Palo Alto’s new dewatering policy takes effect on May 4, 2017. The stated goal for this new policy is to minimize the discharge of groundwater from construction dewatering; it applies to projects that do not have their building permits as of May 4th. Application forms and information for applicants and contractors are available in the section titled “Construction Dewatering Plan Guidelines” on the City’s website. You can see the City’s map of pending dewatering sites for 2017 here. The new dewatering policy is summarized below.
Summary of Regulations: The applicant needs to submit a Comprehensive Geotechnical Study, stamped by a California licensed Geotechnical Engineer, that verifies the anticipated drawdown curve with a pump test using actual wells. The actual pumping rates and total amount of water allowed to be pumped will be limited to what is determined in the Geotechnical Study. If projects can demonstrate, through design techniques such as cut off walls, that the groundwater pumping is continuously limited to 30 gallons/minute, the Geotechnical Study and verification are not required.
During a 2-week “startup period” applicants will need to demonstrate to City inspectors that the site is in compliance with all performance standards and water quality standards, including maximum 10-minute water truck fill time and 2 hose bibs and hoses with each having required flow rates of 10 gallons/minute for use by neighbors.
After the two week start up period, applicants will need to report on all measurements and requirements, and will need to submit biweekly reports throughout the 10-week dewatering period. The sites will only be allowed to pump the groundwater down no deeper than 3 feet below the center of the basement slab. Once the slab is poured, the depth to the center of the slab shall be 1 foot. Additionally, during dewatering, applicants are required to offer to water trees/plants on adjacent properties and do so if requested.
Did Save Palo Alto’s Groundwater want or request more regulations and new policies? No. In our view, the simplest solution (based on this USGS study) to minimize groundwater waste is a simple “No dewatering for underground construction where the groundwater table is less than 13 feet below ground surface.” This would substantially decrease groundwater waste, diminish flooding risk and protect our canopy, our properties, and our infrastructure.
The City, however, is not willing to go that far and we believe the regulations above are a step in the right direction. Our job is not done, however, until we achieve zero waste of groundwater and maximum protection of our canopy, neighboring properties and infrastructure. The City and Save Palo Alto’s Groundwater will monitor how well these new 2017 policies help with our stated goals. City Staff is expected to return to Council later this year with additional proposals for 2018 and later. We need your continued and unwavering support to help us achieve our goals.