07 - Laserfiche WebLink

BACKGROUND In 2013, the City converted the irrigation system in Val Vista Park to use recycled water, including irrigation of the sand-bed soccer fields which include an underdrain piping system. This was the City's first use of recycled water and was relatively easy to accomplish due to Val Vista Park's close proximity to the DSRSD treatment plant that produces the recycled water. However, as the soccer fields include an underdrain system, new operational procedures were developed as part of the conversion to recycled water. The new procedure was required because when the fields and underdrain system were constructed, the system was designed to be irrigated with potable water allowing the underdrain system to discharge to the storm drain system, and then through the storm drain outfalls into the nearby Alamo Canal. Under the State Water Board General Order that governs the operations of recycled water systems, the recycled water used for irrigation cannot flow into the Alamo Canal. The operational procedure developed to avoid recycled water entering the Alamo Canal involved the City's Parks Maintenance staff installing plugs in the storm drain outfalls during the dry season when irrigation of the fields is required. The procedure allowed the underdrain system to continue the collection of the recycled water and keep the fields in top playing condition, but the recycled water was then stored in the storm drain piping. The stored recycled water was then periodically pumped into the sanitary sewer system. While this operational procedure has allowed the use of recycled water for irrigation for many years, it has proven to be very labor-intensive. In addition, the use of the corrugated metal storm drain piping for storing recycled water has caused significant corrosion of the piping, affecting both its structure and its ability to hold water. In 2018, a study was performed to determine other options to convey the recycled water from the underdrain system to the sanitary sewer system. The alternative chosen by Operations and Engineering staff consisted of making additional connections to the underdrain system and installing approximately 1,800 feet of new piping to convey the recycled water collected by the underdrain system to the sanitary sewer system for disposal. When this alternative was chosen, it was recognized that due to the limited elevation difference between the underdrain system outfalls and the sanitary sewer connection point, pumping would still be required. However, the alternative offered the benefit of using the underdrain system for storage instead of the corrugated metal storm drain piping. As envisioned, the plan includes directional boring of some pipe sections to avoid impacts to the park and its use, as well as open-cut trenching (where feasible) for cost control reasons. The study also identified that two corroded storm drain outfalls, of the several storm drain outfalls servicing Val Vista Park, needed repair. On July 14, 2021, Pakpour was authorized to design and prepare project plans under their on-call agreement with the City for the not-to-exceed amount of$74,480. This task authorization was approved at a staff level as it was under the $100,000 authority- threshold granted to staff. Pakpour's scope of work included the design of the discharge piping from the underdrain system, a detention pit in which a portable pump would be used to empty the stored water, and the design of the repair needed on the two storm drain outfalls. As stated previously, it was understood that pumping would be required. The concept for pumping was modeled after the currently utilized operational procedure, but would intercept the recycled water before it entered the storm drain system. During the design Page 2 of 4