Sinkhole threatens San Mateo home: Property owner questions who’s responsible for stormwater

San Mateo property owner Douglas Ervin looks out at a sinkhole that undermined his deck and swallowed his koi pond after the latest storm washed through the Bay Area.

As the skies began to clear after the most recent storm system swept across the Bay Area this week, San Mateo property owner Douglas Ervin is left with a big problem — a glaring sinkhole that ripped apart his yard swallowing a Japanese maple tree and draining his koi pond out toward the Bay.

“If we get another bad storm, I will lose the house,” Ervin said Tuesday afternoon before recalling what it was like during the storm. “It was running through like a big river, it was flowing at full speed.”

Ervin, who’s owned the single-family home on Alameda de las Pulgas for more than a decade and rents it out, is now left wondering who will take responsibility for the apparently mysterious unregulated drainage that could compromise his property.

Is it coming from the golf course immediately up hill? Was there a government-owned pipe that failed? Who is responsible for regulating the uphill stormwater?

These are all questions Ervin said he’s begun to ask, but to which he hasn’t yet received definitive answers.

“The county says it’s not our problem, the city says it’s not our problem, the country club says it’s not our problem,” Ervin said. “But drain lines built by [someone else] is not my responsibility; it’s just my problem.”

All things considered, the 74-year-old Belmont resident has a fairly calm demeanor considering he believes the property could be red-tagged should another storm hit and the sinkhole grows even closer to the occupied home.

The sinkhole widened since it first began Monday as the recent storms wreaked havoc across the state causing flooding, downed power lines, fallen trees and forced the evacuation of hundreds in San Jose.

By Tuesday, the danger zone marked by bright yellow caution tape expanded and the balcony appeared to teeter over the hole filled with mud, debris, trees and other material from his garden.

Ervin was first notified Monday by his tenant who heard a loud crash in the side yard — a maple tree in the Japanese-style garden sunk nearly 8 feet as rushing water poured down from up near the Peninsula Golf Course and Country Club. Firefighters responded quickly to rope off the sinkhole and placed sandbags near a parking lot to the golf course.

But overnight, the storm continued exacerbating the erosion that ultimately swallowed up a koi pond and several $500 fish living in the yard, Ervin said.

Ervin is no stranger to complicated engineering problems. He’s a retired civil engineer who spent four years working in intelligence for the U.S. Army, followed by a 30-year career as an engineer for San Bruno naval facility. But like several others he called Tuesday for help, he was stumped.

“Helpless,” Ervin said when asked how he felt. “Even as a professional engineer, I have no further avenues to go. I’ve gone to the city, I’ve gone to the Peninsula Golf club.”

The county determined it had no property in the immediate area while San Mateo city officials pulled records but couldn’t find easements on his property either. There’s supposedly a 36-inch storm drain running through or past his lot before heading under Alameda de las Pulgas then daylighting near a creek by Serra High School. But the pipe wasn’t immediately visible in the sinkhole if it was the culprit, Ervin said.

But since water is clearly trickling down from above and he has no control over drainage upstream, Ervin was losing confidence that any type of fix would be easy. He did however note per state laws, if someone does something on another property that alters the flow of stormwater and causes problems elsewhere, they can still be liable, Ervin said.

So the next question is who is responsible? Ervin pointed to a recently-paved parking lot the Peninsula golf club built atop a previously permeable dirt area. What’s now a new maintenance yard appears to have runoff drain along a ditch that borders the club and a nearby office complex before it hits the border of Ervin’s backyard. On Tuesday the country club property manager said it wasn’t their pipe and suggested it flowed from further upstream, possibly even State Route 92, Ervin said.

A representative with the golf club did not return multiple requests for comment Tuesday.

Ervin, while not entirely hopeless, suggested the financial wherewithal of the private club that likely has multiple attorneys would be difficult to convince.

San Mateo city staff on the other hand were responding to his concerns, Ervin said. However, it still wasn’t immediately clear who’s responsible for maintaining the drainage or stemming any further damage as this season’s storms aren’t believed to be over.

“It’s not fully clear at this moment,” said Public Works Director Brad Underwood. “The main thing is what can we do to maybe make things safe out there in the meantime?”

Underwood said city staff hadn’t found any recorded easements at Ervin’s property, but suggested they may visit the site Wednesday to better gauge the situation.

Ervin, who’s lived in neighboring Belmont for nearly 50 years, wasn’t sure what would happen to his property or his tenant for whom he worries. Tuesday morning, he hired a company to remove two large trees that were compromised by the sinkhole and had begun leaning toward the two-bedroom home he said he was recently offered $1.4 million for by a Realtor.

Even though Ervin is dealing with the loss of a good portion of his yard and potential threats to the structure of the house, he noted extreme concern for nearby infrastructure.

“If that [stormwater] is running under Alameda de las Pulgas without a pipe, that could undermine the road,” he said. “If someone doesn’t speak up and try to figure out what’s going on, it could be a life safety issue.”

(650) 344-5200 ext. 106

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