Key Conclusion:  The Low Threat Closure Policy (LTCP) can be used to obtain case closure for sites with residual contamination.  Most of these sites will require a Site Management Plan as part of a Deed Restriction that describes limitations and additional requirements for future redevelopment.

In August 2012 the California Regional Water Quality Control Board instituted the Low Threat Closure Policy (LTCP) in order to expedite the environmental case closure of leak cases based on a case-by-case analysis of risk to human health and safety and the environment. 

LTCP case closures are often subject to long-term management of residual contamination by recording a deed restriction (aka land use covenant or environmental lien).  The deed restrictions often require a Site Management Plan (SMP) to be implicated as a condition of the case closure.  Additional investigation, remediation or mitigation is required if the site will be redeveloped and/or the use is changed.

The LTCP requires the contamination site to meet several criteria (conditions) including the following:

  1. The unauthorized release is within the service area of a public water system
  2. The leak has been stopped and ongoing sources including free product, have been removed or remediated,
  3. the site has been adequately characterized, 
  4. The dissolved plume is not migrating,
  5. No water wells, deeper drinking water aquifers, surface water, or other sensitive receptors are likely to be impacted. 
  6. the site presents no significant risk to human health or the environment. 

Note that for volatile chemicals such as solvents, the threat to indoor air must also be addressed.