Comments

Comments

  • Matt Fox

    This is a question for a lawyer. Not sure if the city is required to get a Phase I, but they would certainly be foolish not to. Someone is eventually going to take title to the property and will get a Phase I. If there are issues, best to know about them before they do the renovation.

  • JG

    A receiver is treated like a lender.  See the legal background appendix of 1527-13.  "The secured creditor exemption also includes liability protections for persons and financial institutions acting in a fiduciary capacity" including "...trustees, receivers, executors, administrators, custodians..."

  • Matt Fox
     
     

    I think the assumption are:

    • A river would likely have eroded down to bedrock in which case the contamination wouldn't migrate under it. 
    • A moderate sized creek would likely have eroded down to a confining layer, so contamination above the confining layer wouldn't migrate past the creek, although contamination in deeper aquifers might.
    • Creeks and rivers are essentially pumping water into the aquifer, which would likely block contamination from migrating past it, if the contamination is in the same aquifer as the base of the creek/river.
     
  • Here2Learn

    Very cool! This is the kind of thing I was suspecting. I'll be more cautious when screening out sites in the future based on the presence of a creek/river between the Property and the site. I understand the DNAPL migration much better now (thanks) but I don't see how you would be able to tell when this scenario is occurring. Is drilling the only way? 

    Man! I learned more today than all last month. Thanks JG

  • JG

    DNAPL sinks and follows the bedrock contours.  So you could have the groundwater flowing east but a DNAPL plume drifting down along a localized bedrock "dip" to the west.

     

    Regarding the river, I came across this figure yesterday that I thought you would find informative.  Of course, it's specific to this particular location.

  • Here2Learn

    Referring to your comment about DNAPL not necessarily following groundwater flow direction... if this is the case, how does DNAPL migrate? Radially? Dealing with a site now that has a Non-HSI site with reported TCE about 1,500 feet away just barely on the opposite side of a ridge line. Curious if it still may have the potential to migrate toward the site. 

    As far as the terminology discussed above, I've come to like "groundwater divide" for topographic ridge lines. But as far as when a creek is located between the subject property and the site, I'm still working on that term. 

  • JG

    I would probably consider a railroad spur a REC. You can search the forum for a related reference document I posted previously.  I would also probably note that any impact would likely be limited to the immediate area of the spurs.  If the future plans include removing the spurs then it could just be addressed at that time.

  • JG

    Too bad MW-1 was dry.

  • Here2Learn

    The site with the highest concentration shows 360 ug/L benzene adjacent to the tank pit and then the wells up-gradient approximately 100 feet are non-detect. This is the site that when sampled four years later 80 ug/L benzene was detected. Unfortunately no data for the down-gradient wells was provided for that sampling event. Figure attached

  • JG

    Are the downgradient wells below the standard?  Is there a significant decrease in concentrations between the tank and DG wells?  This is important data to consider.

  • JG

    It depends on your experience in the area, soil types, natural attenuation over 10 years, etc.  If you feel that it's likely that the TP has been impacted then don't be afraid to call it like it is.  Just because you identify a REC doesn't mean the client has to do anything about it.  Talk it through and they can decide if a Phase II is worthwhile or not.

  • Here2Learn

    And there are wells down-gradient of the tank pits.... just not at a significant distance. 

  • Here2Learn

    Actually yea I think it is a sewer pump station so never mind that. Typically, would you call these sites RECs based on this information? From what I've read most petroleum products do not migrate more than 1,200 feet. These sites are 1,000 feet away. At one site, benzene was reported at 360 ug/L in 2000, in 2004 benzene was reported at 80 ug/L. This is by far the highest reported concentration out of the LUST sites... but still not very significant. Tough call... might have to go conservative and say the presence of four LUST sites 1,000 feet away and up-gradient constitutes a REC. Just not very confident on my dissolved petroleum product migration knowledge. 

  • JG

    No wells down gradient of the tanks?  That's too bad.

    Is this a sewer pump station?  It could draw down the GW if there's an infiltration issue I suppose.

  • Here2Learn

    Ahh I see what you mean. The regulatory limit (drinking water standard) for benzene is 5 ug/L in GA. The well data for the LUST sites appear to have elevated concentrations in the vicinity of the tank pits but the up-gradient wells (not adjacent to tank pits) are non-detect. However, only one site has wells up-gradient a significant distance from the tank pit, the others only samples onsite and in close proximity to the tank pits. The highest concentration of benzene reported was 80 ug/L and that was immediately up-gradient of the tank pit. 

    Regarding the pump station on the Property.... in your experience is that considered something that can effect groundwater? Potentially "pulling" groundwater toward the pump station which in other circumstances may not occur?