Norwalk updates Hermosillo Park rehabilitation and stormwater infiltration plan; $43M in secured funding, gap remains

City staff and the progressive design-build team on Sept. 2 provided a detailed update on the Hermosillo Park rehabilitation and a stormwater capture and infiltration project that will combine a new community center, two regulation soccer fields, parking and an underground infiltration gallery designed to capture and percolate runoff.

Scope and goals: City staff said the project’s vision — developed in a 2019 master plan and refined with community input — includes a new roughly 8,000‑square‑foot community center with a banquet hall sized to seat about 200 people, two dedicated soccer fields, tiered amphitheater seating, expanded parking and a play area. The stormwater element will incorporate an approximately 11.8 acre‑foot subsurface infiltration basin sized to capture and treat stormwater that would otherwise flow to Coyote Creek and the San Gabriel River.

Design, cost increases and funding: Staff and consultants said design encountered technical and regulatory constraints that increased estimated costs compared with the 2019 estimate. Engineers described requirements from Los Angeles County Flood Control (including freeboard criteria and minimum separation above seasonal high groundwater) that forced design revisions, added pumping and required additional excavation and rerouting of diversion pipes. City staff said the total project financing package includes about $30 million in Measure W funds (recently increased by $9.9 million pending county action), $8.5 million from California State Parks Prop 68, and about $4.6 million from Measure A, together yielding roughly $43 million in secured funding; staff said a funding deficit remains after accounting for updated costs.

Design-build delivery and schedule: The city used a progressive design‑build procurement. Staff and the contractor, Reyes Construction, said that approach allows the team to finalize designs and arrive at a contractor-based cost estimate so work can proceed quickly once all funds and approvals are in hand. Staff described a tight schedule driven by reimbursement and grant deadlines: 30% design by December 2025, final design by June 2026, construction through Dec. 2027 and a firm deadline to submit final reimbursement paperwork in 2028.

Technical and community issues: Engineers said the park’s location is favorable for infiltration but required added pumps and reconfigured diversion piping because of flood-control freeboard and groundwater-separation rules. Staff said certain recreational elements — the splash pad, basketball court and handball courts — have been deferred to a later project in order to allow the contractor full site control and meet the grant‑driven schedule. Council members pressed staff on tree canopy, shade, the proposed tree palette, parking-count rationale and safety measures. Staff said perimeter block walls required repair and added those works to the contract scope.

Construction methods and public outreach: The team described excavating about 50,000 cubic yards for the cut‑and‑cover underground chambers, using precast vault modules for the subsurface galleries and maintaining dust‑control, traffic control and staging plans during excavation. Staff and the contractor said they will provide community outreach including a project website (myfuturepark.org), regular community meetings, direct mail to adjacent residents and school outreach.

Next steps: Staff said the Los Angeles County Board of Supervisors must approve the additional Measure W funds in November and the city expects to bring a construction agreement to council following county action. Staff and designers said they will finalize planting palettes, shading strategies and detailed safety and lighting plans during final design and before construction starts.