The Park Avenue line has not been updated since it was first installed in the 19th century. However, a new road (Max Solard Drive) was constructed in the 1980s at the entrance to Pioneer Park (Nimrod Road), which included a 6-inch replacement main within the utility easement. This left a 430-foot segment of remnant 4-inch line underneath Park Avenue.
The difference in size between the two lines has resulted in a significant pressure differential, which in turn impacts fire flows and residential water pressure. The critical flow requirement for fighting fires is 1,000 gpm, at 20 pounds per square inch (psi). The line currently provides 336 gpm, occasionally at zero psi. Additionally, because of its age, the pipe has significant deposition of both rust and captured materials, thereby effectively reducing the line size to 2 inches. Finally, the pipe is assumed to be leaking at several locations; however, the City has not had sufficient funds to inspect the line, nor available equipment to detect specific leak locations, and no real capacity to replace the line due to limited funding.
Residents in the area are accustomed to managing their pressure by adaptive strategies, such as turning off the washing machine in order to take a shower, or turning off outdoor irrigation to run their clothes washer. However, in a situation which requires provision of fire flows to the area, there is no available option. Nevada City recently passed an ordinance requiring all new construction to install interior fire sprinklers. There is inadequate pressure on this reach of the Park Avenue main to support the installation of sprinklers in new or remodeled homes.
This project includes improvement of the line to a 6-inch diameter (to accommodate fire flows and pressure requirements), as well as a realignment of the main. Finally, all residential laterals will be reconfigured to allow supply to the realigned main.
Current Status (Sept 2016)
The Park Avenue project was completed in December 2014.
The Park Avenue project design and bid materials were completed in the late spring and early summer of 2014. The project went to bid in July 2014 and the contact was awarded to Hansen Brothers Construction in August. Final Notice to Proceed was issued in in September 2014, with construction fully completed on December 5, 2014. All ‘as built’ drawings and specification were completed in December, as was the post-project demobilization inspection.
Post-project monitoring is completed and documents significant increases in both pressure and flow (an increase in flow volumes from a low of 336 to 1,000 gpm and an increase in pressure from 20 to 60 psi).
City of Nevada City
Catrina Olson, Assistant City Manager, (530) 265-2496 x134, firstname.lastname@example.org
Measurable Physical Benefits
Water Supply , Water Quality