Attachment A - Sao Tome - Limited Phase II ESA - 03072025.pdf

PDF 11 MB Posted Jul 29, 2025

Attached to: USAGM Sao Tome Transmitting Station Decommissioning Support - Hazardous Materials Removal and Off-Island Disposal Request for Proposal
Solicitation number: 951700-25-R-0017
Issued by: US Agency for Global Media

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Written by GovTribe AI · Jul 29, 2025

This Limited Phase II Environmental Site Assessment (ESA) details a comprehensive environmental investigation of the United States Agency for Global Media (USAGM) Transmitting Station in Sao Tome, Sao Tome and Principe. The approximately 346-acre site, which is currently being decommissioned, was evaluated for potential environmental risks through hazardous substances inventory, wipe sampling, and soil sampling. The investigation identified six Recognized Environmental Conditions (RECs), including on-site diesel storage, burn areas, fire-fighting training areas, hazardous substances storage, historical pesticide use, and reverse osmosis brine discharge.

Key findings include the detection of total xylenes exceeding industrial soil screening levels, PFAS (PFOA, PFDA, and PFOS) in surface soils near the hazardous material shed, and total petroleum hydrocarbons in various site locations. The assessment recommends developing a hazardous waste disposal plan and soil management plan, coordinating with Sao Tome municipality for proper waste and soil disposal, and implementing contractor-developed management plans to ensure worker safety during site redevelopment. The investigation was conducted in December 2024 by Langan Engineering & Environmental Services, LLC, with laboratory analysis performed by Eurofins TestAmerica.

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Attachment A - RFP 951700-25-R-0017 Phase II Environmental Site Assessment United States Agency for Global Media Sao Tome, Sao Tome and Principe Langan Project No. 270187301

March 7, 2025

LIMITED PHASE II ENVIRONMENTAL SITE

ASSESSMENT

for

United States Agency for Global Media Transmitting

Station

Sao Tome, Sao Tome and Principe

Prepared for:

Hollingsworth Pack

Oster Sogade 22

DK-1357 Copenhagen

Prepared by:

Langan Engineering & Environmental Services, LLC

1300 Wilson Boulevard, Suite 450

Arlington, Virginia 22209

Tess Reardon

Senior Staff Geologist

Jeff Manuszak, PG

Associate Principal/VP

Project No. 270187301

March 7, 2025

Phase II Environmental Site Assessment

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

TABLE OF CONTENTS

Executive Summary

1.0 Introduction

1.1 Objective

1.2 Scope of Services

2.0 Limited Phase II ESA

2.1 Hazardous Substances and Petroleum Products Inventory and Wipe Sampling

2.2 Soil Investigation and Sampling

2.2.1 Soil Sampling Methodology

2.3 Analytical Results

2.3.1 Wipe Analytical Results

2.3.2 Soil Observations

2.3.3 Soil Analytical Results

3.0 Conclusions

3.1 Soil Conditions

4.0 Recommendations

5.0 References

FIGURES

Figure 1 Site Location Map

Figure 2 Site Property Layout

Figure 3 Sample Location Map

TABLES

Table 1 Summary of Wipe Sample Results

Table 2 Summary of Soil Sample Results

APPENDICES

Appendix A Photo Log

Appendix B Hazardous Substances and Petroleum Products Inventory

Appendix C Soil Boring Logs

Appendix D Laboratory Analytical Report

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

EXECUTIVE SUMMARY

Langan Engineering and Environmental Services, LLC (Langan) has prepared this Limited Phase

II Environmental Site Assessment (ESA) on behalf of Hollingsworth Pack for the United States

Agency for Global Media (USAGM) Transmitting Station property in Sao Tome, Sao Tome and

Principe (Site).

The approximately 346-acre (140-hectare) Site is developed with a Voice of America radio transmitting station that is currently being decommissioned. The station is comprised of the following structures:

Buildings/Structures Size

Transmitter and Administrative Building 20,468 square feet (SQ F)/1,902 square meters

(SQ M)

Facilities Warehouse 7,200 SQ F/669 SQ M

Power Plant Building 7,381 SQ F/686 SQ M

Facilities Office 1,300 SQ F/121 SQ M

Buildings and Grounds Building 3,280 SQ F/305 SQ M

Motor Pool Workshop/Office 1,842 SQ F/171 SQ M

Water Pump House 420 SQ F/30 SQ M

Reverse Osmosis (R/O) Filtration Building 247 SQ F/23 SQ M

R/O Filtration Holding Tank 169 SQ F/16 SQ M

Guard House 321 SQ F/30 SQ M

Old Warehouse 4,695 SQ F/436 SQ M

600 kilowatt (kW) Medium Wave Antenna Tuning

Unit #1

324 SQ F/30 SQ M

600 kW Medium Wave Antenna Tuning Unit #2 169 SQ F/16 SQ M

Fuel Terminal Building 450 SQ F/42 SQ M

Marine Storage Building 961 SQ F/89 SQ M

Fuel Storage Tanks (851,718 liters/225,000 gallons each)

2,514 SQ F/234 SQ M (117 SQ M/1,257 SQ F

each)

Fuel Terminal Surge Tank (90,850 liters/24,000 gallons)

177 SQ F/16 SQ M

Fuel Oil/Water Separator Shelter 100 SQ F/9 SQ M

Water Storage Tank (283,906 liters/75,000 gallons)

661 SQ F/61 SQ M

One kW Medium Wave Transmitter Shelter 160 SQ F/15 SQ M

Swimming Pool Pump House Building 196 SQ F/18 SQ M

American Officers’ Residences

3,345 SQ F/311 SQ M (1,115 SQ F/104 SQ M

each)

Electronic Substation Shelter 144 SQ F/13 SQ M

Hazardous Materials Shed 1,426 SQ F/132 SQ M

Four satellite dishes are south of the Transmitter and Administrative Building, and 15 high-frequency antennas are in the central part of the Site. Asphalt-paved driveways surround the structures, and the remainder of the Site is grass-covered.

The Site stores and uses hazardous substances and petroleum products that will require characterization and removal as part of the station decommissioning. Additionally, Langan understands that facility personnel reported visual evidence of releases from certain storage containers.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

As requested by Hollingsworth Pack, Langan completed this Limited Phase II ESA to inventory the hazardous and petroleum products, and characterize potential releases areas. Potential release areas were identified as Recognized Environmental Conditions (REC) as defined by ASTM

E1527-21. As part of the Site reconnaissance performed in December 2024, Langan identified the following RECs:

• REC-1: On-Site Diesel Storage: Two 851,718-liter (225,000-gallon) diesel aboveground storage tanks (AST) were observed in the central part of the Site west of the Power Plant

Building. Additionally, one 90,850-liter (24,000-gallon) surge tank was observed in the northeastern part of the Site south of the fuel terminal building. The tanks were observed to be in secondary containment with earthen berms; however, the secondary containment was observed to drain into stormwater drainage ditches in the vicinity of the tanks. A mobile gas (mogas) system comprised of one 3,785-liter (1,000-gallon) gasoline

AST and one 3,785-liter (1,000-gallon) diesel AST with associated fuel pumps is south of the Power Plant Building. Used oil and gear oil drums and five 386-liter (100-gallon) diesel

ASTs are west of the Power Plant Building. One 265-liter (70-gallon) diesel AST is north of the Transmitter and Administrative Building. Stained asphalt and soils and diesel-like petroleum odors were observed in secondary containment areas, on asphalt-paved roads, on grass, and in concrete-covered and soil-covered stormwater drainage ditches. Based on Site observations, the staining and odors are indicative of releases and it is likely that the releases impacted the subsurface. Therefore, the presence of the on-Site diesel storage is considered a REC.

• REC-2 – Burn Areas: Langan observed two burn areas in the southwestern part of the

Site. The burn areas appeared to consist of burned vegetation, paper products, plastics, and empty containers of bleach, disinfectants, lube oil, enamel, and other chemicals.

Additionally, facilities staff informed Langan that the burn areas were routinely doused with diesel oil or lube oil to facilitate burning. The burn areas were observed to be surficial in nature and ranged from 40 to 80 square feet in size. Due to the potential for release of hazardous substances in the burn pit areas, the burn areas are considered a REC.

• REC-3: Fire-Fighting Training Areas: Facilities staff indicated that fire-fighting training exercises were previously performed at two abandoned structures at the Site: a concrete foundation slab in the northeastern part of the Site, and a shed in the eastern part of the

Site. Langan observed staining on the concrete floors and walls at the abandoned shed;

however, Langan was unable to observe the concrete foundation slab due to dense vegetation. Facilities staff indicated that water and foam were used during the fire-fighting drills, and the structures were doused in diesel oil or used oil to facilitate burning.

Additionally, 19-liter (5-gallon) buckets of aqueous film-forming foam (AFFF) were observed stored at the hazardous materials shed in the northern part of the Site. AFFF is a well-documented source of per- and polyfluoroalkyl substances (PFAS), including perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The likely presence of PFOA and possible presence of PFOS in the AFFF is considered an REC given

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301 the potential for impacts to soil and groundwater.

• REC-4: Hazardous Substances Storage: The Site has been occupied by a radio transmitting station from 1992 to the present, and historically and currently stores and uses hazardous substances and petroleum products. Hazardous materials observed during site reconnaissance activities included diesel oil, hydraulic and gear oil, used oil, batteries, lubricants, pesticides, various paints and cleaners, and equipment maintenance products stored at the Hazardous Materials Shed, Power Plant Building, Facilities

Warehouse, Motor Pool Workshop/Office, Transmitter and Administrative Building, and

Reverse Osmosis (R/O) Filtration Building. Langan observed several areas of floor stains in the Hazardous Materials Shed and areas of staining on concrete, asphalt, and grass by the Power Plant Building and Motor Pool Workshop/Office. The historical use and spillage of hazardous substances at the Site may have adversely impacted soil, groundwater, and/or soil gas quality at the Site and is considered a REC.

• REC-5: Historical Pesticide Use: According to Facilities staff, a golf course was previously maintained on the eastern part of the Site. Langan also observed bulk storage of pesticides at the Hazardous Materials Shed in the northern part of the Site. As a result of the historical golf course maintenance activities, soils at the Site may contain elevated concentrations of pesticides, herbicides or other agricultural chemicals. The potential historical use of these chemicals may have adversely impacted soil quality at the Site and is considered a REC.

• REC-6: Reverse Osmosis Brine: During the site reconnaissance, Langan observed a hose from the R/O Filtration Building discharging to an adjacent stormwater drainage ditch.

According to Facilities staff, brine generated from the reverse osmosis process is discharged directly to the stormwater drainage ditch. Brine byproducts can include elevated concentrations of salts and heavy metals, and the discharge of the reverse osmosis brine may have adversely impacted soil quality at the Site and is considered a

REC.

On 9 through 13 December 2024, Langan installed 13 soil borings and collected 13 shallow soil samples and 17 wipe samples to evaluate the RECs. The objective of the sampling was to identify soil or wastes that may require additional management considerations during site redevelopment.

Hazardous Substances and Petroleum Products Inventory and Wipe Sampling

Langan identified and documented the contents, volume, location, and condition of containers and equipment containing or potentially containing hazardous substance and petroleum products.

Langan also completed a visual assessment for evidence of releases or spills from the identified containers. Identified stained impervious surfaces and unidentified substance containers were evaluated by collecting wipe samples. The wipe samples were analyzed for one or more of the following parameters including volatile organic compounds (VOC); semi-volatile organic compounds (SVOC); total petroleum hydrocarbons (TPH) – diesel range organics (DRO), gasoline range organics (GRO), and oil range organics (ORO); polychlorinated biphenyls (PCB); the eight

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

Resource Conservation and Recovery Act (RCRA) list metals, pesticides and herbicides, and

PFAS.

Soil Sampling

Observed soil from the 13 borings installed at the Site was primarily comprised of gray, brown, and dark brown sand and clay with varying amounts of silt, gravel, and organic material.

Soil samples were collected from the borings and analyzed for one or more of the following constituents: VOCs; SVOCs; TPH- DRO, GRO, and ORO; PCBs; the eight RCRA list metals, pesticides and herbicides, dioxins and furans, and PFAS.

Analytical Results

Laboratory analysis of the soil and wipe samples collected from the identified REC areas indicate the following:

• SVOCs, PCBs, TPH-GRO, pesticides, herbicides, and dioxins and furans were not detected in the wipe or soil samples or were not detected above concentrations warranting further discussion.

• Soil sample results indicate that surface soils in the storm water drainage ditch by the fuel storage tanks contain concentrations of one VOC (total xylenes) in exceedance of the

USEPA industrial regional screening level (RSL) for soil.

• Surface soils in the vicinity of the hazardous material shed and in the stormwater drainage ditch by the southern boundary of the Site contain concentrations of three PFAS (PFOA, perfluorodecanoic acid [PFDA], and PFOS) in exceedance of USEPA residential and/or industrial RSLs for soil. PFAS was also detected above laboratory reporting limits in surface soil and wipe samples in the vicinity of the shed used for fire-fighting training exercises in the eastern part of the Site.

• Arsenic was detected consistently across the Site soils at concentrations ranging from

2.2 to 4.6 milligrams per kilogram (mg/kg). Regional background studies were not available for Sao Tome and Principe; however, regional background studies of similar volcanic islands in the region indicate that volcanic soils in the region have arsenic concentrations between 0.3 and 7.2 mg/kg. The arsenic concentrations at the Site are within these ranges, and therefore, Langan considers the arsenic detections indicative of regional background concentrations.

• TPH-DRO and TPH-ORO were detected in the wipe and soil samples at concentrations between 12 to 170,000 milligrams per wipe (mg/wipe) and 16 to 1,700 mg/kg, respectively. USEPA does not maintain screening levels for TPH, but the detections are consistent with concentrations typically identified in marginally impacted soil and concrete, with notable releases in the vicinity of the USTs and associated infrastructure, as well as areas of the Motor Pool, Hazardous Materials Shed, and vehicle washing area.

TPH-DRO impacts were also observed in the stormwater drainage ditches discharging to the Atlantic Ocean. The analytical results suggest that marginally impacted soils and concrete may be present throughout the Site with localized areas of TPH contamination.

Contaminants of concern include TPH and xylenes based on analytical results.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

The laboratory analytical results indicate that the historical pesticide use (REC-5) and reverse osmosis brine (REC-6) do not appear to have adversely impacted soil quality at the Site and do not require further investigation at this time. However, the laboratory analytical results confirmed the presence of soil impacts from the on-Site diesel storage, burn areas, fire-fighting training areas, and hazardous substance storage (REC-1 through REC-4), which may require additional considerations during redevelopment, as discussed below.

Recommendations

Based on the findings of the Limited Phase II ESA, Langan recommends the development of a hazardous waste disposal plan and soil management plan by a company that is familiar with the regional procedures for the mitigation of hazardous waste. The hazardous waste disposal plan should outline how to manage identified hazardous waste and appropriate disposal procedures.

The soil management plan should outline how to manage marginally impacted soil, where the soil should be disposed of, restrictions on soil reuse (if any), provisions for unanticipated conditions, and guidance for collecting additional samples, if needed.

Hazardous waste and soil disposal should be coordinated with and approved by the Sao Tome municipality, as well as any other jurisdiction that would need to be involved, in order to ensure the final results of site decommissioning are completed in accordance with applicable rules and regulations. Potential construction worker exposures to the hazardous waste and marginally impacted soil can also be managed during construction with a contractor-developed management plan, if there are local regulations and disposal methods that provide enough structure to ensure compliance for the safety and well-being of the workers.

Additional details regarding the Limited Phase II ESA findings are discussed in the body of the report.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

1.0 INTRODUCTION

Langan Engineering and Environmental Services, LLC (Langan) has prepared this Limited Phase

II Environmental Site Assessment (ESA) on behalf of Hollingsworth Pack for the United States

Agency for Global Media (USAGM) Transmitting Station property in Sao Tome, Sao Tome and

Principe (Site – see Figure 1).

Buildings/Structures Size

Transmitter and Administrative Building 20,468 square feet (SQ F)/1,902 square meters

(SQ M)

Facilities Warehouse 7,200 SQ F/669 SQ M

Power Plant Building 7,381 SQ F/686 SQ M

Facilities Office 1,300 SQ F/121 SQ M

Buildings and Grounds Building 3,280 SQ F/305 SQ M

Motor Pool Workshop/Office 1,842 SQ F/171 SQ M

Water Pump House 420 SQ F/30 SQ M

Reverse Osmosis (R/O) Filtration Building 247 SQ F/23 SQ M

R/O Filtration Holding Tank 169 SQ F/16 SQ M

Guard House 321 SQ F/30 SQ M

Old Warehouse 4,695 SQ F/436 SQ M

600 kilowatt (kW) Medium Wave Antenna Tuning

Unit #1

324 SQ F/30 SQ M

600 kW Medium Wave Antenna Tuning Unit #2 169 SQ F/16 SQ M

Fuel Terminal Building 450 SQ F/42 SQ M

Marine Storage Building 961 SQ F/89 SQ M

Fuel Storage Tanks (851,718 liters/225,000 gallons each)

2,514 SQ F/234 SQ M (117 SQ M/1,257 SQ F

each)

Fuel Terminal Surge Tank (90,850 liters/24,000 gallons)

177 SQ F/16 SQ M

Fuel Oil/Water Separator Shelter 100 SQ F/9 SQ M

Water Storage Tank (283,906 liters/75,000 gallons)

661 SQ F/61 SQ M

One kW Medium Wave Transmitter Shelter 160 SQ F/15 SQ M

Swimming Pool Pump House Building 196 SQ F/18 SQ M

American Officers’ Residences

3,345 SQ F/311 SQ M (1,115 SQ F/104 SQ M

each)

Electronic Substation Shelter 144 SQ F/13 SQ M

Hazardous Materials Shed 1,426 SQ F/132 SQ M

In December 2024, Langan performed a Site-walk and hazardous substances inventory, which identified certain environmental conditions for which Hollingsworth Pack required additional information as input into the future development of the Site. The site reconnaissance identified the following RECs as defined by ASTM E1527-21:

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

• REC-1: On-Site Diesel Storage: Two 851,718-liter (225,000-gallon) diesel aboveground storage tanks (AST) were observed in the central part of the Site west of the Power Plant

AST and one 3,785-liter (1,000-gallon) diesel AST with associated fuel pumps is south of the Power Plant Building. Used oil and gear oil drums and five 386-liter (100-gallon) diesel

• REC-2 – Burn Areas: Langan observed two burn areas in the southwestern part of the

Site. The burn areas appeared to consist of burned vegetation, paper products, plastics, and empty containers of bleach, disinfectants, lube oil, enamel, and other chemicals.

Site. Langan observed staining on the concrete floors and walls at the abandoned shed;

Warehouse, Motor Pool Workshop/Office, Transmitter and Administrative Building, and

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

R/O Filtration Building. Langan observed several areas of floor stains in the Hazardous

Materials Shed and areas of staining on concrete, asphalt, and grass by the Power Plant

Building and Motor Pool Workshop/Office. The historical use and spillage of hazardous substances at the Site may have adversely impacted soil, groundwater, and/or soil gas quality at the Site and is considered a REC.

• REC-6: Reverse Osmosis Brine: During the site reconnaissance, Langan observed a hose from the R/O Filtration Building discharging to an adjacent stormwater drainage ditch.

REC.

Hollingsworth Pack requested a Limited Phase II ESA to further evaluate these identified conditions.

1.1 Objective

The objective of this Limited Phase II ESA was to prepare an inventory of hazardous substances and petroleum products and evaluate and identify soil and impervious surface impacts that may require special management during site redevelopment. The investigation focused on areas identified as potential environmental concerns during the Site-walk and hazardous substances inventory.

1.2 Scope of Services

The scope of services for this investigation are outlined in the 12 April 2023 Proposal for Civil, Environmental, and Geotechnical Engineering Services. In general, the investigation included the following:

• Inventory of hazardous substances and petroleum products;

• Collection of 17 wipe samples; and

• Collection of 13 shallow soil samples.

The methodologies and results of the investigation are provided herein.

2.0 LIMITED PHASE II ESA

Langan completed a limited Phase II ESA between 9 and 13 December 2024 in accordance with the 15 October 2024 Scope of Services. A photo log documenting conditions at the time of the study is included as Appendix A.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

2.1 Hazardous Substances and Petroleum Products Inventory and Wipe Sampling

Between 9 and 13 December 2024, Langan completed a walkthrough of the Site and prepared an inventory of hazardous substances and petroleum products. Langan documented the contents, volume, location, and condition of containers and equipment containing or potentially containing hazardous substance and petroleum products. The inventory log is provided in

Appendix B.

During the walkthrough, Langan also completed a visual assessment for evidence of releases or spills from the identified containers. Identified stained impervious surfaces and unidentified substance containers were evaluated by collecting wipe samples. The wipe samples were collected from the following areas of concern:

• W-1: stained concrete slab in used oil secondary containment area

• W-2: stained concrete slab in used oil secondary containment area

• W-3: stained concrete slab by oil storage and AST

• W-4: stained concrete slab by drain in marine terminal building

• W-5: stained concrete vault above “trash” tank

• W-6: stained concrete slab by insecticide drum storage

• W-7: stained concrete slab by AFFF buckets

• W-8: stained concrete slab by hydraulic fluid drums

• W-9: stained concrete ramp by vehicle washing area

• W-10: stained concrete slab by transformers

• W-11: stained concrete by vehicle storage area

• W-12: stained concrete by motor pool building

• W-13: stained concrete trench by mogas system

• W-14: stained concrete slab inside former structure used for fire-fighting drills

• W-15: stained concrete stormwater trench

• W-16: stained concrete stormwater drain

• W-17: staining on steel drums containing “asphalt”

The samples were placed in laboratory-supplied containers immediately following collection, and shipped to Eurofins TestAmerica in Pensacola, Florida via DHL under chain-of-custody procedures. The wipe samples were analyzed for one or more common urban contaminants including volatile organic compounds (VOC); semi-volatile organic compounds (SVOC); total petroleum hydrocarbons (TPH) – diesel range organics (DRO), gasoline range organics (GRO), and oil range organics (ORO); polychlorinated biphenyls (PCB); the eight Resource Conservation and

Recovery Act (RCRA) list metals, pesticides and herbicides, and PFAS. The selected analytical suite was based observed site conditions. Laboratory analytical results of the wipe sampling are discussed in Section 2.3.

2.2 Soil Investigation and Sampling

2.2.1 Soil Sampling Methodology

Between 9 and 13 December 2024, Langan evaluated the soil quality across the Site, as discussed below.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

Soil borings were advanced using a hand auger with a 3-inch (7.6-centimeter) bucket. The hand auger was decontaminated between each boring location. Continuous soil cores were collected, soil characteristics were logged, and the soil cores were screened for indications of environmental impacts such as staining, odors, or elevated photoionization detector (PID) readings. The boring locations are shown on Figure 3 and soil boring logs are included in Appendix

C. The soil boring locations were selected to assess the following areas of concern:

• SB-1: Stormwater ditch downgradient of two 851,718-liter (225,000-gallon) diesel ASTs

• SB-2: R/O Filtration Building brine discharge

• SB-3: Drum storage near Power Plant Building

• SB-4: Stormwater ditch downgradient of fueling island

• SB-5: Stormwater ditch by septic treatment

• SB-6: Drum storage near Hazardous Materials Shed

• SB-7: Former golf course

• SB-8: Drainage ditch where storm water leaves the Site

• SB-9: Stormwater inlet by 90,850-liter (24,000-gallon) surge tank

• SB-10: Burn areas

• SB-11: Burn areas

• SB-12: Former fire-fighting training area

• SB-13: Stained surficial soil near storage containers and vehicle washing area

One shallow soil sample was collected from each boring. The sample was collected from the interval exhibiting the greatest degree of environmental impact as determined by the field observations and PID readings. If environmental impacts were not observed, the sample was collected from the 0 to 0.5 feet (0 to 0.15 meter) interval. The samples were collected from the following depth intervals:

• SB-1: 0 to 0.5 feet (0 to 0.15 meter)

• SB-2: 0 to 0.5 feet (0 to 0.15 meter)

• SB-3: 0 to 0.8 feet (0 to 0.25 meter)

• SB-4: 0 to 1 foot (0 to 0.3 meter)

• SB-5: 0 to 1 foot (0 to 0.3 meter)

• SB-6: 0 to 1 foot (0 to 0.3 meter)

• SB-7: 0 to 0.75 feet (0 to 0.23 meter)

• SB-8: 0 to 0.5 feet (0 to 0.15 meter)

• SB-9: 0 to 0.25 feet (0 to 0.1 meter)

• SB-10: 0 to 1 foot (0 to 0.3 meter)

• SB-11: 0 to 1 foot (0 to 0.3 meter)

• SB-12: 0 to 1 foot (0 to 0.3 meter)

• SB-13: 0 to 0.25 feet (0 to 0.1 meter)

The samples were placed in laboratory-supplied containers immediately following collection, and shipped to Eurofins TestAmerica in Pensacola, Florida via DHL under chain-of-custody procedures. The soil samples were analyzed for one or more common urban contaminants including VOCs; SVOCs; TPH – DRO, GRO, and ORO; PCBs; the eight RCRA list metals, pesticides and herbicides, dioxins and furans, and PFAS.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

Field observations and laboratory analytical results of the soil sampling are discussed in Section

2.3.

2.3 Analytical Results

2.3.1 Wipe Analytical Results

The laboratory analytical report is provided in Appendix D, and results are summarized in Table 1.

For the purpose of this screening level assessment, analytical data provided by the laboratory were compared to United States Environmental Protection Agency (USEPA) regional screening levels (RSL) for residential and industrial soils using a target risk of 1 x 10-06 and hazard quotient of 0.1.

Because of restrictions on shipping of liquids and preservatives internationally, holding times and temperature requirements were exceeded for some parameters. However, the data are considered acceptable for the due diligence purposes of this investigation.

A discussion of analytical results is provided below:

• VOCs were not detected above the laboratory reporting limit in any of the four analyzed samples.

• SVOCs were not detected above the laboratory reporting limit in any of the three analyzed samples.

• TPH-DRO was detected in all 13 analyzed samples at concentrations ranging from 130 to

170,000 milligrams per wipe (mg/wipe). USEPA RSLs have not been established for wipe samples or TPH-DRO.

• TPH-GRO was not detected above the laboratory reporting limit in the one analyzed sample.

• PCBs were not detected above the laboratory reporting limit in the one analyzed sample.

• 16 PFAS were detected above the laboratory reporting limits in two analyzed samples.

USEPA RSLs have not been established for wipe samples.

• Seven metals (arsenic, barium, cadmium, chromium, lead, selenium, and silver) were detected above laboratory reporting limits. USEPA RSLs have not been established for wipe samples.

2.3.2 Soil Observations

Soil collected from the hand augers generally consisted of fill comprised of gray, brown, and dark brown sand and clay with varying amounts of silt, gravel, and organic material.

2.3.3 Soil Analytical Results

The laboratory analytical reports are provided in Appendix D, and results are summarized in Table

2. For the purpose of this screening level assessment, analytical data provided by the laboratory were compared to USEPA RSLs for residential and industrial soils using a target risk of 1 x 10-06 and hazard quotient of 0.1. Sao Tome and Principe does not currently have soil screening criteria.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

A discussion of analytical results is provided below:

• The following VOCs were detected:

o Total xylenes was detected above the USEPA RSL for industrial soil of 250 milligrams per kilogram (mg/kg) at a concentration of 2,300 mg/kg in SB-1.

o Four additional VOCs (ethylbenzene, m,p-xylenes, o-xylene, and toluene) were detected above laboratory reporting limits in SB-1 but did not exceed USEPA

RSLs.

• Five SVOCs (bis [2-ethylhexyl] phthalate, naphthalene, pentachlorophenol, phenanthrene, and pyrene) were detected above laboratory reporting limits but did not exceed USEPA

RSLs.

• TPH-DRO was detected in all 11 analyzed samples at concentrations ranging from 12 to

22,000 mg/kg. USEPA RSLs have not been established for TPH-DRO.

• TPH-ORO was detected all 11 analyzed samples at concentrations ranging from 16 to

1,700 mg/kg. USEPA RSLs have not been established for TPH-ORO.

• TPH-GRO was not detected above the laboratory reporting limits in any of the nine analyzed samples.

• PCBs were not detected above the laboratory reporting limit in any of the six analyzed samples.

• The following metals were detected:

o Arsenic was detected at concentrations ranging from 2.2 mg/kg to 4.6 mg/kg.

Arsenic detections exceeded the USEPA RSL for residential soil of 0.68 mg/kg in all eight analyzed samples. Arsenic detections exceeded the USEPA RSL for industrial soil of 3 mg/kg in three of the eight analyzed soil samples.

o Six additional metals were detected (barium, cadmium, trivalent chromium, lead, mercury, and selenium) above laboratory reporting limits but did not exceed the

USEPA RSLs.

• The following PFAS were detected:

o PFOA was detected above the USEPA RSL for industrial soil of 0.0000784 mg/kg at concentrations of 0.000082 mg/kg and 0.00087 mg/kg in SB-6 and SB-8, respectively.

o Perfluorodecanoic acid (PFDA) was detected above the USEPA RSL for residential soil of 0.0000126 mg/kg at a concentration of 0.000033 mg/kg in SB-6.

o PFOS was detected above the USEPA RSL for residential soil of 0.000632 mg/kg at a concentration of 0.0024 mg/kg in SB-8.

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301 o Five additional PFAS (perfluorobutanoic acid [PFBA], perfluorohexanoic acid

[PFHxA], perfluorononanoic acid [PFNA], perfluorohexanesulfonic acid [PFHxS], and perfluoroheptanesulfonic acid [PFHpS] were detected above laboratory reporting limits but did not exceed USEPA RSLs.

o Three additional PFAS (perfluoroheptanoic acid [PFHpA], n-ethylperfluorooctane-sulfonamidoacetic acid [NEtFOSAA], and n-ethylperfluorooctanesulfonami-doethanol [NEtFOSE] were detected above laboratory reporting limits. USEPA

RSLs have not been established for these compounds.

• Pesticides were not detected above the laboratory reporting limit in any of the three analyzed samples.

• Herbicides were not detected above the laboratory reporting limit in any of the three analyzed samples.

• 18 dioxins and furans were detected above the laboratory reporting limits but did not exceed USEPA RSLs.

3.0 CONCLUSIONS

3.1 Soil Conditions

Laboratory analysis of the soil and wipe samples collected from the identified REC areas indicate the following:

• SVOCs, PCBs, TPH-GRO, pesticides, herbicides, and dioxins and furans were not detected in the wipe or soil samples or were not detected above concentrations warranting further discussion.

• Soil sample results indicate that surface soils in the storm water drainage ditch by the fuel storage tanks contain concentrations of one VOC (total xylenes) in exceedance of the

USEPA RSL for soil.

PFAS was also detected above laboratory reporting limits in surface soil and wipe samples in the vicinity of the shed used for fire-fighting training exercises in the eastern part of the

Site.

• Arsenic was detected consistently across the Site soils at concentrations ranging from

2.2 to 4.6 mg/kg. Regional background studies were not available for Sao Tome and

Principe; however, regional background studies of similar volcanic islands in the region indicate that volcanic soils in the region have arsenic concentrations between 0.3 and 7.2 mg/kg. The arsenic concentrations at the Site are within these ranges, and therefore, Langan considers the arsenic detections indicative of regional background concentrations.

• TPH-DRO and TPH-ORO was detected in the wipe and soil samples at concentrations between 12 to 170,000 mg/wipe and 16 to 1,700 mg/kg, respectively. USEPA does not maintain screening levels for TPH, but the detections are consistent with concentrations typically identified in marginally impacted soil and concrete, with notable releases in the vicinity of the USTs and associated infrastructure, as well as areas of the Motor Pool, Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

Hazardous Materials Shed, and vehicle washing area. TPH-DRO impacts were also observed in the stormwater drainage ditches discharging to the Atlantic Ocean.

The laboratory analytical results indicate that the historical pesticide use (REC-5) and reverse osmosis brine (REC-6) do not appear to have adversely impacted soil quality at the Site and do not require further investigation at this time. However, the laboratory analytical results confirmed the presence of soil impacts from the on-Site diesel storage, burn areas, fire-fighting training areas, and hazardous substance storage (REC-1 through REC-4), which would require special considerations during redevelopment, as discussed in Section 4.

4.0 RECOMMENDATIONS

5.0 REFERENCES

The sources below were used during the performance of this Phase II ESA:

• USEPA, Regional Screening Levels Summary Table (TR=10-6, THQ=0.1). November

2024.

• United Nations Environment Program. Sao Tome and Principe: new project safeguards nature and climate, https://www.unep.org/technical-highlight/sao-tome-and-principe-new-project-safeguards-nature-and-climate, accessed February 3, 2025.

https://www.unep.org/technical-highlight/sao-tome-and-principe-new-project-safeguards-nature-and-climate https://www.unep.org/technical-highlight/sao-tome-and-principe-new-project-safeguards-nature-and-climate

Sao Tome, Sao Tome and Principe

Langan Project No. 270187301

TABLES

Table 1

Summary of Wipe Sample Results

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Sample ID:

Collection Date:

Volatile Organic Compounds (mg/wipe)

None Detected

Semivolatile Organic Compounds (mg/wipe)

None Detected

Polychlorinated Biphenyls (mg/wipe)

None Detected

Total Petroleum Hydrocarbons (mg/wipe)

Diesel Range Organics 19,000 H H3 850 H H3 6,200 H H3 32,000 H H3 1,700 H H3

Gasoline Range Organics

Metals (mg/wipe)

Arsenic 0.00056

Barium 0.084

Cadmium 0.000069

Chromium 0.019

Lead 0.0084

Selenium <0.00025

Silver <0.000050

Per- and Polyfluoroalkyl Substances (mg/kg)

Perfluorobutanoic acid (PFBA)

Perfluoropentanoic acid (PFPeA)

Perfluorohexanoic acid (PFHxA)

Perfluoroheptanoic acid (PFHpA)

Perfluorooctanoic acid (PFOA)

Perfluorononanoic acid (PFNA)

Perfluorodecanoic acid (PFDA)

Perfluoroundecanoic acid (PFUnA)

Perfluorododecanoic acid (PFDoA)

Perfluorotridecanoic acid (PFTrDA)

Perfluorotetradecanoic acid (PFTA)

Perfluorobutanesulfonic acid (PFBS)

1H,1H,2H,2H-Perfluorooctane sulfonic acid (6:2 FTS)

1H,1H,2H,2H-Perfluorodecane sulfonic acid (8:2 FTS)

N-ethylperfluorooctanesulfonamidoacetic acid

(NEtFOSAA)

N-ethylperfluorooctanesulfonamidoethanol (NEtFOSE)

NANA

NA NA NA NA NA

NA NA NA NA

NANA NA NA -- --

W-4

12/10/2024

W-5

12/10/2024

W-1

12/11/2024

W-2

12/11/2024

W-3

12/11/2024

W-6

12/11/2024

-- -- -- NA NANA

NA NA NA NA NA

NA NA NA

NANA NA

NA NA

NA NA NA

NA NA

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Sample ID:

Collection Date:

Volatile Organic Compounds (mg/wipe)

None Detected

Semivolatile Organic Compounds (mg/wipe)

None Detected

Polychlorinated Biphenyls (mg/wipe)

None Detected

Total Petroleum Hydrocarbons (mg/wipe)

Diesel Range Organics

Gasoline Range Organics

Metals (mg/wipe)

Arsenic

Barium

Cadmium

Chromium

Lead

Selenium

Silver

Per- and Polyfluoroalkyl Substances (mg/kg)

Perfluorobutanoic acid (PFBA)

Perfluoropentanoic acid (PFPeA)

Perfluorohexanoic acid (PFHxA)

Perfluoroheptanoic acid (PFHpA)

Perfluorooctanoic acid (PFOA)

Perfluorononanoic acid (PFNA)

Perfluorodecanoic acid (PFDA)

Perfluoroundecanoic acid (PFUnA)

Perfluorododecanoic acid (PFDoA)

Perfluorotridecanoic acid (PFTrDA)

Perfluorotetradecanoic acid (PFTA)

Perfluorobutanesulfonic acid (PFBS)

1H,1H,2H,2H-Perfluorooctane sulfonic acid (6:2 FTS)

1H,1H,2H,2H-Perfluorodecane sulfonic acid (8:2 FTS)

N-ethylperfluorooctanesulfonamidoacetic acid

(NEtFOSAA)

N-ethylperfluorooctanesulfonamidoethanol (NEtFOSE)

44,000 H H3 3,300 H H3 170,000 H H3 12,000 H H3

0.0026 0.00032 <0.00013 0.00083

0.068 0.030 0.0049 0.11

0.00011 0.000041 0.000033 0.00036

0.046 0.029 0.0044 0.16

0.0060 0.0032 0.00043 0.053

0.00026 <0.00025 <0.00025 0.00037

0.000050 <0.000050 <0.000050 0.00013

0.0011

<0.0004

0.0022 J

0.00089

<0.0004

0.0012 J

NA NA

NA NA NA

NA NANA NA NA NA

W-12

12/11/2024

W-10

12/11/2024

W-11

12/11/2024

W-8

12/11/2024

W-9

12/11/2024

W-7

12/11/2024

NA NA NA

NA NA NA NA

NA NA

NA NA NA NA

NA NA

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Sample ID:

Collection Date:

Volatile Organic Compounds (mg/wipe)

None Detected

Semivolatile Organic Compounds (mg/wipe)

None Detected

Polychlorinated Biphenyls (mg/wipe)

None Detected

Total Petroleum Hydrocarbons (mg/wipe)

Diesel Range Organics

Gasoline Range Organics

Metals (mg/wipe)

Arsenic

Barium

Cadmium

Chromium

Lead

Selenium

Silver

Per- and Polyfluoroalkyl Substances (mg/kg)

Perfluorobutanoic acid (PFBA)

Perfluoropentanoic acid (PFPeA)

Perfluorohexanoic acid (PFHxA)

Perfluoroheptanoic acid (PFHpA)

Perfluorooctanoic acid (PFOA)

Perfluorononanoic acid (PFNA)

Perfluorodecanoic acid (PFDA)

Perfluoroundecanoic acid (PFUnA)

Perfluorododecanoic acid (PFDoA)

Perfluorotridecanoic acid (PFTrDA)

Perfluorotetradecanoic acid (PFTA)

Perfluorobutanesulfonic acid (PFBS)

1H,1H,2H,2H-Perfluorooctane sulfonic acid (6:2 FTS)

1H,1H,2H,2H-Perfluorodecane sulfonic acid (8:2 FTS)

N-ethylperfluorooctanesulfonamidoacetic acid

(NEtFOSAA)

N-ethylperfluorooctanesulfonamidoethanol (NEtFOSE)

130 H H3 640 H H3 640 H H3 850 H H3

<0.00013 <0.00013

0.0013 0.00047

<0.000025 <0.000025

<0.00025 <0.00025

<0.00010 0.00030

<0.00025 <0.00025

<0.000050 <0.000050

0.00063 J

0.00087

0.0047

0.01

0.0085

0.013

0.0096

0.0074

0.006

0.0033

0.0032

0.000084 J

0.0027 J

0.0034

0.000062 J

<0.002

NA NA

NANA

NA NA NA

NA NA NANA

NA NA NA

W-13

12/11/2024

W-17

12/13/2024

W-14

12/12/2024

W-15

12/12/2024

W-16

12/12/2024

NA NA

Notes:

Only detected analytes are provided in this table.

ft: feet m: meter mg/kg: milligrams per kilogram

J = Result is less than the reporting limit but greater than or equal to the method detection limit and the concentration is an approximate value.

H = Sample was prepped or analyzed beyond the specific holding time.

H3 = Sample was received and analyzed past holding time.

<0.0025 = Not detected above laboratory reporting limit.

Table 2

Summary of Soil Sample Results

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Sample ID:

Collection Depth (ft):

Collection Depth (m):

Collection Date:

Volatile Organic Compounds (mg/kg)

Ethylbenzene 5.8 25 0.31 J H H3 <0.0071 H H3 <0.0089 H H3 m,p-Xylenes 55 240 1.5 H H3 <0.0071 H H3 <0.0089 H H3 o-Xylene 64 280 0.80 H H3 <0.0071 H H3 <0.0089 H H3

Toluene 490 4700 0.25 J H H3 <0.0071 H H3 <0.0089 H H3

Xylenes, Total 58 250 2,300 H H3 -- --

Semi-Volatile Organic Compounds (mg/kg)

Bis(2-ethylhexyl) phthalate 39 160 <4.4 H H3 <0.44 H H3 <0.54 H H3

Naphthalene 2 8.6 1.3 J H H3 <0.44 H H3 <0.54 H H3

Pentachlorophenol 1 4 <8.8 H H3 <0.89 H H3 <1.1 H H3

Phenanthrene NS NS 1.3 J H H3 <0.44 H H3 <0.54 H H3

Pyrene 180 2300 <4.4 H H3 <0.44 H H3 <0.54 H H3

Polychlorinated Biphenyls (mg/kg)

None Detected -- -- --

Total Petroleum Hydrocarbons (mg/kg)

Diesel Range Organics NS NS 8600 H H3 33 H H3 93 H H3

Oil Range Organics NS NS 380 H H3 57 H H3 140 H H3

Metals (mg/kg)

Arsenic 0.68 3 2.2 2.3

Barium 15,000 220,000 300 1200

Cadmium 0.71 10 0.45 J 0.33 J

Chromium, Trivalent 120,000 1,800,000 210 160

Lead 200 800 2.3 6.5

Mercury 0.71 3 0.020 J H H3 0.020 J H H3

Selenium 39 580 <2.4 <2.4

Per- and Polyfluoroalkyl Substances (mg/kg)

Perfluorobutanoic acid (PFBA) 7.82 117

Perfluorohexanoic acid (PFHxA) 3.16 41

Perfluoroheptanoic acid (PFHpA) NS NS

Perfluorooctanoic acid (PFOA) 0.0000185 0.0000784

Perfluorononanoic acid (PFNA) 0.019 0.246

Perfluorodecanoic acid (PFDA) 0.0000126 0.000164

Perfluorohexanesulfonic acid (PFHxS) 0.126 1.64

Perfluoroheptanesulfonic acid (PFHpS) NS NS

Perfluorooctanesulfonic acid (PFOS) 0.000632 0.00821

N-ethylperfluorooctanesulfonamidoacetic acid

(NEtFOSAA)

NS NS

N-ethylperfluorooctanesulfonamidoethanol

(NEtFOSE)

NS NS

Pesticides (mg/kg)

None Detected -- --

Herbicides (mg/kg)

None Detected -- --

Dioxins and Furans (mg/kg)

1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin

(HpCDD)

0.00048 0.00217

1,2,3,4,6,7,8-Heptachlorodibenzofuran (HpCDF) 0.000488 0.002210

1,2,3,4,7,8-Hexachlorodibenzofuran (HxCDF) 0.0000482 0.000218

1,2,3,6,7,8-(Hexachlorodibenzo-p-dioxin

(HxCDD)

0.0000493 0.000223

1,2,3,6,7,8-HxCDF 0.0000482 0.000218

1,2,3,7,8,9-HxCDD 0.0000493 0.000223

2,3,4,6,7,8-HxCDF 0.0000493 0.000223

2,3,4,7,8-Pentachlorodibenzofuran (PeCDF) 0.0000164 0.0000744

2,3,7,8-Tetrachlorodibenzofuran (TCDF) 0.000048 0.000217

Octachlorodibenzodioxin (OCDD) 0.0164 0.0744

Total HxCDD NS NS

Total HxCDF NS NS

Total HpCDD NS NS

Total HpCDF NS NS

Total PeCDD NS NS

Total PeCDF NS NS

Total TCDD NS NS

Total TCDF NS NS

NA NA

NA NA NA NA

NA NA

NANA

SB-4

0-0.3

12/11/2024

0-1

USEPA

Residential Soil

RSL

USEPA Industrial

Soil RSL

SB-1

0-0.15

12/11/2024

0-0.5

SB-2

0-0.15

12/12/2024

SB-3

0-0.25

12/11/2024

0-0.5 0-0.8

United States Agency for Global Media

Sao Tome, Sao Tome and Principe

Sample ID:

Collection Depth (ft):

Collection Depth (m):

Collection Date:

Volatile Organic Compounds (mg/kg)

Ethylbenzene 5.8 25 m,p-Xylenes 55 240 o-Xylene 64 280

Toluene 490 4700

Xylenes, Total 58 250

Semi-Volatile Organic Compounds (mg/kg)

Bis(2-ethylhexyl) phthalate 39 160

Naphthalene 2 8.6

Pentachlorophenol 1 4

Phenanthrene NS NS

Pyrene 180 2300

Polychlorinated Biphenyls (mg/kg)

None Detected -- --

Total Petroleum Hydrocarbons (mg/kg)

Diesel Range Organics NS NS

Oil Range Organics NS NS

Metals (mg/kg)

Arsenic 0.68 3

Barium 15,000 220,000

Cadmium 0.71 10

Chromium, Trivalent 120,000 1,800,000

Lead 200 800

Mercury 0.71 3

Selenium 39 580

Per- and Polyfluoroalkyl Substances (mg/kg)

Perfluorobutanoic acid (PFBA) 7.82 117

Perfluorohexanoic acid (PFHxA) 3.16 41

Perfluoroheptanoic acid (PFHpA) NS NS

Perfluorooctanoic acid (PFOA) 0.0000185 0.0000784

Perfluorononanoic acid (PFNA) 0.019 0.246

Perfluorodecanoic acid (PFDA) 0.0000126 0.000164

Perfluorohexanesulfonic acid (PFHxS) 0.126 1.64

Perfluoroheptanesulfonic acid (PFHpS) NS NS

Perfluorooctanesulfonic acid (PFOS) 0.000632 0.00821

N-ethylperfluorooctanesulfonamidoacetic acid

(NEtFOSAA)

NS NS

N-ethylperfluorooctanesulfonamidoethanol

(NEtFOSE)

NS NS

Pesticides (mg/kg)

None Detected -- --

Herbicides (mg/kg)

None Detected -- --

Dioxins and Furans (mg/kg)

1,2,3,4,6,7,8-Heptachlorodibenzo-p-dioxin

(HpCDD)

0.00048 0.00217

1,2,3,4,6,7,8-Heptachlorodibenzofuran (HpCDF) 0.000488 0.002210

1,2,3,4,7,8-Hexachlorodibenzofuran (HxCDF) 0.0000482 0.000218

1,2,3,6,7,8-(Hexachlorodibenzo-p-dioxin

(HxCDD)

0.0000493 0.000223

1,2,3,6,7,8-HxCDF 0.0000482 0.000218

1,2,3,7,8,9-HxCDD 0.0000493 0.000223

2,3,4,6,7,8-HxCDF 0.0000493 0.000223

2,3,4,7,8-Pentachlorodibenzofuran…

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