• A change in construction technique at the Compton Creek crossing (suspension from Sante Fe Avenue bridge versus boring as depicted in the alignment sheets) has been proposed to avoid existing subsurface contamination (diesel, gasoline, napthalene, benzene, ethylbenzene, toluene, and xylenes) associated with a past leak from the GATX pipeline where it crosses Compton Creek. The plume of contamination is located primarily on the south side of Compton Creek, extending to the west and east of Sante Fe Avenue. Excavation of a bore pit within the plume could expose workers and the public to contaminated soil. In addition, bore activities could exacerbate the boundaries of the contaminant plume and provide a preferred pathway for the transport of contaminants.

• As proposed by KMEP and as approved by Los Angeles County, the SFPP Carson to Norwalk Pipeline would be placed on the upstream (west side) of the Sante Fe Avenue roadway bridge using structural steel braces. (The County is currently in negotiations with Dominquez Water District regarding their prior claim to the downstream side of the bridge for future placement of district facilities.) Since the SFPP pipeline has already been constructed within the east side of Sante Fe Avenue to the north and south of the bridge, Sante Fe Avenue would need to be trenched in a perpendicular manner immediately before and after the bridge to hang the pipe on the upstream (west side) of the bridge. Heavy-duty 0.375-inch thick pipe would be used for the bridge crossing. The pipe would be secured to the bridge at eleven locations using steel decking (8- by 24-inches) and casings (1- to 6-inches long), approximately every 20 feet. Valves would be installed to the north and south of Compton Creek, on the west side of Sante Fe Avenue (although KMEP/SFPP has placed the pipeline within the east side of Sante Fe Avenue to the north of the bridge, KMEP/SFPP has not been able to secure land for the placement of valve on the northeast side of Sante Fe Avenue).

•   Compton Creek has concrete sidewalls, but is a soft-bottom channel for its entire length with the exception of a 200 foot concrete bottom where the Creek has its confluence with the Los Angeles River; Compton Creek is the primary tributary to the lower Los Angeles River. The elevation at the creek bottom is 40.00 feet. During 100 year flood events, the water levels rises to an elevation of 51.64 feet, approximately 2.5 to 3.5 feet below the proposed pipe elevation. In anticipation of the 1997-98 winter rains, all substantial vegetation was removed from Compton Creek. When vegetation is present within the creek bottom, it is dominated by bulrush (Scirpus ssp.) and ground cover composed of sedges (Carex ssp.), giant reed (Arundo donax), and smartweed (Polygonum ssp.; County of Los Angeles, 1994). The area is accessible to the public and vegetation has historically shown signs of trampling. The creek lacks the constituent elements for least Bell’s vireo (Vireo bellii pusillus) nesting (USACE, 1991; County of Los Angeles, 1994), however other birds such as killdeer (Charadrius vociferus), red-winged black bird (Agelius phoeniceus), and red-tailed hawk (Buteo jamaicensis) utilize the creek for nesting and foraging when substantial vegetation is present. Additionally, the tri-colored black bird (Agelius tricolor), a California Species of Special Concern, could utilize the riparian habitat present along Compton Creek when vegetation is present. Aquatic resources are limited because of the lack of permanent water.

• The measures noted below shall be implemented:

- Prior to the installation of the pipeline at Compton Creek, KMEP/SFPP shall obtain written approval from Los Angeles County that states that placement of the pipeline on the downstream side of the Sante Fe Avenue bridge crossing over Compton Creek is infeasible. In addition, a copy of the Los Angeles County permit for suspension of the pipeline on the subject bridge shall be provided to the CPUC Environmental Monitor prior to construction.

-   Prior to the installation of the pipeline at Compton Creek, KMEP/SFPP shall obtain written approval from the California State Fire Marshal that states the placement of the pipeline on the upstream side of the Sante Fe Avenue bridge crossing over Compton Creek in the manner proposed would not jeopardize the safety of the pipeline.

-   All applicable mitigation measures shall be implemented during construction at the Compton Creek crossing, including implementation of the Environmental Contamination Contingency Plan and the Traffic Management Plan.

Sincerely,

Moises Chavez

Project Manager

cc: V. Strong, Aspen