News


Pleasanton homeowners search for answers to sinking ground; city to step in

Residents want to know whether well pumping or drought is to blame

In recent years, cracks have continually appeared in the walls and foundations of at least two dozen homes in the same Pleasanton neighborhood.

Neighbors who live just southeast of Sutter Gate Park, frustrated that their homes values are declining due to this damage, claim pumping from two nearby Zone 7 Water Agency wells caused the ground near their homes to sink.

The water agency, however, said a recent study proved the sinking is caused by natural soil water loss due to the intense years-long drought, not from use of the wells.

The issue will be researched and discussed further by city staff, said Vice Mayor Karla Brown.

Brown said it will take some time to collect the existing research and to determine what, if any, additional data needs to be collected, so there is no timeline for when this issue may appear before the Pleasanton City Council.

"We don't know if Zone 7 is even part of the problem, but they (residents) obviously have a problem, so the source still needs to be determined," she said. "We understand their concerns and the ball is in our court now."

About 20 residents, who live just southwest of Santa Rita Road and Stoneridge Drive, filled a Zone 7 conference room Wednesday evening for an informational presentation to learn about the study and to express their frustrations. Two City Councilwomen, Brown and Kathy Narum, attended the presentation.

Residents said the soil under and around their homes has been sinking by inches in different areas over the years. Some blame Zone 7's Mocho Wells 3 and 4, which are used to pump potable water and are located within 100 feet of some neighbors' homes.

Uneven sinking is causing stress to the foundation of their homes and their roadways, leading to cracks and potholes.

"It's affecting our properties. It's affecting our homes," said homeowner Kathy Gunn. "What about the crack in my banister? The crack in my wall?"

The area is spotted with homes with cracks, but not every home in that neighborhood has damage, residents said.

A contracted study, which cost $45,000 and was funded by Zone 7 through water rate funds, was released in June. It looked at all the ways the ground could sink in Pleasanton and surrounding areas, and the cause of the uneven sinking these residents are experiencing seems to be caused by natural drying out of topsoil, Zone 7 assistant general manager Kurt Arends said.

"I don't believe our pumping is what's causing your problems," Arends told residents.

The homes in question, including houses along Sutter Gate Avenue, Lin Gate Street and Laramie Gate Circle, appear to have been built on silty, clay-like soil -- a common culprit of foundation damage to homes across the East Bay during droughts, Arends said. When that type of soil dries out, it shrinks and cracks.

Homes built on this type of soil often experience trouble with their foundation in droughts because the soil on the edges of the home dries out and sinks faster than the soil in the center of the home, causing the foundation to warp, said Phillip Gregory, principal engineer for Cal Engineering & Geology, a Walnut Creek firm that conducted the ground movement study.

The study determined three factors can cause the ground to move: First, the topsoil dries out and shrinks, the soil hundreds of feet underground can shift when water is withdrawn and movement of tectonic plates can make the earth move. In this case, tectonic activity isn't causing any noticeable changes, said G. Reid Fisher, geologist for Cal Engineering & Geology.

Pumping out groundwater at the aquifer level can cause ground in Pleasanton to sink if water is taken out past a certain unsafe level, but it would probably happen evenly and across the entire city, Gregory said.

He also said water agencies are tasked with making sure water never falls below that level of dangerous sinkage. Zone 7 General Manager Jill Duerig said the district's water levels are within a safe range.

Uneven sinking in different parts of a house is more indicative of topsoil drying out during the extreme drought, Gregory said.

He noted the study didn't survey these residents' specific residences but said the reasons soil could sink are the same across the valley, and the valley as a whole didn't appear to have evidence of sinking. If groundwater pumping was causing the ground to shrink, there would be evidence like wells collapsing, and wellheads would be sticking out of the now-sunken ground, which researchers didn't observe.

Resident Michael Grossman said at the meeting he's not convinced topsoil drying is causing the damage to his home. Residents started noticing damage in 2004, about two years after Mocho Well 3 and Mocho Well 4 were installed and started pumping water.

Mocho Well 3 pumps water from 300-400 feet underground, and Mocho Well 4 pumps from 500-700 feet underground, Duerig said.

The homes experiencing damage are near the wells, Grossman said, and he believes it's unlikely the timing is a coincidence.

He said afterward that he was disappointed because the contracted study looked at soil and ground movement in the entire valley, and he and his neighbors were interested in a study that looked at their neighborhood and whether the nearby wells were causing an adverse effect.

However, he said the best course of action now is to wait and see what happens after the city evaluates the situation.

Comments

1 person likes this
Posted by Edward
a resident of Parkside
on Aug 7, 2015 at 8:18 am

It's happening in Parkside also. My home is along the Arroyo and my pool and whole back yard seems to have sunk about 3", mostly on the northeast side of the yard.
Anyone else in Parkside noticing this?


5 people like this
Posted by Citizen
a resident of Another Pleasanton neighborhood
on Aug 7, 2015 at 9:13 am

The area has been "settling" for years! Why do you think the road to the West is called "Hopyard"!!?


4 people like this
Posted by FrequentWalkerMiles
a resident of Another Pleasanton neighborhood
on Aug 7, 2015 at 9:40 am

Soil settling in that area of town is such a well known problem, any realtor worth his or her salt would point that out the first thing when someone thinks about buying in Pleasanton. That's why I am surprised at the prices that people are paying for homes in that area these days.


9 people like this
Posted by Ptown1947
a resident of Happy Valley
on Aug 7, 2015 at 9:58 am

It's called "Hopyard" cause of the hops they use to grow here. When this place was nice and not the ugly urban-sprawl it is today.

Remember that Pleasanton, at least the majority of it, was just a big wetland years ago. With all this water gone now, it is slowly sinking and will continue to. The hard clay that Pleasanton is built on will only funnel water down to water tables and not soak it up. Sinking has been a problem for most homeowners for years.

Study we did at Berkeley showed that it isn't getting any better people. Sorry. The Earth changes. And no it is not human fault, just the normal changes our Earth goes through.

Think it's bad now? Just wait until we the next 7-9.0 earthquake hits. This is nothing. And this will happen, soon.


1 person likes this
Posted by Oliver Heaviside
a resident of Val Vista
on Aug 7, 2015 at 10:26 am

Oliver Heaviside is a registered user.

Here in Val Vista this is a known issue. The clay soils (and I use the word "soil" in the loosest sense - you can make pottery with some of this stuff....) in the area expand and contract with moisture. One palliative is to install French drains and pipes to get ALL rainwater right to the curb, or a cistern. Wet or dry, you want all the clay at the same moisture level. Better yet, when we have purple pipe reclaimed water, we can keep the water level constant year 'round.


5 people like this
Posted by Mickey
a resident of Birdland
on Aug 7, 2015 at 11:08 am

When we moved into our home in 2001, we had cracking then. In 2008 we finally did some foundation work and had a civil engineering evaluation done on our home and there was a 3in difference from front to back. Mudjacking solved the problem, at a $25K cost. Now there are cracks in every single room and at almost every corner of the house. So much so, my kids call it the crack house. The issue goes even beyond the pumping stations because there are no soil reports available from the homes built in bird land from the city. Why is that? But we also discovered that the footings holding our home up are not quite deep enough in the ground. Shody construction practices from back in the early 80's don't help, IMO.


Like this comment
Posted by Al. B.
a resident of Downtown
on Aug 7, 2015 at 11:36 am

The south west corner of my Downfown building has been settling for the last few years, I have been told by people in the know that it's drought related. Is it ?


12 people like this
Posted by Map
a resident of Del Prado
on Aug 7, 2015 at 11:36 am

Us Old timers know that your homes are all built on former marshland and there's no way to go but "down" as your homes slowly sink into that nice clay soil, I've lived over there and got out quick once everything started cracking and the foundation "specialists" were putting fliers in my mailbox!!


6 people like this
Posted by Stacey
a resident of Amberwood/Wood Meadows
on Aug 7, 2015 at 11:38 am

Stacey is a registered user.

The City appears to have lost the original soil report for the Woodmeadows tract from when the tract was built. The entire file folder for the quadrant, which includes Amberwood and parts of Birdland, was missing when I last went to look it up, which was about 5 years ago. I never pursued it further.


1 person likes this
Posted by Bill
a resident of Pleasanton Heights
on Aug 7, 2015 at 12:34 pm

Clay. Its even affecting the hills, but I'm not surprised the old marsh land is settling more. The real fun comes when all that clay rehydrates. Then you'll understand the concept of heaving. Patch work will resplit. Its life in Ptown.


Like this comment
Posted by Capt Peachfuzz
a resident of Donlon Elementary School
on Aug 7, 2015 at 12:46 pm

Everyone - to the bow!


1 person likes this
Posted by Damon
a resident of Foothill Knolls
on Aug 7, 2015 at 1:09 pm

@Mickey: "Now there are cracks in every single room and at almost every corner of the house. So much so, my kids call it the crack house. "

Make sure that your kids don't say that at, say, a 1st Wednesday Street Fair with a Pleasanton Police officer around.

:-)


7 people like this
Posted by A
a resident of Birdland
on Aug 7, 2015 at 1:42 pm

Birdland has shrinkable clay soil. Subsidence is the gradual caving in or sinking of an area of land. Subsidence is the main problem posed by trees and subsidence is the worst in dry years. Tree root shoots will extend under houses to look for water---and will soak up whatever water they can find. This causes houses to shift and crack. However, the city's heritage tree policy protects the overly large trees and not the homeowners houses.
Where is the common sense?


9 people like this
Posted by Joy Montgomery
a resident of Another Pleasanton neighborhood
on Aug 7, 2015 at 1:55 pm

Stop paving over the valley floor and the aquifer might get some help when the rains come back (as with a predicted strong to very strong El Nino this year). In the 1980s I was on a committee for the General Plan rewrite and was ridiculed when I tried to get people to think about building permeable roads and houses on earthquake-proof stilts on what was called then "the San Francisco Water Department Land." The City Planners are approving every effort to cover that land with impermeable vertical and horizontal structures now. You vote - let them know what you think about the lack of foresight.


11 people like this
Posted by Stacey
a resident of Amberwood/Wood Meadows
on Aug 7, 2015 at 1:56 pm

Stacey is a registered user.

I've lived between Pleasanton Meadows and Woodmeadows since 1979 and am very aware of the seasonal expansion of the clay soil. With residents asked to cut back on water usage where many are foregoing yard irrigation, the soil near the surface is drying out even more than during past droughts. One can notice slight surface depressions where the larger trees grow as the trees are trying to suck out as much water as possible from land that used to be irrigated more.

Woodmeadows was built in 1984. There was a drought between 1987-1992 and another one from 2000-2002. It is only since the 2000-2002 drought that people in the neighborhood who have lived here through both those droughts have started reporting foundation issues. The difference between those two droughts is the operation of the well, which is why people find it easy to conclude the well is involved, especially when Zone 7's annual report shows they pumped rather close to the historic low during the 2000-2002 drought.

I'm not so quick to blame the well operation though because ultimately how a home handles the soil's characteristics come down to construction, which is why the missing soil report is rather alarming. Why is it missing and has anyone been able to find it? Is something trying to be hidden?


6 people like this
Posted by RS
a resident of Kottinger Ranch
on Aug 7, 2015 at 5:56 pm

Hey Joy Montgomery, I totally agree...the few times we did have rain last year, I couldn't help but stare at the ground and wonder at the complete "unnatural" state of channeling water to the drains instead of letting it soak back into the ground. Will we ever get to the point of at least trying to coincide with nature instead of dominating it?


3 people like this
Posted by Val Vista Neighbor
a resident of Val Vista
on Aug 11, 2015 at 9:18 am

We've lived here 25 years and have tried everything to adjust to the constant cracks in our home. Our house is now on leveling jacks. At first we thought we were alone, but have come to see this is a problem in most neighborhoods. Just have to get used to it. I wouldn't fix the cracks now, they will come back if it's a wet winter, as predicted.


3 people like this
Posted by Jp
a resident of Mission Park
on Aug 11, 2015 at 9:26 am

Is every part of pleasanton affected by the sinking of soil or just near hopyard?


Like this comment
Posted by Damon
a resident of Foothill Knolls
on Aug 11, 2015 at 10:28 am

@Jp: "Is every part of pleasanton affected by the sinking of soil or just near hopyard?"

I think that we here on the west side are relatively safe since we are partially on a hillside and our foundation runs relatively deep. Not gloating, though. We may get hit the hardest when the Calavaras fault running along Foothill Road goes.


Like this comment
Posted by Kangaroo
a resident of another community
on Aug 11, 2015 at 11:28 am

Is Lemonwood Way sinking?


Like this comment
Posted by Damon
a resident of Foothill Knolls
on Aug 11, 2015 at 2:00 pm

@Kangaroo: "Is Lemonwood Way sinking?"

I dunno. Is it?


3 people like this
Posted by Sutter Gate Resident
a resident of Another Pleasanton neighborhood
on Aug 14, 2015 at 8:53 am

I live in "The Gates" and the settling in and around my home has gotten ridiculous. The coping around my pool has popped, the aggregate that makes up my patio and the majority back yard is either cracked or buckled. Not to mention the cracks in the walls, and the space that now exists between the baseboard and the floor in some area's of my home. I consider myself lucky, because my neighbors across the street can't even shut the doors to the bedrooms because the floor is so uneven. I have a friend who lives in San Jose who had a similar situation with his home. He ended up suing the city and the builder for the cost to repair the damage to his home because they had prior knowledge that soils report was less than truthful. He won.


Like this comment
Posted by Damon
a resident of Foothill Knolls
on Aug 14, 2015 at 11:04 am

@Sutter Gate Resident

Sorry to hear about what's happening there. My wife and I went to an open house in "the Gates" area (Laramie Gate street, I believe) in 2010, and I loved the feel of the neighborhood there with the big mature trees and the style of the houses. Unfortunately, we didn't like the layout of the particular house being sold, but I remember scanning the MLS listings for quite some time after that hoping that another house from "the Gates" would come onto the market.

I do remember now that my wife remarked that she thought that one floor region near a large window of the house that was being sold felt a little uneven to her. I examined the same area and told her I didn't detect anything wrong. Out of curiosity, I planned to drop by the same house for its open house the following week with a level meter to check which of us was right, but never got around to it.


1 person likes this
Posted by Vintage Hills II Resident
a resident of Vintage Hills
on Aug 14, 2015 at 11:17 pm

We have lived in a one story home on Arbor Drive in Vintage Hills II development. In the 28 years we have been here we have not experienced any noticeable cracks beyond some hairline ones in the stucco and maybe one inside. They are so small that I would hesitate to blame shifting soils, as simple aging of the home's materials may be the cause.

Before this, we lived in Livermore, near Jackson School. We had one 3/16-inch crack from corner of front window to ceiling that would open and close depending on the rain. I found that a brief period running a sprinkler near this window was all it took to close the crack in a couple of days.

I really like the floor jack solution one commenter implemented. If you have a raised foundation, this seems like an excellent approach. With today's high tech, it might even be possible to automate the jack adjusting to maintain a flat floor with changing weather. Not certain how they engineered unmounting the home from its foundation. Of course, house moving companies do this all the time.


2 people like this
Posted by Parkside Resident
a resident of Parkside
on Aug 19, 2015 at 11:00 am

We have lived here since 1998 - and moved to Parkside from Payne Road in 2003. Payne road (val vista area) always seemed to have the expansive soils issues. Moving over to Parkside - that area didnt seem to have the same issues as say south valley trails. That area always seemed to have significant shrink swell issues.

However - I have noticed parkside drive - especially near the front of the drive has seemed to developed a noticable subsidence (not just a shrink swell) along both the parkside road and drive into along the park. Also - Las Positas Road also shows significant settling, as did a section of Los Positas west of the DMV along the pine trees section (was recently paved)

These areas seem to demonstrate large areas of subsidence, an not just a seasonaly shrink/swell feature. Someone would have to pull the water reports on the pumping and see where the historical groundwater levels are compared to today and when that pumping started on wells 3/4 from Zone 7. It should all be publically available for review. Generally on subsidence issues you should see features sticking up as compared to the ground surface. So along parkside - you do see the sewer manhole covers sticking out higher than the surrounding ground surface - which could be explained by subsidence and not just shrink swell clays.


Like this comment
Posted by Steve
a resident of Parkside
on Aug 19, 2015 at 1:31 pm

@Sutter Gate Resident..our pool has done the same thing. We now have a gap of about and inch from the top of the tile under the coping.
Not even sure what this is going to take to fix. I'm sure we are not the only one with this problem.
Have you looked in to repairing it?


Like this comment
Posted by MarkSindone
a resident of Las Positas Garden Homes
on Mar 22, 2016 at 10:58 pm

MarkSindone is a registered user.

Let's hope that there's a solution found for this as soon as possible! It looks like there can potentially be a lot of damage from the ground erosion if the problem isn't rectified soon!


Sorry, but further commenting on this topic has been closed.

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