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WQCF a more tenable proposition for the City. To this end,the effluent-to-land disposal Potential Impacts
<br /> strategy selected for consideration under the current economic impact analysis includes high-rate Potential environmental impacts related to the effluent-to-land disposal alternative include
<br /> irrigation(260 in/yr)of City-owned land at the WQCF(4,600 ac-ft/year or 4.11 MGD)and potential impacts from the addition of salts and minerals of local concern to regional
<br /> agricultural irrigation(60 in/yr)on acreage within approximately 10 miles from the WQCF that groundwater supplies,the possibility of groundwater mounding in the area(s)of land application,
<br /> would be purchased by the City(15,560 ac-ft/year or 13.89 MGD)as a means of collectively and temporary construction-related impacts. Additionally,increased air emissions would result
<br /> applying 18 MGD of undisinfected,denitrified,secondary effluent to land when such application a
<br /> from increased power consumption needed to pump secondary effluent to storage ponds and
<br /> is permissible. During the wet season when land application is prohibited or not practicable, then to land application sites. Potential effluent-to-land disposal environmental impacts are
<br /> depending on amount and timing of seasonal rainfall,the City's treated effluent would be held in provided in Table 48. Elevated groundwater TDS concentrations in the Eastern San Joaquin
<br /> lined storage ponds until land application could resume. Valley groundwater subbasin are the result of natural weathering of Coast Range marine
<br /> Costs sedimentary rocks and decades of agricultural irrigation(USGS,1995). Evaporation of sprayed
<br /> irrigation water and evapotranspiration of soil moisture and shallow groundwater leaves behind
<br /> The selection of higb-rate irrigation of existing City-owned land along with agricultural dissolved salts. Land application of treated secondary effluent could further elevate local TDS
<br /> irrigation of future City-purchased land represents a moderately priced land application strategy concentrations in groundwater. Groundwater mounding,as observed in the Kings and Turlock
<br /> from a cost perspective. The effluent-to-land disposal costs provided in Table 47 are planning groundwater subbasins(DWR,2003),could occur if effluent was applied to areas of low or
<br /> levels estimates intended to provide the reader with cost estimates that allow a cost comparison insufficient hydraulic conductivity. Temporary,construction-related impacts associated with the
<br /> between the two treatment alternatives presented in this report. Table 47 presents various costs building of a water conveyance and storage system for treated effluent at some distance from the
<br /> associated with the implementation of an 18 MGD effluent-to-land application operation. In WQCF are anticipated. However,these temporary,construction-related impacts would be
<br /> addition to total project costs,the costs of this alternative are divided among current and fixture mitigated to the greatest extent practicable.
<br /> ratepayers,and further subdivided among residential and non-residential customers. If the City
<br /> was required to treat WQCF effluent to the tertiary level prior to land application,then the costs Table 48: Potential Environmental Impacts Associated with Effluent-to-Land Disposal
<br /> provided in Table 47 would significantly increase as a result of increased operation and
<br /> maintenance costs associated with tertiary wastewater treatment. Potential Effluent-to-Land Disposal Environmental Impacts
<br /> Addition of salts(as measured by TDS)to groundwater at a concentration greater than the Title 22
<br /> Table 47: Effluent-to-Land Disposal Cost Estimates by Ratepayer Group Allocation for 18 MGD Secondary MCL recommended level(')of 500 mg/L,or greater than ambient background quality.
<br /> Disposal Capacity Groundwater mounding in the area(s)of land application.
<br /> Annual Increases in energy consumption and air emissions due to substantial power requirements of pumping
<br /> Annualized Operation and Total effluent to storage ponds and then to site(s)of land application.
<br /> Capital Capital Maintenance Annual Project Life- (1)500 mg/L is the low end of the acceptable Title 22 Secondary MCL range for TDS.
<br /> Ratepayer Group Cost(') Cost Cost(') Cost Cycle Cost
<br /> Current Residential $17,400,000 $1,500,000 $200,000 $1,700,000 $34,000,000 Compliance with Laws and Regulations
<br /> Current Non-Residential $11,600,000 $1,000,000 $100,000 $1,100,000 $22,000,000
<br /> Future Residential $30,100,000 $2,600,000 $400,000 $3,000,000 $60,000,000 State and Federal water quality laws require that discharges not result in an exceedance of water
<br /> quality standards. Effluent-to-land disposal and storage pond operations would comply with
<br /> Future Non-Residential $20,100,000 $1,800,000 $200,000 $2,000,000 $40,000,000 waste discharge requirements set forth by the Regional Water Board. Near-field exceedances of
<br /> Totals $79,200,000 $6,900,000 $900,000 $7,800,000 $156,000,000 the allowable Title 22 Secondary MCL range for TDS(500—1000 mg/L)are not expected to
<br /> (1)Estimated March 2007 costs based on adjusted 2002 costs provided in None,2004. occur. No far-field exceedances of water quality objectives are expected to occur as the result of
<br /> effluent-to-land disposal.
<br /> Benefits Microfiltration and Reverse Osmosis
<br /> Effluent-to-land disposal would allow the reclamation of up to approximately two thirds of Due to the WQCF's Phase III improvements(including nitrification-denitrification,tertiary
<br /> WQCF effluent at the proposed build-out capacity of 27 MGD(ADWF)and would provide an filtration,and UV disinfection facilities),the remaining advanced wastewater treatment options
<br /> additional water supply source to the region. Limiting the discharge of tertiary treated effluent to available to the City are microfiltration and reverse osmosis. RO is a membrane separation
<br /> the San Joaquin River at 9.87 MGD(ADWF)would maintain existing water quality and mass
<br /> loading in the river at currently permitted levels while the WQCF attained its proposed build-out
<br /> capacity of 27 MGD(ADWF).
<br /> Although significant energy would be required to treat effluent with tertiary filtration,a larger amount of energy
<br /> would be consumed by pumping the same volume of secondary effluent a distance of 10 miles.
<br /> City of Manteca Antidegradation Analysis 101 June 2007 City of Manteca Antidegradation Analysis 102 June 2007
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