There are some places in San Francisco where it’s just not safe to build, like Edgehill Mountain. (Sally Stephens/Special to S.F. Examiner)

Monster houses don’t belong on SF’s Edgehill Mountain

There are some places in San Francisco where it’s just not safe to build. Edgehill Mountain, a geologically unstable hill (fifth highest in The City) sandwiched between Mount Davidson and Forest Hill, is one such place. Every time in recent years that developers have conducted large-scale excavations on Edgehill to build multi-home projects, the construction has resulted in extensive mudslides and rockfalls.

Now, developers want to excavate 30 feet into a steep cliff face of fragile Franciscan chert at the base of Edgehill along Kensington Way to build five five-story, 5,000-square-foot single-family homes. The rock is stable if undisturbed, but quarrying long ago and previous home construction have “disturbed” the rock, resulting in a landslide-prone hill.

People who live across the street from the five proposed homes are terrified that a large rainstorm during construction — or even just the construction itself — will result in the mountain coming down on top of them.

It’s happened before.

In the 1970s, damage from an earlier landslide and the continuing threat of more rockfalls temporarily closed a church at the base of Edgehill. In 1982, another slide forced a preschool to move. In 1995, rocks fell on a site at the base of the mountain where 13 homes were being built by developer William Spiers on Knockash Hill Court. Engineers inspected the site, declared it safe, and construction continued.

In January 1997, however, after a torrential rainstorm, the hillside above Knockash Hill Court gave way, and 100 tons of boulders, mud and debris overran a 10-foot-tall retaining wall and slammed into the new homes below.

A year later, another slide, not far from the 1997 disaster, overwhelmed a 60-foot retaining wall and dumped rocks and mud on a site where three new homes were being built. Developers had to build an unplanned third retaining wall that soon began leaking. Twenty years later, water still continually seeps out of the ground at the base of a telephone pole adjacent to the homes.

In 2002, Spiers applied for permits to build five more homes on Edgehill Mountain. Neighborhood opposition was intense. Eventually, then-Supervisor Tony Hall arranged for San Francisco to “swap” a vacant Department of Public Works-owned lot at Gough and Grove for Spiers’ lots on Edgehill. Spiers was able to build significantly more housing on the Gough site than the five homes originally proposed, while the Edgehill plots were added as open space to Edgehill Mountain Park. Some parts of that park had been acquired by The City earlier by eminent domain.

Given the history of landslides on Edgehill Mountain — and mitigation efforts that didn’t work — it’s no wonder that residents who live nearby oppose the five new homes. They understandably don’t trust engineers who claim they can make the mountain “safe” for construction.

Neighbors also note that the five-story monster homes are completely out of scale with the one- and two-story houses across the street. People who live on top of the mountain worry construction could undermine the foundations of their homes. And no one wants to lose an acre of mature forest, home to red-tailed hawks and other wildlife, that would have to be destroyed to build the homes.

According to Planning Department Communications Manager Gina Simi, the Kensington Way project is currently on hold because the department considers the applications to be incomplete because permits for only three of the five homes have been submitted, and those three included inadequate pre-application materials.

The developers, SIA Consulting Corp., did not respond to a request for comment for this column.

Being on hold means the building permits could eventually be granted and construction would then begin. But that really should never happen. Perhaps San Francisco should identify land that is too unstable and unsafe for housing and acquire it — through eminent domain, if necessary — to be preserved as open space. They could start with the lots on Edgehill Mountain.

After all, there are some places in San Francisco where it’s just not safe to build.

Sally Stephens is an animal, park and neighborhood activist who lives in the West of Twin Peaks area. She is a guest opinion columnist and her point of view is not necessarily that of The Examiner.

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