EHR-FAQ’s
What is the best application of this technology?
Remediation of volatile organics such as chlorinated solvents (e.g.TCE, PCE, VC) or petroleum products (e.g. BETX) in low permeability soils (e.g. clay) where SVE will not work, and to remediate DNAPL that has migrated below the water table.
When is the technology not applicable?
Since the technology relies on volatilization of the constituents of concern the technology does not work for the remediation of metals in soil and groundwater. It has limited application for the enhancement of remediation of high molecular weight compounds (e.g. PCBs and heavy organics).
Is the technology applicable to remediation of highly permeable soils such as sands?
Yes, if DNAPL needs to be remediated within the saturated zone. If only the unsaturated zone is impacted Soil Vapor Extraction (SVE) can probably perform the required remediation at a lower cost.
How many sites have you remediated using this technology?
The principals at SMA have successfully managed the closure of 7 sites using ERH. Constituents of concern have included TCE, PCE, VC, BETX and Methylene Chloride.
What size project is appropriate for use of this technology and what are the costs?
Due to the high costs associated with installation of the power control unit it is reasonable to assume a minimal cost of $300,000. However, if your site is over about 5,000 yd3 a reasonable estimate of costs are $80 to $100 yd3, and less if the site is over 20,000 yd3.
Can the electrodes be installed under concrete in an active workspace?
Yes, we have done this on multiple occasions.
Is vapor recovery required?
That depends on the Federal, State or local requirements. When vapor recovery is required we typically use activated carbon, but thermal destruction has also been used.
Will you do firm fixed-price remediations?
We have, and we will be happy to give you a firm fixed-price quotation for your project as long as we have characterized the site or we have confidence in the characterization performed by others.
How long does it take to complete the remediation?
That depends primarily on the remediation goals, and, to a lesser extent, the size of the treatment area. A small project can be completed in about 4 months and a large project should be complete within a year.
Is vapor migration inside a facility a problem?
No. In order to have an effective treatment system without fugitive emissions the treatment area must be covered (typically asphalt or concrete) Vapors are removed by the vapor control system that operates under a vacuum... Typically, indoor air quality is monitored by use of SUMMA canisters to satisfy regulatory agencies.
How do you determine that the remediation goals have been met?
Any Work Plan must have clearly specified remediation goals, such as percent mass removal or maximum constituent concentrations. Documentation of meeting the remediation goals is done by confirmatory sampling. Initial confirmatory sampling is typically conducted after the design energy has been put in the subsurface, the mass evolution of the constituents of concern have dropped significantly and the subsurface temperatures are over about 80 degrees Celsius. Typically there may be a recalcitrant portion of the site that will require some small amount of additional heating.
Is building stability an issue if electrodes are installed in, or near, a building?
Surveys of buildings at numerous sites have shown that this is not a concern.
What procedures are used to ensure safety?
Monitoring of stray current is conducted throughout the startup and the remediation. Security fences are provided to prevent unauthorized entry.