Cliffdale Landfill
Cumberland County/Cliffdale LF
Lowell Harris Road, Fayetteville, NC
Site ID: NCD980502900
Site Overview as of 11/25/2025
NCDEQ’s Division of Waste Management, through its Pre-Regulatory Landfill (PRLF) Unit, is conducting a remedial investigation of the Cumberland County/Cliffdale LF (the Site). The goal of the investigation is to establish the location of the waste disposal area and the extent of associated contamination in the air, soil, groundwater, and surface water/sediments.
Cumberland County/Cliffdale LF is a PRLF operated by Cumberland County from 1972 to 1980. The Site is located on two parcels (60 acres total) owned by Cumberland County (PINs 9487-30-5518 and 9487-40-6015). Part of the Site was used as a convenience center after it was closed. An old, inoperable methane collection system is present onsite which was in operation from the mid-80s until the mid-90s (Air Quality Permit 5846, (paper records destroyed/lost in 2016 due to a flood). Public water and sewer is available in the area surrounding the Site.
Waste disposal area is approximately 44 acres.
Onsite groundwater monitoring wells indicate presence of contaminants over NC 2L Groundwater Standards.
Onsite landfill gas probes indicate methane is present over the lower explosive limit (5% by volume of air); hydrogen sulfide and volatile organic compounds are also present. Risk is exceeded for the residential and non-residential worker soil gas to indoor carcinogenic risk and non-carcinogenic hazard quotient in onsite gas probes.
There are 37 adjacent properties located along Levi Road, Martha Court, Lowell Harris Road, Leslie Drive, and Beverly Drive. These properties share a property line along the western and southern boundary of the landfill. Methane is present over the lower explosive limit in the soil gas at 7 of the 37 properties.
The PRLF Unit is focusing investigative efforts into the residential community surrounding the Site because of the measured methane levels from the landfill and proximity to homes. To date, DWM has installed soil-gas probes on 30 of the 37 properties that share a property line with the old landfill. Up to two probes are installed on each of those 30 properties. The soil-gas investigation will expand outward as needed to determine the extent of the contamination.
A public information session was held on October 22, 2025 at the Lake Rim Recreation Center from 6:30-8pm. The presentation can be found here. Action items from the meeting include establishing a website for the Site to include a list of contacts for residents to obtain health and safety information.
Documents and data for the site, including investigation results, will be posted to the following link: Site Documents – Cumberland County/Cliffdale LF
Site activities are outlined below.
Risk Calculator - A risk calculator is a quick, easy, and conservative method to quantify the potential human health risk posed by exposure to contaminated media. The concentrations of contaminants are entered into a risk calculator, based on equations from the US Environmental Protection Agency, to determine if the contaminants pose a potential health risk to people from various exposure routes like drinking water or air. When we say the health risk was exceeded, we mean that the risk calculator shows the contaminants pose a potential risk that is over an acceptable standard.
For contaminants that pose a cancer risk, the acceptable standard in NC is 1 in 10,000 meaning a person has 1 chance in 10,000 of getting cancer if they are exposed to this contamination 24 hours a day over a lifetime (70 years). The baseline cancer risk in the US is approximately 30%. So out of 10,000 people, it is predicted that 3,000 people will get cancer in their lifetime. If 10,000 people were exposed to the contamination we are evaluating, there may be one person that might get cancer in addition to the 3000 people that will get cancer from lifestyle exposures and other factors not related to the contamination.
For contaminants that pose a non-cancer risk (harmful effects other than cancer), the risk is stated by a Hazard Index which is also calculated by the risk tool. A Hazard Index of 1.0 or less suggests that non-cancer health effects are not expected.
Landfill Gas - Landfill gas is the natural by-product of the anaerobic decomposition of biodegradable material that is placed in landfills. The composition of landfill gas produced is typically in the range of 45-60% methane and 40-60% carbon dioxide. Additional components of landfill gas include trace amounts of hydrogen sulfide and volatile organic compounds.
Methane - Methane is a flammable, potentially explosive gas that is colorless and odorless. Explosive conditions exist for a combustible gas between its Lower Explosive Limit (LEL) and its Upper Explosive Limit (UEL). The LEL of methane is 5% by volume in air. At concentrations below 5%, methane cannot ignite. The UEL of methane is 15% by volume. At concentrations over 15%, the air is too rich to burn. Between 5 and 15%, methane is considered highly flammable because there is enough oxygen in the air for methane to produce a flash of fire in the presence of an ignition source (arc, flame, heat). Methane can also displace oxygen, which can result in the potential for suffocation.
NC 2L Groundwater Standards – North Carolina Administrative Code Title 15A Subchapter 2L – Groundwater Classification and Standards
Screening vs sampling – Screening is performed by using portable meters (GEM5000 Plus and MiniRAE 3000) to draw air samples from the ambient air, gas probe, or gas implant to determine levels of methane, hydrogen sulfide, carbon dioxide, oxygen, volatile organic compounds, and barometric pressure. Sampling involves collecting a sample into a sampling canister for laboratory analysis of volatile organic compounds, methane, and hydrogen sulfide.
Historical Files for NCD980502900 (Cumberland County/Cliffdale LF)
SF_F_NCD980502900_04-22-1988_IHS_NF
SF_F_NCD980502900_08-22-1995_SERB_C
SF_F_NCD980502900_01-31-2005_IHS_C
PRLF2900_20200903_Notification of an Inactive HazardousSubstance
Historical Files for NONCD0000733 (Cumberland County Landfill - Bones Creek)
NONCD0000733 Copy of SF_F_NCD980502900_08-22-1995_SERB_C
Clarification to the Site name “Cumberland County Landfill” as noted in the historical files:
The location of NCD980502900 (Cumberland County/Cliffdale LF) was updated in the PRLF inventory in 2020 when a consultant hired by the County submitted a Notification of an Inactive Hazardous Substance when the coordinates for the Site were not in the Lowell Harris Road location. Prior to this, coordinates for both PRLFs were at Winward Cove Road, which is NONCD0000733 (Cumberland County Landfill - Bones Creek). Because of this, the historical files for NCD980502900 (Cumberland County/Cliffdale LF) and NONCD0000733 (Cumberland County Landfill - Bones Creek) are combined/duplicated.
Access
Signed access to PINs 9487-30-5518 and 9487-40-6015, Cumberland County was provided by Toni Stewart, Chairwoman Cumberland County Board of Commissioners on October 18, 2023[AT1] .
First Phase Report
A first phase report dated January 5, 2024 summarizes the historic and current land use, potable water usage, sensitive environments, description of geologic/hydrogeologic conditions, aerial photographs and various maps, site visit photographs, and includes a geophysical survey of the horizontal extent of waste.
The Site is covered with woodland and brush with a cleared area on the west portion of the Site. The Site is located within an area zoned for single family residential. Land use is primarily residential to the south and west, with woodlands and an unnamed tributary to Bones Creek (18-31-24-2; C) to the north and east. Except along Tine Road, the area within 1,000 feet of the waste disposal area is served with public water and sewer.
Remedial Investigation Report - First Phase Activities - January 5, 2024
Waste Disposal Area and Above Ground Vapor Survey
In March 2024, S&ME, a firm under contract with the State, used test pits and hand augers to confirm the waste boundary as indicated by the geophysical survey. In April 2024, S&ME completed an above ground vapor survey by collecting 287 vapor screening readings in a 100-foot grid pattern over the waste disposal area.
No methane, hydrogen sulfide, or volatile organic compounds were detected in any of the above ground vapor screening locations or in the background screening locations. The waste disposal area delineation and above ground vapor survey is summarized in a report dated June 20, 2024.
Sensitive Environments
In April 2024, S&ME submitted an environmental review to the United States Fish and Wildlife Service (USFWS) regarding federally- and state-protected species that are known to have current or historic populations in Cumberland County and the project vicinity. The review package was acknowledged by the USFWS in a letter dated April 18, 2024.
In June 2024, the United States Army Corp of Engineers (Corps) determined 5.34 acres of the Site are considered waters of the United States and under the Corps regulatory jurisdiction. This determination has been conducted to identify the limits of Corps’ Clean Water Act jurisdiction. Section 404 of the Clean Water Act requires a Department of the Army permit be obtained prior to the discharge of dredged or fill material into waters of the United States, including wetlands. The jurisdictional determination is documented in a letter dated July 17, 2024.
Potable Wells
Permission was obtained by a property owner for one of four potable wells within 1,000 feet of the waste disposal area. The well was sampled on June 13, 2024. This residential water supply well is located at 9402 Tine Road, approximately 850 feet northeast of the Site. The potable well water was analyzed for volatile organic compounds, semi-volatile organic compounds, 1,4 dioxane, metals (antimony, arsenic, barium, beryllium, cadmium, chromium, copper, cobalt, lead, manganese, nickel, selenium, silver, thallium, vanadium, zinc, mercury, and hexavalent chromium), nitrate, sulfate, and ammonia.
The laboratory report indicated there were no exceedances to the NC 2L Groundwater Standards for the water supply well at 9402 Tine Road. A summary of the sampling event and the results are in a report dated July 16, 2024.
Water Supply Well Sampling Event - July 16, 2024
Onsite Results
In September 2024, 21 landfill gas probes, 5 soil gas implants, and 9 groundwater monitoring wells were installed inside the waste disposal area on the Site property.
In September 2024, soil gas was screened and sampled. The laboratory reported detections of volatile organic compounds in the soil gas samples. The NCDEQ Risk Calculator was used to assess the risk for the soil gas to indoor air pathway: Risk was exceeded at 25 of 26 sample locations. Methane was detected above the lower explosive limit in 24 of 26 sample locations. Hydrogen sulfide was detected in 25 of 26 sample locations.
Groundwater monitoring wells were sampled in October 2024, and the laboratory reported detections of multiple constituents above the NC 2L Groundwater Standards.
These activities and results are summarized in a report dated March 6, 2025.
Remedial Investigation Report – Onsite Gas and Groundwater – March 6, 2025
Offsite Results
Because methane is present above the lower explosive limit in landfill gas probes near the property line, the investigation was extended offsite onto adjacent properties. The PRLF Unit requested access to 32 adjacent property owners along Leslie Drive, Martha Court, Levi Road, Lowell Harris Road and Beverly Drive. Letters were mailed First Class USPS on December10, 2024. On January 10, 2025, 20 duplicate letters were mailed Certified USPS (with tracking and signature required) to non-responding property owners. By February 25, 2025, 19 access agreements were acquired. The effort to obtain offsite access is summarized in a report dated February 28, 2025.
In March and April of 2025, 11 offsite soil gas probes and 8 soil gas implants were installed on 19 adjacent properties.
In April of 2025, soil gas was screened and sampled. Samples from onsite landfill gas probes indicate detections of multiple volatile organic compounds in the soil gas samples. The NCDEQ Risk Calculator was used to assess the risk for the soil gas to indoor air pathway: Risk was exceeded 22 of 26 sample locations. Methane was detected above the lower explosive limit in 23 of 26 sample locations. Hydrogen sulfide was detected in 15 of 26 sample locations.
Soil gas in offsite residential soil gas probes and soil gas implants was also screened and sampled during the same period. Laboratory reports for the offsite residential soil gas sampling indicate detections of multiple VOCs in the soil gas samples. The NCDEQ Risk Calculator shows risk was exceeded at 6 of 14 sample locations. Methane was detected above the lower explosive limit in 5 of 14 sample locations. Hydrogen sulfide was detected in 4 of 14 sample locations.
Groundwater monitoring wells were sampled in April 2025, and the laboratory reported detections of multiple constituents above the NC 2L Groundwater Standards.
These activities and results are summarized in a report dated July 25, 2025.
Remedial Investigation Report – Offsite Gas and Groundwater – July 25, 2025
The Cumberland County Health Department was notified of the results on August 4, 2025.
Remedial Investigation Report – Offsite Gas and Groundwater – July 25, 2025
The Cumberland County Health Department was notified of the results on August 4, 2025.
Because of the levels of methane measured in offsite soil gas probes, additional efforts were made to obtain access from property owners who previously did not respond or refused, to reach out to agreeable property owners to install additional probes near the foundation of the house, and to offer natural gas alarms to anyone adjacent to the old landfill. A natural gas alarms was offered to each of the 37 adjacent property owners in person and also in a letter dated September 26, 2025. A summary of all efforts to contact the 37 adjacent property owners as of December 2025 is summarized in a report dated December 4, 2025. Please note personal information such as phone numbers and email addresses are redacted.
On August 1, 2025, the PRLF Unit Project Manager received a call from a concerned property owner at 1005 Leslie Drive regarding her family’s safety. On August 4, 2025, S&ME installed two natural gas alarms at 1005 Leslie Drive. S&ME also recorded air samples inside the residence: No methane was detected. Methane measurements at the soil gas probe installed at the property line for 1005 Leslie Drive (SGI-34) was 53.2%. A summary of this effort is in a report dated August 11, 2025.
In September 2025, an additional 38 soil gas probes and 3 soil gas implants were installed next to house foundations so that 30 out of 37 adjacent property owners have 2 probes per lot: one near the back property line/fence, and one near the back of the house near the foundation.
Screening and sampling of the soil gas probes were performed in October 2025. Laboratory reports for the offsite residential soil gas sampling indicate detections of multiple VOCs in the soil gas samples. The NCDEQ Risk Calculator shows risk was exceeded at 7 of 60 sample locations. Methane was detected above the lower explosive limit in 5 of 60 sample locations. Hydrogen sulfide was detected in 6 of 60 sample locations.
These activities and results are summarized in a report dated January 12, 2026.
Remedial Investigation Report – Offsite Soil Gas – January 12, 2026
Because methane levels were detected over the lower explosive limit at the foundations of six properties, additional soil gas probe screening was conducted on October 27 and November 5, 2025.
The property owner at 1021 Leslie Drive informed S&ME that the installed natural gas alarm activated on October 30. The alarm sounds when methane levels at the sensor are detected at or above 10% of the lower explosive limit (5% by volume. The residents called 911, and the Fayetteville Fire Department responded. Indoor air screening performed by the Fire Department confirmed natural gases were present, but the levels did not exceed 10% of the lower explosive limit. The Fire Department opened windows to ventilate the home until it was safe to return. On November 3, S&ME replaced the activated alarm with a new alarm, and a second new alarm was installed in an adjacent room of the home. The indoor air space of the home was screened, and no detections of methane were recorded. S&ME returned to 1021 Leslie Drive to conduct indoor residential air sampling on November 5, 2025. Sampling results were below the lower explosive limit.
These activities and results are summarized in a report dated December 4, 2025.
The natural gas alarm at 1021 Leslie Drive activated again on November 7 and November 15, 2025. The residents called 911, and the Fayetteville Fire Department responded each time. Indoor air screening performed by the Fire Department confirmed natural gases were present, but the levels did not exceed 10% of the lower explosive limit. The Fire Department opened windows to ventilate the home until it was safe to return. After the November 7 alarm, DWM advised the residents to leave until a methane vapor intrusion system (MVIMS) could be installed. DEQ offered to cover temporary housing. A MVIMS installation began Nov. 17, 2025 and on Nov. 20, installation was complete. Monitoring indicated the MVIMS was working to reduce methane levels. The residents were advised they could move back in. An alarm and remote monitoring system is in place at this house.
Pilot testing for a vapor extraction system was completed in December 2025. Design for the vapor extraction system is currently underway. This system will be installed along the property line on Cumberland County property to collect methane in the soil before it leaves the property and can impact homes. The larger system will be installed in phases, with the full system installation being completed in the summer of 2026.
The MVIMS installed at 1021 Leslie Drive has continuous monitoring. Contractors Hartmand & Hickman will perform monthly site visits to check the operation and performance of the fan and system components.
A Vapor Extraction System will be installed along the property line on Cumberland County property to collect methane in the soil gas before it leaves the property.
Background groundwater and potential offsite groundwater contamination will be evaluated as a part of this investigation.
Surface water and sediments will be evaluated as a part of this investigation.
Cover soil, if present, will be evaluated as part of this investigation.
The investigation establishes the site and identifies the risk for the site, and a remedial action plan (RAP) will address the risks identified in the waste disposal area and contaminated media (i.e. groundwater, surface water, sediment, vapor, and/or exposed contaminated soils). The RAP is based on site specific conditions and risk and include the following: management of exposed waste and/or surface debris, landfill leachate, slope stabilization, engineered waste disposal area cover system, stormwater management, required permits, mitigation measures pertaining to waters of the United States, erosion and sediment control measures, identification and evaluation of clean offsite borrow material, establish a vegetative cover, health and safety plan, and land use restrictions.
What do I do if my natural gas or methane detector alarms? CALL 911. A combustible gas detector is meant to be a warning. If the detector sounds an alarm, that does NOT mean you will have an explosion or fire in your home. Open the windows in your home. Put out any open flames such as cigarettes or candles. To be safe, you should get yourself and everyone else out of the house. Do not go back into your house until the fire department checks your house and says it’s safe.
Who should I contact if I have questions or concerns about my indoor air? Contact Analee Thornburg, the PRLF Unit Project Manager - 919-707-8227, analee.thornburg@deq.nc.gov; or Tom Raymond with S&ME - 919-801-5359, traymond@smeinc.com.
Who should I contact to get a methane detector installed in my house? If you share a property line with the landfill and would like to have an natural gas alarm installed and indoor air screening, please contact Tom Raymond with S&ME - 919-801-5359, traymond@smeinc.com. If you do not live adjacent to the landfill and would like an alarm, you may purchase them online or at your local hardware store. DWM is currently installing DeNova Detect 10-Year Battery-Powered Carbon Monoxide + Natural Gas Alarm (Product No. DD623NCV), but any battery powered natural gas alarm will work.
Who should I contact if I have questions regarding the Site investigation, results, or upcoming work? Contact Analee Thornburg, the PRLF Unit Project Manager - 919-707-8227, analee.thornburg@deq.nc.gov; or Tom Raymond with S&ME - 919-801-5359, traymond@smeinc.com.
Who should I contact about my health? Contact your primary care provider; the Cumberland County Department of Public Health - 910-433-3600, jgreen@cumberlandcountync.gov; or North Carolina Department of Health and Human Services - Occupational and Environmental Epidemiology - 919-707-5900, oeeb@dhhs.nc.gov.
Who should I contact about my property values? Contact Cumberland County Tax Administration - 910-678-7507, taxweb@cumberlandcountync.gov.
Who should I contact about building codes? Contact Cumberland County Planning and Inspections Department - 910-678-7600, cumberlandplanning@cumberlandcountync.gov.
Why is the alarm going off at 1021 Leslie Drive? Why aren’t other houses being affected this way?
The investigation is still in its early stages, and it would be premature to draw conclusions at this point. As the investigation continues, we may learn more; however, because many factors influence how soil gases move through soil and enter homes, it is not always possible to identify a single cause. Protecting public health remains our priority, and we are continuing to evaluate the situation to ensure appropriate actions are taken based on the information available.
For questions, comments, or concerns about the site or ongoing project, please contact:
Analee Thornburg
PRLF Project Manager
919-707-8227
For general information about the PRLF Program, please visit the link below: