Posted on Wed, Apr 08, 2009 @ 12:23 PM
By Michael Bricher, Senior Environmental Engineer
Over the past two years, there has been an increase concern from the regulatory community, its Licensed Site Professionals (LSPs), and environmental attorneys regarding Mass DEP's implementation of vapor intrusion requirements at Massachusetts Contingency Plan (MCP) sites.
Over a 100 MCP audited sites have been recently re-opened by Mass DEP due to potential vapor intrusion concerns which include some sites that have been closed for more than 15 years. As a result, the responsible parties have been required to perform additional environmental response actions at a significant expense. In many cases, the audited sites were closed out in accordance with the regulations that applied at that time.
As a result of Mass DEP's revised approach and more stringent requirements (some of which are still in draft) to address potential vapor intrusion, there's much more uncertainty concerning what it takes to achieve MCP closure for VI sites. For example:
• Can you really rely on vapor intrusion modeling now?
• Do you need Mass DEP review and approval of every vapor intrusion site in order to be comfortable that real closure has been achieved?
In response to the increasing degree of uncertainty from the public regarding Mass DEP's policies for addressing potential vapor intrusion at MCP sites, Mass DEP has convened an Indoor Air Workgroup to develop an Updated Vapor Intrusion Guidance Document. In order to stay current with Mass DEP's approach and requirements for potential vapor intrusion, Triumvirate recommends that you review the latest draft version of the Assessment section in the New Vapor Intrusion Guidance (dated March 27, 2009). The link is provided below:
http://indoorairproject.files.wordpress.com/2009/03/assessment-text-draft-3-27-093.doc
Posted on Tue, Mar 24, 2009 @ 01:10 PM
Notification Conditions - Part 2: 72 hour and 120 day Reporting
By Craig Sasse, Senior Engineer
The Massachusetts Contingency Plan, Section 40.0300 presents conditions which require notification to the MA DEP within 2 hours, 72 hours or 120 days. Releases and Threats of Release which require notification of the MA DEP within 72 hours include:
A release to the environment of oil or hazardous material (OHM) that is indicated by the presence of:
• non-aqueous phase liquid (NAPL) with a measured thickness greater than 1/2 inch;
• a soil sample with equal to or greater than 100 parts per million of total organic vapors from within 10 feet of the exterior wall of a underground storage tank (UST) and is greater than 2 feet below grade and collected as part of the assessment or removal of a UST;
• concentration greater than the reportable concentration within the Zone I of a public water supply or 500 feet of a water supply well;
• concentration in groundwater greater than 5 mg/l total volatile organic compounds within 30 feet of a school or occupied residential structure, where the groundwater table is less than 15 feet below grade; or
• a condition of Substantial Release Migration, associated with a release for which notification is required.
A threat of release to the environment of OHM from a UST of a leak equal or greater than 0.05 gallons per hour:
• in a single wall UST;
• in the inner wall of a double wall UST; or
• in the outer wall of a double wall UST.
Notification of the MA DEP within 120 days is required if:
• OHM in soil or groundwater is equal to or greater than the appropriate reportable concentration;
• Oil in soil equal to or greater than the reportable concentration, where the total continuous volume of the contaminated soil is equal to or greater than two cubic yards; or
• a release results in subsurface NAPL having a thickness of greater than 1/8 inch and less than 1/2 inch.
There are exemptions, timing, and actions that may affect notification requirements. Several exemptions are: gasoline releases from passenger car accidents; releases from coal, coal ash, or wood ash; and releases associated with building materials in good repair. Previous cleanup work or cleanup by a Limited Removal Action may eliminate the need to make notification.