Re: National Stakeholders' Forum on MNA Report

["Whitten, Rodney, Mr, SanFAFCEE" <Rodney.Whitten@SANFAFCEE.brooks.af.mil>]

Believe this statement is misleading

 "CZ requires a showing before monitored natural attentuation is
 permitted: either that source removal has been
 accomplished and cleanup has reached asymptotic levels
 or that a cleanup is impracticable or that the "burden" of
 cleanup is disproportionate" to the benefits.".

Monitored Natural Attenuation is allowed as an active remedy without using
section III.H of 92-49 (CZ). For example, Natural Attenuation has been the
final cleanup method of thousands of gas station leaks as well as many other
sites. CZ would be utilized only if convention cleanup (source removal, pump
and treat, SVE, Bioventing and natural attenuation) has not been effective at
reaching the water quality objectives (WQOs). Most likely the trigger for CZ
would be the amount of time (because of quanity of mass and geologic
conditions) that it would take for NA to be reach WQOs in the case of
petroleum discharges. Geologic conditions and long-lived contaminants could
be another. A containment zone could be combined with a down gradient pump &
treat system, if necessary for plume containment, for a contaminant that is
not accessible (ie fractured bedrock), but will continue to leach over the 
years.

Rod Whitten