Agency reviews seawater-intrusion fixes: extraction barrier and aquifer storage discussed
February 28, 2024 | Greenfield City, Monterey County, California
This article was created by AI summarizing key points discussed. AI makes mistakes, so for full details and context, please refer to the video of the full meeting. Please report any errors so we can fix them. Report an error »
The Arroyo Seco Groundwater Sustainability Agency heard staff summarize two seawater-intrusion approaches Tuesday: an aquifer storage and recovery (ASR) project and a conceptual extraction barrier of pumped wells that modeling shows could shift the seawater intrusion front seaward.
The agency’s general manager summarized an ASR presentation by the Monterey Peninsula Water Management District, saying the district currently uses four wells with treatment to drinking-water standards and stores and recovers roughly “about 1,000 acre-feet a year.” He said that approach—injected, treated surface water stored underground and later pumped back—could be adapted in the Salinas Valley, provided the water is treated to meet drinking-water standards before injection.
Staff also described an extraction-barrier concept: a long line of wells placed between the seawater-intrusion front and the ocean, pumping to create a downward gradient that draws the intrusion back toward the ocean. The general manager said modeling considered wells in two aquifer layers and roughly 20 distinct wells arrayed from north of Marina toward Moss Landing; locating wells on the inland side of Highway 1 can make permitting simpler and improve effectiveness, he said.
Modeling indicates the approach is technically feasible, the general manager said, but he and board members cautioned that engineering and modeling remain conceptual. Cost estimates are preliminary: staff noted stainless-steel wells for brackish water are expensive—“north of $2,000,000 a well,” according to the general manager—and that multiplication across many wells plus treatment and distribution systems produces a very large capital bill. The general manager and board members emphasized operations, maintenance and energy costs will add materially to lifecycle expenses.
Board members recommended rigorous economic comparisons before advancing projects. The general manager said a useful method is to annualize capital costs (net present value) and add ongoing O&M to compare alternatives on a per-year basis. He said formal engineering and financing details will depend on further study; the contracted engineering firm is expected to provide more detailed modeling and cost information in coming months.
The agency did not take formal action on the concepts. Staff said it will circulate presentation slides and keep the board informed as technical work and funding discussions proceed.
The agency’s general manager summarized an ASR presentation by the Monterey Peninsula Water Management District, saying the district currently uses four wells with treatment to drinking-water standards and stores and recovers roughly “about 1,000 acre-feet a year.” He said that approach—injected, treated surface water stored underground and later pumped back—could be adapted in the Salinas Valley, provided the water is treated to meet drinking-water standards before injection.
Staff also described an extraction-barrier concept: a long line of wells placed between the seawater-intrusion front and the ocean, pumping to create a downward gradient that draws the intrusion back toward the ocean. The general manager said modeling considered wells in two aquifer layers and roughly 20 distinct wells arrayed from north of Marina toward Moss Landing; locating wells on the inland side of Highway 1 can make permitting simpler and improve effectiveness, he said.
Modeling indicates the approach is technically feasible, the general manager said, but he and board members cautioned that engineering and modeling remain conceptual. Cost estimates are preliminary: staff noted stainless-steel wells for brackish water are expensive—“north of $2,000,000 a well,” according to the general manager—and that multiplication across many wells plus treatment and distribution systems produces a very large capital bill. The general manager and board members emphasized operations, maintenance and energy costs will add materially to lifecycle expenses.
Board members recommended rigorous economic comparisons before advancing projects. The general manager said a useful method is to annualize capital costs (net present value) and add ongoing O&M to compare alternatives on a per-year basis. He said formal engineering and financing details will depend on further study; the contracted engineering firm is expected to provide more detailed modeling and cost information in coming months.
The agency did not take formal action on the concepts. Staff said it will circulate presentation slides and keep the board informed as technical work and funding discussions proceed.
View the Full Meeting & All Its Details
This article offers just a summary. Unlock complete video, transcripts, and insights as a Founder Member.
✓
Watch full, unedited meeting videos
✓
Search every word spoken in unlimited transcripts
✓
AI summaries & real-time alerts (all government levels)
✓
Permanent access to expanding government content
30-day money-back guarantee
