B08_Attach_7_NISI_Pavement_Investigation___Analysis_Report.pdf

National Park Service U.S. Department of the Interior

PAVEMENT INVESTIGATION AND ANALYSIS REPORT

Ninety Six National Historic Site (NISI) NPS Contract No. 140P2022D0002 NPS Task Order No. 140P2025F0167

PMIS 334915

July 28, 2025

Table of Contents

1.0 Project Description

2.0 Scope of Work – Predesign (PD) Phase

2.1 Review of RIP Data

2.2 Review of FY19 Pavement Preservation Design Scoping Report for NISI

2.3 On-Site Scoping

3.0 Scope of Work – Design Development (DD) Phase

3.1 70% Design Site Visit

3.2 Subsurface Sampling and Investigation

3.3 Review of Available Traffic Data

3.4 Construction Estimate Summary

4.0 Pavement Analysis, Findings, and Recommendations

Appendix A – Project Location

Appendix B – Scoping Site Visit Field Notes and Photos

Appendix C – Traffic Data

Appendix D – Construction Cost Estimate Summary

Appendix E – Construction Schedule Summary

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1.0 Project Description

National Park System (NPS) retained AECOM Services, Inc. (AECOM) to provide engineering services related to pavement preservation at multiple parks in South Carolina. Preservation is the strategy designed to maintain and restore the overall condition of relatively new pavements that are in good to fair condition (distress severity and extent are low/moderate) by protecting them from water intrusion and limiting oxidation using treatments such as crack seal, slurry seal, chip seal, micro surfacing, and thin overlays. Pavement preservation treatments generally can extend the life of pavement in good or fair condition by 5-7 years and delay more expensive and intrusive rehabilitation activities.

As outlined in the project Scope of Services, the goal is to evaluate selected paved roads and parking areas at the Ninety Six National Historic Site (NISI) and identify suitable pavement preservation or rehabilitation treatments. AECOM conducted pre-design activities, including an on-site scoping site visit and review of available project documents, to perform an initial pavement assessment. The findings were documented in a Pavement Analysis Report dated February 22, 2025. This report supplements the February 2025 pavement analysis by incorporating findings from additional pavement investigations and analyses conducted by AECOM during the Design Development (DD) phase. It presents the final recommendations for pavement treatment options for the designated roads and parking areas at NISI, in accordance with Chapter 11 of the Federal Highway Administration (FHWA) Project Design and Development Manual.

To ensure continuity and completeness in documenting the pavement evaluation efforts and findings, the activities conducted during the predesign (PD) phase are discussed in Section 2 of this report, while the DD phase activities are documented in Section 3. Section 4 contains the findings and recommendations. The specific roadway and parking lot sections are listed in Table 1, and the project location is provided in Appendix A.

2.0 Scope of Work – Predesign (PD) Phase

AECOM performed the following activities at NISI during the predesign phase:

2.1 Review of RIP Data

NPS provided AECOM with the Federal Highway Administration’s (FHWA) Road Inventory Program (RIP) report for NISI (Cycle 6 Final Report – Road Inventory and Condition Assessment of Paved Road, November 2021). AECOM reviewed the RIP report to obtain the roadway inventory and existing condition information for the target road and parking lot sections of NISI; i.e., sections identified by the RIP report as candidates for pavement preservation as well as sections adjacent to candidate section(s) and/or sections deemed to be in similar condition to candidate section(s).

Table 1 summarizes the relevant RIP data for the candidate/added section of NISI.

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Table 1: NISI Target Road/Parking Lot Sections RIP Data

ROUTE ID ROAD

AREA

(SF)

LENGTH

(MILES)

WIDTH

(FT)

PAVEMENT

TYPE

PCR

RECOMMENDED

TREATMENT

NISI-0400AZ MAINTENANCE ACCESS ROAD A 0.12 11.0 Asphalt 100 Localized Repair

NISI-0900 VISITOR CENTER PARKING 20,974 Asphalt 97 Localized Repair NISI-0901 MAINTENANCE AREA PARKING 6,978 Asphalt 97 Localized Repair

Notes:

1) PCR = Pavement Condition Rating, L3R = Light Rehabilitation, H3R = Heavy Rehabilitation

2) Throughout this report, Added Sections are shown in BLUE.

2.2 Review of FY19 Pavement Preservation Design Scoping Report for NISI

NPS provided AECOM with the Design Scoping Report for the previous round of pavement preservation project for NISI (NP-SER PMS FY19). A review of this report indicated that all NISI target sections were also considered for pavement preservation treatments as part of the FY19 project.

Further discussions with the NPS team and the Park Units and a review of other relevant project documents confirmed that these sections received pavement preservation as part of the SER PMS FY19 Project. The available project plans noted that the applied preservation treatment at the NISI sections included a chip seal with a 2-inch asphalt overlay.

2.3 On-Site Scoping

AECOM performed an on-site scoping field visit on November 25, 2024, along with members of the NPS project team and the NISI Park Unit team. Per the project scope, the on-site scoping field visit was conducted to evaluate the current site conditions of the park sections listed in Table 1. The project team’s on-site scoping field visit activities included the following:

• Conduct tailgate safety briefings with the project team and sign Task Hazard Assessment

(THA).

• Discuss the scope and objectives of the on-site field visits with the Park Unit Team.

• Gather site-specific information from the Park Unit Team including:

- Priorities of roadways to treat,

- Other ongoing/planned projects that may impact the planned pavement treatment work,

- Concerns with existing roadway configurations (one-way roads),

- Any present or anticipated changes in vehicular traffic volume and/or type within the park.

- Past safety incidents/concerns related to roadway signage reported by park users,

- Past pavement preservation/rehabilitation work at the park and experiences with those treatments,

- Any other relevant information such as staging areas, permitting requirements, etc.

• Conducting the site walk of each roadway/parking lot section to:

- Evaluate the existing pavement condition, including estimating cracks and identifying the pavement preservation treatment.

- Evaluate the conditions of existing curbs, gutters, wheel stops, drainage inlets, ADA ramps, etc., and note improvement requirements.

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- Provide opinion on the condition and adequacy of existing roadway and parking signage, including handicap parking signs.

- Review the existing striping (including the need for scarifying thermoplastic prior to treatments) and the need for striping parking stalls, as well as add/relocate handicap parking spots.

The draft on-site scoping field meeting minutes were submitted to NPS on December 15, 2024, and the final meeting minutes (revised per NPS comments) were submitted to NPS on January 17, 2025.

The field notes from the on-site scoping field meeting including geo-referenced photographs taken by the project team are included in Appendix B.

3.0 Scope of Work – Design Development (DD) Phase

AECOM performed the following activities during the DD phase to finalize the pavement preservation treatment recommendations for the NISI sections:

3.1 70% Design Site Visit

A 70% design site visit was deemed unnecessary, as all the required design data had already been collected during the scoping site visit. Any additional information needed was obtained from the NPS’s Pathweb roadway image system.

3.2 Subsurface Sampling and Investigation

Field observations from the scoping site visit indicated that the pavement at NISI is in good condition. It received a relatively robust treatment during the FY19 pavement preservation cycle: a chip seal followed by a 2-inch asphalt overlay. Given its current state, the pavement is considered suitable for a light surface preservation treatment. Additional pavement structure data was not deemed necessary to finalize the treatment recommendations; therefore, no subsurface sampling or investigation was conducted at this site.

3.3 Review of Available Traffic Data

Although a pavement design was not considered necessary for the NISI sections, due to the pavement being considered for a light pavement preservation treatment, AECOM downloaded and reviewed the historical traffic counts at the Park Entrance from the “NPS Stats Report Viewer” website to obtain a general idea of the traffic conditions at the park. An average daily traffic (ADT) of 81 was reported for 2024, while for the current year (2025), the reported ADT through June is 95.

Considering the historical traffic volume counts (from 2021 to 2024), a design ADT of 100 is deemed appropriate for this road, should pavement design calculations are required at a later stage. The reviewed traffic data and the ESAL calculations are included in Appendix C.

3.4 Construction Estimate Summary

A DD-Phase construction cost estimate, aligned with the Department of the Interior (DOI) Estimate Type B, is being prepared based on the proposed pavement treatments for the parking lots and roadway sections of NISI. This estimate will be submitted as a separate deliverable with the 70%

PAVEMENT INVESTIGATION AND ANALYSIS REPORT 6 | P a g e design package. A summary of the estimated construction cost, based on a DOI Estimate Type C for NISI, is included in Appendix D.

3.5 Construction Schedule Summary

The construction schedule was developed based on the pavement preservation treatments proposed for the parking lots and roadway sections of NISI, and it is included in Appendix E.

4.0 Pavement Analysis, Findings, and Recommendations

As noted above, pavement design calculations were not done for the NISI sections. Instead, the pavement treatments were finalized based on a review of the available documents and the field observations during the scoping site visit. The findings and recommendations for each NISI section are discussed below:

Visitor Center Parking (NISI-0900)

The pavement is in good condition with minor thermal (longitudinal & transverse) cracking.

Pavement preservation with crack sealing and seal coating is appropriate for this parking lot.

Maintenance Access Road A (NISI-0400AZ)

This roadway is currently not within the project scope; however, it was included in the SER-PMS- FY19 project, and the pavement condition is similar to that of NISI-0900. This roadway is recommended for the same treatment as NISI-0900.

Maintenance Area Parking (NISI-0901)

This parking lot is currently not in the project scope; however, it was included in the SER-PMS-FY19 project. The existing pavement exhibits no cracking. Pavement preservation via seal coat is recommended for this parking lot.

The following additional design considerations apply to NISI:

• Isolated areas needing more extensive repairs, such as partial- or full-depth patches due to significant damage like high-severity alligator cracks, edge cracks, or potholes are shown in the 70% design plans.

• Aggregate/seed mixes are recommended to fix edge-shoulder drop-off in specific areas at NISI-0900. The locations and quantities of these mixes are detailed in the 70% design plans.

• Revising structural grading is not a part of this pavement preservation project, but the observed adverse drainage conditions were noted during the site scoping field visit. The table below includes the drainage condition observations for each NISI section:

Table 2: Drainage Observations for NISI Sections Route ID Drainage Observation NISI-0400AZ None NISI-0900 RCP Culvert (needs cleaning) NISI-0901 None

Below is a summary of the findings and recommendations for each park section based on the on-site scoping field visit and the discussions with the project team and the Park Unit:

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Table 3: Findings and Recommendations for Each NISI Road/Parking Lot Section

Route ID Previous Preservation

Treatment (FY19)1

From the RIP Report From AECOM’s Field Scoping Site Visit Comment / Reasons for Variance PCR

Recommended Treatment2

Overall Pavement

Condition Predominant

Distress Treatment

Recommendation

NISI-0400AZ

Chip Seal w/ Asphalt

Overlay (2”) 100 Localized

Repair Good Thermal (L&T) cracking, localized tree root damage, edge cracking Crack seal & seal coat

NISI-0900

Chip Seal w/ Asphalt

Overlay (2”)

Localized Repair

Good Thermal (L&T) cracking edge cracking Crack seal & seal coat w/ localized patching

NISI-0901

Chip Seal w/ Asphalt

Overlay (2”) 97 Localized

Repair Good Weathering Seal coat

Notes:

1) The most likely previous pavement preservation treatment based on the visual observations during the on-site scoping site visit.

2) Per the RIP Report, below are the descriptions of the recommended treatment categories:

a. Localized Repair: Pavement in “Excellent” condition (PCR = 95-100). Treatment includes spot repairs.

b. Preventative Maintenance: Pavement in “Good” condition (PCR = 85-95). Treatments include crack sealing, chip seal, slurry seal, micro-surfacing, thin/ ultrathin overlay, concrete joint sealing, diamond grinding, dowel-bar retrofit, and isolated, partial or full-depth concrete slab repairs.

c. Light Rehaiblitation: Pavement in “Fair” condition (PCR = 60-85). Treatment includes single-lift overlay up to 2.5” and milling and overlaying.

d. Heavy Rehabilitation: Pavement in “Poor” condition (PCR < 60). Treatment includes multi-lift overlay > 2.5”.

e. Reconstruction: Pavement in “Poor” condition (PCR < 60). Treatment includes replacing the entire existing pavement structure.

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Note that the overall pavement conditions were rated as Good/Fair/Poor based on AECOM’s on-site scoping field visit observations. Standard pavement engineering practices were applied to determine such rating, a summary of which is included below for reference:

“Good” pavement condition:

• Pavement has minimal surface defects.

• No significant cracks, potholes, or raveling (loss of aggregate).

• Minimum aging (surface color remains dark, indicating minimal loss of asphalt binder due to oxidation).

• Maintenance treatments, e.g., seal coating, crack sealing, etc. are appropriate for a “Good” condition pavement.

“Fair” pavement condition

• Some visible signs of wear, such as minor cracks (hairline to ¼ inch wide).

• Early signs of aging (fading asphalt color).

• Some surface raveling or minor depressions but no major structural issues.

• Patching or previous repairs are intact.

• Heavier preservation treatments, such as localized repair, micro surfacing, or resurfacing are considered to treat a pavement in “Fair” condition.

“Poor” Condition

• Extensive cracking, including alligator (interconnected) cracks or wide transverse/longitudinal cracks (>¼ inch).

• Potholes, ruts, or significant depressions present, causing uneven surfaces.

• Medium to severe raveling or aggregate loss, leading to rough texture.

• Potential water pooling or drainage issues.

• Previous patches or repairs are deteriorating or failing.

• The pavement may be a candidate for a mill and overlay treatment or full-depth reconstruction.

Depending on the treatment types, pavement preservation activities generally can extend the life of a pavement by 5-10 years. For reference, the table below provides a general guideline on the expected performances of the different preservation treatments (when applied to a pavement in appropriate condition):

Table 4: “Expected” Performance Period of Typical Pavement Preservation Treatments Treatment Expected Performance (Years) Crack Sealing + Seal Coating (Slurry Seal) 5-7 Microsurfacing 6-8 Thin Overlay 8-10 Non-structural Mill and Overlay 10+

Appendix A – Project Location

PAVEMENT INVESTIGATION AND ANALYSIS REPORT Appendix A

NISI

PAVEMENT INVESTIGATION AND ANALYSIS REPORT Appendix A

Appendix B – Scoping Site Visit Field Notes and Photos

PAVEMENT INVESTIGATION AND ANALYSIS REPORT Appendix B

NISI-0400AZ: Maintenance Access Road A (added) Section Length/Area 0.12 Mile Other Observations Pavement Type Asphalt Curb None RIP Data (PCR) 100 Sidewalk None Overall Pavement Condition Good Drainage Structure None Predominant Distress Thermal (L&T) Cracking

Localized tree root damage Edge Cracking

Road Signs Good

Recommended Treatment Crack Seal & Seal Coat Handicap Parking None Geotechnical Testing None Existing Striping None

Section Distress Treatment

L L&T 200’ L/M Edge Cracking 150’

Crack Seal & Seal Coat

Legend:

L&T – Longitudinal & Transverse cracking L, M – Low or Medium severity cracks

❶ Lat/Long: 34.147992,-82.022911 Low L&T Cracking from tree roots

❷ Lat/Long: 34.148078,-82.022972 Low L&T Cracking

❸ Lat/Long: 34.148133,-82.023078 Low L&T Cracking, low Alligator Cracking

❹ Lat/Long: 34.147706,-82.022925 Low Edge Cracking

NISI-0900: Visitor Center Parking Section Length/Area 20,974 SF Other Observations Pavement Type Asphalt Curb Concrete Wheel Stops at parking stalls (Good) RIP Data (PCR) 97 Sidewalk Brick (Good) Overall Pavement Condition Good Drainage Structure RCP culvert1 (needs cleaning)

Predominant Distress Thermal (L&T) cracking Edge cracking Road Signs Okay

Recommended Treatment Surface Treatment Handicap Parking Two (1 Van Accessible) (Good)1 Geotechnical Testing None Existing Striping High-Build (Good)

1. Locations on the marked plan.

L L&T 25’ L Edge Cracking 150’

Crack Seal & Seal Coat

Legend:

L&T – Longitudinal & Transverse cracking L, M – Low or Medium severity cracks

12 RCP Pipe

(Needs Cleaning)

Underground Gas & Sprint Utility Line

Single White Center Line (High Build)

Automated Gate with loops

Paved Over (pavement area needs to be updated)

2 Handicap parking (Good) (1 Van Accessible)

9 ft. Arrows (TYP)

Proposed stone/aggregate pavement edge support

Vegetation Overgrowth

Traffic counter

Surface slippage patch

NISI-0900: Visitor Center Parking

❶ Lat/Long: 34.146964,-81.023628 Low Edge Cracking, automated gate

❷ Lat/Long: 34.1469,-81.023675 Handicap parking (good condition)

❸ Lat/Long: 34.147481,-81.023575 Low L&T Cracking, proposed location of aggregate edge support (left)

❹ Lat/Long: 34.1479,-82.023261 Low Edge Cracking. Vegetation overgrowth

NISI-0901: Maintenance Area Parking (added) Section Length/Area 6,978 SF Other Observations Pavement Type Asphalt Curb None RIP Data (PCR) 97 Sidewalk None Overall Pavement Condition Good Drainage Structure None Predominant Distress Weathering Road Signs Good Recommended Treatment Surface Treatment Handicap Parking None Geotechnical Testing None Existing Striping None

1 No Cracking Seal Coat

Fence with Swing Gate (Good)

❶ Lat/Long: 34.147522,-82.02275 Minimal pavement distress

❷ Lat/Long: 34.147656,-82.022867 Minimal pavement distress

Appendix C – Traffic Data

Historical Traffic Data Downloaded from NPS Stats Report Viewer (Website: https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Traffic%20Counts?Park=GRCA) https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Traffic%20Counts?Park=GRCA

Appendix D – Construction Cost Estimate Summary

(Class B Estimate will be submitted separately)

PAVEMENT INVESTIGATION AND ANALYSIS REPORT Appendix D

Class C Summary Estimate for all South Carolina Parks

Class C Summary Estimate for the NISI Sections

Direct Construction

Markups Total Direct Constructio

Markups Total Direct Construction

Markups Total

COWP 334929 $1,869,762 $346,843 $322,077 $668,920 $10,223 $9,493 $19,715 $357,066 $331,569 $688,635 CONG 334914 $615,000 $403,207 $400,969 $804,176 $16,805 $16,712 $33,517 $420,012 $417,681 $837,693 KIMO 334920 $1,155,041 $987,432 $1,084,136 $2,071,567 $9,669 $10,616 $20,285 $997,101 $1,094,751 $2,091,852 NISI 334915 $121,000 $14,000 $15,635 $29,635 $9,608 $10,730 $20,338 $23,608 $26,365 $49,973

Total $3,760,803 $1,751,482 $1,822,816 $3,574,297 $46,305 $47,551 $93,856 $1,797,787 $1,870,366 $3,668,153

Base Bid Options Total W. Options Park PMIS #

PMIS Estimated Budget

ROUTE ID ROAD FMSS#

PAVEMENT

TYPE

PROPOSED TREATMENT

COST W/O

MARKUPS

TOTAL

MARKUP

COST W/

MARKUPS

PMIS ESTIMATED

BUDGET

NISI-0400AZ

MAINTENANCE

ACCESS ROAD A

104866 Asphalt CRACK SEAL & SEAL COAT 6,507 7,267$ 13,774 -$

NISI-0900

VISITOR CENTER

PARKING

75619 Asphalt

CRACK SEAL & SEAL COAT w/

LOCALIZED PATCHING

14,000 15,635$ 29,635 121,000$

NISI-0901

MAINTENANCE AREA

PARKING

75622 Asphalt SEAL COAT 3,101 3,463$ 6,565 -$

Total Base Bid 14,000 15,635 29,635 121,000$

Total Options 9,608 10,730 20,338 -$

Total 23,608$ 26,365$ 49,973$ 121,000$

Appendix E – Construction Schedule Summary

PAVEMENT INVESTIGATION AND ANALYSIS REPORT Appendix E

PARK ID PMIS # Duration (days) 1-Jun 8-Jun 15-Jun 22-Jun 29-Jun 6-Jul 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug 17-Aug 24-Aug 31-Aug

COWP 334929 41

CONG 334914 34

KIMO 334920 20

NISI 334915 13

ROUTE ID ROAD PROPOSED TREATMENT 24-Aug 25-Aug 26-Aug 27-Aug 28-Aug 31-Aug 1-Sep 2-Sep 3-Sep 4-Sep

NISI-0400AZ

MAINTENANCE

ACCESS ROAD A

CRACK SEAL & SEAL COAT

NISI-0900

VISITOR CENTER

PARKING

CRACK SEAL & SEAL COAT w/

LOCALIZED PATCHING

NISI-0901

MAINTENANCE AREA

PARKING

SEAL COAT