Staff: Vineyard Reservoir has leak under floor; repairs likely in spring after harvest

Public works staff told the council that a leak has developed in the Vineyard Reservoir and outlined a repair approach that requires emptying the tank and welding a new steel floor plate.

Chuck, public works staff, described the condition: inside the tank a mixing tube and its foundation meet a penetration in the floor where inflow, outlet and drain piping pass. A diver performed dye testing and confirmed water movement indicating the leak’s location. Staff said the repair plan is to cut the affected piping flush, weld a new steel floor plate, move the inlet/outlet piping to the outside of the tank, and reconnect the system. That approach would require emptying the tank and using temporary tanks already available from a prior refurbishment.

Staff noted logistical constraints: the vineyard’s grape harvest limits access in late summer and fall and the steep, unstable access road makes winter work impractical. For those reasons Chuck said the city is now aiming to carry out the work in April–May next year rather than this fall. Staff said the leak is not worsening and appears not to be draining into the vineyard.

Council and staff discussed sequencing and risk. One council member asked whether leaving the repair until spring increased risk; staff replied the leak appears stable and not creating damage to vineyard parcels. There was no formal action at the session; staff said they will plan contractor/diver scheduling and return with a project timeline and cost estimate.

Background: the reservoir was last sandblasted and refinished around 2012–2013, and temporary tanks from that work are still available for use during repairs.