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Pillar Point Harbor dredging project moves deeper

Posted on July 13, 2022

Ever since Pillar Point Harbor’s eastern breakwater was constructed in 1961, two environmental factors have been at play. Sand hasn’t been able to sweep to the southern beaches, and that has caused rapid erosion at Surfer’s Beach. So the sand has built up inside the harbor, effectively creating another beach at low tide.

Half Moon Bay resident Thomas Lundgard, who has taught surf lessons nearly every summer day at the beach since 2018 as the co-owner of Tommy Tsunami Surf School, has witnessed firsthand how dangerous the lack of sand has become. Exposed clay and rocks have become the norm for him and many surfers at low tide. The issue is especially noticeable after large winter swells when waves undercut the concrete foundation of the stairs to the beach.

“We’ve definitely noticed, year after year, there is less beach,” he said. “Each summer there is less beach and more rocks. This summer, in particular, it’s been bad. At high tide, there’s maybe a sliver of beach.”

After years of planning and permitting, the San Mateo County Harbor District’s Surfer’s Beach and Eelgrass Mitigation Project is expected to begin in a phased approach by summer 2023. The massive undertaking involves removing between 75,000 and 100,000 cubic yards of sand from part of the eastern side of Pillar Point Harbor and pumping it onto Surfer’s Beach.

On top of improving public beach access, the dredging will also reduce the amount of shoaling, or buildup of sand, that has increased in the eastern part of Pillar Point Harbor, making safe anchoring and navigation difficult at low tide. The expected 1,000 feet of new sand on Surfer’s Beach is the final stage in a pilot that planners will monitor and could lead to more consistent dredging.

“It’s a win-win as we see it,” said Brad Damitz, the lead project consultant to Harbor District. “If everything goes according to plan, it’s an effective ongoing approach to dealing with these issues.”

The Harbor District has about 30 percent of its engineering and design plans done. Though Surfer’s Beach is within Half Moon Bay’s city limits, last month the City Council agreed that the California Coastal Commission should take on the lead in monitoring the project. This project must adhere to the Coastal Act as Half Moon Bay’s jurisdiction lies only above median high tide, and the work is designed to be done at or below high tide.

After the breakwater was built by the U.S. Army Corps of Engineers, Surfer’s Beach has suffered a steady and significant amount of sand and bluff erosion. According to an Army Corps of Engineers report from 10 years ago, the bluffs along Surfer’s Beach eroded at an average rate of 1.64 feet per year between 1993 and 2012. That rate is seven times higher than the erosion of similar bluffs in Half Moon Bay.

A key aspect of this plan is the relocation of eelgrass from the eastern to the western basins of the harbor. Before any dredging can take place, 3.9 acres of new eelgrass habitat will be built on an existing eelgrass bed in the far southwest corner. The plan calls for dredging 14,000 cubic yards of sediment from the shallow areas within the west basin to be moved to create a new platform for the eelgrass.

An additional 3,500 yards of sand will come from the launch ramp and east basin before the dredging for Surfer’s Beach occurs. Once that sediment has settled, which could take weeks, the eelgrass along the east breakwater will be picked, bundled and transported across the harbor.

The sand from the east basin would be pumped via a pipeline to a “containment berm” south of the stairway to allow a slurry of sand and water to settle before being spread out by heavy machinery. The benefit of the berm is that it limits slurry runoff into the ocean, Damitz said. He noted that the pipeline shouldn’t close off the bike path, though the beach could be closed intermittently during the process.

The Harbor District has funding for this project in its 2022-23 budget. The Surfer’s Beach dredging alone will cost $2.9 million, and the eelgrass mitigation an additional $1.8 million. The estimate included a 30 percent contingency.

However, construction costs were $1.2 million higher than was initially budgeted, and the district is looking for more grants to avoid paying $3.9 million from its capital budget. The district has received an $800,000 grant from the California Department of Boating and Waterways. If the district opts to dredge 100,000 cubic yards, it will increase costs by an estimated $700,000.

Damitz said the district is still optimistic about the project, even if it opts for the smaller version of digging up 75,000 cubic yards.

“I think it’s going to happen regardless,” Damitz said. “There might be a little delay in the meantime, but there’s a lot of support for this project.”


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