City officials are still negotiating a contract with Bjoin Limestone to complete restoration work in the Monterey lagoon, much of which is under water thanks to recent rains.
Public Works Director Paul Woodard said city officials hope to have the project finished this year, but weather conditions and the length of the negotiation process could change that, he said.
A start date for the work won’t be set until the contract is negotiated, Woodard said.
The city’s restoration plan, which recently was revised, still calls for building a detention pond and peninsula with park space using materials in the lagoon. However, city engineers flattened the slopes of the peninsula and planned for less water in the detention pond, Woodard said.
Drax, the previous lagoon contractor, told the city the “organic muck” at the bottom of the lagoon is not suitable for piling into a peninsula or berm. Drax also expressed concern about contamination in the soil.
The city dropped Drax from the project, saying the company had breached its contract by refusing to complete the project as specified, according to a Sept. 4 letter from the city.
City officials then hired GEI Consultants to help city engineers redesign plans for the lagoon.
GEI tested soil strength in 30 locations within the lagoon and found results consistent with testing done by Soils Engineering Services of Madison, a subcontractor hired by Drax to study the soil’s integrity, according to a report released Monday.
The material in the lagoon consists of about 3 to 5 feet of organic silt and organic clay overlaying sands, according to the report.
GEI found the city’s revised plans met the recommended safety standard for construction conditions in two areas of the bay. Further revision is needed on one section to improve stability, according to the report.
Woodard told The Gazette the GEI report confirmed that the city’s plans for the lagoon should work, with one recommended tweak.
GEI identified concerns and suggestions for improvement based on conversations with city officials. They include:
- Specialized low-contact pressure equipment or an amphibious excavator is needed to work in the lagoon.
- Hydraulic dredging methods could be employed to move soil below river level when the river is high, depending on timing.
- A stabilization berm might be needed in areas with low-strength soils.
- Geotubes could be used for dewatering soils removed from the lagoon area, but geotubes are susceptible to clogging.
Much of the lagoon is under water because of heavy rainfall. The high water will force the contractor to use specific equipment, which is currently being negotiated, Woodard said.
Work in the lagoon will require contractors with “specialized experience in hydraulic dredging or working with amphibious excavation and earth-moving equipment,” according to the GEI report.
The contractors’ perceived risk will be variable, and the bids likely will be higher than conventional earth-moving projects, according to the report.
GEI did not estimate costs in its report.
However, the report includes six restoration options that were ordered from least expensive to most expensive. The city’s plan to regrade the detention pond is what GEI anticipated to be the least expensive.