Concurrent Session K. Contaminants in Maine Waters

Morning Session: Old to New Groundwater Contaminants

Afternoon Session: Emerging Contaminants

* 4 Training Contact Hours are available for this session (2 TCH morning; 2 TCH afternoon).

Improved analytic techniques, a better understanding of the pathways by which contaminants reach groundwater,  and increased knowledge of the importance of trace pollutants to human and ecological health all contribute to the growing body of information on groundwater contamination. This includes contaminants that have been studied for many years and more recently recognized emerging contaminants. These emerging contaminants are frequently organic compounds, and can include pesticides, pesticide metabolites, pharmaceuticals and personal care products, industrial additives and by-products, flame retardants, surfactants, and hormones, as well as caffeine, nicotine, and other drugs and their metabolites. Some studies have also included nanoparticles and microbial materials as emerging contaminants. Many of these are not easily removed from water by conventional treatment processes or natural degradation, and so may persist in drinking water and the environment.

For this session, we invite papers that describe the detection, occurrence, and persistence of these pollutants in soil and groundwater, their known and possible sources, effects on human health through drinking water and other means of contact, and also the pathways by which they reach soil, groundwater, and surface water. Because of the improving understanding of the close relationship between groundwater and surface water resources, we also invite papers that consider the importance of groundwater as a route by which these contaminants may reach surface waters, and discuss findings related to new pathways linking soil, groundwater and surface water for more traditional contaminants as well.

Session Co-chairs:
John Hopeck, Bureau of Water Quality, Maine Dept. of Environmental Protection
Rob Peale, Bureau of Remediation and Waste Management, Maine Dept. of Environmental Protection
Adria Elskus, US Geological Survey

Speakers:

Morning Session:
Old to New Groundwater Contaminants in Maine

8:30am – 8:55am
Pathways of a conservative contaminant:  Infiltration, fracture conduits, and re-emergence of chloride in wells and streams.
Mark Holden, Maine Department of Environmental Protection; mark.k.holden@maine.gov

The hydrologic behavior of road salt can be used as a model for understanding pathways for contaminants in groundwater. Past work has indicated a strong bias in chloride sampling results in residential wells downslope and proximal upslope from the road where salt is seeded in the winter months. This ongoing analysis proceeds with the hypothesis that fracture orientation in bedrock, if steep in dip and with an optimal strike direction further enhances the conductivity of the salt solute.

The results, shown graphically, demonstrate that 61 to 77% of the asymmetric downslope flow is due to fracture conductivity.

In ephemeral and intermittent streams which cross regularly salted roads, the conductivity changes in base flow and groundwater observed downstream of the road show a marked increase (up to 25-30 times greater over the cross road distance). This is particularly notable in dry summer months or drought conditions when the groundwater base flow component of the streams is greater. Measurement of small tributaries and springs along these streams point to long term sequestration underground near the roads and gradual release of the contaminant as base flow. The effect can continue for miles downstream.

9:00am – 9:25am
Trends in Methyl Tert-butyl ether concentration in private wells in southeast New Hampshire, from 2005 to 2015
Sarah M. Flanagan, U.S. Geological Survey; sflanaga@usgs.gov

In southeast New Hampshire, reformulated gasoline, containing methyl tert-butyl ether was sold until 2007. Bedrock type, overburden type, and population density were shown to influence contaminant fate and transport of methyl tert-butyl ether (MtBE) in this region, in which nearly 400,000 drilled bedrock wells are the sole source of drinking water to rural households and small community systems. MtBE concentrations > 0.2 µg/L were found in water from 26.7% of 195 domestic wells sampled in 2005. Ten years later in 2015, and eight years after MtBE was banned, 10.3% continue to have MtBE > 0.2 µg/L. Most wells (140 of 195) had no MtBE detections (concentrations < 0.2 µg/L) in 2005 and 2015. Of the remaining wells, MtBE concentrations increased in four wells, decreased in 47 wells, and did not change in four wells. The percent change in detection frequency from 2005 to 2015 (the decontamination rate) was the lowest (45.5%) where population-densities were high and wells were completed in the Berwick Formation geologic units. The decontamination rate was the highest (78.6%) where population densities were low and wells were completed in bedrock composed of granite, metamorphic, and mafic rocks. Wells completed in the Kittery and Elliot Formations did not have any MtBE detections in 2005 or 2015. These wells have relatively high yields and shallow depths and are located in an area of the seacoast with discontinuous glacio-marine deposits.

9:30am – 9:55am
Characterization of the Pharmaceutical Content in Municipal Solid Waste Landfill Leachate and Impacted Groundwater
Richard H. Heath, Maine Department of Environmental Protection; richard.h.heath@maine.gov

The Department collected and analyzed samples from both operating and closed unlined municipal solid waste landfills for the presence of pharmaceutical and personal care products (PPCPs) in leachate and groundwater. We collected the leachate samples from three operating landfills with engineered liner systems. These landfills received little or no sludge from municipal wastewater treatment plants. Therefore, we expect the presence of PPCPs in leachate from these landfills results primarily from direct disposal in the waste stream. We also determined the PPCP content of groundwater in the vicinity of two unlined closed municipal landfills.

Leachate from the operating landfills contained in excess of 40 PPCP compounds or their breakdown products including antibiotics, steroids, antidepressants as well as heart, asthma, high blood pressure, and a variety of pain medications. Some of the drugs common to the three landfills include: Albuterol, Atenolol, Carbamazepine, Cimetidine, Enalapril, Estrone, Gemfibrozil, Penicillin G and Valsartan. The results from this initial evaluation demonstrate that a large variety of PPCPs, in the form of both prescription and over-the-counter drugs, are discarded in household waste and can appear in landfill leachate.

The groundwater samples collected from monitoring wells adjacent to the unlined landfills contained a variety of PPCPs. Several of the PPCPs observed in groundwater were also found in leachate from the operating landfills. The closure of the landfills occurred 20 to 30 years before sample collection suggesting the detected PPCP are recalcitrant and may be present in groundwater impacted by other closed landfills in similar settings.

10:00am – 10:25am
Using sucralose to assess the impact of septic disposal systems on groundwater quality
Richard S. Behr, Maine Department of Environmental Protection; richard.s.behr@maine.gov

A groundwater quality evaluation revealed a variety of contaminants in a densely developed coastal Maine community where residents and businesses rely on bedrock wells for their drinking water. We conducted several investigations to evaluate possible groundwater impacts by a closed unlined municipal landfill located near the center of the community. The data from multiple sampling rounds found many bedrock wells are characterized by low levels of dissolved oxygen, elevated specific conductance, chloride, redox sensitive metals and total organic carbon.   While some wells may arguably contain contaminants leached from the landfill, the majority of contaminants likely originate from other sources including salt used for winter road maintenance, development activities and residential and commercial septic disposal systems. Water samples from nine water supplies and two landfill monitoring wells were analyzed for sucralose, a synthetic sweetener, to assess the effect individual septic systems have on groundwater quality. Sucralose represents an excellent marker of septic system influence on groundwater because it is water soluble, mobile, recalcitrant and consumed in significant quantities by a large segment of the population. Most importantly, sucralose was not available in the United States until 1998, two years after the landfill in question was closed, thereby eliminating it as a possible constituent of the landfill leachate. The results revealed the presence of sucralose (124 ng/L to 4,000 ng/L) in all nine water supply wells. As expected, sucralose was not detected in the landfill monitoring wells. These results provide evidence the bedrock water supplies are affected by septic system disposal effluent.

Afternoon Session:
Emerging Contaminants in Maine Waters

1:30pm – 1:55pm
PFAS distribution and transport in soils and groundwater at a DOD site
Gail Lipfert, Maine Department of Environmental Protection; gail.e.lipfert@maine.gov

PFAS (poly- and perfluoroalkyl substances) are a major component in AFFF (aqueous film-forming foams) that were used to fight fires and treat fuel spills at DOD (Department of Defense) sites. In 2015, a multi-year investigation of PFAS in soils, sediments, groundwater, surface water, and fish tissue at a former Air Force base provided data to help us understand the sources and pathways of PFAS due to AFFF use. Soil and associated groundwater data will be presented. Eighteen PFAS were analyzed, seven of which were detected in soils and twelve of which were detected in groundwater. PFOS (perfluorooctanesulfonic acid) is the most commonly detected PFAS in soils and groundwater. Although PFAS was detected in off-base drinking-water samples, there were no exceedances of the EPA PHAs (Public Heath Advisories) for PFOS and PFOA (perfluorooctanoic acid). Within the base, PFOS concentrations exceeded the PHA at 17 of 42 monitoring wells and PFOA exceeded the PHA at 7 of these wells. No exceedances of MeCDC screening levels for PFOS and PFOA were measured in 58 soil samples. PFAS precursor compounds, 6:2FTS (fluorotelomer sulfonate) and 8:2FTS, were detected in soils at 9 and 8 locations, respectively (up to 185 ng/g), and groundwater at 8 and 6 locations, respectively (up tp 721 ng/L). There is evidence supporting a decrease of PFOS concentrations in soils with depth. Modeling of leaching of soil contamination to groundwater will be presented.

2:00pm – 2:25pm
Advances in Poly- and Perfluoralkyl Substances (PFAS) Analytical Techniques: Implications for Conceptual Site Models
Allan Horneman, ARCADIS; allan.horneman@arcadis.com

Poly- and perfluoroalkyl substances (PFAS), including perfluorooctane sulfonate and perfluorooctanoate are commonly elevated in soil and groundwater at sites with industrial PFAS applications or past use of firefighting foams, including aqueous film-forming, fluoroprotein and film foaming fluoroprotein foams (AFFF, FP, and FFFP). The products contain a complex mix of fluorinated compounds that include perfluorinated compounds, where all carbons are saturated with F atoms, and polyfluorinated compounds where some carbons have hydrogen bonds. The polyfluorinated compounds, termed precursors, are transformed in the environment to form perfluorinated compounds which are extremely persistent and not susceptible to further transformation. The precursors are not accounted for by the U.S. EPA analytical method 537; however, precursors represent a “hidden” mass that should be considered in fate and transport assessments and conceptual site models, especially given that many PFAS are anionic and are not retarded significantly in the subsurface, whereas some precursors are cationic and bind to soils via ion exchange mechanisms and represent a less mobile source mass.

This presentation will discuss three new analytical methods developed to quantify the total concentration of precursors and PFAS in water and soil samples. The analytical methods include the total oxidizable precursor (TOP) method, particle induced gamma emission (PIGE) spectroscopy, and adsorbed organic fluorine (AOF).

This next generation of PFAS analytical techniques are generating more comprehensive analytical data that supports more robust conceptual site models and are improving our understanding of PFAS fate and transport. Accounting for precursors is also key for the successful design of remedial systems.

2:30pm – 3:00pm
Afternoon Break

3:00pm – 3:25pm
Removal of PFAS From Groundwater in an Extraction and Treatment System
Chris Evans, Maine Department of Environmental Protection; gordon.c.evans@maine.gov

Poly- and perfluoroalkylated substances (PFAS) are a large class of emerging contaminant compounds that are or have been used in numerous consumer products and in aqueous film-forming foams (AFFF) used in fire suppression. Their chemical properties and the strength of the carbon-fluorine bond make them challenging to remediate in groundwater. USEPA has released Health Advisory drinking water criteria for two of these compounds, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS).

Due to their use in fire training, PFAS are co-located with a chlorinated solvent plume at a former Naval Air Station, where the Navy has had a groundwater extraction and treatment system (GWETS) in operation since the mid-1990s. The treatment train includes two carbon vessels and an oxidation unit. In response to detections of PFAS in the effluent water at the GWETS, and delineation of PFOA and PFOS in groundwater and surface water exceeding Health Advisory criteria at the base, the Navy modified the system in 2015. They replaced the existing carbon, and collected data to evaluate the effectiveness of two different granular activated carbons to remove PFAS and the chlorinated solvents from groundwater at this site.

Monitoring of the system at multiple points demonstrated that the carbon is effective for removal of PFAS to non-detect levels. Breakthrough occurs at faster rates for shorter chain PFAS than for longer chain compounds. Performance of coconut-based activated carbon was not as good as coal-based carbon. The oxidation unit may enhance degradation of precursor compounds into the target compounds PFOS and PFOA.

3:30pm – 3:55pm
PFAS distribution and transport in surface water, sediment and fish tissue at a DOD site
Gail Lipfert, Maine Department of Environmental Protection; gail.e.lipfert@maine.gov
Barry Mower, Maine Department of Environmental Protection

PFAS (poly- and perfluoroalkyl substances) were investigated within surface water, sediment, and fish tissue from two stream drainages originating at a former Air Force base. PFOS (perfluorooctanesulfonic acid), PFHxS (perfluorohexane sulfonate), and PFOA (perfluorooctanoic acid) were the most commonly detected PFAS in surface water. PFOS, PFHxS, and PFOA concentrations in surface water ranged from 0.47 to 392 ng/L, 1.55 to 371 ng/L, and 1.9 to 33.2 ng/L, respectively. PFOS concentrations exceeded the Maine Center for Disease Control (MeCDC) surface water screening levels at 2 of 17 stream and lake locations draining the base, but PFOA did not exceed any screening level. PFOS concentrations in 17 sediment samples ranged from 0.63 to 10.7 µg/kg (PFHxS and PFOA were below the reporting limit) and did not exceed MeCDC screening levels. PFOS was the most commonly detected PFAS in fish tissue samples (PFHxS and PFOA were mostly below the reporting limit) and concentrations ranged from 2.17 to 457 µg/kg. All fish tissue samples exceeded the subsistence fisher screening levels except the background samples. Most fish tissue samples (85%) exceeded the recreational fisher screening levels.