Two extraction trenches were constructed at the south side of the site to mitigate seeps which were visually offensive. The long term monitoring program provides information on the degradation rates and will monitor. At ST41, elevated levels of b appear to coincide with areas where high organics are present.
Slug test and porosity data indicate that the travel time required for groundwater to flow a distance of feet to the northwest across ST41 would be on the order of 40 years. In addition, there were no identifiable base activities which would result in a source of elevated gor of arsenic or manganese.
Furthermore, based upon the poor yield of the aquifer at ST41, it is unrealistic to expect it would be suitable for recreational or commercial use.
Additional risk reduction is realized by abandoning the tanks in situ, removing the piping system and removing grossly contaminated soils due to possible line leaks. It should be noted that manganese has been found at similar levels throughout the base in both contaminated and uncontaminated areas. This method, called the "risk-based screening approach", compares the highest concentrations of each chemical detected at a site to a risk-based screening concentration.
Air Force, contained in the Administrative Record. If the ongoing treatability study does not validate the feasibility of natural attenuation then a more active remedial action will be implemented.
Alternative S-I does not involve any action to provide ,ooking of human health and the environment. These comments and the resulting responses are documented in a responsiveness summary attached to the Interim ROD, which is part of the Administrative Record for this site. Long term monitoring will be used to monitor plume migration, the reduction in contaminant concentration, and the reduction in free floating product.
All comments received are documented in the administrative record file for the site. This study concluded that natural attenuation of all contamination at ST41, including that contributed by the free phase product, should occur successfully. For non-cancer risks, a chemical was eliminated in soil or groundwater if the maximum concentration resulted in a hazard quotient HQ of 0.
Bank Index 0. The cancer risk level is the additional chance that an exposed individual will develop cancer over the course k a lifetime.
The primary purpose of the IRA shifts from a free product recovery system to a groundwater recovery and treatment system after the all technically practicable free product is removed. The seeps and springs are included as contaminant treatment areas ww the Elmendorf natural resource assessment. A long-term monitoring plan is all that is required to periodically assess the existing monitoring well High Littleton then maybe something else. HI Hazard Index.
Operation should continue until such time that it can be determined that long-term monitoring for natural attenuation of the contamination indicates that continued operation of the IRA is not necessary to prevent degradation of the environment. The following analysis briefly reviews and compares each of the alternatives for groundwater and source control with the evaluation criteria.
Figures through present maximum concentrations of fuel-related apounds detected, by well, over the four different sampling events. In order to encourage public comment,'the U.
Some of the assumptions and uncertainty factors associated with the baseline risk assessment include the following. These morainal soils are composed of a heterogeneous mixture of interbedded sands, silts and days.
Exposure to contaminated surface water, sediment and surface soil at ST41 was not considered. It appears that contamination underlying source area ST20 is the result of releases that occurred upgradient, at source area ST A seasonal smear zone of contamination has been identified in the southern portion of ST41, and a free phase occurrence of floating product is present on the water table in the northern portion of the site.
Located yards northeast and upgradient of ST20 is a SERA source area, ST48, which has a known history of lookihg fuel line leaks and diesel fuel spills. A groundwater divide roughly coincides with the crest Of the Elmendorf Moraine, with flow diverging away from the divide and down the flanks of the moraine generally to the north and south. The IRP was initiated in with a records search to identify past disposal sites containing contaminants s may pose a hazard to human health jver the environment.
Contamination in the soil found in Adult looking sex MD Hagerstown 21742 area thought to contain the ST41 source is attributable to leaks in the tank system. This drops to 4. The fuel contamination oloking believed to be associated with former line leaks at the site.
Institutional controls are also included as part of this alternative. Air discharge from the system is treated by a carbon filter and then discharged. Table presents a summary of the ificant constituents identified in the groundwater at ST The risk to human health at OU2 occurs if someone were to drink the contaminated groundwater daily over a thirty year period.
In addition, while a risk was identified at ST20 in the groundwater, this risk was based on the highly conservative residential male, and Sparta TN housewives personals based primarily on constituents emanating from an upgradient source. The first of these is poorly sorted glacial sediment till.
To the extent the selected remedies result hi the removal of petroleum contaminated soil the contaminated soil will be handled and treated consistent with the requirements of 18 AAC The piping and tanks associated with ST41 are depicted on Figure OU4 is in the decision making phase, and will be seeking public comment in April S. Both Alternatives S-n and S-ffl provide for long term effectiveness and permanence. Development of a Geneva-IL sex on the side map showing the areas currently and potentially impacted by groundwater contaminants that will be included in the Base Comprehensive Plan; 2.
The groundwater flow in this area is also locally, influenced by loiking irregular surface of the Fkr Cove Formation. Surface soil, surface water, and sediment contamination were not addressed during RI activities or the Risk Assessment at ST Only the non-carcinogenic hazard is above acceptable levels. A small, one-acre palustrine wetland is located approximately feet to the northwest of ST41 in a utility corridor see Figure The shallow aquifer consists of either till or outwash deposits, depending on location.