Stormwater Capture Facility Project at Cartan Field

The Town has hired Tetra Tech Inc. to prepare preliminary engineering concept designs for a stormwater capture facility at Cartan Field, 30 Alejandra Avenue, adjacent to the campuses of Menlo College and Menlo School. The project would include a diversion structure to re-direct dry-weather urban runoff,  and low-flow wet-weather runoff from the Atherton Channel through a pre-treatment device to remove trash, debris, and sediment before conveying the water into a buried multi-chambered storage/infiltration facility with a targeted storage capacity of up to nine (9) acre-feet. The facility would also be managed to reduce peak flows from forecasted high-flow storm events.

The need for a stormwater detention/storage facility was identified in in the Town-wide Drainage Study Update prepared in 2015 to reduce flooding associated with the Atherton Channel. Approximately 10 acre-feet of detention/storage capacity is needed to manage a 10-year storm event to minimize flooding associated with the existing Marsh Road box culvert. Additionally, the Town is required to comply with the Municipal Regional Permit (MRP) issued by the San Francisco Bay Regional Water Quality Control Board. The MRP requires all permittees to implement green infrastructure improvements to reduce the amount of mercury and polychlorinated biphenyl (PCB) in stormwater discharges to the San Francisco Bay. Caltrans has agreed to contribute funding to the Town of Atherton for the construction of a stormwater capture and treatment facility in the Town, to assist with their stormwater permit requirements.

The 2015 Town-wide Drainage Study Update identified three possible sites to capture stormwater from the Atherton Channel: Las Lomitas Elementary School, Holbrook-Palmer Park, and the JL Dixon Stables. Because of the complexity of working with a privately owned site at some distance from the Channel, the Town chose not to locate the project to the JL Dixon Stables. The Town first attempted to work with the Las Lomitas Elementary School District on a stormwater capture project at the school. However, the Town was not able to come to an agreement with the School District for the use of their site. The Town also considered locating the facility at Holbrook-Palmer Park, however that site was ultimately rejected.  Following discussions around a facility at Holbrook-Palmer Park, the Council opted to research alternative locations. The Council directed staff to look into the possibility of a facility in partnership with Menlo College and Menlo School. After initial consultation with the schools, engineering concept designs were developed for a stormwater capture facility located in the outfield of the Menlo College baseball diamond at Cartan Field. The project includes a diversion structure to re-direct dry-weather urban runoff and low-flow wet-weather runoff from the Atherton Channel through a pre-treatment device to remove trash, debris, and sediment before conveying the water into a buried multi-chambered storage/infiltration facility with a targeted storage capacity of up to nine (9) acre-feet. The facility would also be managed to reduce peak flows from forecasted high-flow storm events. Depending on the results of a geotechnical analysis, portions of the storage chamber would be constructed to facilitate infiltration.

A similar project funded by Caltrans is under development at Orange Memorial Park in South San Francisco.

The Town of Atherton has prepared an Initial Study / Mitigated Negative Declaration (IS/MND) for the project, finding that although the proposed project could have a significant effect on the environment, the design features, best management practices, and mitigation measures incorporated into the project will avoid potentially significant impacts. The Town is the Lead Agency and proponent for the project.  The public review period for the IS/MND is from January 8 to February 7, 2020.

CARTAN FIELD STORMWATER CAPTURE PROJECT IS/MND

Please send your comments to:

Lisa Costa Sanders, Town Planner                                                                                         Town of Atherton                                                                                                                         150 Watkins Avenue                                                                                                                     Atherton, CA 94027                                                                                                                 Email: lcostasanders@ci.atherton.ca.us                                                                                     (650) 752-0544 

The Town of Atherton will hold a Community Informational Meeting concerning a proposed Stormwater Capture Facility at Cartan Field on Tuesday, January 21, 2020 at 6:00 p.m. in the Pavilion at Holbrook-Palmer Park, 150 Watkins Avenue, Atherton, at which time and place all persons interested are invited to attend, listen to the presentation, and raise questions or make comments about the proposed Project and/or the Initial Study and draft Mitigated Negative Declaration.  No action on the proposed Project or the Initial Study and draft Mitigated Negative Declaration will be taken at this meeting. Subsequent public hearings will be held by the Planning Commission and City Council on the proposed Project or the Initial Study and draft Mitigated Negative Declaration.

Atherton Water Capture Project Meeting Notices:

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