I. DEFINITION OF SOIL GROUP NAMES ASTM D-2487 Symbol Group Name

GW WELL GRADED GRAVEL Clean Gravels Less than 5% fines GP POORLY GRADED GRAVEL

GM silty GRAVEL

Gravels More than 50% of coarse fraction retained on No. 4 sieve

Gravels with Fines More than 12% fines GC clayey GRAVEL

SW WELL GRADED SAND Clean Sands Less than 5% fines SP POORLY GRADED SAND

SM silty SAND

Coarse-Grained Soils More than 50% retained on No. 200 sieve

Sands 50% or more of coarse fraction passes No. 4 sieve Sands with fines

More than 12% fines SC clayey SAND CL LEAN CLAY Inorganic ML SILT

ORGANIC CLAY

Silts and Clays Liquid Limit less than 50 Organic OL

ORGANIC SILT CH FAT CLAY Inorganic MH ELASTIC SILT

ORGANIC CLAY

Fine-Grained Soils 50% or more passes the No. 200 sieve

Silts and Clays Liquid Limit 50 or more Organic OH

ORGANIC SILT Highly Organic Soils Primarily organic matter, dark in color, and organic odor PT PEAT

II. DEFINITION OF MINOR COMPONENT PROPORTIONS

Minor Component Approximate Percentage of Fraction by Weight Gravelly, Sandy (adjective) 30% or more coarse grained Sand, Gravel (with) 15% to 29% coarse grained Silt, Clay (with) 5% to 12% fine grained III. GLOSSARY OF MISCELLANEOUS TERMS

SYMBOLS Unified Soil Classification Symbols are shown above as group symbols. Use “A” Line Chart for laboratory identification. Dual symbols are used for borderline classification.

BOULDERS & COBBLES Boulders are considered pieces of rock larger than 12 inches, while cobbles range from 3 to 12 inches.

DISINTEGRATED ROCK Residual rock material with a standard penetration test (SPT) resistance between 60 blows per foot and refusal.

ROCK Rock material with a standard penetration test (SPT) resistance of 100 blows for 2 inches or 50 blows for 0 inches, or less penetration

DECOMPOSED ROCK Residual rock material exhibiting rock-like properties that can be excavated by backhoe equipment. Similar to Disintegrated Rock, but cannot be classified as such because SPT N-Values were not obtained.

ROCK FRAGMENTS Angular pieces of rock, distinguished from rounded transported gravel, which have separated from original vein or strata and are present in a soil matrix.

QUARTZ A hard silicate mineral often found in residual soils. Only used when describing residual soils. CEMENTED SAND Usually localized rock-like deposits within a soil stratum composed of sand grains cemented by

calcium carbonate, iron oxide, or other minerals. Commonly encountered in Coastal Plain sediments, primarily in the Potomac Group sands (Kps).

MICA A plate-like phyllosilicate mineral found in many rocks, and in residual or transported soil derived there from.

ORGANIC MATERIALS (Excluding Peat)

Topsoil - Surface soils that support plant life and contain organic matter. Lignite - Hard, brittle decomposed organic matter with low fixed carbon content (a low grade of coal).

FILL Man made deposit containing soil, rock, and other foreign matter. PROBABLE FILL Soils which contain no visually detected foreign matter but which are suspect with regard to origin. LAYERS ½ to 12 inch seam of minor soil component. COLOR Two most predominant colors present should be described. MOISTURE CONDITIONS Wet, moist, or dry to indicate visual appearance of specimen.

Test Boring Notes 1. Classification of soil is by visual inspection and is in accordance with the Unified Soil Classification

System. 2. Estimated groundwater levels are indicated on the logs. These are only estimates from available data

and may vary with precipitation, porosity of soil, site topography, etc. 3. Sampling data presents standard penetrations for 6-inch intervals or as indicated with graphic

representations adjacent to the sampling data. 4. The logs and related information depict subsurface conditions at the specific locations and at the

particular time when drilled. Soil conditions at other locations may differ from conditions occurring at the test locations. Also, the passage of time may result in a change in the subsurface conditions at the test locations.

5. The stratification lines represent the approximate boundary between soil types as determined in the

sampling operation. Some variation may be expected vertically between samples taken. The soil profile, groundwater level observations and penetration resistances presented on the logs have been made with reasonable care and accuracy and must be considered only an approximate representation of subsurface conditions to be encountered at the particular location.

6. Disintegrated rock is defined as residual earth material with a penetration resistance between 60

blows per foot and refusal. Spoon refusal at the surface of rock, boulders, or obstructions is defined as a penetration resistance of 100 blows for 2 inches penetration or less. Auger refusal is taken as the depth at which further penetration of the auger is not possible without risking significant damage to the drilling equipment.

320.0

316.0

314.3

D2

D3

Topsoil = 12 inches

silty SAND (SM) with gravel, moist, brown

DISINTEGRATED SILTSTONE ROCK, moist, brown

Auger and Spoon Refusal at 6.7 ft

1+1+2+2

3+5+12

12+50/6

100/2

24

18

10

1.5

29.9

19.9

PROJECT NUMBER:

DATE STARTED:OWNER/CLIENT:

GROUND SURFACE ELEVATION (ft): DRILLING METHOD:

2/15/13

2/15/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:

Loudoun Co. Dept. of Transportation and Capital Infrastructure

12079.05

C. Leatherman

321.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/16/2013

LOCATION:

LOGGED BY:PROJECT:

GROUND WATER LEVELS:

REMARKS:

SB-B1

ft

None

Dry

2.8

THE STRATIFICATION LINES REPRESENT APPROXIMATE BOUNDARIES. THE TRANSITION MAY BE GRADUAL.

SAMPLE TYPES:

MATERIAL DESCRIPTION

Split Spoon

DRILLING CONTRACTOR:

BORING NUMBER:


Aldie, Loudoun Country, Virginia Connelly and Assoicates, Inc.

J. April

703-726-8030703-726-8032 fax

19955 Highland Vista Dr. #170Ashburn, VA 20147

BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.ELEV.

316.0

316.0

ELEV.(ft)

318.2

20 40 60 80

STANDARDPENETRATION

TEST RESISTANCE(BLOWS/FOOT)

2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

5.0

5.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

328.5

320.5

319.0

D1

D3

Topsoil = 6 inches

sandy LEAN CLAY (CL), moist, brown

reddish brown below 2.5 ft.

DISINTEGRATED SILTSTONE ROCK, moist, brown

Bottom of Boring at 10.0 ft

2+2+2+4

9+9+6

5+5+8

5+19+41

24

18

18

18

23.2

PROJECT NUMBER:



2/15/13

2/15/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

329.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/16/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-B2

ft

ft

5.0

7.0

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

ELEV.

ELEV. 322.0

325.0

ELEV.(ft)

324.0

322.0

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

7.0

4.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

339.5

337.5

335.0

330.0

B1

B2

B3

Topsoil = 6 inches


clayey SAND (SC), moist, brown

DISINTEGRATED HORNFELS ROCK, moist, brown andpurple


2+2+3+4

27+50/6

36+50/6

23+31+44

24

9

11

18

17.7

PROJECT NUMBER:



2/15/13

2/15/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

340.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/16/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-B3

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

334.5

336.0

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

5.5

4.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

337.5

335.5

328.0

D1

D2

Topsoil = 6 inches


clayey SAND (SC), moist, brown


2+4+4+5

4+5+9

6+9+12

6+10+11

24

18

18

18

18.4

PROJECT NUMBER:



2/15/13

2/15/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

338.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/16/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-B4

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

330.5

334.0

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

7.5

4.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

323.5

321.5

315.3

D1

D3

Topsoil = 6 inches

sandy LEAN CLAY (CL) with gravel, moist, brown

DISINTEGRATED SILTSTONE ROCK, moist, reddish brown


2+2+4+5

11+37+50/2

50/6

100/2

18

14

6

2

8.8

20.6

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

324.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-B5

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

320.0

320.0

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

4.0

4.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

>>

374.5

372.5

370.9

C1

C3

Topsoil = 6 inches

LEAN CLAY (CL) with sand, moist, brown

DISINTEGRATED DIABASE ROCK, moist, brown


2+2+2+4

27+50/2

100/1

14

8

0

21.2

24.9

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

375.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S1

ft

None

Dry

3.0


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.ELEV.

372.0

372.0

ELEV.(ft)

372.0

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

3.0

3.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

383.5

381.5

374.0

C1

C2

Topsoil = 6 inches

sandy SILT (ML) with gravel, moist, brown

POORLY GRADED GRAVEL (GP-SM) with silt, moist, grayand brown


2+2+4+7

4+10+42

43+37+22

29+33+16

24

18

18

14

21.7

8.0

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

384.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S2

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

377.5

377.5

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

6.5

6.5

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

342.5

340.5

334.5

333.6

C1

C2

C3

Topsoil = 6 inches


clayey SAND (SC) with gravel, moist, brown

DISINTEGRATED DIABASE ROCK, moist, brown


1+2+3+4

5+11+14

8+13+18

34+50/4

24

16

18

7

11.2

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

343.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S3

ft

None

Dry

7.0


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.ELEV.

336.0

336.0

ELEV.(ft)

336.0

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

7.0

7.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

338.5

336.5

332.4

D1

D3

Topsoil = 6 inches


DISINTEGRATED SILTSTONE ROCK, moist, reddish brown


2+2+3+4

32+50/4

36+50/3

100/1

2

6

7

0

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

339.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S4

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

335.0

331.5

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

4.0

7.5

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

>>

334.0

332.5

326.1

C1

C3

Topsoil = 12 inches

sandy SILT (ML), moist, brown

DSINTEGRATED DIABASE ROCK, moist, brown


1+2+4+7

30+50/6

19+26+32

50/6

19

11

10

5

22.1

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

335.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S5

ft

ft

ft

4.0

3.0

2.0


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

ELEV.

ELEV.

ELEV.

330.0

333.0

ELEV.(ft)

331.0

332.0

333.0

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

5.0

2.0

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

327.5

325.5

319.3

D1

D3

Topsoil = 6 inches

sandy LEAN CLAY (CL) with sand, moist, reddish brown

DISINTEGRATED SILTSTONE ROCK, moist, reddish bron


1+2+3+5

50/6

50/3

50/2

20

6

3

2

22.4

21.9

PROJECT NUMBER:



2/14/13

2/14/132.25" I.D. HSA

DRILLER:

DATE COMPLETED:


12079.05

C. Leatherman

328.0 ±

SHEET 1 OF 1

ENCOUNTERED:

UPON COMPLETION:

2/15/2013

LOCATION:

LOGGED BY:PROJECT:


REMARKS:

SB-S6

None

Dry

Dry


SAMPLE TYPES:


Split Spoon


BORING NUMBER:



J. April

703-726-8030703-726-8032 fax


BO

RE

HO

LE/T

ES

T P

IT L

OG

S.G

PJ

GE

OC

ON

CE

PT

S.G

DT

4/2

6/1

3

ELEV.

ELEV.

320.5

320.5

ELEV.(ft)

20 40 60 80

STANDARDPENETRATION


2

4

6

8

10

12

14

ST

RA

TU

M

DEPTH(ft)

ft

ft

CAVED:

CAVED:

7.5

7.5

SP

TB

LOW

CO

UN

TS

RE

CO

VE

RY

(in)

SA

MP

LET

YP

E

MC

(%

)

>>

>>

>>

SB-B2

SB-B4

LDN60

LDN601MILEBUFFER

74B

60C

73B

74B

79A

73B

79A

73C

73B

79A

79A

73B

74B

60C

14B

73C

78A

78A

73C

77C

3

WAT73

C

73B

79A

74B

73B

WAT

74B14

B

ISL

73C

73C

73C

WAT

WAT

79A 73

B

78A

74B

WAT

WAT

66A

62B

60C

60C

WAT

69A17

B 17B

67B

WAT

64C

WAT

67B

64C

63A

65B

69A

WAT

63A

60C

60C

62B

79A

79A

79A

PDH

4

TR3U

BF

TR3U

BF

TR3U

BF

TR3U

BF

3BORING LOCATION PLAN

HANSON REGIONAL PARKEVERGREEN RIDGE ROAD, ALDIE, VIRGINIA

SB-S1

NO. DATE REVISION

Fig.

(703) 726-8032 fax

(703) 726-803019955 Highland Vista Dr., Suite 170

Ashburn, Virginia 20147

14B Manassas silt loam

Concave upland positions II-Fair potential

17B Middleburg silt loamConcave upland positions III-Poor potential

60C Sycoline-Catlett

complex

Convex side slopes II-Fair potential

62B Kelly-Sycoline

complex

Gently sloping to nearly

level ridge crests

III-Poor potential

63A Kelly silt loam

Gently sloping to nearly

level uplands with low

relief

IV-Very poor potential

64C Legore loamSide slopes II-Fair potential

66A Waxpool silt loamNearly level upland flats IV-Very poor potential

67B Haymarket and

Jackland soils

Convex ridgetops and side

slopes

IV-Very poor potential

69A Elbert silty clay loam Drainageways IV-Very poor potential

73B Penn silt loam

Sloping convex landscapes I-Good potential

73C Penn silt loam

Sloping convex landscapesI-Good potential

74B Ashburn silt loam

Level to gently sloping

landscapes

II-Fair potential

77C3 Nestoria gravelly

silt loam

Highly dissected terrain

with gullies

II-Fair potential

78A Dulles silt loam

Nearly level landscapes IV-Very poor potential

79A Albano silt loam

Concave landscapes IV-Very poor potential

Appendix B Soil Laboratory Test Results Gradation Test Data (8 pages)

Moisture Density Relationship Test Data (2 pages)

Project No.

Test Boring No.

Lab Order No.

#4 #200

SILTY SAND with gravel 33 24 9 80.2 46.5 SM 19.9

Color

Test Method: ASTM D 4318Soil Classification by ASTM D2487 and AASHTO M 145

Tested by Reviewed by

2/25/2013

LIQUID AND PLASTIC LIMIT - ASTM D4318Project Name Hanson Regional Park

Depth (Feet) 2.5-4.0

12079.05

SB-B1

2917-3 Date

AASHTO Classification

% Passing USCS

A-4

w (%)Material Description LL PL PI

Brown

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)

19955 Highland Vista Dr., Suite 170Ashburn, Virginia 20147(703) 726-8030www.geoconcepts-eng.com

Project No.

Test Boring No.

Lab Order No.

SIEVE % Passing1 ½ " 1003/4" 1003/8" 94#4 80#10 68#20 60#40 56#60 54#100 52#200 46Pan -- Test Method: ASTM D 422

Soil Classification by ASTM D2487 and AASHTO M 145

Tested by: Reviewed by:

2917-3

Project Name

Depth (Feet)

Date

GRAIN SIZE ANALYSIS - ASTM D42212079.05

SB-B1


2.5-4.0

USCS Group Symbol

USCS Group Name

SM

2/25/2013

Cu Cc LL PI

46.5

SILTY SAND with gravel------33

19.833.8

Color BrownA-4

9GravelSand Fines AASHTO Classification

0102030405060708090

100

0.010.1110100Grain Size Diameter (mm)

No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200

CLAYEY SAND 39 25 14 99.8 25.0 SC 17.7

Color



2/25/2013



12079.05

SB-B3

2917-4 Date


% Passing USCS

A-2-6


Brownish Gray

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




2917-4

Project Name

Depth (Feet)

Date


SB-B3


2.5-4.0

USCS Group Symbol

USCS Group Name

SC

2/25/2013

Cu Cc LL PI

25.0

CLAYEY SAND------39

0.274.7

Color Brownish GrayA-2-6


0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200

CLAYEY SAND 31 21 10 100.0 29.5 SC 18.4

Color



Gray

Material Description LL PL PI


% Passing USCS

A-2-4

w (%)

2/25/2013



12079.05

SB-B4

2917-5 Date

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




Color GrayA-2-4


29.5

CLAYEY SAND------31

0.070.5

Cu Cc LL PI

USCS Group Symbol

USCS Group Name

SC

2/25/2013


SB-B4


5.0-6.5

2917-5

Project Name

Depth (Feet)

Date

0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200sandy Lean Clay with gravel

28 20 8 84.6 63.4 CL 8.8

Color



Reddish Brown



% Passing USCS

A-4

w (%)

2/25/2013



12079.05

SB-B5

2917-1 Date

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




Color Reddish BrownA-4


63.4

sandy Lean Clay with gravel------28

15.421.2

Cu Cc LL PI

USCS Group Symbol

USCS Group Name

CL

2/25/2013


SB-B5


0.0-5.0

2917-1

Project Name

Depth (Feet)

Date

0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200

Lean Clay with sand 37 20 17 93.5 80.8 CL 21.2

Color



2/25/2013



12079.05

SB-S1

2917-2 Date


% Passing USCS

A-6


Light Brown

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




2917-2

Project Name

Depth (Feet)

Date


SB-S1


0.0-5.0

USCS Group Symbol

USCS Group Name

CL

2/25/2013

Cu Cc LL PI

80.8

Lean Clay with sand------37

6.512.6

Color Light BrownA-6


0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200POORLY GRADED GRAVEL with silt and sand

28 23 5 45.4 10.0 GP-GM 8.0

Color



2/25/2013


Depth (Feet) 8.5-10

12079.05

SB-S2

2917-6 Date


% Passing USCS

A-1-a


Gray

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




2917-6

Project Name

Depth (Feet)

Date


SB-S2


8.5-10

USCS Group Symbol

USCS Group Name

GP-GM

2/25/2013

Cu Cc LL PI

10.0

POORLY GRADED GRAVEL with silt 142.6

7.428

54.635.5

Color GrayA-1-a


0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200

CLAYEY SAND with gravel 32 23 9 74.5 19.5 SC 11.2

Color



Light Greenish Gray



% Passing USCS

A-2-4

w (%)

2/25/2013



12079.05

SB-S3

2917-7 Date

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




Color Light Greenish GrayA-2-4


19.5

CLAYEY SAND with gravel------32

25.555.0

Cu Cc LL PI

USCS Group Symbol

USCS Group Name

SC

2/25/2013


SB-S3


5.0-6.5

2917-7

Project Name

Depth (Feet)

Date

0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

#4 #200

Lean Clay with sand 36 23 13 91.3 76.2 CL 21.9

Color



Brown



% Passing USCS

A-6

w (%)

2/25/2013



12079.05

SB-S6

2917-8 Date

0

10

20

30

40

50

60

0 10 20 30 40 50 60 70 80 90 100

LIQUID LIMIT (LL)

PLA

STIC

ITY

IN

DEX

(P

I)


Project No.

Test Boring No.

Lab Order No.




Color BrownA-6


76.2

Lean Clay with sand------36

8.715.1

Cu Cc LL PI

USCS Group Symbol

USCS Group Name

CL

2/25/2013


SB-S6


1.5-2.0

2917-8

Project Name

Depth (Feet)

Date

0102030405060708090

100


No.

200

No.

40

No.

4

¾ in

Per

cent

Fin

er


Project No.

Test Boring No.

Lab Order No.

Nat. Moist. (%)

Sp. G. (Assumed)

LL PI% > # 4

% < #200

USCS AASHTOCL A-4

VTM-001


TEST RESULTSMaximum Dry Density (pcf)

After Correc.Before Correc.Color

MOISTURE DENSITY RELATIONSHIP - VTM-001Hanson Regional Park

0.0-5.0

2/25/2013

12079.05

SB-B5

2917-1

Project Name

Depth (Feet)

Date

Optimum Moisture Content (%)

Material

28 8sandy Lean Clay with gravel

Classification

8.8 2.65

Reddish Brown

15.4 63.4

114

15

120

13

105

110

115

120

125

130

0 5 10 15 20

Water Content (%)

Dry

Den

sity

(pc

f)

100% Saturation


Project No.

Test Boring No.

Lab Order No.

Nat. Moist. (%)

Sp. G. (Assumed)

LL PI% > # 4

% < #200

USCS AASHTOCL A-6

VTM-001


80.8

104

20

--

--Optimum Moisture Content (%)

Material

37 17Lean Clay with sand

Classification

21.2 2.65

Light Brown

6.5

Project Name

Depth (Feet)

Date


0.0-5.0

2/25/2013

12079.05

SB-S1

2917-2

MOISTURE DENSITY RELATIONSHIP - VTM-001

Maximum Dry Density (pcf)After Correc.Before Correc.

ColorTEST RESULTS

98

100

102

104

106

108

110

112

114

0 5 10 15 20 25 30

Water Content (%)

Dry

Den

sity

(pc

f)

100% Saturation


preliminary geotechnical engineering report hanson

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