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Page 1 of 1 .Harlin Knoll [EH] 1 From: Nuel Henderson [EH] Sent: Wednesday, July 14, 2010 4:11 PM To: 'szeze5l @aol.com' Cc: Adrienne Ellsaesser [EH]; Harlin Knoll [EH] Subject: Cleanup Goals for,Groundwater Attachments: WQOs and MCLs_pdf Mr. Abdelwahed, Attached is a table I created that shows the water quality objectives (WQOs) and maximum contaminant levels (MCLs)that can be utilized as cleanup goals for closure of contaminated underground storage tank (UST)sites. This agency does not have any set contaminant concentrations that must be achieved for site closure, but if a responsible party or their consultant wants absolute numbers, these are the only ones we can provide. As I mentioned to you during our telephone conversation on Monday, July 12, 2010, it is not necessary for the contaminant concentration in groundwater to actually be at or below these very low concentrations, but we do want to be able to show that concentrations are declining and will reach the WQOs and/or MCLs in a reasonable time period under natural conditions (no active remediation). Your site appears to need more remediation to reduce the remaining contaminant mass to a level where natural conditions can effectively finish the job. At this time, the concentrations of the contaminants of concern (CDCs) in groundwater in the most impacted monitoring well on your site are as follows. TPHg = 80,000 micrograms per liter, Benzene =4,000 micrograms per liter, Toluene = 16,000 micrograms per liter, Ethylbenzene = 2,200 micrograms per liter, Xylenes = 13,000 micrograms per liter, 1,2-dichloroethane =320 micrograms per liter, If you compare these concentrations to those in the chart, you will notice that they are quite high. While your site doesn't appear to be ready for site closure at this time, the remediation system does appear to be having some effect on the CDCs concentrations, particularly on TPHg, benzene, toluene, and ethylbenzene. The contaminant mass recovery rate of the soil vapor extraction unit has declined significantly over time, but still appears to be effective. It may be that another remediation technology will eventually need to be employed to more effectively reduce the contaminant concentrations in groundwater. You had also requested a list of analytical laboratories that work in our county; while my unit maintains such a list of consultants and drilling companies, we do not have one for laboratories. If you really want to find a laboratory to check samples, you might check the phone book or make a search on the.internet. You may find repeating the analyses to be fairly expensive, several hundreds of dollars. In my very brief review of the site data, I did not notice anything that suggested that there may be a problem with the data. I really don't think you need to check the analytical data yourself, but that is certainly your choice. If you want to proceed with running your own samples just to satisfy yourself, the laboratory may advise you on how to collect and ship the samples; if you want to be able to use the data with a regulatory agency such as ours t ' or in court, you should retain the services of a professional consulting firm that is experienced in environmental work in order to obtain data that will be considered valid,for decision making. This can be quite expensive, and your costs may not be reimbursable by the State Cleanup Fund:- Please und-Please let me, or Harlin Knoll know if we can be of further assistance to you. I also recommend that you discuss your concerns with the primary responsible party or their consultant_ Nuel Henderson �h T. 7/15/2010 _ ,��