Mad River Union
TRINIDAD – The installation of subterranean eight-foot poles on the south and west sides of the Trinidad Memorial Lighthouse might be the answer to stabilizing the structure if shortages of time and funds rule out more extensive and costly alternatives.
Notionally, the pilings would be placed at 18-inch intervals to stave off landslides. That might require tearing out the sidewalk around the lighthouse, but it would be less disruptive and expensive than moving it, even 10 or 15 feet, within the small Civic Club parcel.
Pilings would not encroach on city property.
Cost estimates are pending, but time pressures are even more salient than funding requirements.
An analysis by SHN Consulting Engineers & Geologists, Eureka, warned the city council in late July that action is essential before the winter rains set in. SHN Engineer Gary Simpson said if this winter’s storms are as heavy and prolonged as those of 2016/2017 – which were well above the historical average – both the lighthouse and its foundation could be compromised. There is an outside chance the structure could fall over if it isn’t reinforced or moved promptly, Simpson added.
A tension crack has continued to develop in the summer dry season, engineers have found.
In the wake of the engineering report to the city council on July 26, an offshoot Memorial Lighthouse Preservation Committee of the Trinidad Civic Club requested a follow-up analysis of pilings or moving the lighthouse some 10-15 feet. Simpson is among those working on the alternative proposals, which are pending.
Patti Fleschner, chair of the Preservation Committee, said after a lengthy meeting last week that there is no fixed date when the follow-up study and cost estimates will be finished. Nor is there a site plan as yet.
The city council is attempting to expedite the requisite Coastal Development Permit, although it is uncertain if the proposal could be ready for the Sept. 13 council meeting.
In Fleschner’s words, “The City Council has been very supportive about submitting an actual Coastal Development Permit plan in September, but it is doubtful we will make this deadline.”
The Civic Club is scheduled to meet again on Sept. 7. It’s an open question whether it will have SHN’s follow-up report in hand by then.
Fleschner, who has done a joint site inspection with the engineers, said, “It is notable that with examination of the interior walls and floor and exterior of the cement lighthouse structure, there are no signs of cracking or tilting in the [lighthouse] itself.”
The south and west concrete sidewalk around it is tilting slightly and starting to buckle.
Also on the plus side, there are no signs of stress to the support structure around the two-ton Bronze Bell housed in a gantry just a few feet from the lighthouse. It is the fog bell that was situated on the bluff near the Trinidad Head Lighthouse, 1898-1949.
Fleschner said SHN is continuing to monitor the lighthouse site inclinometer, which measures angles of slope or tilt, and the piezometer, which measures the ground water level near the lighthouse.
“Costs are as yet unknown, but the club has confidence in the professionals making recommendations,” she said.
Whatever the nature of the fortification which community leaders decide to endorse, it will be subject to reviews by the state Coastal Commission and the Coastal Conservancy.
The preservation committee is also in touch with the Tsurai Ancestral Society. The 12.5 acre parcel often referred to as the Tsurai Study Area has its own management plan entirely separate from the Civic Club parcel.
SHN’s initial report a month ago to the city council concluded that the slope that undergirds both the lighthouse and Edwards Street, the thoroughfare that lies just above the structure, needs long-term reinforcement. The company estimated construction costs at $100,000 to $1 million.
Soil stabilization measures are only interim fixes, the company concluded. The best and most lasting mitigation measure would be the installation of a retaining wall about 160 feet long, with construction costs estimated at $560,000 to $1 million.
High expenses would be incurred from the extensive grading and temporary access roads that would have to be built along the edge of Edwards Street to enable heavy construction equipment to enter the site.