The new issue is the way rising groundwater (yay conservation efforts) is complicating cleanup efforts. Journal graphic artist Russ Ball made an extremely helpful graphic illustrating the problem.
Here’s the key language from the new Kirtland quarterly report underlying the issue I wrote about in Sunday’s story. (“NAPL” is “non-aqueous phase liquid”, which is jargon for fuel; “bgs” is “below ground surface”):
- Historical water level data from well KAFB-3 show that the groundwater table has declined approximately 140 ft since 1949 with the majority (about 100 ft) of this decline occurring since the mid-1970s.
- As the water table declined as a result of regional groundwater extraction, the NAPL from the initial and subsequent releases followed the falling water table downward. Over time, this has had the effect of creating a residual NAPL “smear zone” from nominal depths of 400 to 500 ft bgs.
- Based on an analysis of historic and present groundwater levels at the site, the water table has risen between approximately 4 and 6 ft since 2009. This can be attributed to the water conservation practices implemented by the City of Albuquerque to reduce groundwater withdrawals, starting in 2008 and 2009.
- Rising groundwater levels continue to result in decreases in NAPL thickness and observations in monitoring wells. During the last three quarters, NAPL has been consistently observed in only a few monitoring wells. The majority of the NAPL mass observed in 2009, the year of lowest water levels, is now trapped below the water table.
- NAPL chemical analytical results show that the trapped NAPL will be an ongoing source of dissolved groundwater contamination indefinitely.