The White Slough Water Pollution Control Facility is a wastewater treatment plant in Lodi, California and consists of just over 1,000 acres of land[1]. This plant aims to treat wastewater to meet the environmental standards necessary for keeping the San Joaquin-Sacramento Delta waters healthy.[2] The City of Lodi is located in San Joaquin county and is just a few miles east of the Delta. Effluent enters the plant from the City of Lodi and San Joaquin County’s Flag City Service Area Number 31[1]. The wastewater plant currently has four storage ponds where effluent from the plant is discharged to. Through a series of canals built for the purpose of allowing surrounding agricultural land to drain, the treated effluent from the plant is expelled into the Delta.[3]
History
editThe plant was first built in 1966 and had a maximum capacity of treating 6.5 million gallons a day. As environmental regulations began to change and the City's demands grew, the facility underwent an extensive upgrade and currently holds the capacity to treat upwards of 8.5 million gallons a day[4]This upgrade also addressed how wastewater is treated by adding UV disinfection abilities as well as processes such as partial denitrification and conversion of harmful ammonia species.[4] These upgrades were necessary as some of the treated effluent exits to the Delta through the Dredger Cut slough. A portion of the treated effluent is stored in the existing four unlined ponds and used for irrigation purposes. It is distributed to the City owned agricultural land during the irrigation season or later stored, along with storm water, in the ponds[1]. Some treated water is also distributed to the Northern California Power Agency (NCPA) power plant for steam production and system cooling purposes and the San Joaquin County Mosquito and Vector Control District (SJCM&VCD) for rearing ponds[1].
Land Use
editThe site is currently surrounded by City owned agricultural fields. The fields consist of corn, alfalfa and ryegrass. Because the treated effluent is applied to these agricultural fields, it is crucial that nitrate levels be below the Environmental Protection Agency (EPA) mandated Maximum Contaminant Level (MCL) of 10 part per billion (ppb)[1].
Local Geology, Hydrogeology and Hydrology
editIn the general vicinity of the plant groundwater is approximately encountered at a depth of 30 ft, however within the facility bounds groundwater is encountered at much shallower depths, between 5 to 10 ft.[2]This potentially poses problems to the treatment plant as it is susceptible to liquefaction. Liquefaction typically affects areas with shallow groundwater and that consist of silts and sands[5]. This issue is encountered during an earthquake when loose silts and sands allow for the shallow groundwater to "liquefy" the soil causing harm to existing infrastructure[5].
Water quality issues that have been identified at the site include contamination of groundwater from Chloride, dissolved Manganese and Nitrate (N) which have concentrations of 38 to 160 µg/l , <0.17-1,150 µg/l and 5.5-48 µg/l where the maximum contaminant level (MCL) are 106 µg/l , 50 µg/l and 10 µg/l respectively[1]. The cause of such contaminants are not due to practices at the WPCF site but historical and surrounding activities such as nearby dairy farms, saline groundwater intrusion and naturally occurring anoxic conditions.
The nearest natural water bodies to the site are the Mokelumne River which lies north of the site and the Calaveras River to the south. The Dredger Cut and Peripheral canals are man-made bodies of water that are legally a part of the Delta[1].
Combating Groundwater Over Extraction
editGroundwater over extraction occurs when the rate of water pumped from groundwater exceeds the rate in which it can be replenished. Issues that can arise from this include lowering of the water table and land subsidence[6]. As the water table becomes deeper, wells go dry which leads to increased costs from remediation purposes. Land subsidence occurs when too much water from clays in the soil are extracted thus causing them to collapse and ground elevation to subside[6].
Future Project Plans
editThe Water Pollution Control Facility (WPCF) is installing 4 percolation ponds that will store a total of 388 acre-feet of water over 70 acres for the purpose of using it as potable water and recharging the local basin. Currently the 70 acres are City owned agricultural fields[1]. Studies have encouraged the idea that the installation of these ponds will offset some of the damage caused by groundwater over extraction in the surrounding agricultural fields. These ponds will be built approximately 1,000 ft west of the existing storage ponds. The reason for the location of these ponds are as follows (1) they will be located far enough from the Kingdon Airport and thus birds that are attracted to the ponds will not be likely to interfere with air traffic (2) they will be close in proximity to the current irrigation distribution box which lessens the cost for water transportation and (3) they will be at the tail end of the irrigation distribution box which decreases the amount of changes in the current irrigation system required for the implementation of these ponds[1].
The facility's Filter Pump Station will connect to the newly installed ponds through an 18-inch diameter pipe , which will also be used to connect the ponds to the irrigation box used to store excess water for irrigating City owned fields. Approximately 90 acres of agricultural fields will benefit from this project by depending solely on the stored water from the ponds for irrigation and will eliminate the need for groundwater pumping[1]. The new ponds are expected to recharge the aquifer by about 29 to 51 million gallons per year.
References
edithttp://www.lodi.gov/community_development/pdf/White_Slough_WPCP_Phase_III_Negative_Declaration.pdf
http://www.lodi.gov/public_works/body_white_slough_waterpollution_cont.htm
https://www.westyost.com/project/white-slough-water-pollution-control-facility-expansionupgrade
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Peer Review
editPending
editGet your article done woman! Then I'll review it. Leidelar78 (talk) 13:47, 3 April 2018 (UTC)
- ^ a b c d e f g h i j City of Lodi (January 2017). "White Slough Water Pollution Control Facility Storage Expansion and Surface, Agricultural, and Groundwater Supply Improvement Project" (PDF).
- ^ a b "White Slough WaterPollution Control Facility". www.lodi.gov. Retrieved 2018-04-19.
- ^ West Yost Associates (2007). "The City of Lodi White Slough Water Pollution Control Facility" (PDF). lodi.gov.
- ^ a b "White Slough Water Pollution Control Facility Expansion/Upgrade - West Yost Associates". West Yost Associates. Retrieved 2018-04-19.
- ^ a b "Liquefaction Susceptibility". earthquake.usgs.gov. Retrieved 2018-04-26.
- ^ a b USGS, Howard Perlman. "Groundwater depletion, USGS water science". water.usgs.gov. Retrieved 2018-05-10.