HEALTH CONSULTATION
Hydrogen Sulfide Exposure in Warren Township
Private Well Water Pathway
WARREN RECYCLING
WARREN, TRUMBULL COUNTY, OHIO
BACKGROUND AND STATEMENT OF ISSUES
On April 22, 2002, a petition was submitted that asked the Agency for Toxic Substances and Disease Registry (ATSDR) to evaluate ambient air hydrogen sulfide levels in the Warren Township, Ohio community. The petition noted exposure of children attending schools and residents living in close proximity to Warren Hills Landfill/ Warren Recycling, Inc. (WHL/WRI), a local construction and demolition debris (C&DD) landfill, as a special concern [1]. ATSDR has addressed air issues in two public health consultations dated September 2002 and November 2003, as well as at a community meeting on June 27, 2003.
During ATSDR's first meeting in Warren Township on August 8, 2002, residents expressed concerns about an "egg-like" odor in their water [2]. In response, the Ohio Department of Health (ODH) collected water samples from 15 residential wells (November 14-15). This health consultation will address the impact of water off-gassing hydrogen sulfide into residential homes and if exposure may impact the health of residents. Additionally, the document will evaluate metals and water quality analysis performed on the residential well samples. Schools in the area of concern use city water and do not rely on private wells for drinking water.
Site-specific conditions can affect groundwater quality. Such conditions include land formations such as hills, valleys, and planes (physiography), soils and rock formations (geology), movement of water through geologic formations (hydrogeology), and other potential influences on groundwater quality (e.g., area industry). We will review the site geology, physiography, and hydrogeology to determine if it is likely that the landfill can be impacting private well quality. The impact of area oil and gas wells on water quality will also be assessed.
Private Well Water Quality in the vicinity of the Warren Recycling Landfill
Sampling Locations and Sampling Methods
Most residents living within 2 miles of WHL/WRI are on city water. At two community meetings, ATSDR and ODH requested that private well owners volunteer for well testing. Fifteen residential wells were tested in the impacted area. The wells that were sampled are located south, west, and north of the WHL/WRI facility (see map in Appendix C). Consent forms were obtained from each property owner prior to testing. Water samples were collected in the basement sink, or bathroom or kitchen sink if there was no basement. To establish a worst-case scenario, all treatment systems were bypassed. No background samples were collected. The waterlines were flushed for 20 minutes before a water sample was collected to ensure that the sample was representative of groundwater quality.
Samples were handled, stored, and shipped in accordance with applicable Ohio EPA Guidelines. Wells were tested according to Ohio EPA Drinking and Ground Water methods. ODH sent individual results, along with a letter interpreting the results, to each home that participated. The letters were mailed in April 2003 prior to a community meeting to inform the community of the results.
Air monitoring during well water sampling was conducted to determine if any of the contaminants present could off-gas (volatilize out of the water and into the air) and be inhaled by residents. Therefore, to record gas levels, ATSDR and USEPA Emergency Response Team's Response, Engineering, and Analytical Contractor (REAC) conducted air monitoring during the flushing of the water systems and during sampling. MultiRAE Plus hand-held air monitoring instruments were used to measure real-time concentrations of hydrogen sulfide, and the presence of volatile organic compounds (VOCs ) and oxygen content (in volume %). The MultiRAE Plus is a programmable multi-gas monitor designed to provide continuous exposure monitoring in parts per million (ppm) range. The monitoring took place in basements, bathrooms, or other living areas while waterlines were being flushed before sampling.
Site Physiography and Hydrogeology
This section will explain how these factors impact groundwater in Warren Township. Please note that a glossary which defines some of the terms used in this discussion can be found in Appendix F.
Physiography
The area under investigation, at the western edge of the City of Warren in Warren Township, is flat, with an average elevation of 900 feet above sea level. The entire area of concern is within the Mahoning River watershed (the land area that drains into a water source). The WHL/WRI property is drained by two north-south flowing tributary streams: Duck Creek to the west of the facility and South Leavitt Road, and Mud Creek to the east. These streams flow 1,500 feet to the north to the Mahoning River (Appendix A). Surface and shallow subsurface soils on the WHL/WRI property form level areas or gentle slopes. They are poorly drained and are clay-rich, with minor amounts of silt and fine sand [3]. Prior to the beginning of land-filling operations in the mid-1990s, the WHL/WRI property consisted primarily of a swampy, wetlands area, with a large pond at the north-central edge (Brick Pond). Prior to land filling operations, this large pond was connected by a bow-shaped drainage way to a smaller pond to the west, in a residential area immediately south of Elm Street [3]. WHL/WRI is situated in a low, poorly drained, former wetlands area, but the property is outside of the 500-year flood plain of the Mahoning River as delineated by National Flood Insurance Program maps [4,5].
Land filling operations at the WHL/WRI Site have resulted in two large mounds of waste. The closed landfill area at the northern edge of the WHL/WRI property, directly west of the Waste Transfer Building, is built in a west to east direction, and is 1,800 feet long, 800 feet wide, and 30-40 feet high. The active landfill area is roughly 800 feet to the south-southwest of the closed landfill, immediately south of the Brick Pond. As of February 2003, this mounded area was 1,000 feet long, 600 feet wide, and 30 feet high. In addition to mounding the wastes up as high as 40 feet above the ground surface, the landfill operators also initially disposed of waste in excavations as deep as 15 feet below the ground surface. These waste mounds drain primarily toward the northwest corner of the WRI property (based on a review of topographic maps) most likely into the Brick Pond and eventually to the smaller pond just south of Elm Street. The south flank of the active landfill appears to drain off to the southwest, toward a small, intermittent, west-flowing tributary of Duck Creek, just south of Choctaw Avenue. It is possible that through these drainage sources, that untreated leachate is migrating offsite. However, leachate is unlikely to impact residential wells because wells tap into a "confined" aquifer (see explanation below), unless this confining layer were somehow compromised.
Site-Specific Hydrogeology
The glacial soils near the WHL/WRI property consist of 35 to 120 feet of largely impermeable clays and clay-rich till (mixed glacial soils) with a thin, discontinuous water-bearing saturated sand layer near the underlying shale bedrock. Soil boring data for the WHL/WRI property, however, indicate that the entire 30-35 foot thick, glacial section was typically damp or wet, including the clay-rich portions in the upper 15 feet [9]. The inability of the lacustrine clay and clay-rich glacial till to hold and transmit groundwater and the discontinuous nature of the underlying sand layer make the glacial soils at the site a potentially poor drinking water source.
A review of ODNR well logs for area residential wells, as well as the Groundwater Resources Trumbull County map [14], indicates that almost every residential well in the Warren Township- WHL/WRI vicinity obtains water from the underlying Cuyahoga Formation bedrock. Most of these wells are 'low-yielding wells,' typically generating 10 gallons of water per minute or less, but they provide enough water to supply individual households. Private wells in the vicinity of the WHL/WRI facility range from 50 to 210 feet in depth, but average between 100 and 125 feet and are typically cased to some depth within the bedrock. Well logs were obtained for 5 of the 15 sampled residential wells and indicate shafts from 100 to 190 feet in depth, averaging about 150 feet. Water levels in these wells indicate that the bedrock aquifer that is the source of the drinking water in these wells is operating under "confined conditions", separated from the surface by impermeable clay-rich layers. "Confined aquifers" are generally not directly affected by surface contamination. Compared to other groundwater-bearing bedrock formations in Ohio, Cuyahoga Formation groundwater quality is typically only fair, with somewhat elevated levels of iron, manganese, sulfate, and total dissolved solids [15].
Although there are clay and clay-rich soils of varying thickness underlying the WHL/WRI facility, there is uncertainty about whether this clay layer is a continuous barrier to the migration of landfill contaminants into the underlying drinking water aquifer. In addition, excavation activities in the landfill may have compromised the integrity of this "natural barrier". Therefore, the question of whether landfill activities have impacted the drinking water source for this community will only be answered with a more complete hydrogeologic investigation of the landfill property. Such an investigation will require the installation and sampling of on-site monitoring wells.
Local Oil and Gas Wells
Data obtained from the Ohio Department of Natural Resources (ODNR) indicate that 15 oil and gas wells are in the general vicinity of the WHL/WRI facility. Five of these wells are located either on or adjacent to the WHL/WRI property [10]. Oil and gas wells can be a source of naturally occurring hydrogen sulfide gas. Review of the ODNR data indicated that all of these wells are drilled into the "Clinton Sandstone" geologic zone to an average depth of 4,500 feet below ground surface. Most wells became operational between 1987 and 1989. These wells pump an average of 200 to 400 barrels of oil and 9,000 to 11,000 million cubic feet of natural gas per day. The Clinton Sandstone, while a prime source of natural gas, is not known to produce significant quantities of "sour gas" or hydrogen sulfide. In October 2002, Ohio EPA Northeast District staff and ODNR Oil and Gas staff inspected a number of the oil and gas wells on or near the WHL/WRI facility for hydrogen sulfide gas. Although a strong hydrogen sulfide odor was detected in the ambient air on-site at the WHL/WRI facility, no significant quantities of hydrogen sulfide were detected coming from vents associated with these oil and gas wells, including the gas well at the northwest corner of the WHL/WRI property. Therefore, it does not appear that they are a significant source of hydrogen sulfide for ambient air.It is unknown if these wells, through fracturing to extract natural gas and petroleum, could be impacting area groundwater quality. Currently, there is no evidence that local oil and gas wells have impacted the local environment, including the bedrock aquifer system.
Water Quality Analysis
All well water samples contained several metals and inorganic compounds commonly found in groundwater. The levels detected were compared to ATSDR health-based guidelines as well as to USEPA drinking water guidelines and standards. The ATSDR health-based guidelines included the Environmental Media Evaluation Guide (EMEG) and the Cancer Risk Evaluation Guide (CREG) for non-cancer and cancer effects, respectively.
The USEPA drinking water guidelines used in this evaluation included the Maximum Contaminant Levels (MCLs and the Secondary Maximum Contaminant Levels (SMCLs). MCLs are enforceable standards of contaminant concentrations in public drinking water supplies. Although these regulatory standards only apply to public drinking water and not to private wells, they still provide a basis for comparison for well water safety in Warren Township. SMCLs, on the other hand, are non-enforceable guidelines for regulating contaminants. Exceeding the SMCLs could affect drinking water by causing cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (taste, odor, or color).
All of the wells had fairly saline (salty) water, with sodium content in one well as high as 510,000 ppb (parts per billion or micrograms per liter. No metal concentrations exceeded ATSDR health-based guidelines. One well exceeded the USEPA MCL of 15 ppb for lead in public drinking water supplies (at 25 ppb), but all of the other metals detected were below MCLs. ODH and the Trumbull County Health Department notified the owner of this exceedance. The home owner was advised to have a plumber evaluate his water distribution system and/or contact a water treatment company with regard to a treatment system that would remove the lead prior to the tap. Most cation-exchange water softener systems will efficiently remove lead from a drinking water supply [11].
Out of 15 wells, USEPA's SMCLs were slightly exceeded for manganese (1 well), iron (5 wells), sulfates (5 wells), and total dissolved solids (12 wells). These data are presented in Appendix B, Table 1. Certain water filtration systems will help to reduce the level of metals and other substances that might affect the taste of well water. None of these wells pose a health threat to the residents using them for drinking water, although the recorded levels of sulfates and total dissolved solids (TDS) could adversely impact water quality in these wells.
Well logs indicate that many of the wells in this area are cased 25-40 feet through the intervening glacial cover and they penetrate into the underlying bedrock. All wells with elevated sulfate and TDS levels appear to draw water from the same interval within the Cuyahoga Formation aquifer. Most wells in the vicinity of Raveloe Court, West Market Street, and the north end of South Leavitt were constructed in the mid 1950s or the early 1970s [6]. Comparisons to sandstone bedrock aquifer systems sampled as part of the Ohio EPA Ambient Groundwater Network indicate that a number of these wells exceeded the maximum levels of sulfates (>322 ppm) and TDS (>1,100 ppm) recorded for wells in eastern Ohio [7,8]. The wells with elevated sulfate and TDS levels are in the same neighborhoods that have reported the most odor complaints and the greatest number of health complaints [2]. They are also the wells closest to the mounded land filled waste piles at the WHL/WRI site [12,13]. See the map in Appendix C to view these data.
It is important to note several limitations of these data. It is not appropriate to directly compare the results of one home to another given inherent variation in the samples. For example, each of the homes had a different water flow rate, and the temperature of the water in each case was different. These issues could influence the levels of contaminants detected in the water samples.
Indoor Air Results
In general, sulfates in groundwater could be converted by bacteria to form hydrogen sulfide. If the water is aerated (e.g., showering), hydrogen sulfide will escape into the indoor air. As confirmed by air monitoring during well water sampling, some homes had a noticeable hydrogen sulfide odor off-gassing while tap water was running. The highest air concentrations of this compound would be expected during heavy water usage. Air readings were collected every five minutes while the water lines were flushed.
Hydrogen sulfide was detected off-gassing from water taps in 12 of the 15 wells tested, with peak levels ranging from 1.0-8.0 ppm [12]. High water usage (e.g., showering, laundry, etc.) in an enclosed environment can result in short-term exposures to hydrogen sulfide in levels greater than 1 ppm, as demonstrated by data collected during the water investigation.Flushing water pipes for 15 to 20 minutes resulted in measurable hydrogen sulfide as high as 8 ppm in one home.
The data discussed indicate that hydrogen sulfide gas is present in the aquifer (geologic formation) residents use for drinking water, however, it is also possible that nearby industry may also be impacting the hydrogen sulfide levels. The relative contributions of these potential hydrogen sulfide sources is unknown. Some long-time residents indicated that the odor in drinking water was present before the landfill was developed; others associated the odor in drinking water with landfill construction and with area oil and saltwater injection wells.
The elevated gas detected in homes during real-time monitoring was hydrogen sulfide. The source of the hydrogen sulfide appears to be the water-levels were detected while the tap water was on and were not detected when tap water was off. However, indoor odors can also occur by the permeation of hydrogen sulfide from outdoor to indoor air. Many residents on city water (not residential wells) complained of hydrogen sulfide odors from outside "getting trapped" indoors, where it would not completely dissipate for hours. Thus, there are both indoor and outdoor sources for residential exposure to hydrogen sulfide for residents who have untreated well water.
These data have the same limitations as those discussed in the well sampling section. Levels of hydrogen sulfide off-gassing from the well are likely influenced by the water flow rate and temperature. For example, hot water is more often associated with the odor than cold water. Although all air samples were collected during what would be considered a typical period for bathing (20 minutes), variation in data make it inappropriate to compare the levels detected in these homes to one another. However, this information gives important evidence regarding exposure of these families to hydrogen sulfide in their groundwater.
Sodium
Sodium is an essential nutrient that is involved in the control of blood pressure. Excessive sodium intake can cause high blood pressure. Sodium is needed for the muscles and nerves to function properly. The FDA's recommended daily sodium intake for adults is 2400 mg. By drinking 2 liters of private well water per day, Warren Township residents would consume from approximately 200 mg to 1000 mg of sodium in addition to sodium consumed through food. If residents use water softeners, the sodium level in the water will be even higher. Warren Township residents should be aware that drinking well water with elevated sodium levels increases their sodium intake. Those who already are on a sodium-restricted diet should consult their health professionals.
Hydrogen sulfide
Under normal conditions, hydrogen sulfide is a colorless, flammable gas. In air, one can smell hydrogen sulfide at extremely low levels (0.0005 ppm (or 0.5 ppb)). The odor is usually characterized as smelling like 'rotten eggs.' The detection of an odor does not necessarily mean that hydrogen sulfide is present at a level that would affect a person's health. Hydrogen sulfide occurs naturally as a constituent of crude petroleum, natural gas, and volcanic gases. In addition, it is often the result of bacterial breakdown of organic matter. Industrial sources of hydrogen sulfide include petroleum refineries, natural gas plants, and landfills [16].
The hydrogen sulfide in area residential wells is naturally occurring in the geologic formations of the drinking water source aquifer. It also can result from the impacts of oil and gas wells and landfilling operations. In Ohio, sulfur compounds often occur usually in the same places as oil, gas, and coal deposits [17]. Shallow, poorly constructed wells or those close to sewer lines and septic systems can become contaminated with sewage and can develop hydrogen sulfide problems [18,19].
As discussed previously, some homes had elevated hydrogen sulfide off-gassing from their wells Health effects can occur from hydrogen sulfide exposures. Short-term exposures to high levels of hydrogen sulfide can cause adverse health effects. For example, bronchial constriction was observed in 2 out of 10 asthmatics exposed to 2 ppm hydrogen sulfide for 30 minutes [20]. Other studies have documented respiratory distress in an occupational setting with exposures of greater than 40 ppm hydrogen sulfide and changes in oxygen uptake and shortness of breath in subjects exposed to between 5 and 10 ppm hydrogen sulfide for short periods of time [21-25]. A recent study examining health effects in a community exposed to low levels of hydrogen sulfide has noted an increase in asthma-related hospital visits among children following days when hydrogen sulfide levels are above 0.03 ppm [26].
Precautions can be taken to reduce these exposures, including water treatment and ventilation. Most of the homes tested have water treatment systems that would reduce or remove the hydrogen sulfide gas. In fact, many residents whose homes had treated water did not notice the 'rotten-egg' smell in their water.
CHILDREN'S HEALTH CONSIDERATIONS
ATSDR recognizes that in communities faced with contamination of air, water, soil, or food, the unique vulnerabilities of infants and children demand special emphasis. ATSDR is committed to evaluating the health impact of environmental contamination on children. The ambient air in homes where air monitoring was conducted is of health concern to children. Children could be or currently are exposed to elevated levels of hydrogen sulfide during bathing or other periods of high water usage. If parents notice that their children become ill during these brief exposure periods, water treatment or bathroom ventilation is recommended.
Residential wells in the Warren Township area tap into a geologic formation known to have only "fair" water quality. Moreover, compared to other groundwater-bearing formations in Ohio, the Warren Township area has naturally elevated concentrations of iron, manganese, sulfate, and total dissolved solids. Based on current data, ATSDR classified groundwater in this area "no apparent health hazard". Additional data identifying sources other than natural geologic formations may require a re-evaluation of exposures in this community. Also based on the available private well data, ATSDR concludes that:
If you smell hydrogen sulfide coming from your water supply, you might be exposed to hydrogen sulfide. You can reduce exposure to hydrogen sulfide gas by practicing the following precautions:
(scroll down until you see the page for Trumbull County).Michelle A. Colledge, MPH
Environmental Health Scientist
Office of Regional Operations, Region 5
ATSDR
Bob Frey, PhD
Chief, Health Assessment Section
Bureau of Environmental Health
Ohio Department of Health
Reviewed by:
Wallace Sagendorph
Editor
Office of Policy and External Affairs
ATSDR
Mark D. Johnson, PhD
Senior Environmental Health Scientist/Toxicologist
Office of Regional Operations, Region 5
ATSDR
Tina Forrester, PhD
Acting Director
Division of Regional Operations
ATSDR
Susan Moore, PhD
Section Chief
Health Consultations Section
DHAC/ATSDR
. Last accessed May
2003..
Last accessed May 2003.. Last accessed November 2002.APPENDIX A: AREA AND DEMOGRAPHIC MAPS
Figure 1. Demographic Statistics
APPENDIX B: GROUNDWATER MONITORING RESULTS
Table 1. Detected Metals and Water Quality Parameters (all concentrations in part per billion (ppb))
| Sample ID# | Arsenic | Cadmium | Iron | Lead | Manganese | Sodium | Sulfate | TDS |
| Comparison Value¶§†* | 10¶ | 5¶ | 300§ | 15¶ | 500† | 20* | 250§ | 500§ |
| RW-01 | ND | ND | 358.0 | ND | 0.6 | 300.0 | ND | 760.0 |
| RW-02 | ND | ND | ND | ND | ND | 450.0 | ND | 1,100.0 |
| RW-03 | ND | ND | 225.0 | ND | 47.0 | 300.0 | 157.0 | 850.0 |
| RW-04 | ND | ND | ND | ND | 39.0 | 470.0 | 293.0 | 1,400.0 |
| RW-05 | ND | ND | 146.0 | ND | ND | 460.0 | 295.0 | 1,200.0 |
| RW-06 | ND | ND | ND | ND | ND | 390.0 | 140.0 | 1,000.0 |
| RW-07 | ND | ND | 420.0 | ND | ND | 110.0 | ND | 300.0 |
| RW-08 | ND | ND | 459.0 | ND | ND | 100.0 | ND | 290.0 |
| RW-09 | ND | ND | ND | ND | ND | 340.0 | 87.0 | 890.0 |
| RW-10 | ND | ND | 303.0 | ND | ND | 440.0 | 617.0 | 1,500.0 |
| RW-11 | ND | ND | 222.0 | ND | 30.0 | 510.0 | 710.0 | 1,900.0 |
| RW-12 | ND | ND | ND | ND | ND | 350.0 | ND | 850.0 |
| RW-13 | ND | ND | ND | 6.0 | ND | 280.0 | ND | 690.0 |
| RW-14 | ND | ND | ND | 25.0 | ND | 200.0 | ND | 490.0 |
| RW-15 | ND | ND | 1,780.0 | ND | 141.0 | 440.0 | 381.0 | 1,600.0 |
Note: highlighted concentrations are elevated above
comparison values.
ND = below the detection limit
of the monitoring instrument, or not detected
ppb = parts contaminant per billion parts water
ppm = parts contaminant per million parts water
¶ Guideline is a USEPA enforceable drinking water standard (MCL or Maximum Contaminant
Level).
§ Guideline is a non health-based, non-enforceable standard (SMCL: Secondary Maximum Contaminant Level)
* USEPA's Drinking Water Equivalent Level (DWEL)
† ATSDR's Reference Dose Media Evaluation Guide (RMEG)
Table 2. Peak Hydrogen Sulfide Levels Measured
During Water Sampling†
| Hydrogen sulfide levels in parts per million (ppm)¶ | |
| Sample ID # | Concentration§ |
| RW-01 | <1 |
| RW-02 | <1 |
| RW-03 | 3.0 |
| RW-04 | 8.0 |
| RW-05 | 7.0 |
| RW-06 | 1.0 |
| RW-07 | 0.0 |
| RW-08 | 2.0 |
| RW-09 | 7.0 |
| RW-10 | 1.0 |
| RW-11 | 1.0 |
| RW-12 | 1.0 |
| RW-13 | 1.0 |
| RW-14 | 3.0 |
| RW-15 | 4.0 |
† Highest concentration
detected of the grab sample collected at each location.
ppm = parts contaminant per million parts water
¶ Sample ID numbers are consistent with the previous table (for example,
RW-01 in Table 1 is the same location as RW-01 in Table 2).
§ Minimum detection limit of the instrument was 1 ppm. Concentrations
may be present at levels lower than 1 ppm and may not have been detected by
the sampling instrument.
APPENDIX C: SAMPLING AND ANALYTICAL METHODS
Water Sample Handling and Storage
Samples were handled, stored, and shipped in accordance with applicable Ohio EPA guidelines. Specimens were transported on ice and delivered to the lab within the required holding time (24 hours).
Laboratory Analysis
The Ohio EPA Drinking Water Laboratory Certification Program is managed by two divisions with Ohio EPA: the Division of Environmental Services, Laboratory Certification Section and Division of Drinking and Ground Waters. All water samples were collected by Ohio Department of Health, who contracted with Ohio Department of Agriculture Drinking Water Lab, for analysis. Water samples were analyzed for metals, nitrate/nitrite, sulfate, alkalinity, and total dissolved solids; using methods in accordance with Ohio EPA Drinking and Ground Waters. A detailed list of the analytes and analysis method is provided in the table below.
| Analytes | Testing Methods |
| Aluminum | SM 3111 B |
| Arsenic | SM 3113 B |
| Barium | EPA 200.7 |
| Cadmium | SM 3113 B |
| Calcium | EPA 200.7 |
| Chromium | SM 3113 B |
| Copper | EPA 200.7 |
| Iron | EPA 200.7 |
| Lead | SM 3113 B |
| Magnesium | EPA 200.7 |
| Manganese | EPA 200.7 |
| Nitrate/Nitrite | EPA 353.2 |
| Potassium | EPA 200.7 |
| Sodium | SM 3111 B |
| Strontium | EPA 200.7 |
| Sulfate | EPA 375.2 |
| Alkalinity | SM 2320 B |
| Total Dissolved Solids | SM 2540 C |
SM= Standard Method
QA/QC
Sample collection, storage, and analysis descriptions were documented on the chain-of-custody forms. The originals of these forms were sent to the laboratory with the sample. Laboratory analysis was conducted with method-specific QA/QC requirements.
Consent Forms
Consent from the property owner was obtained by Ohio Department of Health prior to sampling.
Residential Notification
Each resident was mailed the results from their well testing along with a letter interpreting the meaning of the data. This occurred well before the public meeting regarding the groundwater results.
APPENDIX D: GLOSSARY OF SCIENTIFIC TERMS USED IN THIS REPORT
