Rainbow MWD approves lift station replacement MND

The work which includes the replacement of the Rainbow Municipal Water District’s Lift Station No. 1 will have an environmental Mitigated Negative Declaration along with a Mitigation Monitoring and Reporting Program.

Rainbow’s board voted 5-0, Tuesday, Jan. 26, to approve the environmental analysis prepared by Kennedy/Jenks. The motion also formally approved the project, which is already in the district’s five-year capital plan, although the approval of the project does not include the approval of any designs or other plans nor does it authorize a construction contract or appropriate any funding.

The environmental documentation also covers a force main from the Thoroughbred Lift Station to Old River Road, upsizing the existing sewer line along Highway 76, and a gravity main from Olive Hill Road to the Thoroughbred Lift Station.

“This is part of the project to increase the capacity of our wastewater system to handle the flow from the new development,” Tom Kennedy, Rainbow general manager, said.

He is not related to the principal with the Kennedy/Jenks consulting firm.

Lift Station No. 1 is off of Old River Road and delivers sewage effluent to the city of Oceanside, which has an ocean outfall. The package lift station has three 5-horsepower wet well/dry well pumps and a 750-gallon working volume wet well. The pump station was built in 1974, and the pumps were replaced in 1994.

The lift station’s firm capacity is 1,250 gallons per minute. During wet weather flows, the station pumps an average of 1,400 gallons per minute by running pumps up to 13 times per hour. Additional development is expected to increase the necessary lift station volume, and the ultimate required capacity is more than 2,600 gallons per minute.

The lift station is also in need of structural, electrical, and mechanical repair. Rainbow’s master plan in 2000 identified the need for the eventual replacement of Lift Station No. 1 and adjacent pipelines.

In March 2014, Rainbow’s board approved a contract with Kennedy/Jenks to provide design, environmental permitting and construction oversight services for the replacement of Lift Station No. 1. Kennedy/Jenks submitted a predesign report which summarized the required improvements.

According to the report, upsizing the existing sewer siphon to accommodate the predicted ultimate flows would require a new siphon to be drilled horizontally under the San Luis Rey River with a depth of approximately 80 feet to avoid bedrock. A new lift station on the north side of the river would avoid the need for a deep siphon, and after a 1.36-acre site on Thoroughbred Lane adjacent to Bonsall Village Center became available, Rainbow’s board approved the purchase of the property in February 2017.

The initial design was reevaluated, and it was determined that upsizing a stretch of sewer main along state Route 76 and placing an equalization basin upstream of the existing siphon could level out the flows through the siphon to meet existing capacity requirements for Lift Station No. 1.

Moving the flow equalization upstream would also allow the new Schoolhouse Lift Station at Old River Road and Calle De Las Estrellas to replace Lift Station No. 1 without upsizing the line to the Old River Lift Station. The equalization basin will be constructed near Thoroughbred Road and Route 76.

Rainbow now has an out-of-agency service agreement between Rainbow and the Valley Center Municipal Water District for Rainbow to serve Pardee Homes’ planned Meadowood development. Rainbow is also working with San Diego County's Local Agency Formation Commission to annex the Meadowood area and detach that area from the Valley Center district.

Dexter Wilson analyzed Rainbow’s existing wastewater conveyance system to determine what facilities would be needed to accommodate Meadowood’s sewer discharge requirements. The needs included the Thoroughbred Lift Station and appurtenant pipeline modifications, a force main from the Thoroughbred Lift Station to Old River Road, upsizing the existing sewer line along Route 76 and a gravity main from Olive Hill Road to the Thoroughbred Lift Station.

The analysis also projected needed improvements to wastewater facilities along North River Road and to gravity sewer mains along Old River Road.

Some of the improvements recommended by Dexter Wilson were included in draft scenarios prepared by Kennedy/Jenks but never completed. On Dec. 8, the Rainbow board approved a change order to the Kennedy/Jenks contract for the design of the Thoroughbred Lift Station, the force main, the upsized sewer line along Route 76 and the gravity main along with the necessary documentation for California Department of Transportation permitting and a mitigated negative declaration.

Helix Environmental was a subconsultant to Kennedy/Jenks and conducted California Environmental Quality Act analysis before preparing the Mitigated Negative Declaration and the Mitigation Monitoring and Reporting Program for the Rainbow board’s adoption.

The initial study determined that no significant environmental impacts would occur if mitigation measures were taken. Rainbow released the draft initial study for a public review period, Nov. 6.

Before releasing the draft for public review, meetings were held with the Pala Band of Mission Indians, Oct. 28, and the San Luis Rey Band of Mission Indians, Nov. 5. The Rincon Band of Luiseño Indians was also notified.

“We are removing some facilities that are very near to some cultural resources,” Kennedy said.

The notice of the public review was also mailed to nearby residents, municipalities, regulatory agencies and other stakeholders. Comments during the public review period were received from Caltrans and from a resident. The comments and responses are included in the final environmental document, and the responses were also mailed to Caltrans and to the resident.

A qualified archaeologist and Native American monitor will be present during ground disturbance activity. The final monitoring report will include daily logs and, if cultural resources are found, the work will cease, and all parties will assess the finds. If fossils are found, a qualified paleontologist will ensure their preservation.

A sewer system management plan for the lift station with safety features will be implemented prior to construction. The safety features include an emergency generator and basin and monitoring protocol along with contingency plans for any leaks or spills. The preconstruction mitigation also includes fire prevention best management practices to minimize the fire threat from foliage.

The lift station will be designed to have a maximum operational one-hour noise level of 50 average decibels during daytime and 45 average decibels during nighttime. The construction will be limited to an eight-hour average of 75 average decibels, and residences within 300 feet will be notified one week before the construction activities.

A sensitive bird survey and a noise attenuation plan will be required if any construction between Jan. 14 and Sept. 15 is near sensitive bird habitat. A nesting bird survey will be required if any vegetation is removed between Feb. 15 and Aug. 31.

The final design of the lift station, force main, upsized sewer line and gravity main is expected to be complete by June 2021. Rainbow and Kennedy/Jenks expect the construction contract to be advertised for bid in summer 2021.

Joe Naiman can be reached by email at [email protected].