Army Corps Proposes MNA to Deal with Perchlorate in Groundwater

Allen Hengst: I have two quick questions about the Groundwater Feasibility Study [stemming] from this sentence in the December Partnering meeting minutes: "USACE Baltimore has been instructed by Headquarters to redraft the Groundwater FS to include ‘Monitored Natural Attenuation’ (MNA) as an alternative" ...  [At the January] RAB meeting, I asked if you had changed the Groundwater FS to address objections by the partners and you said you had added an alternative.  Is this the alternative that you are talking about: "Monitored Natural Attenuation"?

Dan Noble confirmed this.

Hengst: The second question is, assuming you still have Land Use Controls (LUCs) as an alternative, how is MNA  different from LUCs?

Steve Hirsh explained that what is needed is some physical or chemical process that will eventually remediate the groundwater to the point where it could be used as drinking water.  With LUCs, there is no physical or chemical process specified that would degrade the contaminant.  If MNA were selected, the contaminant would be monitored over time to see if the concentration of contaminant is declining.  If the contaminant is not declining, then at some point – usually every 5 years – a decision would be made whether to try a different approach.

Hengst: ... Are the Partners going to accept MNA?

S. Hirsh explained that he had not seen the Groundwater FS yet.  USACE has evaluated the alternatives but has not made a recommendation.

Spring Valley FUDS
RAB Meeting Minutes  
March 13, 2018 (pg. 3)  

 The RAB meets on 2nd Tuesday of every odd month (USACE)