Source Water Assessment Program
Advisory Committee Meeting Agenda
August 4, 1998 1:00 PM
DEQ, Maynard Ketcham Bldg., Rm. 326
- Welcome & Introductions
- Data Collection
- Differential Delineation and Assessment Approaches (Transient Non-Community Systems and the Mississippi River)
- Susceptibility Analysis for Ground Water Systems
- Sensitivity (well and aquifer characteristics, recharge)
- Vulnerability (types and numbers of potential sources of contamination & distance from well)
- Contaminants of Concern
- Significant Potential Sources of Contamination
- Weighting of Sensitivity and Vulnerability Factors
- Examples of Risk Ranking
- Susceptibility Analysis for Surface Water Systems
- Vulnerability (type & number of potential sources of contamination, distance from intake & pertinent water bodies)
- Role of EPA
- Significant Potential Sources of Contamination
- Coordination of SWAP with WHPP
- Wrap up
- Discuss agenda for next meeting
- Committee preparations for next meeting
NEXT MEETING IS MONDAY SEPTEMBER 14th at 1:00 PM in Room 326, Maynard Ketcham Building at DEQ.
SWAP Advisory Committee Meeting
August 4, 1998
Questions and Answers/Comments Summary
Meeting Qs & As
Suggestion: Should the weighting of potential sources of contamination within 1000 feet of the well be more reflective of the distance from the well, since this is considered the most critical area? In other words, isn't a UST 50 feet from the well more significant than one 999 feet from the well? The current weighting matrix would apply the same weighting factor to both of these.
We propose to substitute a 5 to 6-tier approach to the 2-tier approach presented in the August 4th meeting of the committee. Based on the comments of committee members, instead of assigning one value to each potential source of contamination inside of 1000' (high = 10, medium = 5, low = 1), we will utilize five (5) tiers inside of 1000' as follows:
|Distance from well Potential Source of Contamination
|0' - 200'
|>200' - 400'
|>400' - 600'
|>600' - 800'
|>800' - 1000'
In the presentation, we used an example of one well to demonstrate the susceptibility analysis. In the cases where there are two or more wells clustered together, we propose to inventory the delineated area around each well and assign a susceptibility number to each well separately. The method we propose to use is to divide the susceptibility score for each well by the unit area of the specific delineated area for that well. This will allow us to compare the relative susceptibility totals of all wells in a system and statewide.
A 1000' radius translates to 0.1127 square miles.
A 2640' radius (1/2 mile) translates to 0.785 square miles.
A one (1) mile radius translates to 3.142 square miles.
Large systems will automatically have large totals because of the number of wells. The susceptibility number divided by the unit area eliminates the bias introduced by large systems with a large number of wells.
How do we determine what is a "significant" potential source of contamination?
Quantity and the likelihood of a release were discussed at length. A source will be significant if it is an "open" versus a "closed" system. An example discussed was a hobby shop versus a paint shop. The hobby shop sells very small quantities of paint in sealed or "closed" cans. The customers purchase the paint and leave the store with the small, sealed container. A paint store not only carries large quantities of paint, but also mixes and thins the paint. The paint and thinners are then in "open" containers and the equipment must also be washed down. The likelihood of a release from the hobby shop is extremely small and the quantity is so small it is not considered significant. On the other hand, the likelihood of a release from the paint store is much greater and the quantity would be considered significant. Experience in the Wellhead Protection Program (WHPP) tells us that certain potential sources of contamination have a higher likelihood of release than others do. For example, there is a history of public water supply contamination from leaking underground storage tanks and surface spills of gasoline. Solvents have also caused contamination of public water supplies. Solvent contamination of one water supply was known to have originated from a manufacturing plant, and a suspected discharge from a body shop into a ditch near a wellfield impacted a second water supply.
Is the average ground water velocity used in the sensitivity determination horizontal or vertical velocity?
The average ground water velocities for the major aquifers in the state were calculated using hydraulic conductivity ranges and potentiometric surface maps published by the U.S.G.S. The resultant velocities are horizontal velocities.
What is the depth of soil recharge considered in the sensitivity analysis? Does it take into account confining layers?
The soil recharge potential map constructed by the Louisiana Geological Survey is being used for the sensitivity analysis. The interpretations are based on soil characteristics up to 6 feet below land surface. This do not take into account any deeper confining layers. However, the heavy weighting on the well depth factor indirectly takes confining layers into account, as deep wells are usually protected by these layers.
Has there been any attempt to locate abandoned oil & gas production brine/mud pits? There have been shallow ground water problems (shallow subsurface - 30 to 40 feet deep) associated with these pits. According to the pit regulations of 1990, there are about 12,000 of these pits.
If any pits are discovered in source water protection areas they will be inventoried and included in the database. We are not aware of an existing database of pit locations. The Department of Natural Resources regulations require pits to be registered so there are records on file. No latitude or longitude data exists but they are usually located in the vicinity of oil wells, which have locational data associated with them. The data is not in digital format, it is only in hard files.
Will an attempt be made to identify seismic shotholes? How are they regulated?
We spoke with Mr. Larry LeBlanc of the Department of Wildlife and Fisheries regarding this matter. He is in charge of the section in that agency which issues letters of permission to companies to conduct seismic surveys. There are only 5 inspectors in addition to Mr. LeBlanc to cover the entire state, so monitoring is difficult. The seismic companies are required to place a bentonite plug 10 to 15 feet below land surface depending on the size of the hole. Also, a plastic cap is required 18 inches below the top of the ground above the plug. Vermilion Parish requires a cement plug. There are no regulations with regard to assurance that all seismic shotholes are plugged properly. The only authority that LDAF has is to revoke permission for the seismic company to do further work if they are non-compliant. Seismic shotholes are much more extensive than in the past due to the innovation of 3-D seismic technology. Rules or regulations are now being written that will allow better oversight with regard to the plugging of seismic shotholes. No database of seismic shothole locations exists and they are very hard to identify in the field, unless their exact location is known. If any are discovered in the inventory process they will be included in the database.
Is the list of potential sources of contamination still under development or is it finalized?
The list is only in draft form. We are asking for input from the committee on what should be included and how the potential sources should be ranked (high, medium, or low). The list will not be finalized until we have received all feedback from the committee.
What is the difference between a buffer and a setback and what are the criteria? It appears that these terms are often used interchangeably in the EPA material and it's very unclear.
We define a setback as the area delineated as a source water protection area around a surface water body that will be inventoried for potential sources of contamination. For surface water, it will be site specific. The arbitrary fixed radius method will be used for wells as discussed in the last meeting. It is synonymous with a source water protection area. We define a buffer zone as a "green area" used to filter overland flow to the water body. The Natural Resource Conservation Service (NRCS) is providing a list of all Conservation Reserve Program sites and Environmental Quality Incentives Program (EQIP) sites. Both of these programs offer incentives to farmers to take land out of crop production or livestock usage. These could be considered as "buffers", but not every water body will have buffer zones.
How will "ground water under the direct influence of surface water" (GWUDI) be handled?
As was discussed in the previous committee meeting, the Dept. of Health and hospitals conducted a study along with the Army Corps of Engineers using micro-particulate analysis (MPA) on wells considered to be high risk. They did not identify any community ground water systems that are GWUDI. They will start sampling non-community wells in 1999 and if any are determined as GWUDI they will be required to treat as a surface water source and the source water protection area delineation will include the watershed delineation.
Does SWAP address the siting of new wells (or intakes) as the WHPP does?
No specific reference to siting of new wells or intakes is made in the guidance but we strongly encourage all water systems to use the information developed in the SWAP program for this purpose as we do for the WHPP.
How can we address abandoned oil and gas wells addressed that are not properly constructed or plugged? There is concern for their potential to contaminate ground water over a long period of time.
According to LDNR, if the potential responsible party (PRP) can be located they must properly plug and abandon the well and conduct any necessary remediation. If no PRP can be found, the well becomes part of the orphan well program. This program is a perpetual fund for plugging abandoned wells for which no PRP can be identified. Approximately 300 wells are plugged under the program each year. They are prioritized by potential or actual adverse impacts on the environment. LDNR has provided the orphan well database for use in the SWAP. The problem is identifying abandoned wells is very difficult unless their location is known, and there are thousands of wells out there. They usually have to "spring a leak" to be found.
Can GPS data be collected statewide without gaps in the system?
In the past there were "gaps" in the system (there were no base stations needed for data correction) in the northern portion of the state, but we now have full coverage statewide.
How accurate are the readings from the GPS instruments?
The accuracy is 1 to 3 meters. The GPS unit is accurate to 1 meter. The 2 ?3 meter error can be introduced by the laser range finder if it cannot be located directly on top of the antenna, but is very adequate for this application.
What is the cost of the GPS equipment?
The cost is $10,000 for the GPS unit and $3600 for the laser range finder.
Will information be exchanged with EPA Region 4 for Mississippi River issues (interstate coordination)?
We will coordinate with the State of Mississippi River since they border the Mississippi River at the state border.
Is dredging a problem in surface water? Particularly, does it cause contaminated sediments to release the contaminants to the water?
The biggest problem with dredging is that it increases turbidity. A study conducted by the U.S.G.S. on the Mississippi River water and sediments in the 1980's showed no problems with sediment contamination.
Comment/Suggestion Form, E-Mail, and Telephone Qs & As
Database Suggestion: The DEQ Air Division has an Emission Inventory System (EIS) database on GIS. Locations will be roughly correct since they are supplied by industry and may be old. For smaller facilities, usually only one latitude and longitude point is listed for the whole facility. Specific tanks or compressor buildings may not be located by latitude and longitude in the database but should be close. Alice Fredlund is the coordinator of the EIS database in the Air Division.
We will contact Alice and see what information is there. While we are looking at potential sources of contamination to water, many facilities with air permits also have water permits and use chemicals. This is likely another very good source of information and can be easily obtained.
Database Suggestion: I believe Louis Johnson was leading a project to do GIS mapping (actual field work) of NPDES discharges along the Mississippi River.
The project is still in progress and is about 80% complete. We will incorporate this data into the source water protection program.
Abandoned wells are listed as "higher risk" for groundwater impacts. Does the DEQ plan to treat "properly plugged" and abandoned wells differently from wells that are not properly plugged prior to abandonment?
Assuming we're talking about oil and gas wells, we will treat all such wells as "higher risk". There was some lengthy discussion during the meeting regarding abandoned oil and gas wells and their potential for impacting ground water. There was concern that records were incomplete or inaccurate. In light of this, the "safest" approach is to treat all wells the same.
Once a susceptibility score is determined, how will DEQ track changes (a new facility, for example) that will change the potential source score?
As is the case for the Wellhead Protection Program, it will be the community or water system's responsibility to notify DEQ of changes within the delineated source water protection area. We do not have sufficient time and staff to revisit each system on a regular basis to update inventories. Once DEQ is notified of any changes, the new facilities will be surveyed by GPS and added to the inventory and likewise the susceptibility ranking. The water system will then be provided with a new map and susceptibility analysis.
The surface water intake list may not be complete. For example, the Mobil refinery in Chalmette (south of N.O.) uses Mississippi River water in the plant for cooling water purposes and it's not on the list.
There are many intakes that are not on the list because they are not used for public water supply. The list we are using was provided by the Department of Health and Hospitals and contains only those intakes used for public water systems. The Source Water Protection Program addresses only public water supplies.
What must a water system do if a MCL is exceeded?
All active sources of drinking water are sampled for all regulated and unregulated chemical compounds required under federal regulations on a one or five year cycle. Surface water sources are sampled annually and ground water sources are sampled on a three to five year cycle. For ground water systems these samples are collected at the wellhead. Surface water is sampled at the water treatment plant after treatment. If a detection of a compound occurs, the system is re-sampled at the wellhead and from the distribution system near the well. If the detection of a regulated compound is confirmed in a ground water or surface water distribution system sample, or at the wellhead, quarterly distribution system samples are collected. The system is put on annual sampling if the average of four quarterly samples remains below the maximum contaminant level (MCL). A system with an average above the MCL is in violation of drinking water regulations and is required to notify their customers and to undertake corrective action.
Suggestion: Add "bridges and bridge abutments" to the Higher Risk category for surface water. After listening to the comments, it is obvious that any bridge over a surface water body adds significantly to its vulnerability. When BMPs are considered, bridge design could be a BMP.
Bridges and bridge abutments have been added to the potential source of contamination list for surface water under the Higher Risk category.
Suggestion: Another risk factor for some surface water is if there is an outlet to the coast within a certain distance. These sources are susceptible to sub-surface salt water intrusion under certain conditions that is not true of landlocked surface water or stream segments further away from the coast.
Salt water intrusion will be added under the low risk category for surface water. While this is not a "point source" that can be inventoried, it is certainly a consideration for water systems near the coast. As Mr. Prosper Toups of Terrebonne Parish Waterworks District #1 mentioned in the meeting, it can't be prevented but the system needs to be prepared for the possibility. A future solution could possibly be the construction of locks on ship channels leading to the Gulf that could be closed when salt water threatens a drinking water supply.
What about restoration businesses that refinish metals such as old iron work?
"Metal Plating" already appears under the Lower Risk category for ground water, but will now read "metal plating/metal working".
If a car wash has an engine washing service using spray solvents, would that be different from a water/detergent operation only?
General permits are issued by the DEQ Office of Water Resources for exterior vehicle washing (excluding tanker-type trucks). The permit limits chemical oxygen demand (COD) to a 200 mg/l average per month with a maximum of 300 mg/l on any single sample. It also limits total suspended solids (TSS), oil and grease, pH, and soaps and detergents. Engine cleaning or the use of solvents is not allowed under this permit. An individual permit would have to be issued to cover this and there would be strict limits with regard to any solvents used. These types of facilities usually perform repairs as well, so they would be inventoried as "auto repair shops". Any car wash using solvents is likely doing so in violation of their permit and that activity would be reported to the Water Pollution Control Division for enforcement.
Sites of old battery recyclers should be placed in higher risk category. Quite often these closed sites buried their batteries on site.
Battery recyclers have been placed in the Higher Risk category for ground water.
How about contacting Joel Lindsey of the Institute for Environmental Issues and Policy Assessment at Southern University? Joel has done some great studies on surface water in Louisiana and he would be well qualified to look over the assessment plan. He could add to the advisory committee work. His phone number is 504-771-4723.
We will contact Mr. Lindsey and get any information we can use.