Frequently Asked Questions
Does 811 cover all the utility lines in Forest Grove?
No. Oregon 811 locates only utilities whose owners are registered with the notification center and have active service. Private lines from the main to your building, abandoned pipes that were taken out of service but left in the ground, and any utility installed before registration was required will not appear on a locate ticket. In Forest Grove, where infrastructure has accumulated since 1850, those unlisted lines are common enough that we treat every trench as potentially occupied until potholing confirms otherwise.
What is potholing and when do you use it?
Potholing means digging a small test hole by hand or with a vacuum excavator directly over a suspected utility crossing to expose the actual pipe or conduit and confirm its depth and position. We use it whenever a locate ticket shows a utility crossing our planned trench line, and whenever the site history suggests buried infrastructure that did not show up on the locate. It takes less than an hour per crossing and prevents the much longer delay of a struck line and emergency repair.
Why does my trench need dewatering if it has not rained recently?
The Tualatin Valley water table rises through the October-to-May wet season and stays elevated in low areas near surface water. Forest Grove has 0.14 square mile of surface water within its 5.88 square miles, which keeps groundwater close to the surface in surrounding areas even during dry stretches. A trench that intercepts the water table will fill from the bottom regardless of recent rainfall. Dewatering pumps the groundwater out continuously while pipe is being placed so the bedding stays dry and compactable.
What bedding material do you use in Forest Grove trenches?
We use clean, angular crushed rock in the bedding zone rather than native soil. Tualatin Valley silty clay retains moisture and does not compact uniformly enough to support a pipe without long-term settlement. Crushed rock in the correct gradation for the pipe diameter is imported, placed in the trench, tamped in lifts, and tested before the pipe goes down. Above the bedding zone, native soil is returned and compacted in lifts to match surrounding density.
How much does utility trenching in Forest Grove typically cost?
Cost depends on trench length, depth, soil conditions, and whether dewatering equipment is needed. An urban lateral in reasonably clear ground costs less per foot than a trench that requires potholing at multiple crossings, continuous dewatering, and hand work around existing tree roots or hardscape. We give fixed quotes after a site visit because Forest Grove’s variable subsurface history makes per-foot estimates unreliable until we know what we are actually dealing with underground.
Do I need a permit to trench across my own property?
A permit is typically required any time the trench crosses or opens a public right-of-way, connects to a public utility main, or disturbs soil within a Clean Water Services buffer near a waterway. Work entirely within private property that does not touch a public right-of-way may not require a separate trench permit, but the utility connection itself usually requires an inspection. Washington County and the City of Forest Grove each have permit offices; we identify which applies and what is required before the job starts.
