Award of Merit: Historic Category
Point Arena Lighthouse Restoration
Point Arena, California
Submitted by Sika Corporation
Point Arena Lighthouse Keepers, Inc.
Point Arena, CA
Alpha Restoration & Waterproofing
South San Francisco, CA
Menlo Park, CA
Point Arena Lighthouse, owned and operated by the small nonprofit organization Point Arena Lighthouse Keepers, Inc., is located in Mendocino County along the Pacific Coast of California, northwest of San Francisco. The original lighthouse was erected in 1870 with brick- and mortar-type construction common to most construction of this era.
In April 1906, a devastating earthquake struck the Lighthouse Station and so severely damaged the tower and residence that they had to be demolished. A San Francisco-based company—which normally built factory smokestacks—was chosen to rebuild the lighthouse to withstand earthquakes, which accounts for the final construction method of the concrete tower. The current lighthouse tower stands 115 ft (35 m) tall and began operation in 1908, nearly 18 months after the earthquake.
By 2005, the harsh marine environment had accelerated the degradation of the concrete tower. Sections of concrete were falling, putting the public at risk. Sections of the corbel supporting the balcony had fallen to ground level and there was marked deterioration around the tower windows. The lighthouse balcony was eventually closed to the public due to the continued degradation of the concrete structure caused by corrosion and water intrusion.
An assessment survey was performed after removing the existing exterior coating and repair areas were identified. Deteriorated concrete was removed and steel was cleaned and coated with an epoxy-modified cementitious anti- corrosion coating with replacement being performed as needed. For larger areas, cathodic protection anodes were installed and then all repair areas were filled with two- component, fast-setting, polymer-modified, cement-based mortar. In addition, a three-component, epoxy-modified, cementitious structural resurfacing compound and an elastomeric, crack-bridging, anti-carbonation acrylic protective coating were applied to the exterior of the entire structure.