“Predictable” isn’t usually the first word that comes to mind in relation to remediation projects—the various components can be unstable, regulations change frequently, and the challenges are rarely straightforward. However, one of the most valuable lessons we’ve learned in our years of experience working at a Superfund site in the Northeast has been the substantial cost savings and improved sustainability you can see from strategic planning and value engineering from the very beginning of the project.
This project site is a 40-acre former waste oil disposal and recycling facility surrounded by residential properties. The town the site is in has limited drinking water resources, with no municipal water utility or local wastewater treatment facility, so the residences rely on private drinking water wells and septic systems. In 1995, the state’s environmental regulatory agency detected the presence of volatile organic compounds (VOCs) at levels that exceed drinking water standards in groundwater from onsite monitoring wells and two private residential wells, and the site was later listed on the Superfund National Priorities List. The primary contaminants detected at the site include polychlorinated biphenyls (PCBs), VOCs, polyaromatic hydrocarbons (PAHs), and lead, with 1,4-dioxane being discovered much later, in 2008.
Resequencing multi-component site remedy
The Record of Decision (ROD) for this multi-remedy site sequenced the different phases of the remediation work at the site to begin with the excavation and off-site disposal of shallow soil across a large portion of the property, followed by landfill debris removal, and sediment excavation and restoration. Once the excavation work had been completed, groundwater management (via a pump and treat system) and deeper source area thermal treatment would be implemented. In collaborating with the client and regulatory team on the remedial approach, we were able to identify strategic opportunities within this plan that could improve the project outcomes and provide a more sustainable design, while balancing cash flow for the client team.
After identifying that groundwater migration was a priority, 1,4-dioxane was discovered in the site’s groundwater, as well as in off-property residential wells during the initial design work. As a result, the remedy sequence was formally shifted to begin with the design, installation, and operation of the groundwater system to control migration. Though there was no public water utility in the area, bottled water was provided and additional individual point of entry (POE) treatment systems were added to address drinking water concerns, and later worked with a private utility to connect downgradient residential properties to their water system.
In addition to the re-ordering of these remedy components, one of our other suggestions was to combine the three separate excavation activities—site-wide shallow soil, landfill, and sediment excavation—into a single larger component, which was beneficial in that it will reduce the overall remedy timeframe and eliminate duplicative mobilization activities and the associated carbon footprint, (and reduce the number of design submittals!).
Risk reduction with sustainable methods
Reducing the risk to the environment and human health was the obvious priority at the site, but sustainability also played a big role in our remedy design and implementation. The ROD-specified remedy to address the two separate deeper groundwater source areas was steam enhanced extraction (SEE) thermal treatment, which involves injecting steam into wells to heat the soil, facilitating the removal of contaminants through multi-phase extraction. In many groundwater treatment systems, treated groundwater is sent to an off-site treatment facility. However, water conservation was crucial in our design development for this site given the lack of a public water source and concerns of drawing down the localized drinking water wells and adjacent brook. With this in mind, we developed a closed loop water conservation program where the treated groundwater was used to produce the steam necessary for thermal treatment, and the extracted groundwater was treated to drinking water standards at the on-site treatment system prior to be discharged back to the ground. This system was water neutral—all the water remained onsite and was discharged back to the local drinking water aquifer. Thermal treatment on the first of two source areas conserved over 6.6 million gallons of water, and achieved the remedial objectives of meeting ROD soil leachability goals, maintaining the base flow conditions in the adjacent brook, and protecting off-site drinking water.
Many believe that sustainable solutions will automatically cost more, but in fact, many can actually result in cost savings. The opportunities for increased sustainability on this project were identified during value engineering throughout the project; initially the goal of these reviews was improved efficiency and cost savings, but many of the actions implemented resulted in a greener, more sustainable approach. The water conservation measures we took, combined with our efforts to reuse materials; reduce waste, energy usage, and air pollutants; and restore the local ecosystem, resulted in a combined cost-savings of $2 million for the client. Many of the greener approaches implemented based on value engineering evaluations are intuitive for most projects, while others are very specific to the site. In addition to the risk reduction and improved sustainability, our re-sequencing of the remediation activities moved the highest capital expense project phase from the beginning of the schedule to the end, assisting in cash flow management. The combination of financial savings, risk reduction, and improved sustainability demonstrate that strategic sequencing and upfront planning can positively impact capital-intensive, complex remediation projects.
