Rainbow MWD approves purchase of 1.36 acres for lift station

The Rainbow Municipal Water District (RMWD) has approved the purchase of 1.36 acres for what is expected to be a site for a district lift station.

The 5-0 Rainbow board vote Feb. 28 approves the purchase of the land from Lashanko Family 2001 Trust for $740,000. The land is on Thoroughbred Lane adjacent to Bonsall Village Center.

"We need to purchase land for a lift station," said Rainbow general manager Tom Kennedy.

Lift Station Number 1 is off of Old River Road and delivers sewage effluent to the City of Oceanside, which has an ocean outfall. The Smith and Loveless package lift station has three five-horsepower wet well/dry well pumps and a 750 gallon working volume wet well. The lift station was built in 1974, and the pumps were replaced in 1994.

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

The district also approved a relocation agreement with the California Department of Transportation regarding the State Route 76 widening which includes resizing a sewer line for increased capacity. Rainbow had prior easement rights for its water lines, so Caltrans will incur the entire cost of that system’s relocation, but Caltrans’ easement rights preceded the district’s sewer line rights so Rainbow was required to reimburse Caltrans for that relocation work. The reimbursement agreement also covered increasing the diameter of the sewer line between Sweetgrass Lane and Gird Road from 12 to 18 inches, so the agreement allowed both the relocation and the capacity

enhancement to be performed by a single contractor.

In addition to insufficient wet well volume and pumps not capable of meeting wet weather flow once anticipated development within the next

five years is complete, the lift station is in need of structural, mechanical, and electrical repair.

In March 2014 the Rainbow board authorized a $616,346 professional services contract with Kennedy/Jenks Consultants to provide environmental permitting, design, and construction oversight services for the replacement of Lift Station Number 1. Kennedy/Jenks subsequently submitted a pre-design report which summarized the required improvements.

The current infrastructure crosses the San Luis Rey River by the Camino Del Rey Bridge. "Right now our wastewater line goes underneath the river," said Kennedy, who is not affiliated with Kennedy/Jenks.

The Kennedy/Jenks report noted that upsizing the existing sewer siphon for the predicted ultimate flows would require a new siphon to be horizontally drilled under the San Luis Rey River with a depth of approximately 80 feet in order to avoid bedrock. Cultural grinding stones adjacent to the existing siphon also create the risk that environmental constraints will prevent a replacement siphon.

"We want to not go under the river again," said Kennedy.

A new lift station on the north side of the river will avoid the need for a deep siphon.

"We evaluated many potential locations and this was the most feasible for a variety of reasons," Kennedy said. "This was available property that was already listed for sale, so we came to terms with the property owner."

The $740,000 purchase price matches the May 2016 appraised value. The total project estimated cost of $9,715,000 also includes $4,345,000 for the site improvements, $370,000 for a gravity sewer, $2,690,000 for a gravity sewer on Old River Road between Lift Station No. 1 and Lift Station No. 2, $1,110,000 for a force main over the Camino Del Rey Bridge to Old River Road, and $460,000 for design and staff time.

The design phase is currently approximately 30 percent complete.

"We didn't go full bore on the design until we knew which exact site we were designing for," Kennedy said.

The purchase of the land will allow for the remainder of the design work.

"They're going to complete the design within the next couple of months," Kennedy said.

Once the design phase is completed district staff will prepare a bid package. The board is expected to approve a bid for the work in late summer.