Report shows contaminated groundwater is migrating toward Teer Quarry, site of Durham’s future water supply

High levels of several toxic chemicals have been detected in groundwater near Teer Quarry, storage site for Durham’s future water supply, and are migrating toward the pit itself, state documents show.

However, it is still uncertain if these compounds will reach the quarry, and if so, at what concentrations.

The contaminant of greatest concern is 1,4-Dioxane, a likely carcinogen. It was found in more than half of the 26 groundwater monitoring wells at levels 3 to 50 times above the state’s target value for water supplies, according to a consultant’s report filed with the NC Department of Environmental Quality. 

Neither the EPA nor DEQ has set a legally enforceable maximum for 1,4-Dioxane, but state officials have recommended that raw water supplies, such as those stored in the quarry, contain no more than 0.35 parts per billion. The EPA announced yesterday that it would add 1,4-Dioxane to the latest list of contaminants that could be regulated within the next five years under the Safe Drinking Water Act. PFAS, or perfluorinated compounds, also widespread in drinking water supplies, including Durham’s, is also on the list

1,4-dioxane can be found in solvents, plastics production, industrial spills and discharges from municipal wastewater plants. Contaminated wastewater was used to make compost in Sampson County, Policy Watch previously reported.  The chemical is also found in many household products like laundry detergent, shampoos and cosmetics as a byproduct of manufacturing.

Along with Jordan Lake, Teer Quarry is a potential new water resource for Durham.  A confluence of climate change and the city’s rapid growth – its population could double over the next 25 years – is forcing Durham to seek additional sources of drinking water.

Currently, the city’s primary drinking water sources are Lake Michie and the Little River Reservoir. Durham also has agreements with Cary, Hillsborough, Chatham County and OWASA, in Orange County to buy and sell water.

For 15 years, city officials have eyed the Teer Quarry as storage for water. Pending approval from DEQ, they are proposing to pump water from both Lake Michie and a segment of the Eno River and store it in Teer Quarry for future treatment and use.

DEQ is holding a meeting tonight to add the designation “critical area” to part of the Eno River watershed’s classification to protect the area from further contamination.

Durham construction mogul Nello Teer originally owned and operated the rock quarry, then sold it to Hanson Aggregates. Mining stopped in the late 1980s, and the city now owns the quarry. Hanson still operates a crushed stone sales yard onsite.

At 200 feet deep, the quarry can hold 1.58 billion gallons, or nearly two months’ worth of water. Durham uses 28-to-30 million gallons of water per day, according to the city.

There are two sources of the contamination on quarry property: underground storage tanks from an old gasoline station and spills from a former asphalt plant and NC Department of Transportation testing laboratory.

Contamination levels and groundwater flows vary depending on the aquifer zones. Compounds in the groundwater in the intermediate and deep zones are “likely migrating toward the pit,” according to a Phase II Remedial Investigation Report commissioned by DEQ. The deep zone is the most likely area to discharge directly into the quarry pit. 

Five of six monitoring wells in the deep zone detected 1,4-Dioxane, at concentrations ranging from 3 to 20 times higher than DEQ’s target value, according to state records. 

Monitoring records since 2017 show that levels have gradually decreased but still far exceed target values. 1,4-Dioxane is often called a “forever chemical” because it does not quickly degrade in the environment.

The Durham Environmental Affairs Board has not discussed the city’s proposal or contamination near the quarry. Juilee Malavade, the EAB chairperson, told Policy Watch in an email that the group had not yet been briefed on the issue. “We plan on inquiring regarding the environmental condition of the quarry,” Malavade said.

Other contaminants include benzene and vinyl chloride, known to cause cancer; naphthalene, which the EPA has classified as a possible carcinogen; and bix(2-ethylhexyl) phthalate, a probable carcinogen.

DEQ has ranked the site as “high risk,” even though all of the nearby homes are now connected to public water supplies. In 2008, the consulting firm Highlands Environmental, working on behalf of Hanson Aggregates, asked DEQ to lower the site hazard ranking because no private drinking water wells were in use. DEQ declined to do so “when it was determined the quarry pit may be used as an emergency supply reservoir for the City of Durham water supply,” state documents read.

Joe Lunne, spokesperson for the Durham’s Department of Water Management, told Policy Watch that 1,4-Dioxane has never been found in Teer Quarry water, which would be treated before it flowed from public taps.

A DEQ memorandum related to Durham’s proposal recommends annual surface water monitoring of quarry water. Lunne of the Durham Water Management Department said the location of monitoring points “will depend, at least in some part” on where the intake would be installed in the quarry.

Extreme weather, driven in part by climate change, has forced the city to re-examine its water options. Durham and the rest of North Carolina suffered from a historic drought in 2007. In August of that year, temperatures soared well above 100 degrees for several days, making it the second-warmest and second-driest August on record, according to the NC State Climate Office.

As lakes and rivers dried up – Falls Lake looked like a moonscape – Durham at one point had just 38 days of water left in its reservoirs. The city supplemented it with water from Teer quarry. 

(Also in 2007, extreme winter weather halted progress toward cleaning up the quarry site. Two major snowstorms damaged the remediation system, which stopped operating and did not resume.)

The USDA Forest Service in Raleigh issued a report in 2013 projecting that by 2060, the Upper Neuse River Watershed , which provides the water supply for Raleigh and Durham will to experience a 14% decrease in water yield while population growth will increase water demand by 21%.

Meanwhile, more frequent droughts, floods and long periods of hot weather — all markers of climate change will alter the supply and demand for clean water. (Even during rainy stretches, the water can evaporate because of high temperatures.)

If 1,4- Dioxane does reach the pit, levels could be diluted as long as the there is enough water to dilute it. The city also has a consultant “that will soon be studying treatment technologies” Lunne added, for the removal of 1,4-Dioxane and PFAS, or perfluorinated compounds. In 2018, high levels of two types of the compounds, PFOA and PFOS, were detected in Lake Michie, an existing drinking water supply; some of that water will also be stored in Teer Quarry.

Traditional water treatment methods can’t remove PFAS or 1,4-Dioxane. 

PFAS and 1,4-Dioxane have been detected in both the Haw River and the Cape Fear River, as well as in drinking water in Pittsboro, Sanford, Fayetteville and Wilmington, according to DEQ data. Industrial dischargers and wastewater treatment plants are the likely sources.

For 1,4-Dioxane, ultraviolet irradiation and hydrogen peroxide, coupled with granulated activated charcoal, is one potential treatment. Cost depends on several factors, including the amount of raw water to be treated and the level of contamination.

Wilmington spent upward of $46 million to treat its drinking water for PFAS, which have been almost completely removed, and 1,4-Dioxane, whose levels have been reduced by two-thirds

And unless federal or state grant money covers the expense, Durham water customers would likely have to pay for any such upgrades through higher rates.

In addition to tonight’s meeting, DEQ is accepting public comment on Durham’s proposal through Nov. 14. Instructions are in the box at the top of the story.