![\"\"](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/IMG_8593.jpg\")
Engineers contracted\u00a0by the city work on pipes of Cesar Chavez Park\u2019s largely underground gas collection system earlier this month. Credit: Tracey Taylor<\/p>\nEngineers contracted\u00a0by the city work on pipes of Cesar Chavez Park\u2019s largely underground gas collection system earlier this month. Credit: Tracey Taylor<\/p>\n
The results of recent follow-up testing<\/a> for hazardous radiation at Cesar Chavez Park, linked to its long ago history as a landfill, are reassuring for recreational use, from jogging to kite-flying to family picnics. They essentially affirm earlier city findings of above ground park safety.\u00a0<\/p>\n But, the subsequent testing brings new concerns for underground work at the waterfront park\u2019s gas extraction system, a buried network of wells and pipes for trapping and removing methane, a common byproduct of decomposing landfills.<\/p>\n The new round of testing, conducted in summer to drill down on earlier tests showing some elevated radiation underground, included first-ever park checks for radon, a radioactive gas which can become a health hazard at higher levels. Radon occurs naturally, but is also linked to chemical waste suspected of being dumped at the old landfill decades ago.\u00a0<\/p>\n Above ground air tests for radon indicated no safety worry, reflecting average outdoor ambient air standards per the Environmental Protection Agency (EPA), according to city documents. Air measurements were taken at 11 spots across the park from an average upright adult\u2019s breathing zone.<\/p>\n But underground radon testing of vapor at the gas collection system\u2019s extraction wells, essentially holding tanks, found potentially dangerous levels, especially at one of the 12 wells tested.\u00a0\u00a0<\/p>\n Radon detected in the vapor from 12 extraction wells ranged from 6.0 to 876 pCi\/L, according to city data. The EPA sets 4 pCi\/L as an indoor air threshold for taking action to clear radon. The 876 pCi\/L levels is considered \u201cextremely high\u201d by the EPA.<\/p>\n Underground radon levels fluctuate based on changes in temperature, water flows, and soil conditions, and these results could differ at different times. Berkeley\u2019s policy is to follow the precautionary principle<\/a> with potential health threats, which means enacting strict safety or preventative measures even before risks are scientifically proven.<\/p>\n In response to the radon findings, the city has enacted a new set of radiation safety procedures for workers on the gas system. The new testing results, and related updated city policies were presented to the City Council in a memo from city manager Paul Buddenhagen<\/a> earlier this month.<\/p>\n \u201cWhile there is potential for LFG [landfill gas] extraction system worker exposure to elevated radon during certain work activities, Cesar Chavez Park remains safe for members of the public,\u201d Buddenhagen said in the detailed memo.<\/p>\n The city emphasizes that the gas collection infrastructure is locked, and can\u2019t be accessed by the public.<\/p>\n \u201cThe GCCS [subsurface gas collection and control system] is a closed system that is maintained under vacuum, minimizing the risk of releases of radon to the surface, as made evident by the low levels detected in the ambient air sampling,\u201d\u00a0 Buddenhagen said in the memo.<\/p>\n \u201cWhen work occurs on the GCCS that has potential for radon exposure, workers will follow all applicable health and safety protocols and have radiation monitoring instruments for both area and individual monitoring.\u201d<\/p>\n Radon exposure is a leading cause of lung cancer, with risk tied to exposure time, and radiation levels. Berkeleyside has asked the city for information on how long workers typically spend or spent at or near the underground gas extraction wells, and will provide updates if we learn more.\u00a0<\/p>\n Follow-up testing for radiation detected last year in the former landfill\u2019s groundwater and leachate, subsurface leakage that\u2019s often polluted, found significantly lower levels this time around. The new testing used a different method to second-check or verify initial results.\u00a0<\/p>\n In fact, it was the finding last year of concerning levels<\/a> of two radionuclides, radium-226 and radium-228, in the site\u2019s underground liquids that prompted this year\u2019s testing for radon in well vapor and air.\u00a0\u00a0<\/p>\n These radionuclides are naturally occurring radioactive elements<\/a> that can become hazardous after human activities. Radon is a decayed state of radium-226, and a form of radionuclide. Therefore, the discovery of elevated radium-226, linked to chemical waste that could have been dumped at the site decades ago, was a red flag for radon.\u00a0<\/p>\n \u201cBased on these results, future screening for radionuclides in groundwater and leachate appears to be unnecessary,\u201d the city manager\u2019s report said.<\/p>\n In response to the recent results, the city has updated park use rules enacted early last summer<\/a> before the new testing, included in the city manager\u2019s November report. The restrictions applied only to activities that could disturb park soil, such as gardening and digging dogs, as a precaution until more was learned about underground radiation.<\/p>\n The revised rules refine soil contact to prohibit activities below 1 foot deep. Previous rules halted anything that stirred up even surface soil.<\/p>\n \u201cThe updated RHASP [radiology health and safety plan] has determined that safety precautions apply to any work that disturbs the ground surface at depths of one foot or deeper,\u201d the city report said.<\/p>\n This means dogs still aren\u2019t allowed to dig at the park, according to the new rules. For fear off-leash critters out of sight of their owners could paw deep.<\/p>\n But gardeners tending to the park\u2019s native plants, put on notice last summer to hang up their trowels during the testing, can now resume weeding and sowing seeds, as long as they don\u2019t disturb earth deeper than 1 foot.<\/p>\n The same rules apply to city work. Maintenance down to 1 foot underground is OK. Deeper than this triggers the new radiation safety protocols.<\/p>\n The aim is to prevent anything that could break a clay seal covering the old landfill, which was installed as one element of the park conversion process. The clay cap, which averages 1-foot thick, ranges from 3 to 30 feet below the surface, depending on park topography.<\/p>\n \u201cFor volunteer planters at the park, we expect they will follow the standard of not digging more than a foot. Off-leash dogs are animals, but they have owners who we expect will control their dogs from digging and accidentally breaching the landfill cap,\u201d said Seung Lee, city spokesperson.<\/p>\n The city will also continue monitoring the activities of rodents, notorious for tunneling in park soil, and burrowing owls<\/a>, who winter at Cesar Chavez, living and breeding underground, often in rodent tunnels.<\/p>\n At this point, no one really knows how long restrictions on deeper soil activities will be in effect.\u00a0<\/p>\n As with all former landfills in the state, Cesar Chavez Park is regulated by several government agencies which enforce environmental laws. Located along the San Francisco Bay, a primary regulatory agency is the state Water Resources Control Board.<\/a> One concern about subsurface landfill toxins is runoff into the bay.<\/p>\n The summer\u2019s radon testing was ordered by the water board, in response to the elevated radionuclides found last year.\u00a0<\/p>\n The city has submitted its latest findings to the water board, and is awaiting next steps.<\/p>\n The water board must approve the city\u2019s plans for addressing toxics at the site, including if additional testing is needed.<\/p>\n Eileen White, executive officer of the San Francisco Bay regional office of the water board, said they\u2019re still reviewing Berkeley\u2019s recent testing results and \u201cexpect to respond in a month.\u201d<\/p>\n Permanent bathroom, new perimeter trail off the table<\/p>\n Regardless of what comes next, previously budgeted and approved plans to build a new perimeter trail around the park, and permanent bathrooms, are victims of construction precautions.<\/p>\n Funding for these projects was re-directed by the City Council to other waterfront projects when deep-soil disturbance was banned.<\/p>\n \u201c12 inches [deep] is enough to do most small maintenance projects, but not deep enough for larger CIP [capital improvement] projects,\u201d said Scott Ferris, Berkeley\u2019s director of parks and recreation.<\/p>\n \u201cPerimeter pathway maintenance will consist of mill and overlay of existing asphalt but cannot disturb the underlying soil one foot more below the ground surface,\u201d he added.<\/p>\n A once-planned brick-and-mortar, plumbed-and-wired bathroom may be out at Cesar Chavez Park, but it\u2019s now home to one of the city\u2019s new semi-portable Throne Labs bathrooms<\/a>, self-maintaining units with flush toilets and sinks with running water.<\/p>\n The city is testing Thrones at five locations, including the park.<\/p>\n The legacy of a landfill endures<\/p>\n Recent concern over unsafe toxins at Cesar Chavez Park point directly back to a little-known chapter of its landfill past.\u00a0<\/p>\n The landfill operated from 1961 to 1983, and then was converted to a park, which opened in 1991.\u00a0<\/p>\n Last year, the water board notified Berkeley that the park could have been dumping grounds for industrial waste<\/a> with radioactive and other hazardous materials.\u00a0<\/p>\n This was linked to newly discovered information by the water board, and the California Department of Toxic Substances and Control, that Berkeley\u2019s landfill was among several in the East Bay used for waste by the former Stauffer Chemical Company<\/a> in Richmond, including potentially toxins and radioactive materials. Notably, Stauffer dumped alum or red mud<\/a>, a\u00a0byproduct of processing bauxite ore into aluminum.\u00a0<\/p>\n Other former landfills in Albany, Richmond and Benicia got the same alert.<\/p>\n This came as a surprise to city and regulatory officials, as Berkeley\u2019s dump was licensed for non-hazardous municipal waste.<\/p>\n Stauffer, starting around 1897, processed sulfuric acid and made pesticides and fungicides at its bayside site for decades, eventually becoming Zeneca, Inc., then Astra-Zeneca, after several sales and mergers. It closed in 1997 leaving a heavily contaminated site<\/a>, which the company and city are still dealing with.<\/a>\u00a0<\/p>\n Based on this, the water board required Berkeley, and the other former landfills, to test for a number of toxins linked to Stauffer\u2019s waste.<\/p>\n Thus launched a couple of years and counting of city focus on lingering possibilities from Cesar Chavez Park\u2019s past.\u00a0<\/p>\n In addition to testing for underground radionuclides, measured at lower levels last summer than initial results, the city last year conducted overhead drone monitoring, finding \u201ctypical background levels of radiation<\/a> expected in the ambient environment\u201d at the park\u2019s surface and shallow subsurface.\u00a0<\/p>\n Required testing for DDT, the once common pesticide banned in 1972 for significant health risk, came up negative.<\/p>\n The water board also asked the city to test Cesar Chavez Park for Per- and Polyfluoroalkyl Substances (PFAS), also known as \u201cforever chemicals,\u201d because they don\u2019t completely break down and show up in human tissue.<\/p>\n Berkeleyside has asked the city for an update on this testing.<\/a><\/p>\n As well, the city continues working on fixes and upgrades to the gas collection system related to flaring, or periodic methane gas burn offs.\u00a0<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/large-Cesar-Chavez-Park-drone-photo.jpg\")
Cesar Chavez Park in June 2020. Credit: Phil Rowntree<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/large-IMG_1231.jpg\")
Cesar Chavez Park sits directly on top of a former city landfill. Since the 1980s, a flare station at the park\u2019s eastern edge has turned methane-filled landfill gas into less harmful carbon dioxide. File photo: Kelly Sullivan<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/OffLeashDogs_CesarChavez__Natera_241024_02-scaled.jpg\")
Lou, a 1-year-old dog, laps up water from a hose at Cesar Chavez Park in 2024. File photo: Ximena Natera, Berkeleyside\/CatchLight Local<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/20250706_102915_1.jpg\")
Carlene Chang uses scissors to weed the Native Plant Area on July 6. Credit: Martin Nicolaus<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/us-ca\/wp-content\/uploads\/2025\/11\/Screenshot-2024-09-11-at-3.29.58\u202fPM.png\")
The city conducted overhead drone monitoring in 2024, finding \u201ctypical background levels of radiation expected in the ambient environment\u201d at the park\u2019s surface and shallow subsurface.\u00a0Credit: City of Berkeley<\/p>\n