Superfund Site
Fact Sheet
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Date | Title | PDF/xls/mdb File |
11/2001 | Kenwood Avenue UPDATE | |
UPDATE on Response Action Activities
Kenwood Storm Water Drainage Pathway
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Update for November 9, 2001
This and all previous updates can be found at http://www.epa.gov/region09/waste/sfund/npl/siteinfo.htm
EPA now has now initiated or completed cleanup activities at 18 of 22 yards in the Kenwood Stormwater Drainage Pathway. Excavation is complete at 16 of 22 properties. Property access has been provided at 22 of 25 properties along the pathway. We anticipate that work will be complete by the end of the fiscal year. Temporary relocation benefits are being provided to 23 households currently, and more than 100 persons are temporarily relocated. More than 70 field staff associated with EPA, the US Army Corps of Engineers, and their contractors, are operating on this cleanup at the present time. 15-20 EPA staff are working on this project in EPA's regional office, as well.
The following is a summary of the status of the yards at which construction has been initiated:
1202 W. 204th Street - Excavation underway
20413 S. Kenwood - Excavation complete, backfill complete, restoration underway
20419 S. Kenwood - Preparation for excavation underway
20429 S. Kenwood - Excavation nearing completion, backfill soon
20437 S. Kenwood - Excavation complete, backfill in - construction of retaining wall underway
20503 S. Kenwood - Excavation complete, backfill in - construction of retaining wall underway
20509 S. Kenwood - Excavation complete, backfill in - construction of retaining wall underway
20513 S. Kenwood - Excavation complete, backfill in - construction of retaining wall underway
20523 S. Kenwood - Removal action complete (pending action for under structure)
20531 S. Kenwood - Excavation xomplete, backfill in, construction of driveway and restoration underway
20535 S. Kenwood - Removal action complete
20603 S. Kenwood - Removal action complete
20615 S. Kenwood - Excavation complete, backfill complete, restoration underway
20619 S. Kenwood - Excavation complete, backfill complete, restoration underway
20703 S. Kenwood - Removal action complete
20713 S. Kenwood - Removal action complete (pending action for under garage structure)
20723 S. Kenwood - Removal action complete - pending arrival of some plants on backorder
1209 Torrance - Removal action complete
Last week, EPA issued an Action Memorandum Amendment to address: 1) Checking for depositional layer material where necessary, and 2) addressing depositional layer material under structures. As discussed in previous updates and information, there are three yards out of 18 excavated so far at which a very thin layer (1-3 inches thick) of depositional material has been found. No such material has been found in 15 of 18 yards. It is clear that this material is undisturbed Kenwood Ditch, and exists only in the limited locations where particles of DDT could settle out of storm water. Where present, it is found only at the depth of the former ditch and not at multiple depths in the soil column. This layer material has layer material ranging from 35,000 ppm to 173.000 ppm. In all cases, samples from above and below the layer material indicate very low DDT indicating the DDT was concentrated in the layer itself.
At 20713 Kenwood, the layer was present only at 4.5 feet below the grade of the street and extended across the front yard. The layer was excavated from this yard except for an area extending no more than 10 feet under the garage, and an area under the driveway to the right of the garage. The excavation has been backfilled will clean soil. EPA now is working on methods to remove the small amount of remaining depositional layer material from the yard as well as that under the structure.
At 20523 Kenwood, a very limited and irregular patch of layer material was found at 3.5 feet below street grade, but only near the southeastern corner of the house. Again, the layer material was very It did not extend across the yard. It extended just barely into 20531 Kenwood and did not extend under the house at 20531. All of the layer material from this yard has been removed except for a small portion under the structure at 20523 Kenwood. The excavation has been backfilled. EPA now is working on methods to remove this small amount of layer material from under the structure.
At 20437 Kenwood, small ribbons of the layer material were visible at 3 feet below street grade. An old corrogated iron pipe was also found, oriented under the driveway, at this location. In aerial photos, these pipes could be seen carrying stowmwater under the driveways when the former ditch existed. The bottom of the pipe was about 3 feet below street grade - The layer material could be seen at precisely the location of the bottom of the corrugated iron pipe, indicating this was the former ditch. All of the layer material was removed from this yard. Excavation was advanced to at least 6 feet below street grade. The excavation has been backfilled. The layer material is not under structures in this yard.
No other layer material has been encountered so far.
The observations about the layer material indicate that the bottom of the ditch was about 4.5 feet below the grade of the current street at the south end of the street, and progressively closer to the current grade of the street as one moves northward up the street (hence, at 20437, it is only 3 feet below street grade)... EPA has taken this into account and made sure that in all yards a check is performed for the layer material to at least that depth. This is only needed in yards that are not already dug out to that depth. The check is being done with trenches and/or borings where necessary. In most cases, we have already dug deep enough to see any layer if it were to exist - without performing a special "check." This is to make sure that if layer material is present in yards, it is identified. It is noted that we are checking to 4.5 feet below the grade of the street, even when a yard has 1-4 feet of soil above street grade, such as exists for several yards in the north block of the pathway.
EPA is also advancing the depths of most excavations deeper than originally planned, especially in the area of the ditch itself, where the layer material could potentially be. For example, most excavations originally planned to 2 feet in plans have been advanced to at least 4-6 feet.
By using these procedures, we are confident of identifying the layer material and removing it as part of the cleanup action.
EPA has filled four of five containment storage cells at the former Montrose plant property with soil from Kenwood - these are scheduled to be sealed shortly. Each cell holds anywhere from 1500 - 2200 cubic yards of soil. The soil sits in a bermed area, with a base of a double liner of 45 mil. polypropylene with geotextile fabric and synthetic mesh layers in between. On the top will be a 45 mil. polyproplyene layer and a second 30 mil. polypropylene layer. The cells will be sealed so all water runs off outside the bermed area and no water enters the soil. The cells are engineered so that samples can be collected and analyzed from inside the cell if any water were to ever develop inside. The cells are designed to last at least 10 years with minimal maintenance. EPA plans to make a final cleanup decision for all soil at the former Montrose plant property, including the soil in the cells, within a few years time. This decision will be subject to a proposal by EPA and public comment.
All procedures for ensuring safety during the cleanup action remain in effect.
Jeffrey A. Dhont
Remedial Project Manager
Superfund Division
Direct/VM: (415) 972-3020
Fax: (415) 947-3526
Email: dhont.jeff@epa.gov
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