SKA Consulting, L.P. (SKA) is pleased to offer the following project closure strategies for the purpose of explaining the four groundwater remedies available under the Texas Risk Reduction Program (TRRP) where the regulated entity does not have to meet the TRRP protective concentration levels (PCLs) for the chemicals of concern (COCs). These remedies are:
Waste Control Unit (WCU). A WCU is defined at §350.4(a)(91) as a municipal or industrial solid waste landfill, including those RCRA regulated units classed as landfills, with a liner system (i.e., synthetic or clay) and an engineered cap that have been closed pursuant to an approved closure plan, previous regulations, or will be implemented pursuant to an approved RAP. Once approved by the Texas Commission on Environmental Quality (TCEQ), the regulated entity is not required to achieve PCLs directly under the WCU. A WCU can be implemented for any class of groundwater though it is unlikely that the TCEQ would approve a WCU over a Class 1 groundwater-bearing unit (GWBU). The WCU must be institutionally controlled.
Technical Impracticability (TI). TI demonstrations as described in §350.33(f)(3) can be used for Class 1, 2, and 3 groundwaters. The regulated entity must demonstrate to the TCEQ that is it technically impractical to remove, destroy, or render immobile the COCs. Cost is not a consideration for a TI demonstration and the advent of new in-situ remediation technologies has made it more difficult to demonstrate TI.
Plume Management Zones (PMZs). To establish a PMZ as provided in §350.33(f)(4), the regulated entity must demonstrate to the TCEQ that a groundwater COC plume will not expand beyond certain geographical limits, essentially lines drawn on a map. The demonstration is usually made through the analysis or modeling of empirical groundwater monitoring data. Usually, lengthy monitoring is required after implementation of a PMZ to verify that the COC plume is attenuating. An important limitation of a PMZ is that all of the landowners within the PMZ must agree to an institutional control to restrict access and use of groundwater on their property. By rule, a PMZ is not available for a Class 1 GWBU (only Class 2 and Class 3 GWBUs which already contain a groundwater PLCE zone).
Municipal Setting Designation (MSD). A MSD is actually codified in statute rather than in the TRRP rule (30 TAC 350). However, the implementation of a MSD directly affects a TRRP groundwater remedy by removing the groundwater-ingestion pathway from consideration in a risk assessment in lieu of the municipality making potable water available.
For the purposes of this discussion, it will be assumed that a WCU designation and a TI demonstration will not be applicable. Therefore, the groundwater remedy comparison is between a PMZ and an MSD. These remedies are compared in more detail below.
Plume Management Zone
A PMZ is a remedial response objective where the groundwater Protective Concentration Level Exceedence (PCLE) zone is controlled instead of removed or decontaminated, and managed to prevent human or ecological exposure to the groundwater COCs. A PMZ must be proposed in a Response Action Plan (RAP) and, if approved by TCEQ, documented in an Institutional Control (deed notice or restrictive covenant, as applicable).
The PMZ is a Remedy Standard B closure remedy that is a geographic area in which the groundwater COC plume (i.e., PCLE Zone) resides. Remedy Standard B allows for the control of COCs while Remedy Standard A requires the removal or decontamination of COCs. Under TRRP, an Affected Property Assessment Report (APAR) must be submitted and approved by TCEQ when pursuing a PMZ strategy. Once delineation is complete, the PMZ can be proposed in a RAP. The PMZ remedy can not be self-implemented by the regulated entity. Generally, enough groundwater COC data can be obtained during the site assessment phase to determine if a PMZ is feasible. Many historical plumes have attenuated and may be stable upon discovery; however, the TCEQ generally requests a minimum of 8 quarters of groundwater monitoring to demonstrate stability. A Response Action Completion Report (RACR) documents implementation of the PMZ and subsequent Response Action Evaluation Reports (RAER) may be required during the monitoring period after implementation. Groundwater monitoring is usually not continued to the point where the COC concentrations fall below their applicable PCLs. COC plumes within a PMZ are allowed to expand, but the expansion is limited to the lesser of the following:
25% of the current length of the groundwater PCLE zone; or,
To within two years of groundwater travel to the closest downgradient off-site property that is not within the PMZ.
If a COC plume is still expanding and exceeds the lesser of the three measures described above, the TCEQ could require a new remedy be implemented to limit the plume expansion including active remediation.
PMZs require that access and use of the affected groundwater be restricted; therefore, all property owners within the PMZ must agree to this restriction (i.e., Institutional Controls).
TRRP requires the placement of institutional controls (i.e., deed notices or restrictive covenants) on an affected property in different circumstances as part of completing a response action. In its simplest form, an institutional control (IC) is a legal document that is recorded in the county deed records. The fundamental purposes of an IC are to:
Provide a permanent notice to subsequent owners/operators that residual chemicals of concern (COCs) are present at the affected property above the protective concentration level (PCL), and/or
Impose conditions on the future use of the affected property in order to ensure protective use of the property.
The advantages of a PMZ strategy are:
It is a regulatory and technical process.
All affected landowners (onsite and offsite) agree to the groundwater restriction (i.e., Institutional Controls) and therefore, have some buy-in into the process.
Groundwater monitoring confirms the location of the COC plume.
Potentially long-term (multiple years) groundwater Monitored Natural Attenuation (MNA) approach to groundwater response objectives (passive approach).
The disadvantages of a PMZ strategy are:
Requires full delineation of the groundwater PCL exceedance zone.
Potentially long-term groundwater monitoring period (multiple years) to establish plume stability and to confirm after implementation.
Requires all property owners (onsite and offsite) within the PMZ to agree to restrict groundwater (i.e., Institutional Controls) on their property. Any one property owner who is unwilling to restrict their property can derail the PMZ strategy.
Generally can be more time consuming and more expensive than other groundwater remedies.
Municipal Setting Designation
An MSD closure strategy is the elimination of the groundwater ingestion exposure pathway though implementation of the MSD.
Effective September 1, 2003, the Texas Legislature promulgated Subchapter W Municipal Setting Designation to Chapter 361 Solid Waste Disposal Act. The Legislature’s purpose for his statute was to provide for certification of MSD for municipal properties in order to limit the scope of or eliminate the need for investigation or response actions addressing contaminant impacts to groundwater that has been restricted from use as potable water by ordinance or restrictive covenant.
The MSD removes the groundwater ingestion pathway from the site so that groundwater ingestion PCLs are no longer applicable. Therefore, the MSD strategy is one where response actions would not be required to address contaminate concentrations in groundwater in excess of their respective ingestion PCLs. Likewise, contaminate concentrations in soil in excess of their soil-to-groundwater PCLs are also no longer applicable to the soil assessment. Groundwater PCLs for other exposure pathways like groundwater-to-air inhalation pathways must still be evaluated and addressed if there is a PCL exceedance. Likewise, other soil exposure PCLs must also be evaluated and addressed.
The MSD statute placed the responsibility for certifying the MSD applications with the TCEQ and the TCEQ has developed an application process. The MSD statute does require written support in the form of a resolution or ordinance from:
Municipalities in which the property is located;
Municipalities within 1/2-mile of the property;
Municipalities which own or operate a water supply well within 5-miles of the property; and
Retail Public Utilities (RPUs) that own or operate a groundwater supply well within 5-miles of the property.
Obtaining written support for the MSD from these parties is essential. In addition to obtaining the written support of the parties described above, the MSD statute also requires notification of:
All private water well owners within 5 miles of the subject property; and
All property owners within 2,500 feet of the subject property.
The MSD statute does not require the private water well owners or property owners to necessarily provide written support of the MSD; however, they can comment to the municipality in which the subject property is located and/or the TCEQ.
The MSD statute allows municipalities to remove groundwater ingestion as an exposure pathway as long as the municipality is willing to provide potable water service to the property. A number of municipalities quickly embraced the MSD process as a way to help redevelop urban properties that had impacted groundwater. Effective November 1, 2007, the City of Houston (COH) adopted a procedural ordinance (Section 5 of Ord. 07-959) providing a process for establishing MSD ordinances within the COH. The COH MSD application must include:
Evidence of the municipal drinking water supply with ½ mile of the property;
Soil and groundwater contamination delineation including PCL exceedances;
A statement as to whether the groundwater plume is stable, expanding, or shrinking (the application contains a template statement);
A statement as to whether the groundwater plume has impacted off-site properties; and
A statement as to whether the subject property is in a TCEQ regulatory program like the Voluntary Cleanup Program (VCP) or similar program.
In addition to the written support and notification requirements noted above, the COH requires applicants for the MSD to conduct and attend the following in order to discuss or explain their applications for an MSD ordinance:
Public meeting; and
City Council Public Hearing
The MSD program enjoys widespread support with the COH. In addition, our experience has been that other municipalities in the Houston area such as the City of Bellaire, West University Place, and Missouri City have been supportive of MSD applications.
Most municipal RPU water wells near MSD sites are owned by the COH, so the COH provides written support of the MSD if the COH favorably reviews the MSD application. Municipal utility district (MUD) RPUs have been favorably approached for support of an MSD. Private RPUs need to be contacted individually for support.
Recently (June 2011), the 82nd Texas Legislature passed House Bill (HB) 2826, relating to MSD, that expands and modifies the applicability of the existing MSD statute (Section 361.804(b), Health and safety Code). The significant change to the existing legislation that was provided by this new legislation, at this time, only appears to apply to the City of Houston. The incorporated language reads:
“If the property for which the municipal setting designation is sought is located in a municipality that has a population of two million or more and the applicant intends to comply with the requirements of Section 361.8065 for issuance of a municipal setting designation certificate under Section 361.807 by complying with the requirements of Section 361.8065(c), a statement that a municipality described by Subsection (a)(1)(B) or (C) of this section or a public utility described by Subsection (a)(3) of this section has 120 days from the date of receipt of the notice required by this section to pass a resolution opposing the application for a municipal setting designation.”
What this language means in general terms is that each municipality within the City Limits of the City of Houston (or its Extraterritorial Jurisdiction [ETJ]): (1) with a boundary located within onehalf mile from the MSD property boundary; or (2) owns or operates a groundwater supply well located within five miles from the MSD property boundary is no longer required to pass an ordinance supporting the MSD Application. Rather, the municipality has the option to: (1) affirmatively oppose the MSD Application within 120 days of notice of such Application, or (2) offer no response at all. In the case of no opposition at all, the supporting documentation showing notice to the municipality is sufficient for the TCEQ to affirm the support of these municipalities of the MSD Application. This new legislation became effective September 1, 2011.
The effect of this legislation to the City of Houston is that many MSD Applications have been stalled for several months and/or years due to the absence of support or opposition by the Memorial Villages municipality. This legislative change provides a pathway forward for these stagnant MSD Applications.
The advantages of a MSD strategy are:
Can be implemented without full delineation of the groundwater COC plumes;
Reduces or eliminates soil and groundwater response requirements;
No long-term groundwater monitoring requirements;
Does not require off-site property owner approval (i.e., Institutional Controls) even if there are off-site impacts; and
Municipalities and RPUs no longer have to provide written support of the MSD application (City of Houston or ETJ); and
Generally quicker and cheaper process than other groundwater remedies.
The disadvantages of a MSD strategy are:
Political process, so worthwhile applications can be derailed by politics;
Public meeting and comment can affect the political process; and,
Requires action by City Council for approval.