~ The Land and the Site

The soil is finely divided clay about 1000 feet deep, the water table is about 35 feet below the surface. Conditions ideal for both building and gardening. Because of its composition, seismic soil liquefaction is not considered to be probable. The site is behind the Sepulveda Dam in the Sepulveda Flood Control basin which could impound 17,300 acre feet of water in about 2¼ square miles. The dam is earthen, 57 feet high, and located at the Northwest corner of the San Diego and Ventura Freeways. The basin is roughly bounded by Balboa and Victory Blvds. In 1980 the TWRP-JG was built near the basin's Northeast corner at an altitude of 706 feet. According to the Army Corps of Engineers this was safe from the "100 years" flood, whenever that might happen. The Army has since revised its estimation of safety (in part due to the extensive paving of the Valley), and an altitude of 714 feet is now considered the minimum for flood safety. The TWRP-JG engineers are working on plans to conform, probably with walls and berms. The basin was selected for the TWRP-JG on the basis of six considerations. -

1. Availability of land. About 90 acres are now involved. As Los Angeles increases in population, TWRP must increase in size - the land need becomes formidable.

2. Forestalling disruption to the community. As almost continuous construction over two decades was planned, the TWRP site had to have substantial distance from residences and a clear shot at freeways.

3. Proximity to the main sewage line. The Valley's main sewage disposal line, built in the early l950's, roughly begins in Canoga Park and traverses Eastward alongside the River, through the basin to Toluca Lake where it abruptly turns South and dives under the Santa Monica mountains en route to El Segundo. The TWRP-JG site is right above this line.

4. Altitude. For both reliability and economy disposing of sewage demands the use of gravity. While possibly TWRP could have been located at a higher altitude, e.g. Tarzana, this would have severely restricted the area it could serve. There is no site at a lower altitude.

5. The river. Catastrophes do happen. TWRP has to have some last resort dumping facility. While certainly a final option, dumping sewage in the river is better than dumping it in the streets. TWRP is next to the river.

6. Donald C. Tillman. The City Engineer was determined in his desire that Los Angeles have the best and most beautiful sewage processing plant in the world.

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