The mudslide behind the site of Garberville Sanitary District's new drinking water treatment plant, triggered by heavy rains in February and March, continued to move during the past month, GSD's capital projects manager Jennie Short told the board at their monthly meeting last Tuesday, April 22.
The estimated cost to stabilize the slide area permanently with a retaining wall and drainage system has increased from approximately $49,000 as estimated last month by contractor Wahlund Construction to more than $200,000, Short said.
Since the initial report at GSD's March board meeting, the flow of mud rotated and moved in closer to the backwash tank. Contractors responded by installing a "soil nail wall," mats of steel mesh secured with steel nails 15 to 20 feet long that hold the mesh in place with 10-inch bolts.
This represents the start of the second phase of what has now become a three-phase project, Short said. The first phase was the "emergency fix" completed last month, when the slide was covered with plastic tarps on rainy days to keep it from getting wetter and then uncovered on sunny days so the soil could dry out.
But the slope above the initial slide fissured and released more soil into the slide as well as causing a rotating movement that brought the debris even closer to the construction area.
The soil nail wall should hold the slide in place so that crews can safely build a permanent retaining wall, which will require further excavation to firmly anchor the wall to a stable base.
Phase three will begin this summer when the hillside is thoroughly dried out. The cracks in the hillside above the slide must be smoothed out so that they can't fill with water when the rain begins again.
Ralph Emerson, GSD's new general manager, said he felt this phase could be completed by GSD's own staff with rented equipment.
The California Department of Public Health (CDPH), which provided the $3.2 million grant-loan package to fund construction of the new water treatment plant, has agreed to give GSD an additional 30-year, no-interest loan to cover the cost of permanently stabilizing the slide, Short said.
During the design review process in December 2011, GSD and its consulting engineers, SHN Engineering, decided to lower construction costs by decreasing the footprint of the plant and eliminating the retaining wall that was part of the original design, Short reported.
"The design was a good one on paper, but the amount of water that comes out of the hillside was much higher than estimated, and the competency of the soils was not as good as the boring pits indicated," Short said in her written report to the GSD board.
A nearby property owner, Kristin Vogel, stated that the district had been warned "years ago" that the site is on unstable ground. Emerson responded that regardless of what happened in the past, the district has invested large amounts of effort and money in the project and the best course is to move ahead to make the site work.
The board approved a resolution authorizing Short and Emerson to go forward with the plan as outlined in Short's report, to give Emerson the same authority to sign checks as Short, and to authorize board chair Rio Anderson to sign a check equal to the amount of the change order required to complete the work.
The GSD board also approved a resolution to send the district's annexation application to the Humboldt Local Agency Formation Commission (LAFCo) for consideration and possible approval this summer.
GSD proposes to bring all the parcels that it currently serves with water within the district's legal boundaries. [See map included with this article.] This includes the Kimtu subdivision, the Connick Creek subdivision, and areas to the northwest and southwest of town that received water from the Garberville Water Company, either directly or through GSD's connection at the wastewater treatment plant, according to the application documents.
Ed Voice, whose family owns property just outside the annexation boundaries, said that not all the parcels in the Connick Creek subdivision are currently being served with water.
Short replied that the entire Connick Creek subdivision was approved by the county with the understanding that GSD would be able to serve water to all the parcels, which gives GSD an obligation to live up to its word.
LAFCo initially approved the connection of the Kimtu subdivision prior to annexation with the condition that any further connections to the 8-inch pipeline installed on Sprowel Creek and Kimtu Roads must be approved by LAFCo.
GSD later received permission from LAFCo to install two stub-outs on the line close to properties on Leino Lane. As part of the annexation application, GSD will also request LAFCo's approval to connect those parcels to the Kimtu line because their current connections are inadequate.
Both Voice and Vogel expressed concerns that the annexation of nearly 650 acres, including several properties zoned for agriculture, will increase development potential and that this potential was not adequately addressed in the district's environmental documents.
The board unanimously approved the resolution to submit the annexation to LAFCo. Short said she hopes that the annexation will be on the agenda for discussion at LAFCo's next regular meeting, Wednesday, May 21, and that the commission would agendize it for a public hearing at LAFCo's July meeting.
The only item to report on the Alderpoint tank replacement project was that the geotechnical reports are done and staff is waiting for the results, Emerson told the board.
Short noted that the leak is getting worse, which underlines the necessity of proceeding with this project as soon as possible.
GSD board members also heard a report from the district's auditor, Keith Borges of Anderson, Lucas, Somerville & Borges, certified public accountants in Fortuna. The GSD's 2012-13 audit showed everything in good order.
When board member Linda Brodersen asked Borges whether he thought GSD had any "cash flow issues," Borges assured her that the district's financial statements indicated that GSD is in good financial condition and should have no problem making its loan payments.
The large increase in assets during this period is because of the CDPH funding for the water treatment plant project, and the increase in liabilities reflects the depreciation of the new wastewater treatment plant, which was completed in 2012. These fluctuations in assets and liabilities are typical of large capital projects, Borges explained.
Finally, the board declined to take any action on a request to complete a brief survey about installing a port-a-potty to test the viability of a public restroom in Garberville.
The survey was sent out by the Garberville Redway Area Chamber of Commerce at the request of the Garberville Redway Public Restroom Working Group.
Board members felt that they did not wish to respond collectively as a board, although members may do so as individuals.
GSD's next meeting is scheduled for Tuesday, May 27, beginning at 5 p.m. at the GSD office at the south end of Garberville.
More information, including all board meeting materials and the complete annexation documents, can be found at GSD's website, www.garbervillesd.org. For questions, call the office during business hours at 923-9566.
1. PHOTO BY DENNIS RYAN, COURTESY OF GSD
Rain-drenched soil on the hillside above GSD's new drinking water treatment plant continued to slide in the past month, threatening the filtration tank. Contractors are installing steel-mesh mats and 15-to-20 foot long soil nails at the toe of the slide to stabilize it so that a permanent retaining wall and drainage system can be safely constructed.
2. MAP COURTESY OF GARBERVILLE SANITARY DISTRICT
If Garberville Sanitary District's proposed annexation is approved by the Humboldt County Local Agency Commission, GSD's boundaries will expand to cover all the green and green-striped areas on this map. The solid green areas have water and sewer service, and the striped areas have water service only.