Environmental remediation services can range from fast-track source removal to more complex, multi-faceted solutions involving inter-related remedial approaches, GeoInsight designs, builds, and operates a variety of remedial solutions that reduce risks to both human health and the environment. We focus our efforts on returning your property to a productive and valuable state. GeoInsight has remediated formerly-impaired property for:
GeoInsight can design, construct, and operate a variety of remediation systems to solve multi-media environmental impacts. Often a combination of remedial solutions is used in conjunction to rapidly reduce site impacts. Our staff’s technical capabilities continue to evolve as new and innovative remedial solutions enter the marketplace. We have no vested interest in a particular remedial approach or technology; therefore our analyses and recommendations are never limited or biased. You get the solution that is right for you and your site. Our experience with a multitude of technologies in a wide variety of settings is highly valuable when it comes to preserving your financial resources.
Ground water extraction is used to recover impacted ground water and, often at the same time, exert hydraulic control. Our hydrogeologists are experts at interpreting and modeling your site to optimize an extraction system design and configuration.
Treated water can be discharged to surface water, re-injected at the site, discharged to a municipal treatment facility, or disposed of off-site. The effectiveness of ground water extraction and treatment is primarily a function of the subsurface characteristics and the design and location of recovery wells.
Multi-phase extraction (MPE) uses a high-vacuum and/or multiple-pump system to remove ground water impacted with combinations of dissolved-phase petroleum constituents, soil vapors from the vadose zone, and/or light non-aqueous phase liquid (LNAPL). The MPE system lowers the water table around the extraction well, exposing more of the vadose zone such that adsorbed-phase constituents are liberated. Once above ground, the extracted vapors, ground water, and LNAPL are separated, treated, or recovered. MPE is generally effective in remediating dissolved and adsorbed-phase “light” constituents like gasoline and LNAPL, and is most often used as a short-term solution which quickly removes significant contaminant mass.
In-situ chemical oxidation (ISCO) involves injecting an oxidizing chemical solution (such as sodium permanganate, persulfate, ozone, or hydrogen peroxide) into the subsurface of the immediate vicinity where impacts were observed. We carefully define site geochemistry to optimize the injection process to save you money. Oxidation of contaminants typically occurs quickly upon contact with the oxidant and will liberate carbon dioxide, water vapor, and possibly heat.
A catalyst is typically used with hydrogen peroxide to increase the reaction rate. The reaction must be controlled through careful oxidant addition to avoid excess or uncontrolled vapor and heat production. Although the reaction is rapid, multiple injection events may be required to achieve remedial goals because the oxidant is also consumed by organic material and reduced minerals that are naturally occurring in the subsurface. We closely monitor progress to gauge the overall performance effectiveness.
The use of ISCO in a particular area is not necessarily incompatible with bioremediation or monitored natural attenuation. Although naturally-occurring organisms are usually destroyed in the oxidation process, their recovery to pre-injection conditions is common. As an additional benefit, residual oxygen, due to peroxide decomposition, may assist biodegradation in down-gradient areas after ISCO injections are complete. We will devise the appropriate combination of these approaches, depending upon your objectives (i.e. cost-minimization focus or schedule focus).
Soil vapor extraction is a widely-accepted and proven technology that collects volatile vapors from the unsaturated and vadose zones. Typically, soil vapors are collected using a mechanical blower connected to a carefully-designed extraction well. Soil vapor extraction is highly effective at reducing overall volatile mass in the subsurface, including separate phase liquids (free products such as gasoline). We have significant experience with the systems in a wide variety of soil conditions.
When designed and constructed properly, soil vapor extraction can also reduce the potential for vapor intrusion into buildings. Because soil vapor extraction is highly effective at collecting vapors in the unsaturated zone, it is often used in conjunction with air sparging to collect volatile compounds liberated from ground water (via sparging). If necessary, we can treat collected vapors before discharging them to ambient air using technologies such as:
Air sparging involves pressurized injection of air (usually ambient air) into the saturated zone below the water table to remove volatile compounds as injected air bubbles through impacted ground water. Typically, air is injected into the subsurface in a pulsed manner through an injection well connected to an air compressor. We carefully design the sparge point layout to prevent mobilizing vapors or adversely affecting the direction of local ground water flow.
Air sparging often increases aerobic biodegradation by increasing oxygen levels in the saturated zone. In some cases, ozone may be injected in place of ambient air to further stimulate aerobic biodegradation. Therefore, air sparging may be paired with in-situ bioremediation. Soil vapor extraction is also typically used in conjunction with air sparge to collect vapors liberated from the subsurface.
Similar to air sparging, ozone sparging delivers a high concentration of ozone gas directly to ground water. This approach provides more continuous oxidation. Typically, ozone is injected in controlled time-duration sequences via ozone injection points. Ozone sparging is usually most effective for short-term “hot spot” remediation. In general, ozone-based processes for remediation are similar to other chemical oxidation techniques, in which the oxidant of choice is injected into the desired treatment area. However, the use of ozone is different from most oxidation processes because it can be injected as a gas or a liquid (as ozonated water).
Biosparging, or bioventing, is the process of aerating soils to stimulate in-situ biodegradation of aerobically-degradable compounds in soil by providing supplemental oxygen to existing microorganisms. This process is typically applied to the vadose zone by injecting low volumes of air under relatively low pressure. Biosparging systems are designed to maximize biodegradation while minimizing volatilization.
GeoInsight encourages natural degradation when possible. Sometimes, the natural biota responsible for the degradation need a little help. In-situ enhanced bioremediation involves treating soil and ground water by delivering:
These additions enhance subsurface conditions, promoting naturally-occurring microorganisms to consume or degrade compounds adsorbed to soil or dissolved in ground water. This approach requires careful evaluation of geochemistry to design the correct combination of additives, and then purposeful performance monitoring to verify microbial activity and associated contaminant degradation.
GeoInsight typically implements sub-slab depressurization to prevent vapor intrusion into buildings and residences. We have designed a wide variety of systems for all types of structures and can tailor a system specifically to your site. Sub-slab vapors can be collected using motor- or wind-driven fans or blowers connected to wells or other collection points. Implemented properly, these systems are:
Excavation is a practical and extremely effective approach to physically remove impacted soil, and to a limited degree, separate phase product and ground water when used in conjunction with dewatering. Typically, excavation is cost-effective for removing source-area soil that continues to act as a source of impacts to ground water. Excavation may be limited by the depth of impacts or the presence of structures such as buildings, utilities, roadways, and underground tanks. We carefully consider the physical constraints of material handing and stockpiling during excavation, as well as proper characterization of the excavated material for disposal. A major benefit of excavation is the ability to visually confirm the remedial progress and collect representative samples.
Non-aqueous phase liquid (NAPL) recovery (separate phase recovery) product is implemented when impacts are present in the free phase. NAPL recovery can be conducted:
GeoInsight often recovers NAPL from specially-designed wells; however, NAPL may also be collected and recovered from interceptor trenches. Whenever practicable, GeoInsight involves your facility’s personnel in NAPL recovery efforts, thereby reducing project costs.
Monitored natural attenuation (MNA) allows contaminates to diminish in-situ (in the ground) under natural attenuation mechanisms, such as biodegradation and dispersion. Natural attenuation is typically suited for sites where the release source has been removed, and where it can be demonstrated that the dissolved plume is not expanding and has reached a relatively steady state.
Use of MNA is only appropriate as part of a definitive remedial action plan and is not simply a “do nothing” approach. Continual monitoring of the physical and chemical ground water parameters aids our evaluation of this remedy. In situations where regulatory closure is not required immediately, MNA can be a very cost-effective remedial approach.
Vapor phase treatment is used to treat vapors extracted from remedial systems prior to discharge to ambient air. The typical technologies chemically-impacted include granular activated carbon, catalytic oxidizers, and internal combustion engines. Our selection of the appropriate treatment technology is based upon the vapor recovery rate and the concentration and type of compounds being treated (e.g., gasoline, chlorinated solvents). Quite often, as the concentrations of contaminants in soil vapor decrease, the initial treatment technology is exchanged for a second alternative, or, if warranted, removed all together. We perform specific calculations to predict the pre-treatment requirements based upon air quality regulations.
Treatment operations often involve the need for us to improve the chemical or physical quality of fluids. We use liquid phase treatment to treat:
The technologies range from granular activated carbon, air strippers, oil/water separators for product removal, to more complex treatment technologies such as ultraviolet oxidation and ion exchange. Our selection of the technology is based upon the anticipated flow rates, the concentration and type of compounds being treated (including ancillary compounds such as iron), and the applicable treatment standards.
Ion exchange is a commonly used method for treating water and involves a chemical reaction in which there is an exchange of positively or negatively-charged ions. GeoInsight has designed ion exchange systems to treat hardness (caused mainly by the presence of calcium and magnesium) and naturally-occurring metals such as arsenic and uranium. The process uses a media, generally a special resin that exchanges positively-charged ions (cations) for negatively-charged ions (anions), or vice versa. To keep the ion exchange system working optimally, the system is designed to allow efficient change-out of resin media.
Ultraviolet (UV) oxidation is an increasingly popular technology used for on-site remediation of extracted ground water. It uses hydroxyl radicals generated from the interaction of UV light with either hydrogen peroxide or ozone to oxidize a wide variety of dissolved organic compounds. Hydroxyl radicals are highly-reactive oxidizing agents that have the ability to destroy persistent contaminants such as 1,4 dioxane, methyl tert-butyl ether, and several chlorinated and aromatic solvents that are difficult to treat using more traditional technologies. UV oxidation has the capability to achieve very low concentration thresholds, often making it a logical choice as a part of a municipal water supply treatment train.
A key advantage of UV oxidation treatment technology is that it is a destruction process (i.e. toxic byproducts are not generated in the reaction). Therefore, there is a significant reduction in potential disposal costs that can potentially be associated with other remedial technologies. When necessary, UV oxidation can also be combined with other treatment methods such as activated carbon adsorption, air stripping, or filtering to result in a total system solution.
Soil stabilization is a technique used to chemically alter potentially-toxic metals in soil, allowing the soil to be handled as a non-hazardous waste, resulting in substantial cost savings for disposal. Prior to this technology, the primary option to dispose of soil that exhibited concentrations of metals above the toxicity characteristic leaching procedure disposal criteria was to ship soil to expensive, hazardous waste accepting facilities for treatment and/or disposal.
The soil stabilization process reduces the leachability of metals and allows soil to meet the non-hazardous disposal requirements. We assess the physical and chemical properties of the soil to identify appropriate stabilization methods and whether the mixing or stabilizer application should occur in-situ or after excavation.
GeoInsight provides environmental remediation services throughout the states of New Hampshire, Massachusetts, Connecticut, Rhode Island, Maine, Vermont and New York.
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