SITE INFORMATION AND CORRESPONDENCE

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Sent ByT BASELINE; 510 420 1707; Nov-9-99 16:2a; Page 17/29 j V will be posted in the area under the proposed site redevelopment(Braune, 1999). No drinking water uses of the Channel are located near or downgradient of the project site, which is located at the terminus of the Chtinnel. 1n addition, no irrigation of food or forage crop land is located near or downgradient of the project Site. Surface Water Algae Studies Prolific blue-green algal mats developed in the Stockton Channel during the summer of 1997. The h mats and other accumulated debris were unsightly and odorous. The same condition was not present in 1998. A study of Channel water quality by Drs. Chen and Tsai based on data from 1996-1998 was conducted to determine why the blue-green algae grew excessively in 1997,but not in 1998,and evalua.tod several engineering alternatives for discouraging blue-green algae growth(Chen and Tsai, 1998). A water quality model was used to review the data. The major conclusion of this study was that high river flows,reduced solar radiation,and cooler air temperatures in 1997 caused blue-green algal growth to be greater than it was in 1998 (Chen and Tsai, 1998). Two engineering alternatives were identified by Drs.Chen and Tsai for controlling blue-green algae, including destratification and skimming of surface water. Skimming of surface water from McLeod Lake and discharging it to the San Joaquin River was deemed the most effective strategy for controlling the blue-green algae. Water would be taken from the surface of the McLeod Lake and discharged in the San Joaquin River through a pipe on the bottom of the Channel. The purpose of moving this water would be to reduce the temperature and, as a result, the algal growth. Artificial circulation was rejected by Drs. Chen and Tsai as a possible alternative because it would possibly star up bottom sediments and release algae-stimulating nutrients from the sediments, and facilities required for aeration would be unattractive in a commercial setting(Chen and Tsai, 1998). Black&Veatch(1999)also evaluated options for remedying the algae problem in the Channel. Two algae control methods for the Channel were recommended, including nutrient inactivation and ifiuial 6rculation. The nutrient inactivation method would use alutninum sulfate alum to attt ( } precipitate phosphorus in the water column and seal it to the bottom sediment.Artificial circulation could be implemented without stirring up the bottom sediments,by proper placement of air diffusers. The artificial circulation is believed to prevent phosphorus release from the sediments and would it induce turbulence that would interfere with the floating mechanisms of blue-green algae,preventing mat formation. Artificial circulation,as is currently proposed for the Weber Block redevelopment, was identified as the best algae control solution(Black & Veatch, 1999). r. FACTORS RELATED TO AIR PATHWAY There have been no known releases of hazardous substances to the atmosphere.There is no current threat of a release since the site is currently capped and the area is fenced. No dispersal of hrazardous materials has.been observed visually, documented in the past, or has been subject to known fires or explosions at the site. The project site is located in the San Joaquin Vallcy air basin.'Winds measured in Stockton are dominantly west to northwesterly(California Department of Water Resources, 1978,as cited in Paoli and Associates, 1991). The average wind speed for Manteca,located approximately 10 miles south of Stockton, is 4.8 milesP er hour, and for Lodi, approximately 15 miles north of Stockton, is 3.9 k 97369stk.put.wpd 1 P9199 11,