Uniroyal Groundwater Clean-up and Treatment, Elmira

Conestoga-Rovers & Associates, Waterloo, Ontario

Category: Environment

Uniroyal Chemical Co. has operated a manufacturing plant in Elmira, Ontario since 1942 producing rubber chemicals, specialty chemicals and agricultural products. In the past, wastes were disposed of on the plant site and in-ground lagoons were used for wastewater treatment.

These historic practices of waste disposal and wastewater treatment contaminated the soil, surface water and sediment on site, and contaminated groundwater on and off the site. The main contaminants present are N-nitrosodimethylamine (NDMA), benzene, toluene, chlorobenzene, aniline, carboxin, mercaptobenzothiazole, and chlorinated phenols.

In 1989 Uniroyal retained Conestoga-Rovers & Associates to provide environmental consulting engineering services to address the investigation and clean up of the results of the historic disposal practices. One of the most significant activities completed has been the clean-up of the contaminated groundwater both on and off the site, in an area of nearly two square miles.

The project integrated a vast array of engineering and scientific disciplines to generate a clean-up approach that minimized capital costs and was effective. The engineering approach was based on comprehensive hydrogeologic evaluations and analytical and mass balance models that were used to refine and develop the design, and to predict performance.

As an example, Conestoga-Rovers completed contaminant flux calculations indicating that over 95 per cent of the contaminant loading to the creek originated from the southwest quadrant of the site. The resulting Certificate of Approval, which was the subject of controversy, required the company to contain only the southwest portion of the site. This approach saved Uniroyal millions of dollars that would have been required to contain and treat groundwater from the rest of the site even though it would have had no measurable improvement in the water quality of the creek.

The treatment processes use both physiochemical and biological treatment processes to treat groundwater that contains one of the more diverse combinations of chemicals of which Conestoga-Rovers and the Ontario Ministry of the Environment are aware. The remediation uses novel technology combinations and a patent has been obtained for the wastewater treatment system.

Goals and remedies

Uniroyal had several objectives for the clean-up of groundwater as follows:

— Contain shallow (upper aquifer) groundwater on-site from discharging to Canagagigue Creek which transects the site.

— Contain deeper (municipal aquifer) groundwater from migrating off site.

— Collect contaminated off-site groundwater to clean it up in a 30-year time frame, and

— Provide, monitor and optimize effective treatment to meet stringent criteria for surface water discharge.

On-site rehabilitation

In January 1992, Uniroyal began operating an on-site containment and treatment system to prevent contaminated groundwater migrating further off site into the municipal aquifer which had supplied drinking water to Elmira.

Once the municipal aquifer was contained beneath the site, Conestoga-Rovers began to assess how to contain and treat the upper aquifer groundwater. Uniroyal wished to integrate an existing pretreatment system into a new treatment process.

Several types of treatment were required to address the different types of contaminants. Respirometry studies indicated that chemicals that acted as biological inhibitors would have to be removed prior to biological treatment. Biological treatment was necessary to render the ultraviolet oxidation treatment step effective (necessary for one contaminant, NDMA). The final treatment train included the following elements: phase separation; upflow granular activated carbon (GAC); heat exchange; nitrification; clarification; filtration; ultraviolet oxidation; and GAC polishing. Construction of the network of extraction wells and treatment system began in April 1996 and they commenced operating in January 1997 on schedule.

Surface water impact modeling provided the technical basis for establishing which portion of the upper aquifer would have to be contained. This modeling was accepted by the Ministry as an appropriate rationale for not containing the entire length of the creek on both sides. By focusing on the most significantly contaminated portions the cost was reduced to $4 million from an estimate of $11.3 million.

The system has met and exceeded performance expectations. Effluent requirements have been consistently met for all 18 primary contaminants with infrequent, minor exceptions. Creek water downstream of the site has greatly improved and generally meets the Ministry’s criteria. Previously found compounds are now rarely detected, and the biological activity in the creek has grown markedly. Simple operational modifications now allow for both nitrification and denitrification in the treatment system.

Off-site collection and treatment

Concurrent with working on on-site systems, Conestoga-Rovers designed and supervised the construction of the off-site collection and treatment system. This system was based on a comprehensive three-dimensional groundwater transport model. The model predicted it will be difficult to meet the 30 year clean-up objective, but that tremendous progress will be achieved.

The modeling also showed that the initial extracted groundwater would contain ammonia at concentrations that would require treatment. The consulting engineers assessed the hydraulic loading at the Elmira sewage treatment plant which showed it could treat the ammonia without compromising service to the community. The operation of the system commenced on August 1998 on schedule. Using the Elmira sewage treatment plant saved up to $7.3 million.

The 53 L/sec capacity off-site collection and treatment system consists of extraction wells, a pipeline system through Elmira and a treatment system using upflow granular activated carbon (GAC), and ultraviolet oxidation technologies. The Elmira sewage treatment plant provides ammonia treatment for up to two years. Additional extraction wells (and more groundwater) will be added to the system over time.

Conestoga-Rovers also consulted with Uniroyal to develop a thermophilic biological treatment system for Uniroyal’s wastewater. This process was patented in August 1997 and has permitted Uniroyal to reduce its wastewater treatment costs substantially.

The project has received a high degree of lengthy public, government and client scrutiny. Conestoga-Rovers played a key liaison role in communicating with government and with the people of Elmira and nearby Woolwich.

Award winner: Conestoga-Rovers & Associates (prime consultant). Project team leaders: Stephen Quigley, P.Eng., Peter Hicks, P.Eng., Bruce Polan, P.Eng., Alan Deal, Steve Harris, P.Eng., Andrew Lugowski, P.Eng., Jan Kochany, Craig Hebert, P.Eng., Gerry Kestle, P.Eng., Bob App, P.Eng.

Client/owner: Uniroyal Chemical Co.

Other key players: Uniroyal Chemical Co. Environmental Engineering and Project Engineering staff: Jeff Merriman, P.Eng., Richard Fobel, P.Eng., Mark Garnett, Tim Boose, Glenn Martin, P.Eng., David Ash.

Calgon Corporation/Solarchem (UV system testing); Maxxam Analytics Inc. (analytical services)