Manteca has added 20,000 residents since 2003 yet the amount of wastewater per se flowing to the city’s treatment plant has barely increased.
Users sent an average of 6.5 million gallons of water a day to the treatment plant in 2017. That’s a bit more than what it was in 2008 and it’s just about 500,000 gallons more than the daily average in 2003.
That’s good news as far as water volume the plant can handle as it is rated at 10 million gallons a day. The bad news is the biological load — various solids flushed and sent down the drain— have increased substantially.
While that reflects 20,000 more people using the system it also underscores issues involving everything from salts that water softeners inject into the system to what is put into garbage disposals. It is the reason the city is now in the process of doing $10.5 million worth of work to replace the digester at the wastewater treatment plant.
The reduction in water sent to the plant can be attributed to things such as low flow showerheads, low-flow toilets, low water use washing machines, and stepped up conservation habits implemented during the drought.
Given the current plant when it was built employed technology that is close to still being cutting edge today and was laid out in a manner that essentially a duplicate plant could be put in place to significantly increase its capacity, the treatment plant has a long useful life ahead of it as long as it can adjust to the challenges represented by biological loading.
It’s against that background that Public Works Director Mark Houghton this month brought the City Council up to date on planning staff is pursuing involving wastewater.
uStaff is recommending that processes and facilities at the plant be analyzed to assess current and future capacity as well as technologies that should be considered to maximize the benefit of existing investments as well as guide future investments.
uThe city needs to determine how — or where — water sent to the treatment plant site from the processing of bell peppers at Eckert’s Cold Storage on Moffat Boulevard will be handled. The water, which requires some treatment before it is disposed on land at the treatment plant a farmer leases to raise corn for dairy feed has to be factored into planning. That’s because much of the disposal land is being converted to other uses such as the family entertainment zone where Great Wolf Lodge is building a 500-room resort hotel and indoor waterpark. The city has more than 200 acres on Hays Road several miles to the south that could be used to dispose of the Eckert wastewater but the infrastructure needed to get it there is unfunded.
uThe city is working with the Oakwood Lake Water District at the western end of Woodward Avenue that includes the Oakwood Shores gated community to possibly take wastewater generated by more than 300 existing plus a possible additional 300 homes.
uThe city is looking at making the treatment plant a regional facility due to the 200-year floodplain mandate from the state that eliminated Lathrop’s ability to use 2,000 acres for land disposal from their own plant that is being positioned to handle growth. That would require sending treated wastewater to the San Joaquin River that the state is virtually adamant against since the out fall would be too close to Manteca’s and would create a number of problems with river water. The solution could be sending wastewater from Lathrop for treatment at the Manteca plant or having their treated wastewater sent to the same out fall point. Should Lathrop secure a state permit for an out fall to the river it could lead to limitations on the Manteca out fall. Lathrop for a number of years has used 17 percent of the Manteca treatment plant capacity in addition to their own facilities.
uThe possible sale of treated wastewater to agencies down river as allowed by state law.