Project Description

Philadelphia Former Dow Site

Philadelphia, Pennsylvania

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Project Details


September 2021





Perform ISS/ISCO on 4,512 cubic yards of soil contaminated with chlorinated solvents & petroleum.

The following presentation features an ISS/ISCO project that Lang Tool Co. performed in Philadelphia. ISS/ISCO soil mixing uses persulfate activated with Portland cement. A persulfate solution is mixed in tanks on the ISCO Mixing Plant and pumped in controlled quantities to the ISS Mixing Plant where it is mixed with cement and pumped to the LTC Dual Axis Blender. The blender mixes the slurry into the contaminated soil. This process is extremely efficient as it accomplishes both ISS and ISCO in one pass. The project involved 4,500 cubic yards of mixing & was completed in 7 working days.
On this project the top 3 ½’ of soil was clean and did not require treatment. When this upper layer was removed the interval that required treatment was saturated as you will see in the presentation. With only an ISCO approach the site would have been too wet to do anything with for a long period of time. The ISS/ISCO approach made it possible to use the site immediately after the ISS/ISCO procedure was completed.
ISS/ISCO is extremely efficient as it eliminates remote stockpiling of the clean soil and returning the stockpiled soil at a later date reducing the project timeline and costs. This process is shown in detail in the presentation. ISS/ISCO has the added remedial advantage of reducing the hydraulic conductivity of the soil.

This is the cell layout for an ISS/ISCO project in Philadelphia. The property belonged to Dow but
was leased to Carvana. The entire site was a large paved parking lot. The elevations listed are in
mean sea level. Note that the cell designation uses East columns and South rows.

The soil above the water table was determined to be clean. ISS/ISCO was required from 3.5’ MSL to the various
elevations shown on PA-001. To avoid the double handling associated with stockpiling the clean soil Lang Tool
Co. excavated the clean soil from the S9 row and placed it immediately adjacent to the south side of the S9 row.
Treatment on the S9 row was started. The next morning clean soil was excavated from the S8 row and placed
on the treated soil in the S9 row. The work continued in that manner until ISS/ISCO was completed on the
entire site. This extremely efficient procedure greatly reduces project costs.

The asphalt was removed from the treatment area by another contractor. Buried cement was encountered immediately upon the start of excavating the clean overburden.

Some concrete was found in the mixing interval

Excavating the overburden in the S9 row. Excavation and soil mixing started in this row and worked north. The excavation extended to the saturated zone.

Mixing in the S9 row. Note the saturated soil conditions.

Performing ISS/ISCO in the S7 row. The excavated soil from the S8 & S7 rows has been placed on the previously mixed rows as the work progressed to the north. No remote stockpiling has taken place.

Performing ISS/ISCO in the S6 row.

Backfilling after ISS/ISCO

Treatment area the day after ISS/ISCO was completed.

Dry and Hard

LTC ISCO Plant. Sodium Persulfate is mixed with water & pumped to the ISS Plant.

ISCO Plant & ISS Plant delivering reagent mixture to the Dual Axis Blender

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