Florida Administrative Code › 62 - DEPARTMENT OF ENVIRONMENTAL PROTECTION › 62 - Departmental › Chapter 62-780 - CONTAMINATED SITE CLEANUP CRITERIA › Section 62-780.690 - Natural Attenuation Monitoring

Current through Reg. 50, No. 138; July 16, 2024
(1)
				Natural Attenuation Monitoring and long-term natural attenuation monitoring are
				allowable strategies for site rehabilitation depending on the individual site
				characteristics, provided human health, public safety, and the environment are
				protected. The individual site characteristics may include the current and
				projected use of the affected groundwater and surface water in the vicinity of
				the site, the current and projected land use of the area affected by the
				contamination, the exposed population, the location of the plume, the degree
				and extent of contamination, the rate of migration of the plume, the apparent
				or potential rate of degradation of contaminants through natural attenuation,
				and the potential for further migration in relation to the site's property
				boundary. Fate and transport models as defined in rule
				 62-780.610, F.A.C., may be
				utilized to support the appropriateness of natural attenuation monitoring.
				Natural attenuation monitoring is allowable provided the following criteria are
				met:
(a) Free product is not present or free
				product removal is not technologically feasible and no fire or explosive hazard
				exists as a result of a release of non-aqueous phase liquids;
(b) Contaminated soil is not present in the
				unsaturated zone, except that applicable leachability-based soil CTLs may be
				exceeded if it is demonstrated to the Department that the soil does not
				constitute a continuing source of contamination to the groundwater at
				concentrations that pose a threat to human health, public safety, and the
				environment, and it is demonstrated that the rate of natural attenuation of
				contaminants in the groundwater exceeds the rate at which contaminants are
				leaching from the soil. The determination shall be based upon individual site
				characteristics and demonstrated by USEPA Test Method 1312 (SPLP), or USEPA
				Test Method 1311 (TCLP) if the contamination is derived from used oil or
				similar petroleum products, followed by the appropriate analyses of the
				leachate, and based upon groundwater modeling, site stratigraphy, or site
				assessment results;
(c)
				Contaminants present in the groundwater above background concentrations or
				applicable CTLs are not migrating beyond the temporary point of compliance or
				migrating vertically, which may contaminate other aquifers or surface water
				resources or result in increased site rehabilitation time;
(d) The physical, chemical or biological
				characteristics of each contaminant and its transformation product(s) are
				conducive to natural attenuation;
(e) The available data show an overall
				decrease in the contamination; and,
(f) One of the following is met:
1. The site is anticipated to meet the
				applicable No Further Action criteria of Rule
				 62-780.680, F.A.C., as a result
				of natural attenuation, the background concentrations or the applicable CTLs
				are not exceeded at the temporary point of compliance as established pursuant
				to subsection  62-780.690(2) 
				or  62-780.690(3),
				F.A.C., and contaminant concentrations do not exceed the criteria specified in
				chapter 62-777, F.A.C., Table V, or
2. If the criteria of subparagraph
				 62-780.690(1)(f) 
				1., F.A.C., are not met, the appropriateness of natural attenuation monitoring
				may be demonstrated by the following:
a. A
				technical evaluation of groundwater and soil characteristics, chemistry, and
				biological activity that verifies that the contaminants have the capacity to
				degrade under the site-specific conditions. A listing of the site-specific
				conditions and geochemical parameters, as applicable, is provided in chapter
				62-777, F.A.C., Table IV,
b. A
				scientific evaluation (historical data or modeling results, as appropriate; the
				model used shall be demonstrated to be appropriate for the site conditions) of
				the plume migration in relation to the temporary point of compliance as
				established pursuant to subsection
				 62-780.690(2) 
				or  62-780.690(3),
				F.A.C., an estimation of expected annual reductions in contaminant
				concentrations in monitoring wells, and an estimation of the time required to
				meet the applicable No Further Action criteria of rule
				 62-780.680, F.A.C. Available
				technical information (including historical water quality data) shall be used
				for model calibration; and,
c. A
				life-cycle cost analysis of remedial
				alternatives.