Significant Project Features
- Excavation, off-site T&D of 21,000 CY of soils contaminated with lead and arsenic from 23 residential properties in the vicinity of the former Kil-Tone Company pesticide manufacturing plant
- Offsite T&D of contaminated soil and backfill with clean material
- Restoration to pre-excavation condition including tree and shrub plantings, topsoil, seed and hardscapes
- Achieved 117,140 manhours without a lost-time incident using Level D PPE
History & Location Details
The former Kil-Tone Company property encompasses approximately 4 acres at 527 East Chestnut Avenue in a mixed residential and commercial. The former Kil-Tone Company manufactured pesticides from the late 1910s until the 1930s. Contaminated soil has been identified on the property itself, at various residential and commercial properties surrounding the former Kil-Tone Company property, and in soil, sediment, surface water and groundwater downgradient of the property.
Manufactured pesticides included arsenic and lead. In 1926, the Kil-Tone Company sold the property to Lucas Kil-Tone Co., a New Jersey company, which continued to manufacture pesticides at the property until at least 1933. The concentration of lead was 0.002ug per 1ug of soil and the concentration of arsenic was 0.001ug per 1ug of soil.
Prior to any activities, interface with homeowners occurred. This was done with the purpose of briefing the residents on the scope of work impacting their property and to document any concerns they had (such as wheelchair access). A mobilization checklist was completed with each homeowner for property condition and inventory. Photos were taken of each property to record the site features. Site preparation included clearing and grubbing of trees. All tree stumps were disposed of as non-hazardous waste to the landfill along with the impacted non-hazardous soil. Prior to demolition, Sevenson disconnected all electric utility feeds to the structures. In addition, Sevenson’s superintendent performed a pre-demolition survey of these structures to identify any hazards or demolition concern that may require additional consideration prior to demolition.
All existing garages, sheds, and the workshop structures within the area were demolished. Sevenson used excavation equipment (Komatsu 78, Komatsu 120, and CAT 416 rubber tire backhoe) to demolish the structure from the top-down. First, glass windows were removed from the structure with care to prevent shattering glass. Once windows were removed, starting at the top of the structure, the roof was pulled in towards the center of the structure and crushed downward. The walls followed, pushed towards the center of the structure and crushed. Once the structure was demolished, Sevenson used the excavator to load debris into 30 CY dumpsters for disposal.
Foundations and floor slab demolition followed demolition of the structure. Sevenson used a combination of concrete saws and jack hammers to demolish the slab, and a hydraulic impact hammer attached to the excavator to demolish larger foundations. Concrete slabs and footings located in contaminated areas were removed and segregated from materials that are not in direct contact with contaminated materials. Concrete was disposed as non-hazardous construction debris. Prior to demolition work at Property 14, Sevenson demolished an existing CMU wall that abutted the property and was located adjacent to the garage at the rear of the property. The wall was the remnants of a partially demolished structure and posed a work hazard during demolition at Property 14. The wall was demolished in a controlled manner from the top down using excavation equipment and the demolished materials were disposed of as debris. The construction and demolition material was approximately 1,600 tons. Sevenson placed this material into the dump truck or directly from the excavator to the temporary storage location immediately after excavation.
Sevenson conducted pre-excavation soil sampling to confirm the limits of excavation. Samples were collected from each sidewall and bottom of each excavation and tested using an off-site laboratory. The limits of excavation were finalized and submitted for Government approval. Sample areas were biased towards locations most likely to have contamination, based upon field indicators (field instrument measurements, visual contamination, odors).
Excavation included mass excavation, on-site handling and loading of excavated material; transporting material to the stockpiling area (when needed); constructing, covering, monitoring, and maintaining stockpiles so each did not exceed 1,000 CY. Approximately 21,000 CY were excavated at depths between 2 and 3 feet. Sevenson used a fleet of company-owned equipment, including rubber tracked small/medium sized excavators, rubber tracked skid-steer, and moderately sized (12 CY) rubber-tired dump trucks to remove debris and contaminated soil.
The work sequence was such that two properties concurrently were demolished, excavated, backfilled, and restored prior to proceeding to the next two properties. Each property was excavated from back to front in order to prevent trucks from carrying contaminated soil over clean areas. Where dump truck access was limited, incrementally staged stockpiles were created by the excavation process and a second machine (skid-steer loader) loaded the dump trucks.
Site excavation and handling equipment was dry-decontaminated with brooms prior to departing each property. Debris and soil were loaded into roll-off containers or dump trucks directly from each property. Once the waste was moved to the stockpile area, it was transferred to larger trucks for offsite disposal.
Site restoration included restoring properties to pre-existing conditions including the replacement of trees, shrubs, soil, sod, concrete sidewalks and asphalt driveways. Common backfill was used for general backfill up to four inches below final grade.
Common fill consisted of material free of clay, rock, or gravel larger than 2 inches in any dimension, debris, waste, frozen materials, vegetation and other organic matter, and other deleterious materials. Backfill was placed in 8-inch lifts prior to compaction. Compaction was conducted by sheepsfoot rollers, pneumatic-tired rollers, steel-wheeled rollers, and other approved equipment. Approximately 40,000 square feet of sod was placed on the private properties.