The Environmental Quality Control Board, at a special meeting on Wednesday, May 1, 2024 unanimously received and filed the geotechnical report for the First Street Parking Lot. The geotechnical report concerned whether there were potential sinkholes in the area. The report was concerned with a sinkhole found in the city-owned parking lot following the winter storms of late December 2023. The repair work was completed Jan. 16, 2024, according to Assistant City Manager Patrick Gallegos.
The geotechnical report described the findings of a survey by GMU Engineers and Geologists that used ground penetrating radar to look possible voids under the parking lot after a sinkhole was found in the parking lot following the storms of late December 2023. (For a chronology of the city’s response to the storm, taken from city emails, visit sunnews.org.)
The survey was performed on Feb. 28, 2024, according to the staff report to the Environmental Board.
District One Board Member Gary Allen was absent.
The board reviewed the report following a request from District Three Councilwoman Lisa Landau during a March council meeting.
Board comments and questions
The following are highlights of some of the remarks made at the meeting. There is not enough space to print the entire 8,318 word transcript of the meeting.
District Five Board Member Ken Horning asked if a sinkhole had appeared previously at this site.
Associate Engineer David Spitz said he had been with the city about 17 years and there had not been any detectable sinkholes in that time. He said he ran the project to rebuild the First Street lot around 2011, give or take, and did not find any sinkholes during that project.
Horning asked if there were stormwater drains in the area.
Spitz said no. He said stormwater wouldn’t exit anywhere.
Horning said he looked at the map and it looked to him like the planter area that was not paved was integral to where the sinkhole was. He wondered if all the water drained into the area and the hydraulic flow caused the sinkhole.
Spitz said most of the parking lot actually drains toward the grassy areas on the east side of the lot. He said during the December flood, most of the water was pumped out over the beach area or into the San Gabriel River.
Spitz said it was tough to make any conclusions on what actually caused the sinkhole.
““So there wasn’t any plumbing or piping found near where the problem was,” said District Two Board Member Nick Massetti.
“I believe the only piping we might have had were just some irrigation lines,” Spitz said.
District Three Board Member Susan Perrell gave her own presentation to the meeting that she said would help put the questions in context, help everyone think, and come up with some recommendations and conclusions about the survey.
District Three Board Member Susan Perrell had suggested a review in early January 2024 in an email to Landau.
She started by reviewing the powers and duties of the Environmental Board according to the Seal Beach Municipal Code. Those included investigating all threats to a high quality environment to the city and recommending legislation to the City Council.
Her second slide showed a photo taken between 1936 and 1944.
According to Perrell, there used to be a steam plant in what is now the parking lot.
“Well the steam plant obviously got abandoned, but did they abandon it completely” Are there still pipes underneath a steam plant that they didn’t necessarily remove and
could have collapsed? Were there underground storage tanks there, were there other kinds of basements that weren’t properly filled and compacted?” Perrell asked.
She said soil sinking into buried things perhaps would cause a sinkhole.
“In fact it’s very frequent cause of sinkhole, so, and this I just say that’s one thing I don’t think the report actually took a look at,” Perrell said.
Perrell argued that the company that reviewed the site should look for and then look at the hydro-geologic setting of the parking lot.
“There could be some things underground,” Perrell said.
“There is a lot of movement in the sand, a lot of movement of fluids and sand in the river that could influence this parking lot,” Perrell said.
She turned to a slide showing the parking lot before the December 2923 storm that was marked with the approximate location of the sinkhole.
She referred to two strips that she said could be called planters, also known as swales. “They help when stormwater lands on the parking lot. They help direct some of that stormwater. They detain it, retain it, and send it back into the groundwater table where it’s useful for preventing saltwater intrusion and we want to preserve groundwater, not run it off to the ocean,” Perrell said.
Perrell then discussed the causes of sinkholes and asked if the city had done everything to prevent another one.
“Basically, when you remove underlying soil from the surface, or fluids from that surface, fluids in the pore space of the soil, and that causes the surface to finally collapse,” Perrell said.
She also cited groundwater pumping as a cause of sinkholes.
Another cause Perrell cited was tidal surge.
“This was my biggest concern when we saw when we saw the sinkhole, I actually thought we
could possibly have a breach of the levy underneath the levy from the river and things could be washing out, which would be terrible and so I’m really glad the city went after and did the geophysical survey,” Perrell said.
She said that proved to a reasonable level of assurance that the tidal surge wasn’t happening.
One of the slides Perrell showed a photo of the water pumps in the parking lot, the surface of which was submerged in water. Perrell said it pretty much looked like the intake on the broken pump was in in a swale on the parking lot. “So a concern would be that we might have been pulling a lot of sediment out of that planter,” Perrell said.
According to Perrell, that was exactly where the sinkhole formed.
She said there was no one to angry with or to blame.
“But it’s something that we have to consider, I think, as a possibility so that we don’t do this next time,” Perrell said.
She also had comments on the GMU geotechnical report.
Perrell said “we,” apparently meaning the board, recommended looking at the sinkhole with the geotechnical engineer before it was filled in. “But somehow it didn’t happen,” Perrell said.
“I’m sure there were safety um concerns they wanted to fill that hole as soon as they could so no one fell into it, I’m sure, but the problem is we wanted to learn what happened there so that we don’t have another hole later that someone might fall into,” Perrell said.
She asked for thoughts from the other board members.
“Well to me that looked like a pretty good explanation what could happen I guess we may not ever know what did happen,” said Horning.
“But bottom line is, that was the first time we’ve ever had, at least from recent memory, a sinkhole in that area and then that’s the first time that we really had that much precipitation that led to whatever that was,” said Horning.
Perrell described the location of the water pumps was one of the deepest places in the parking lot and that was close to the river, where they were trying to discharge the stormwater, so it made sense that the did that.
“But I would recommend not doing it in the future,” Perrell said.
District Four Board Member Catherine Showalter functioned as the meeting chair.
Showalter said she appreciated the fact that staff worked as quickly as they did. Showalter asked Public Works Director Iris Lee if the Army Corps of Engineers was contacted.
According to Lee, it wasn’t their jurisdiction. She described the Army Corps’ jurisdiction is navigable water.
“So it wasn’t a matter of the city spending money on a consultant when we could have had some service done by a government agency,” Showalter said.
“Correct,” Lee said.
Showalter said she would ask staff based on what they know, is there anything they would do differently.
Lee said she didn’t believe the declaration of emergency that was issued would change.
“Soil migration is very complex and geotechnical engineering for the most par is based on a deduction of available material and information,” Lee said.
Lee put the risk of the placement of the pumps at a millionth of a possibility, apparently referring to the pumps being the cause of the sinkhole.
“However our reaction to what happened, I don’t think we would be changing it at all,” Lee said.
Showalter asked if Lee was satisfied that the geotechnical report was thorough enough to answer whatever questions people might have.
Lee said from a purely scientific and engineer perspective, there was never enough. However, this was enough information for staff to be comfortable with the parking lot’s condition at this moment.
Perrell recommended that if there was another sinkhole the city should try to get a geotechnical engineer out the next day or two. Perrell said the city had a contract with Stantec and they had a lot of geotechnical experience.
Another recommendation she had was to not fill in a sinkhole before taking a look at it.
Perrell said she wouldn’t call the GMU report a geotechnical report. “It was just a geo physics report. There wasn’t really much geotechnical information in there at all,” Perrell said.
She said it was just the ground penetrating radar survey which she described as part of a geotechnical report.
Perrell said she didn’t see the date the data was collected, the purpose, the hydrogeologic setting, or the historical setting.
Perrell thought the survey should include some recommendations.
Perrell also said the survey should have been done sooner.
Horning suggested the parking lot surface be inspected from time to time after a rain.
Horning said it did seem that the pump might have had something to do with the sinkhole.
Perrell agreed. She didn’t recommend doing surveys of all the parking lots after a storm.
“We have to remember for this sinkhole to occur, a lot of soil got removed and it went somewhere and it had to have a way to get somewhere, so it’s probable not going to happen just from a rain,” she said.
Following a motion to receive and file the report, Perrell seconded the motion and asked if the board could make recommendations.
Community Development Director Alexa Smittle said it was up to the board if they come to a consensus.
Perrell said the board should not just receive the report but comment on it.
Horning asked what recommendations she had.
Perrell suggested putting water pups away from loose materials and having an engineer firm come in before filling a sinkhole. She also suggested doing the ground penetrating radar survey before opening the parking lot to traffic.
Showalter said they could have the report received and filed. “One thing I don’t want to do is get into micromanaging the actual step by step process for city staff when something like this does happen,” Showalter said.
Perrell suggested asking city staff to incorporate some of the Board’s thoughts into their own thoughts and procedures and make their own decisions based on the Board’s recommendations.
Horning suggested using another word, such as “consideration” or “awareness”.
“In terms of a formal recommendation, you would be making it to the City Council,” Smittle said.
“You might want to think about how you might want to structure that if it’s a recommendation,” Smittle said.
Lee said all the comments received that night were noted. “There’s always something that can be learned,” Lee said.
Board Member Massetti said they should keep it simple.
“I’m a little bit uncomfortable that we’re getting beyond the purview of what I think this board is supposed to do by giving specific recommendations to our Public Works Department,” Massetti said.
Showalter suggested an addition to the motion to receive and file the report. She suggested making mention of the recommendations in the staff report to the City Council when that comes up.
“Something to that effect,” Showalter said.
Massetti, apparently referring to Associate Engineer Spitz and Public Works Director Lee, said the people involved heard what was said and he was sure they took it to heart.
“Unless there’s a need for this committee to appear as though it’s sending something back to the council that I’m kind of unaware of, being new,” Massetti said. (Massetti until recently served on the Planning Commission.)
Perrell said she thought her council person would appreciate knowing what the board’s recommendations were.
Horning said he thought the recommendations should be noted.
Showalter said noted, but that wasn’t part of the motion.
Horning suggested just incorporating the comments the board had made so it should just be noted that the Environmental Board had made internal recommendations.
The four board members present voted unanimously to receive and file the GMU report.
The City Council received and filed the GMU report at the council’s March 25 meeting.
