If vacuum relief is needed in the main lines these are additional to those used to prevent soil ingestion. The ingested soil can lodge between the diaphragm and the labyrinth sealing surface and cause an increase in flow. Use slow closing valves. Gophers have not been a significant problem. Ensure that the wetted circles from the emitters overlap so that all the dripline is in wetted soil.
Gophers appear to prefer to dig through dry soil.
Injection of acids and other chemicals which may legally be used for this application is not a long term solution for permanent crops. There is one grade of trifluralin which as of February 1995 may be applied to a buried drip system at the rate of one teaspoon per 15,000 emitters three time per annum. If the grower has 1,500 drippers per acre then the application rate is one teaspoon for ten acres. This registration is new and at this time there is no published evidence that this dose is either practical or effective. When the system is installed a standard flow rate at standard pressures should be established for each section.