Environmental Assessment and Remediation

A Recognized Environmental Condition (REC) means there is a presence or likely presence of conditions that indicate one of the following:

• An existing release
• Past release
• Material threat of a release

• Spill Incident
• Release from underground vessel or system
• Regulatory requirement
• Liability concerns related to a property transaction
  • Findings of a Phase One Environmental Site Assessment
  • Data gap identified in a Phase One Environmental Site Assessment
  • A REC identified in a Phase One Environmental Site Assessment

When investigating for Dense Non-Aqueous Phase Liquids (DNAPLs), one must consider the following:

• Not likely to observe free product in subsurface
• Must not create new vertical migration pathways
• Need to be able to discretely sample multiple vertical zones

If you have questions regarding DNAPLs, contact August Mack Environmental at 800.579.0770 and ask to speak to one of our environmental remediation specialists.

• Immiscibility with water - they form separate ‘phases’, eg. Oil & water
• Low solubilities - DNAPL can’t dissolve quickly in groundwater: it may persist for decades before dissolving
• Relatively high densities - DNAPLs are denser than water, and can therefore sink beneath the water table, polluting the full thickness of an aquifer
• Low viscosities - allows rapid subsurface migration
• Toxicity - Many DNAPLs are suspected or...

Understanding Light Non-Aqueous Phase Liquid (LNAPL) is important for the following reasons:

• LNAPL is common problem: several hundred thousand petroleum underground storage tanks (USTs) in the United States.
• LNAPL in soil/groundwater serves as continuing source of contamination.
• Can have dangerous physical characteristic – e.g., flammable vapors.
• Can migrate rapidly in subsurface(vertically and horizontally).
• Many LNAPLs are toxic and can cause cancer (e.g., benzene).

When mitigating vapor intrusion, it is important to eliminate the source of the vapors or prevent the upward migration of the contaminants into inhabitable spaces. In order to eliminate the source of the vapors, one must either remove the contaminated media or treat the contaminated media in place. The following are vapor intrusion mitigation approaches:

• Sub-slab depressurization system
  • Seal cracks & seams, coat floors and subsurface walls, if needed
  • Plastic sheeting in crawl spaces
  • Use fan to...

Environmental issues can impact real estate and real estate transactions in the following ways:

• Decrease marketability and direct property values
• Complicate conventional financing options
• Slow and potentially jeopardize future sales
• Introduce the potential for regulatory and third party legal liabilities
• Require costly environmental assessment and remediation

Vapor intrusion (VI) is the migration of volatile chemicals from the subsurface into overlying buildings. The chemicals associated with VI are the following:

• Volatile Organic Compounds (VOCs)
  • Chlorinated Hydrocarbons, e.g., TCE, PCE, 1,2-DCA, Vinyl Chloride, etc. – drycleaners, manufacturers
  • Benzene & Other Volatile Petroleum Constituents
• Methane – in certain areas of U.S. (e.g., LA Basin)
• Semi-Volatile Organic Compounds (SVOCs) - Less Common

• Preventing moisture will prevent mold.
• Buildings should not have mold growth.
• You can clean hard, non-porous surface, but should remove porous surfaces. DO NOT CLEAN WITH BLEACH.
• Handle tenant complaints promptly.
• Be proactive by developing...

House Enrollment Act (HEA) 1162 requires the Indiana Department of Environmental Management (IDEM) to consider risk-based solutions while evaluating environmental closures. Risk-based closures can include several approaches for example:

• Applying pre-approved closure levels
• Determining site-specific closure levels
• Considering risk of exposure

Another in-situ remedial technology is enhanced bioremediation which is also known as enhanced aerobic bioremediation. Natural bioremediation (breakdown) requires the continued presence of bacteria, nutrients, oxygen and moisture whereas enhanced bioremediation is used to accelerate naturally occurring bioremediation of contaminants in the subsurface. Bioremediation provides a supplemental supply of oxygen to bacteria (normally limiting factor). It can increase the rate of contaminant breakdown...

One of the in-situ remedial technologies available is air sparging (AS). This remedial technology reduces the concentrations of volatile constituents in soils and groundwater by the injection of contaminant-free air into the subsurface saturated zone. It produces a phase transfer of hydrocarbons from a dissolved sate to a vapor phase. Then, the air is vented through the unsaturated zone. It is commonly used with soil vapor extraction (SVE).

The advantages of air sparging are the following:

• Proven...

The in-situ remediation technology of dual phase extraction (DPE) is also known as multi-phase extraction or vacuum-enhanced extraction. During DPE, the following occurs:

• DPE uses vacuums to remove contaminated groundwater, free-phase product and contaminated vapors from soils.
• Extracted liquids and vapor are treated and collected for disposal.
• DPE pulls air through pore space in contaminated soils and pulls contaminated groundwater and free product from the same well location.
• Requires permits for...

In today’s economic condition, an abundance of commercial and industrial properties have been surfacing in the marketplace. While the list of availability grows, the environmental stigma associated with past business at these facilities has continued to rise and continues to be one of the largest deterrents for perspective buyers.  It seems unless the property is “clean”, no one wants to assume “the environmental skeletons” that may reside in the property’s proverbial closet. But “How clean is...

In the in-situ remedial technology of soil vapor extraction (SVE), the following occurs:

• Vacuum is applied to the unsaturated zone through extraction wells.
• Vacuum causes movement of vapors toward extraction wells.
• Volatile constituents are removed through the extraction wells.
• The extracted vapors are discharged to the atmosphere.

• Proven performance; readily available equipment; easy installation; agency approved.
• Minimal disturbance to site...