montrose chemical corp.


Montrose Chemical Corporation of California (Montrose) manufactured the technical grade of the pesticide DDT (dichloro-diphenyl-trichloroethane) from 1947 until 1982 at a plant located at 20201 Normandie Avenue, Los Angeles, near the City of Torrance. The 13-acre former plant property is located in the Harbor Gateway, a narrow half-mile-wide strip of land extending southward from Los Angeles proper to the Los Angeles Harbor. The plant was historically called the Torrance Plant because of its immediate proximity to Torrance. The former plant operations included manufacturing, grinding, packaging, and distributing the DDT pesticide. Various locations on the former plant property were used for storing chemical raw materials, DDT and waste products. In 1982, after Montrose ceased operations, the plant was disassembled and removed from the property. In 1985, Montrose regraded and paved the majority of the former plant property with asphalt. This temporary measure has prevented DDT in surface soils from being dispersed by the wind or stormwater while EPA completes the selection of permanent cleanup remedies for the site. The Montrose Chemical Corporation plant property is undeveloped and unoccupied at this time. Approximately 3,000 people live or work within 1/4 mile of the former plant property. The Del Amo Superfund site is located immediately adjacent to the Montrose Chemical Corporation and groundwater contamination from the two sites has commingled (overlapped). Various hazardous substances, pollutants or contaminants entered the environment via several pathways over the 35 years of operation of the former Montrose plant. These pathways included, but were not limited to, releases of non-aqueous phase liquid (NAPL) and wastewaters to the ground, releases to the stormwater drainage pathways, discharge of hazardous substances to sanitary sewers and to the Pacific Ocean, aerial dispersion of DDT dust, and disposal of DDT in soil fill materials. EPA has been conducting investigations into whether, where, and how much of this contamination persists today from these mechanisms. Where appropriate, EPA is selecting cleanup actions to address contamination from the former Montrose plant site. The following discussions provide an overview of the components of the Montrose Chemical Corporation project. For more detailed and specific discussions, please use the links, or review this section and then proceed to Cleanup Approach, below. NAPL. In the DDT production process, Montrose used large quantities of monochlorobenzene (chlorobenzene) as a raw material in the process of making DDT. In its pure form, chlorobenzene is a dense non-aqueous phase liquid, known as a dense "NAPL," meaning it is heavier than water and dissolves little in water. Chlorobenzene entered the ground at the former Montrose plant by way of trenches and a settling and recycling pond. The pond and trenches were used for process wastes and were initially unlined, then lined with acid resistant brick or concrete. Chlorobenzene also entered the ground within the former plant property by way of a rework facility, leaks from valves and clogged lines, and other elements of the DDT manufacturing process. Most of the chlorobenzene DNAPL is located under the former Central Process Area in the north-central portion of the former plant property. Significant quantities of DDT remain dissolved in the chlorobenzene in the ground. For more site-specific information about NAPL at the Montrose site, see below or click here. Groundwater at the Montrose site is contaminated. EPA is addressing the groundwater from the Montrose Chemical Corporation and Del Amo sites with a cleanup action for groundwater at both sites at the same time in what is called a Dual-Site Remedy. Groundwater contamination from the former Montrose site occurs in six (interconnected) aquifer units and extends more than 1.3 miles from the former Montrose site. No one is presently drinking or using this water. However, the groundwater is considered a municipal drinking water supply beneficial use under the Regional Water Quality Board Basin Plan. The closest drinking water well is located 1.5 miles southwest of the former Montrose site and draws water from the two deepest aquifers. EPA is concerned about ensuring that people are not exposed to the contaminated groundwater in the future and that the groundwater resource is preserved. See below or click here for more detailed information on groundwater at the Montrose site. Surface soils at the former Montrose plant property are contaminated with DDT at high concentrations. For more information about soil contamination at and adjacent to the former Montrose plant property, see below or click here. During the Montrose operations, some DDT was dispersed by wind into the surface soils in residential neighborhoods immediately southeast and southwest of the Montrose property. However, extensive investigation by EPA indicates that levels of DDT in residential soils within 30 square blocks of the former Montrose plant property are very similar to levels of DDT in soils in background areas, 2-4 miles from the former Montrose plant (a previous exception was soils in the Kenwood Stormwater Drainage Pathway, see below). This sampling indicates that low levels of DDT are ubiquitous in the south LA area, most likely due to former widespread use of DDT in the United States before its sale was banned in 1972. This means that the amount of residual DDT from historical areal dispersion of DDT dust from the plant site is small. In the areas tested, DDT in residential soils is present at levels that do not pose a significant health risk For more detailed information about DDT in residential areas and areal dispersion of dust at the Montrose site, see below or click here. Stormwater Pathways. Contaminated surface water from the Montrose site occasionally flowed off the property along a surface water drainage pathway. This contamination originally flowed in an open ditch, called the Kenwood Ditch, which ran paralleled to Kenwood Avenue. EPA refers to this pathway as the Kenwood Stormwater Drainage Pathway. The Kenwood stormwater drainage emptied into a slough, or marshy area south of Torrance Boulevard, where it turned eastward and entered the Dominguez Channel. EPA found high levels of DDT in soil in residential yards along the Kenwood Stormwater Drainage Pathway, and has conducted a cleanup action to remove this soil and restore the yards. More detailed information is provided below, or click here. In the 1970s, Los Angeles County filled the Kenwood Ditch and replaced it with the Kenwood Drain, an enclosed pipe buried under Kenwood Avenue. The slough was filled and the Kenwood Drain now empties into the Torrance Lateral storm water collection system. About 10 miles downstream from the former Montrose plant property, the Dominguez channel empties into the Los Angeles Harbor about 10 miles from the Montrose plant (7 miles direct). EPA is evaluating the potential for DDT-contaminated sediments along the existing stowmwater pathway and any associated ecological risks (the potential for DDT in the pathway to cause harm to wildlife and water organisms). For more detailed information about the existing stormwater pathway, see below or click here. Palos Verdes Shelf and the Sanitary Sewers. Montrose discharged wastes containing DDT, chlorobenzene, and caustic scrubber wastes/liquors, into the sanitary sewers during much of the history of its operations. Sediments in the sanitary sewers were contaminated by this discharge. For more information, see below or click here. The sanitary sewers flowed into the Joint Water Pollution Control Plant and then into the Pacific Ocean at the White's Point Outfall. Sediments on the ocean floor of the Palos Verdes Shelf are contaminated with DDT. During its later years of operations, Montrose disconnected almost all plant operations from the sanitary sewers except for showers and toilets. During these years, Montrose hired companies to haul large quantities of the wastes already mentioned, as well as waste acids and acid tars, to hazardous material landfills in the areas used for hazardous materials. Some were also sent out to sea by barge and then dumped in the Pacific Ocean. For more information on the DDT in ocean floor sediments associated with the Montrose Chemical Corporation plant, please leave this site overview and go to the separate overview for the Palos Verdes Shelf. In the early-to-mid 1950s, EPA believes that Montrose also hauled DDT-contaminated material from its property to a ravine between 204th Street and Del Amo Boulevard. Additional (clean) fill was subsequently brought into this area and additional residences built. EPA found bowling-ball-sized pieces of technical grade DDT in this fill material. EPA has subsequently removed the DDT-contaminated material on 204th Street from the site. For more information, see below or click here.

Hazardous Ranking Score

32 / 100

A score of 28.5 or higher qualifies a site for the Superfund National Priority List.

Regional Contact

Region 9
Phone: (415) 947-4251

Contact Region



Site Inspection
Preliminary Assessment
Final Listing On NPL

Contaminants & Health Effects

      Endocrine Disrupter
      Reproductive Toxin
      Persistent, bioaccumulative and toxic


        African American
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        People living
        within a 1 mile radius


        Average Income


        Occupied homes

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