Infiltration and Pavement Design Report by GET Solutions.pdf

RESCUE SWIMMER TRAINING FACILITY

USCG AVIATION TECHNICAL TRAINING CENTER (ATTC)

AT

US COAST GUARD SUPPORT CENTER

ELIZABETH CITY, NORTH CAROLINA

PROJECT NO: 32-X3617

February 26, 2010

Infiltration and Pavement Design Report

UNITED STATES COAST GUARD

FACILITIES DESIGN & CONSTRUCTION CENTER

(FDCC)

5505 ROBIN HOOD ROAD

SUITE K

NORFOLK, VIRGINIA 23513-2413

Frick Building 437 Grant St., North Mezzanine Pittsburgh, PA 15219 Phone: (412) 201-4900 Fax: (412) 201-2338 www.kimballcorp.com

504 East Elizabeth Street Elizabeth City, NC 27909 Phone: (252)335-9765 Fax: (252)335-9766 info@getsolutionsinc.com

February 17, 2010

TO: L. Robert Kimball & Associates 437 Grant Street North Mezzanine – Frick Building Pittsburgh, PA 15219

Attn: Mr. Keith Williams

RE: Report of Subsurface Investigation and Geotechnical Engineering Services Rescue Swimmer Training Facility USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Dear Mr. Williams:

Pursuant to your request, G E T Solutions, Inc. has completed our shallow subsurface investigation and Geotechnical Engineering services associated with the above noted project site. The purpose of this report is to provide the results of our subsurface investigations and our recommendations for storm water and pavement design parameters.

Furthermore, this report is provided in conjunction with our previously completed Subsurface Investigation and Geotechnical Engineering Services reported on the date of December 16, 2009.

Field Exploration and Subsurface Soil Conditions:

Field Exploration:

In order to explore the general subsurface soil types and to aid in developing associated pavement design parameters, four (4) 6- to 7-foot hand auger borings (designated as CBR- 1 through CBR-4) were drilled by G E T Solutions, Inc. within the proposed pavement areas. These explored locations were generally located within the limits of the existing rigid (concrete) paved hangar apron, which was observed to have several areas of pavement failure (cracking, sink-holes, and/or slab rotation). Accordingly, in order to complete the subsurface exploration and sampling procedures a 6 inch diameter core was performed at each “CBR” boring location. In addition to the hand auger boring explorations, bulk CBR soil sampling was performed at each of the “CBR” boring locations.

In order to explore the general subsurface soil types and to aid in developing associated storm water design parameters, four (4) 7.5- to 9-foot hand auger boring (designated as BMP-1 through BMP-4) were drilled by G E T Solutions, Inc. within the proposed storm water management area located south of the proposed building. The boring exploration depths were limited to that noted above due to cave-ins occurring as a result of the encountered ground water levels. In addition to the hand auger boring explorations, Saturated Hydraulic Conductivity (infiltration) testing was performed at the location of borings BMP-1 and BMP-4.

Report of Shallow Subsurface Investigation and Geotechnical Engineering 2/17/10 Rescue Swimmer Training Facility USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

The boring locations were established and located in the field by a representative of G E T Solutions, Inc. by measuring from existing landmarks. The approximate boring locations are shown on the attached “Boring Location Plan” (Appendix I) which was developed based on the site plan provided to G E T Solutions, Inc. by L. Robert Kimball and Associates.

Following the drilling procedures, the recently completed borings were backfilled with boring-grout backfill. Additionally, the borings performed within the existing pavement areas were patched with the use of cold-patch to facilitate continuing use of the apron area

Subsurface Soil Conditions:

The results of our recently and previously completed soil test borings at this site indicated that the existing concrete pavements encountered at the “CBR” boring locations ranged from approximately 6 to 8 inches in thickness. Underlying the existing concrete materials, the typically occurring Aggregate Base Course (ABC) materials were not encountered.

Topsoil encountered at the location of borings BMP-1 through BMP-4, where concrete pavement was not encountered, was noted to range from approximately 6 to 8 inches in thickness. More detailed information regarding the surficial material types and thicknesses are provided in the table below:

Table I: Summary of Surficial Materials

Core / Boring No.

Core / Boring Location Topsoil

Thickness (in.)

Concrete Pavement Thickness

(in.)

BMP-1 Storm Water Management Area; West End 6 N/A BMP-2 Storm Water Management Area; West Third 8 N/A BMP-3 Storm Water Management Area; East Third 7 N/A BMP-4 Storm Water Management Area; East End 6 N/A CBR-1 Pavement Area West of the Proposed Building N/A 6 CBR-2 Pavement Area North of the Proposed Building N/A 7 CBR-3 Pavement Area East of the Proposed Building N/A 8 CBR-4 Pavement Area West of the Existing Taxi-Way N/A 6

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Beneath the existing concrete pavements and/or TOPSOIL, where encountered, the subsurface soils encountered at the boring locations were consistent at the boring locations, to their explored depths, and were arranged in a two (2) layer configuration.

More specifically, the subsurface soils consisted of a CLAY with varying amounts of sand (CL, CH) and/or SILT (ML) underlain by SAND (SP, SP-SM, SM, SC) with varying amounts of silt and clay.

A shallow subsurface deposit of SAND (SP), which appears to be previously placed fill, was encountered at the location of boring CBR-4 and extended from beneath the existing concrete pavement to a depth of about 2 feet. Additionally, underlying this layer of Fill, a deposit of very soft Clayey PEAT (PT) was encountered and noted to extend to a depth of about 2.5 feet below the existing site grade elevations.

The subsurface description is of a generalized nature provided to highlight the major soil strata encountered. The records of the subsurface exploration (Boring Log and the Generalized Soil Profile sheets) attached to this preliminary report should be reviewed for specific information as to individual borings. The stratifications shown on the records of the subsurface exploration represent the conditions only at the actual boring locations.

Variations may occur and should be expected between boring locations. The stratifications represent the approximate boundary between subsurface materials and the transition may be gradual.

Groundwater Information:

The groundwater level was recorded at the location of borings BMP-1 through BMP-4 and CBR-1 through CBR-4 as observed through the wetness of the recovered soil samples during the drilling operations. The initial groundwater table was measured to occur at depths ranging from 4 to 5.3 feet below current grades at the boring locations.

The boreholes were backfilled upon completion for safety considerations. As such, the reported groundwater levels may not be indicative of the static groundwater level.

Shallow perched groundwater levels are anticipated to occur throughout the site as a result of restrictive SAND (SC) and/or CLAY (CL, CH) soil layers, which were encountered throughout the site at depths extending from below the surficial concrete pavements and/or topsoil to depths ranging from 4 feet to 6 feet.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Groundwater conditions will vary with environmental variations and seasonal conditions, such as the frequency and magnitude of rainfall patterns, as well as man-made influences, such as existing swales, drainage ponds, underdrains and areas of covered soil (paved parking lots, sidewalks, etc.). Typical seasonal groundwater fluctuations of 3 feet are common in the project’s area. However, based on our experience with the ground water conditions within the vicinity of the project site, our evaluation of the encountered subsurface soil and ground water conditions, as well as the recent amounts of precipitation occurring within the region, it is our professional opinion that the normal seasonal high ground water level is estimated to occur at an average depth of about 4.5 to 5 feet below the existing site grade elevations within the existing pavement areas, and about 4 to 4.5 feet below the existing site grade elevations within the storm water management area located south of the proposed building. We recommend that the contractor determine the actual groundwater levels at the time of the construction to determine groundwater impact on the construction procedures.

Clearing and Grading Recommendations

The cut depth required to remove the Topsoil materials from within the proposed storm water management area is anticipated to range from about 6 to 8 inches. Clean topsoil should be stockpiled separately from cohesive soils (CLAY; CL, CH, ML) and/or granular soils (SAND; SP, SP-SM, SM, SC) as encountered for later use in landscaped areas.

The proposed pavement overlay areas should be repaired as necessary to remove existing rigid pavements that have experienced failures (cracking, slab rotation, sink-holes, etc.).

This will likely require saw-cutting to minimize disturbance to the existing concrete adjacent to the areas of failing pavements. Based on the results of our subsurface exploration procedures, it is anticipated that the existing pavements range from about 6 to 8 inches in thickness. Accordingly, the removal of the existing concrete pavement within the areas of failure as well as the pavement areas requiring removal to facilitate building construction will require saw cutting to a depth ranging from about 6 to 8 inches (full depth saw-cutting).

The areas of pavement failures should be delineated in the field during construction by G E T Solutions, Inc. immediately prior to paving operations due to the potential for additional pavement failures to occur during its continuing use. Furthermore, the existing storm drain piping is suspected to be causing subsurface erosion and sink-holes. It is considered necessary to further evaluate the condition of the existing storm drain piping in order to prevent pavement failures from re-occurring and/or to prevent new failures from developing within additional areas.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Following the removal of the concrete pavements, where required, the newly exposed subgrade soils should be evaluated as indicated in the following section of this report. It is likely that undercut operations will be required within pavement repair areas that are located within the vicinity of boring CBR-4 as unsuitable organic soils were encountered at this explored location. In the event that the subsurface organic soils within this general area extend beyond the areas of pavement failure to be replaced, it would be considered advisable to remove the existing pavements and underlying organic soils as necessary in order to provide suitable pavement support and to develop the associated pavement design parameters indicated herein. In the event that these subsurface organic soils are allowed to remain in-place, future pavement settlements, failures, and/or a reduced pavement life span are anticipated to occur.

The subsurface soils recovered at the location of borings BMP-1 through BMP-4 and CBR- 1 through CBR-4 typically contained appreciable amounts of fines. Accordingly, combinations of excess surface moisture from precipitation ponding on the site and the construction traffic, including heavy compaction equipment, may create pumping and general deterioration of the bearing capabilities of the surface soils. Therefore, undercutting to remove very soft soils may be required. The extent of the undercut will be determined in the field during construction, based on the outcome of the field testing procedures (subgrade proofroll).

Furthermore, inherently wet subgrade soils combined with potential poor site drainage make this site particularly susceptible to subgrade deterioration. Thus, grading should be performed during a dry season if at all possible. This should minimize these potential problems, although they may not be eliminated. The project’s budget should include an allowance for subgrade improvements (undercut and backfill with select fill or Aggregate Base Course material).

Control of surface water is very important to the successful completion of the proposed construction. The contractor should plan his grading activities to control surface water and minimize erosion of exposed cut or fill material. This may include constructing temporary berms, ditches, flumes and/or slope drains to intercept runoff and discharge it in a controlled fashion, while complying with state and local regulations.

It is recommended that the clearing operations extend laterally at least 3 feet beyond the perimeter of the proposed construction areas. The project’s budget should include an allowance for subgrade improvements (undercut and backfill with select fill).

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Subgrade Preparation – Pavement Areas

The subgrade soils should be densified with a large vibratory drum roller. After the subgrade soils have been densified, they should be evaluated by G E T Solutions, Inc. for stability. Accordingly, the subgrade soils should be proofrolled to check for pockets of very loose material hidden beneath a crust of better soil. Several passes should be made by a large rubber-tired roller or loaded dump truck over the construction areas, with the successive passes aligned perpendicularly. The number of passes will be determined in the field by the Geotechnical Engineer depending on the soils conditions. Any pumping and unstable areas observed during proofrolling (beyond the initial cut) should be undercut and/or stabilized at the directions of the Geotechnical Engineer.

It is recommended that the subgrade evaluation include a series of test pit excavations in order to further evaluate the suitability of the subgrade soils to properly support the proposed pavement sections. The depth and location of the test pit excavations should be determined in the field during construction by the Geotechnical Engineer. Those areas requiring undercut as well as the test pit excavations should be backfilled as indicated in the following section of this report.

The existing storm drain piping is suspected to be causing subsurface erosion and sink-holes. It is considered necessary to further evaluate the condition of the existing storm drain piping in order to prevent pavement failures from re-occurring and/or to prevent new failures from developing within other areas.

As indicated in the previous section of this report, undercut operations are anticipated to be required to remove unsuitable organic soils where pavement repair areas occur within the vicinity of boring CBR-4. In the event that the subsurface organic soils within this general area extend beyond the areas of pavement failure to be replaced, it would be considered advisable to remove the existing pavements and underlying organic soils as necessary in order to provide suitable pavement support and to develop the associated pavement design parameters indicated herein. Additionally, the condition of the existing storm drain piping should be evaluated if it coincides with the location of the necessary repair areas. In the event that subsurface organic soils and/or unimproved storm drain piping are allowed to remain in-place, future pavement settlements, failures, and/or a reduced pavement life span are anticipated to occur.

Following the proofroll and approval by the engineer, it is recommended that, within the construction areas, natural soils below stripped grade should be compacted to a dry density of at least 95 percent of the Modified Proctor maximum dry density (ASTM D 1557), as tested to a depth of 24-inches, where possible. This densification will require the use of a large vibratory roller and should be evaluated by G E T Solutions, Inc. during the compaction operations to ensure the deterioration of the subgrade soils does not occur.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Select Fill and Placement

Any material to be used for backfill or select fill should be evaluated and tested by G E T Solutions, Inc. prior to placement to determine if they are suitable for the intended use. Suitable select fill material should consist of sand or gravel containing less than 20 percent by weight of fines (SP, SM, SW, GP, GW), having a liquid limit less than 20 and plastic limit less than 6, and should be free of rubble, organics, clay, debris and other unsuitable material.

All select fill should be compacted to a dry density of at least 95 percent of the Modified Proctor maximum dry density (ASTM D1557). In general, the compaction should be accomplished by placing the fill in maximum 10-inch loose lifts and mechanically compacting each lift to at least the specified minimum dry density. A representative of G E T Solutions, Inc. should perform field density tests on each lift as necessary to assure that adequate compaction is achieved.

Backfill material in utility trenches within the construction areas should consist of structural fill (as described above), and should be compacted to at least 95 percent of ASTM D1557.

This fill should be placed in 4 to 6 inch loose lifts when hand compaction equipment is used.

Pavements

The California Bearing Ratio (CBR) test results indicated soaked CBR values ranging from

11.3 to 12.3, averaging 11.9. The CBR results from the bulk sample obtained at the location of CBR-4 were not considered when calculating the average CBR value due to the underlying PEAT (PT) layer encountered at this boring location. The average CBR value obtained from the laboratory CBR testing procedures was multiplied by a factor of two-thirds to determine a pavement design CBR value. The two-thirds factor provides the necessary safety margins to compensate for some non-uniformity of the soil. Therefore, a CBR value of 7.9 was used in the pavement design analysis. A comprehensive summary of the CBR test data and the moisture density relationship curves (Proctors) are attached to this report.

As indicated previously in this report, the project’s budget should include an allowance for subgrade improvements. It is anticipated that subgrade improvements may be required where very soft and/or unstable CLAY (CL, CH) and/or SILT (ML) soils occur within the pavement areas. These soils may require subgrade improvements in the form of undercut and replacement with the use of select backfill materials. Alternatively, the use of Geotextile Geofabric or Geogrid may be used to provide suitable pavement support. This should be determined in the field by G E T Solutions, Inc. during the subgrade evaluation process.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

At this time, it is proposed that the existing concrete materials to be removed from the project site are to be crushed and re-used as Aggregate Base Course (ABC) materials within areas requiring pavement “replacement”. In the event that quality control testing in the form of sampling and laboratory analysis is not performed during crushing operations, the crushed concrete materials can exhibit slightly finer gradations and slightly lower CBR values than that of crushed granite. Accordingly, it is considered to be essential to develop and maintain a quality control program during the crushing operations to ensure that the proposed ABC materials adhere to the NCDOT requirements for ABC materials and that a minimum CBR value of 50 is obtained in order to develop the design criteria used to determine the allowable loading criteria discussed in the following sections of this report.

The pavement design criteria were not available for our pavement analysis. Accordingly, at this time we selected the minimum pavement section thicknesses required in the RFP documents and determined the allowable Average Daily Traffic (ADT) with percent trucks and resulting Equivalent Single Axle Load (ESAL) values. More detailed information regarding the results of our analysis is provided in the following sections of this report relative to each type of pavement construction.

Pavement Replacement:

The portion of the pavement areas located adjacent to the proposed building (north, east, and west perimeters) are to be replaced following the construction of the building.

Furthermore, the complete removal of the existing concrete pavements is to occur and replaced with asphalt pavements. Accordingly, subgrade evaluations should be performed as previously indicated prior to the placement of the ABC materials.

The RFP pavement section provided in the following table (Table II) was used along with WinPAS software and the results of our laboratory CBR testing to determine the allowable loading criteria (ADT, %trucks, and associated ESALs). In the event that the allowable loading criteria noted in the following table are considered to be insufficient, a supplemental pavement design analysis will be required and will result in increased pavement section thicknesses.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Table II –Pavement Sections: Asphalt Pavement Replacement

Hot Mix Asphalt Section Surface

(S-9.5b) Aggregate Base* Subgrade**

Asphalt Pavement Replacement (Light Duty –

Vehicles Only) 2” 6”

Firm, Stable, and Compacted

Average Daily Traffic: Up to 100 Vehicles/Day Percent Trucks: 4% Design Life Criteria: 20 Years Percent Growth Rate: 0.0% Total Design ESALs: 38,426 Reliability = 75.0%

Overall Deviation = 0.45 Soil Resilient Modulus = 7,989.8 psi Initial Serviceability = 4.20 Terminal Serviceability = 2.50 Required Structural No. = 1.77 Pavement Section Structural No. = 1.78

* NCDOT ABC compacted to a dry density of at least 100% of the Modified Proctor maximum dry density

(ASTM D 1557).

** Compacted to a dry density of at least 95% of the Modified Proctor maximum dry density (ASTM D 1557).

The results of the pavement design analysis are attached to this report. All pavement material and construction procedures should conform to Unified Facilities Criteria (UFC) and/or North Carolina Department of Transportation (NCDOT) requirements.

Following pavement rough grading operations, the exposed subgrade, where exposed, should be observed under proofrolling. This proofrolling should be accomplished with a fully loaded dump truck or 7 to 10 ton drum roller to check for pockets of soft material hidden beneath a thin crust of better soil. Any unsuitable materials thus exposed should be removed and replaced with a well-compacted material. The inspection of these phases should be performed by the Geotechnical Engineer or his representative. The subgrade soils are likely to be unstable at the time of construction and some ground improvements are likely. As such, the project’s budget should include a contingency to accommodate the potential ground improvements.

Where excessively unstable subgrade soils are observed during proofrolling and/or fill placement, it is expected that these weak areas can be stabilized by means of thickening the base course layer by 2 to 4 inches and/or lining the subgrade with geotextile fabric (Mirafi 500x or equivalent). These alternatives are to be addressed by the Geotechnical Engineer during construction, if necessary, who will recommend the most economical approach at the time.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Asphalt Pavement Overlay:

Following the completion of our pavement analysis for the portions of the existing concrete pavements to remain and to be overlaid with asphalt, it was determined that the overlay thickness indicated in the RFP documents (1.5 inches) would not appreciably increase the allowable loading criteria. Initially, the use of a 1.5 inch overlay would improve the appearance of the surface conditions. However, it will not provide a significant increase in structural integrity, and will likely exhibit similar surface conditions of the existing pavements within a relatively short period of time.

Furthermore, based on our pavement design analysis with the use of PCASE software (Army Corps of Engineer Design methods) the existing pavements can withstand a loading criterion of about 100 vehicles per day with 10% trucks, or 1 trip per month with a C-130 aircraft. Any slight increase of this allowable loading criterion will result in the necessity to overlay the existing pavements with a minimum of 4 inches of asphalt. Additional information regarding the loading criteria and the PCASE minimum required asphalt overlay thickness is provided in Tables III and IV below and on the following page of this report.

Table III –Pavement Sections: Light Duty Overlay

Hot Mix AsphaltSection Surface (S-9.5b)

Concrete Pavement *

Aggregate Base** Subgrade***

Existing Concrete Pavement With Asphalt Overlay (Light Duty –

Vehicles Only)

4.0” Existing

Pavement = 6”

6” Within Areas of Existing Failure

Requiring Corrective

Procedures

Areas of Existing Failure Should Be Removed and The Subgrade Soils Should be Firm, Stable, and Compacted Average Daily Traffic: Up to 100 Vehicles/Day Percent Trucks: 15% Design Life Criteria: 20 Years Percent Growth Rate: 0.0% Equivalent Passes: 73,000 passes of a 3 axle 35,000 lb Truck Effective Subgrade Modulus = 180 pci

* The proposed concrete repair noted above should be constructed as necessary to match the existing grades and thickness of the original concrete pavement (minimum concrete thickness of 6 inches).

** NCDOT ABC compacted to a dry density of at least 100% of the Modified Proctor maximum dry density

(ASTM D 1557).

*** Compacted to a dry density of at least 95% of the Modified Proctor maximum dry density (ASTM D 1557).

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Table IV –Pavement Sections: Heavy Duty Overlay

Hot Mix AsphaltSection Surface (S-9.5b)

Concrete Pavement *

Aggregate Base** Subgrade***

Existing Concrete Pavement With Asphalt Overlay (Heavy Duty –

Aircraft)

4.0” Existing

Pavement = 6”

6” Within Areas of Existing Failure

Requiring Corrective

Procedures

Areas of Existing Failure Should Be Removed and The Subgrade Soils Should be Firm, Stable, and Compacted Average Monthly Aircraft Traffic: Up to 1 Trip/Month Design Life Criteria: 20 Years Percent Growth Rate: 0.0% Equivalent Passes: 950 passes of a C-130 Aircraft Effective Subgrade Modulus = 180 pci

* The proposed concrete repair noted above should be constructed as necessary to match the existing grades and thickness of the original concrete pavement (minimum concrete thickness of 6 inches).

** NCDOT ABC compacted to a dry density of at least 100% of the Modified Proctor maximum dry density

(ASTM D 1557).

*** Compacted to a dry density of at least 95% of the Modified Proctor maximum dry density (ASTM D 1557).

The results of the pavement design analysis are attached to this report. All pavement material and construction procedures should conform to Unified Facilities Criteria (UFC) and/or North Carolina Department of Transportation (NCDOT) requirements.

Portions of the existing concrete pavements that are to be overlain with asphalt materials have experienced failures. Accordingly, the areas of pavement failure should be removed and the underlying subgrade soils improved as necessary to provide suitable pavement support. The areas requiring removal and the associated subgrade improvements should be determined in the field by G E T Solutions, Inc. prior to placement of the asphalt pavements.

It is likely that undercut operations will be required where areas of concrete pavement repair are required that occur within the vicinity of boring CBR-4. This is anticipated to be required in order to remove subsurface organic deposits and to develop the soil design parameters indicated herein. In the event that the subsurface organic soils within this general area extend beyond the areas of pavement failure to be replaced, it would be considered advisable to remove the existing pavements and underlying organic soils as necessary in order to provide suitable pavement support and to develop the associated pavement design parameters indicated herein. In the event that these subsurface organic soils are allowed to remain in-place, future pavement settlements, failures, and/or a reduced pavement life span are anticipated to occur.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Following the subgrade improvements within the pavement repair areas, where necessary, it is recommended that the existing concrete pavement be reconstructed to match the existing grades and thicknesses. Furthermore, it is recommended that any area requiring removal of pavement failures and re-construction of the concrete pavements be underlain by at least 6 inches of ABC materials, which is anticipated to consist of crushed concrete.

It is recommended that the Civil Engineer of Record determine if dowels are required and/or necessary spacing of dowels for load transfer at the interface of the existing and replacement concrete pavement areas.

The existing storm drain piping is suspected to be causing subsurface erosion and sink-holes. Accordingly, it is considered necessary to further evaluate the condition of the existing storm drain piping in order to prevent pavement failures from re-occurring and/or to prevent new failures from developing within other areas.

Additionally, it is likely that reflective cracking from the existing concrete pavement control and/or construction joints will transmit to the surface of the asphalt overlay. This reflective cracking will decrease the overall appearance and lifespan of the asphalt overlay and raveling and/or delimitation of the overlay is likely to occur. In order to minimize the potential for reflective cracking to occur, it is recommended that an extensive joint repair program be implemented and that an appropriate crack control material (such as Petromat, or equivalent) be placed on the exposed surface of the existing concrete pavements prior to placement of asphalt materials. Furthermore, it is considered to be advisable to consult with a product manufacturer to further determine the appropriate material suitable for the existing conditions in order to effectively reduce the potential for reflective cracking to occur. It is noted that the use of crack control methods will reduce, but not completely eliminate, the potential for reflective cracking to occur.

Following pavement rough grading operations, the exposed subgrade, where exposed, should be observed under proofrolling. This proofrolling should be accomplished with a fully loaded dump truck or 7 to 10 ton drum roller to check for pockets of soft material hidden beneath a thin crust of better soil. Any unsuitable materials thus exposed should be removed and replaced with a well-compacted material. The inspection of these phases should be performed by the Geotechnical Engineer or his representative. The subgrade soils are likely to be unstable at the time of construction and some ground improvements are likely. As such, the project’s budget should include a contingency to accommodate the potential ground improvements.

Where excessively unstable subgrade soils are observed during proofrolling and/or fill placement, it is expected that these weak areas can be stabilized by means of thickening the base course layer by 2 to 4 inches and/or lining the subgrade with geotextile fabric (Mirafi 500x or equivalent). These alternatives are to be addressed by the Geotechnical Engineer during construction, if necessary, who will recommend the most economical approach at the time.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

Storm Water Design Parameters

Two (2) infiltration tests were performed at the location of borings BMP-1 and BMP-4. The tests were performed at depths of about 3.5 feet below current grades. The boreholes were prepared utilizing an auger to remove soil clippings from the base. Infiltration testing was then conducted within the vadose zone utilizing a Precision Permeameter and the following testing procedures.

A support stand was assembled and placed adjacent to each borehole. This stand holds a calibrated reservoir (200 ml or 2000 ml) and a cable used to raise and lower the water control unit (WCU). The WCU establishes a constant water head within the borehole during testing by use of a precision valve and float assembly. The WCU was attached to the flow reservoir with a 4-meter (approximately 13-foot) braided PVC hose and then lowered by cable into the borehole to the test depth elevation.

As required by the Glover solution, the WCU was suspended above the bottom of the borehole at an elevation of approximately 5 times the borehole diameter. The shut-off valve was then opened allowing water to pass through the WCU to fill the borehole to the constant water level elevation. The absorption rate slowed as the soil voids became filled and an equilibrium developed as a wetting bulb developed around the borehole. Water was continuously added until the flow rate stabilized. The reservoir was then re-filled in order to begin testing.

During testing, as the water drained into the borehole and surrounding soils, the water level within the calibrated reservoir was recorded as well as the elapsed time during each interval. The test was continued until relatively consistent flow rates were documented.

During testing the quick release connections and shutoff valve were monitored to ensure that no leakage occurred. The flow rate (Q), height of the constant water level (H), and borehole diameter (D) were used to calculate Ks utilizing the Glover Solution. Based on the field testing and corroborated with laboratory testing results (published values compared to classification tests), the hydraulic conductivity of the shallow soils is tabulated in the following table (Table III) and is presented on the attached “Hydraulic Conductivity Worksheet” reports.

Table IV - Saturated Hydraulic Conductivity Test Results

Average Infiltration Test Results (Ksat Values)Test No.

Test Depth (ft*)

Groundwater Level (*ft.)

Percent Silt and/or Clay cm/sec cm/day in/hour

BMP-1 3.5 5.2 90.7 8.72E-08 0.0 0.000

BMP-4 3.5 5.3 78.9 1.00E-07 0.0 0.000

* The ground water level was initially encountered at depths ranging from 5.2 to 5.3 feet below the existing site grade elevations at the BMP boring locations. 48-hour ground water level readings were not performed.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

It is noted that the granular soils noted to occur slightly below the tested depths could provide greater rates of infiltration. However, these soils were encountered at or below the groundwater level encountered during our field exploration and testing procedures.

Accordingly, the saturated hydraulic conductivity testing could not be performed within these soils. Furthermore, these soils were evaluated to occur at depths below the estimated normal seasonal high groundwater levels.

Drainage and Groundwater Concerns

It is expected that dewatering may be required for excavations that extend near or below the existing groundwater table. Dewatering above the groundwater level could probably be accomplished by pumping from sumps. Dewatering at depths below the groundwater level may require well pointing.

If water collects in any excavations, it will be necessary to remove the water form the excavation, remove the saturated soils, and re-test the adequacy of the bearing surface soils to support the pavements.

Perched water table conditions within the select fill materials and/or shallow subsurface soils may be encountered throughout the project site during periods of heavy precipitation and/or during the “wet” season. This is expected to occur as a result of the surficial and/or shallow subsurface restrictive soil layers generally encountered throughout the project site at depths ranging from about 0.5 feet to 6 feet.

Accordingly, some undercut and backfill with suitable structural fill materials and/or de-watering of the structural fill materials and/or shallow subsurface soils may be required during the subgrade preparation procedures. Alternatively, an under drain system may be used in order to aid in alleviating the potential for saturated bearing soil conditions and/or to aid in minimizing foundation undercutting procedures.

It would be advantageous to construct all fills early in the construction. If this is not accomplished, disturbance of the existing site drainage could result in collection of surface water in some areas, thus rendering these areas wet and very loose. Temporary drainage ditches should be employed by the contractor to accentuate drainage during construction.

If water collects in foundation excavations, it will be necessary to remove water from the excavations, remove saturated soils, and re-test the adequacy of the bearing surface soils to support the design bearing pressure prior to concrete placement.

USCG Support Center Pasquotank County, North Carolina GET Project No: EC09-278G

We trust that the information contained herein meets your immediate need, and we would ask that you call this office with any questions that you may have.

Respectfully Submitted, G E T Solutions, Inc.

Gerald W. Stalls Jr., P.E.

Senior Project Engineer NC Reg. # 034336

Camille A. Kattan, P.E.

Principal Engineer NC Reg. # 14103

Attachments: Boring Location Plan Log of Borings (BMP-1 through BMP-4 and CBR-1 through CBR-4) General Soil Profile (BMP-1 through BMP-4 and CBR-1 through CBR-4) Summary of CBR Test Results and Moisture Density Relationship Test Reports Pavement Design Analysis Saturated Hydraulic Conductivity Worksheet(s); (BMP-1 and BMP-4)

Copies: (3) Client

0.8

1.6

2.4

3.2

6 inches of Topsoil

0.5 Tan, moist, Lean CLAY (CL) to Fat CLAY (CH)

Gray-Tan from 1 foot Tan from 1.5 feet

Gray with slight Reddish Tan mottling from 3 feet

Mottled Reddish Tan-Gray and with Sand from 4 feet

Estimated Normal Seasonal High Water Table = 4.5 feet

Mottled Gray-Reddish Tan, moist to wet, poorly graded fine to medium SAND (SP-SM) with silt to Silty fine SAND (SM) with trace Clay

Wet from 5.2 feet Tan from 6 feet

Mottled Tan-Gray from 7 feet

Tan from 8 feet

Boring terminated at 9 ft.

90.7

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA MSL

BORING LOG

BMP-1

DRILLER: P. Lankford, E.I.T. LOGGED BY: G. Stalls, PE

DRILLING METHOD: Hand Auger DATE: 1-27-10

DEPTH TO WATER - INITIAL*: 5.2' AFTER 24 HOURS: CAVING> 9'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

8 inches of Topsoil

0.7 Tan, moist, Lean CLAY (CL) with sand to Fat CLAY (CH)

Tan- Gray from 2 feet

Mottled Gray-Reddish Tan from 2.5 feet Mottled Reddish Tan-Gray from 2.75 feet

Mottled Gray-Reddish Tan from 3 feet 3.5

Mottled Gray-Reddish Tan, moist, Silty fine SAND (SM) with trace Clay

3.75 Mottled Tan-Reddish Tan, moist, Clayey fine SAND (SC) with silt, with poorly graded fine to medium SAND (SP-SM) lenses

Tan, moist to wet, poorly graded fine to medium SAND (SP-SM) with silt to Silty fine SAND (SM) with trace clay

Estimated Normal Seasonal High Water Table = 4 feet Reddish Brown from 5 feet

Wet from 5.1 feet

Tan from 6.5 feet

Boring terminated at 9 ft.

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA MSL

BORING LOG

BMP-2

DRILLER: P. Lankford, E.I.T. LOGGED BY: G. Stalls, PE

DRILLING METHOD: Hand Auger DATE: 1-27-10

DEPTH TO WATER - INITIAL*: 5.1' AFTER 24 HOURS: CAVING> 9'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

7 inches of Topsoil

0.6 Tan-Gray, moist, Lean CLAY (CL) with sand to Fat CLAY (CH)

Mottled Gray-Reddish Tan from 2.5 feet

Mottled Gray-Reddish Tan from 3 feet

Mottled Reddish Tan-Gray, moist to wet, poorly graded fine to medium SAND (SP-SM) with silt to Silty fine SAND (SM) with trace clay

Estimated Normal Seasonal High Water Table = 4 feet Tan-Brown from 4.5 feet

Wet from 4.9 feet

Tan from 7 feet

Boring terminated at 9 ft.

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA MSL

BORING LOG

BMP-3

DRILLER: P. Lankford, E.I.T. LOGGED BY: G. Stalls, PE

DRILLING METHOD: Hand Auger DATE: 1-27-10

DEPTH TO WATER - INITIAL*: 4.9' AFTER 24 HOURS: CAVING> 9'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

6 inches of Topsoil

0.5 Tan-Gray, moist, Lean CLAY (CL) with sand to Fat CLAY (CH)

Mottled Tan-Reddish Tan from 2 feet

Mottled Gray-Reddish Tan from 3 feet

Mottled Reddish Tan-Tan, moist, poorly graded fine to medium SAND (SP-SM) with silt to Silty fine SAND (SM) with trace clay

Estimated Normal Seasonal High Water Table = 4 feet Tan from 4.5 feet

Tan, moist to wet, poorly graded fine to medium SAND (SP) to poorly graded fine to medium SAND (SP-SM) with silt Wet from 5.3 feet

Boring terminated at 7.5 ft.

78.9

13.4

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA MSL

BORING LOG

BMP-4

DRILLER: P. Lankford, E.I.T. LOGGED BY: G. Stalls, PE

DRILLING METHOD: Hand Auger DATE: 1-27-10

DEPTH TO WATER - INITIAL*: 5.3' AFTER 24 HOURS: CAVING> 7.5'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

6 inches of Concrete Pavement

0.5 Gray-Tan, moist, SILT (ML) to Lean CLAY (CL)

Mottled Gray-Reddish Tan from 2.5 feet

3.5 Mottled Gray-Reddish Tan, moist, Fat CLAY (CH)

4.5 Tan-Gray, moist to wet, Silty fine SAND (SM) with trace Clay

Wet from 5 feet

Tan, wet, poorly graded fine to medium SAND (SP) to poorly graded fine to medium SAND (SP-SM) with silt

Boring terminated at 7 ft.

HA

BS

HA

HA

HA

84.4

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA

BORING LOG

CBR-1

DRILLER: G E T Solutions, Inc. LOGGED BY: P. Lankford, EIT

DRILLING METHOD: Hand Auger DATE: 2-1-10

DEPTH TO WATER - INITIAL*: 5' AFTER 24 HOURS: CAVING> 7'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

7 inches of Concrete Pavement

0.6 Gray, moist, SILT (ML) to Lean CLAY (CL)

Mottled Gray-Reddish Tan from 1.5 feet

Mottled Tan-Reddish Tan, moist, Clayey fine SAND (SC) with silt

3.5 Tan-Gray, moist to wet, poorly graded fine to medium SAND (SP-

SM) with silt to Silty fine SAND (SM)

Wet from 4.5 feet

Boring terminated at 6 ft.

HA

BS

HA

HA

90.2

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA

BORING LOG

CBR-2

DRILLER: G E T Solutions, Inc. LOGGED BY: P. Lankford, EIT

DRILLING METHOD: Hand Auger DATE: 2-1-10

DEPTH TO WATER - INITIAL*: 4.5' AFTER 24 HOURS: CAVING> 6'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

8 inches of Concrete Pavement

0.7 Gray-Tan, moist, SILT (ML) to Lean CLAY (CL)

Mottled Gray-Reddish Tan from 1 foot

4.5 Mottled Gray-Reddish Tan, moist to wet, poorly graded fine to medium SAND (SP-SM) with silt to Silty fine SAND (SM) Wet from 5 feet

Boring terminated at 7 ft.

HA

BS

HA

89.3

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA

BORING LOG

CBR-3

DRILLER: G E T Solutions, Inc. LOGGED BY: P. Lankford, EIT

DRILLING METHOD: Hand Auger DATE: 1-29-10

DEPTH TO WATER - INITIAL*: 5' AFTER 24 HOURS: CAVING> 7'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R ec ov er y S am pl e T yp e

B lo w s pe r

6"

N -V al ue

0 TEST RESULTS

10 20 30 40 50 60 70 N-Value - Moisture Content - Plastic Limit Liquid Limit

T h is i n fo rm at io n p er ta in s o n ly t o t h is b o ri n g a n d s h o u ld n o t b e in te rp re te d a s b ei n g i n d ic it iv e o f th e si te

Standard Penetration Tests were performed in the field in general accordance with ASTM D 1586.PAGE 1 of 1

1.6

2.4

3.2

6 inches of Concrete Pavement

0.5 Tan, moist, poorly graded fine to medium SAND (SP); FILL

Black, moist, Silty, Clayey PEAT (PT)

2.5 Gray, moist, SILT (ML) to Lean CLAY (CL)

3.5 Gray, moist to wet, Fat CLAY (CH)

Wet from 4 feet

Boring terminated at 6 ft.

HA

BS

HA

HA

1.7

PROJECT: Rescue Swimmer Training Facility; USCG Support Center

CLIENT: L. Robert Kimball & Associates

PROJECT LOCATION: Elizabeth City, North Carolina PROJECT NO.: EC09-278G

BORING LOCATION: See Attached Boring Location Plan SURFACE ELEVATION: INA

BORING LOG

CBR-4

DRILLER: G E T Solutions, Inc. LOGGED BY: P. Lankford, EIT

DRILLING METHOD: Hand Auger DATE: 1-29-10

DEPTH TO WATER - INITIAL*: 4' AFTER 24 HOURS: CAVING> 6'

Notes: SS = Split Spoon Sample ST = Shelby Tube Sample HA = Hand Auger Sample BS = Bulk Sample

*The initial groundwater reading may not be indicative of the static groundwater level. WOH = Weight of Hammer

E le va tio n (M

S L) ft)

D ep th (m et er

s) D ep th

(f ee t)

Description

G ra ph ic

S am pl e

N o.

S am pl e

R…