Innovative approach to unforeseen site conditions – case study

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Courtesy of Sustainable Resources Group, Inc. (SRG)

The Crater Resources Quarry 3 Remediation site was a former limestone quarry that was later used as a disposal site for Waste Ammonia Liquor (WAL) generated by the coke making facility at a steel mill. The WAL contained water, ammonia, and small amounts of various hydrocarbons formed during the coking process. Coking operations shut down by the mid 1980's and discharge into the quarry ceased. The site was subsequently listed by the U.S. Environmental Protection Agency (EPA) as a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) site, commonly referred as Superfund.

Crater_pond_equip

Sustainable Resources Group, Inc. (SRG), formerly ECOR Solutions, was contracted to provide various services for remediation of the Superfund Site. These services include

  1. Site preparations to set up a support area for the engineer and regulatory personnel and prepare the quarry for remediation
  2. Oversight of the design, construction and operation of an on site waste water treatment system to treat contaminated water and discharge it to a nearby creek
  3. Preparation, excavation, and load-out of sediments from three separate ponds, a plateau area, and peripheral areas within the quarry
  4. Management of transportation and disposal for all waste materials leaving the site
  5. Traffic control for pedestrians & trucks entering or leaving the area of the site
  6. Odor control with foaming agent to contain odors to the Quarry 3 area
  7. Backfilling excavated areas and the quarry bottom and installation of drainage features to meet Federal, State, and local requirements for long term maintenance of the site

All pond water, storm water, and infiltrating perched groundwater was processed through an on-site water treatment facility. Treated water was originally discharged to a nearby stream. However, as the work progressed the wastewater contaminants changed necessitating changes to the treatment system.

crater-set_wtThe treatment system consists of two (2) 20,000 pound activated carbon vessels, two (2) ion exchange resin vessels, and multiple banks of bag filters. In order to discharge to the nearby stream, a 2,000 foot long HDPE discharge line was installed. SRG closely coordinated installation of this pipeline with the adjacent golf course as the pipeline path ran through their property.

After initially treating all the collected pond water, subsequent storm water and infiltrating groundwater became impacted with high levels of ammonia and benzo(a)anthracene that were not initially anticipated during treatment plant design. This problem was solved by additional treatment steps and discharging to the Upper Merion Township sewer authority. SRG was able to meet the POTW's pretreatment standards with minor modifications to the original treatment system.

Pond sediments required conditioning prior to load out and disposal to assure acceptance at the disposal facilities. A combination of lime kiln dust (LKD), pebbled quicklime, and shredded corn cobs was used on pond sediments in order to meet the paint filter test criteria. Stabilizing agents were distributed through an excavator mounted injector, or by distribution and mixing with an excavator bucket, or crane mounted clam shell bucket. Conditioned sediment was then tested before being loaded into tri-axle trucks for off-site disposal.

crater_too_deepcrater-depth_of_pond_1Excavation work began in Pond 3 where the initial estimate of sediment depths ranged from 3- 7 feet. Immediately upon entry it was determined that the sediment depth was in excess of 18 to 22 feet to bedrock. A change in approach became necessary, and SRG mobilized a 110 ton lattice boom crane with a two cubic yard clam shell bucket. The crane provided access to the sediments without entry into the pond and allowed for the removal of soft sediment without excessive stabilization. Once bedrock was established, an excavator and bulldozer were used to complete the cleanout and push pond sediment toward the load out area.

During excavation and load-out of the plateau area sediment odors became an issue. Naphthalene is one of the main site contaminants, and pockets of sediment with high levels of naphthalene were removed throughout the plateau area. Due to the strong odors, employees working in this area upgraded to level C personal protective equipment (PPE) and odor suppressant foam was applied as needed to control migration of odors from the site. Sediment was pushed to a load-out stockpile with a bulldozer and an excavator loaded it into tri-axle trucks for off site disposal.Crater_odor_control

Between the months of May and December 2009, significant rainfall above the normal monthly amounts was experienced at the site. Water management was accomplished with sumps and drainage swales within the ponds. Collected water was pumped to a central location where it was processed by the water treatment system and discharged to the POTW. Over 3 million gallons of water were treated and discharged without permit violations to either the Matsunk Creek or to the Lower Merion Township sewer.

Ultimately, three areas within the original quarry were pumped empty and cleaned to the original limits of each former rock pit. In addition, the shallow plateau area at the western end of the quarry and peripheral areas at the eastern end of the quarry were cleaned to bedrock or to passing soil sample analytical results. A total of 86,810 tons of impacted materials were removed from the site.

SRG was able to minimize costs to the client for disposal of stabilized waste by effective management of the excavation activities. An overall stabilization additive ratio of 2% was achieved by mixing dryer impacted soil with wet sludges from the ponds and appropriate choice of stabilization reagents.

After each contaminated pond or area was excavated to bedrock or to clean sampled limits, approval to backfill was granted by EPA. SRG imported over 120,000 tons of clean fill to return the cleaned pits to the engineer's desired finish grade. The entire quarry was covered in 6' of topsoil then seeded to restore vegetation.

In addition to the Quarry 3 work, SRG was requested to provide proposals to remediate three additional areas of contamination near the Quarry. SRG provided and implemented three separate work plans.

The first task was to remove several hundred feet of abandoned pipeline and impacted soils behind residential property. This task involved crossing an active natural gas pipeline in order to complete the abandoned pipeline removal. The work was completed on time and without incident.

crater_piling_dam_3Two additional areas in the commercial business park adjacent to the Quarry were also remediated. Work plans for each of these areas were provided and successfully implemented on time and on budget.crater_after

All of the remediation and site restoration has been completed and accepted by the client and EPA. The project was completed with over 20,000 man-hours and no safety incidents.

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