Contaminated groundwater issue causes short term delay in downtown project; Additional lanes to open after Memorial Day; project is still on schedule to be completed by late 2018

TILLAMOOK— A goal to open two lanes of U.S. 101 in both directions by Memorial Day will be delayed until later this summer because of a significant amount of contaminated groundwater that was discovered during excavation at the site of the U.S. 101/OR 6 Project in Tillamook.

To address the problem, the contractor will need to perform extra work, pushing back the first deadline for work accomplished.    The plan was to have the east half of the Hoquarton Slough Bridge finished by Memorial Day with two lanes open on U.S. 101 in both directions.  Now, that will not happen until later in the summer.

The contractor is currently working on the east half of the bridge with one lane open in both directions.  The goal is to have one additional southbound lane open before June 9. Also, after Memorial Day, the contractor will have two lanes open on Pacific Avenue in Tillamook.  Overall, the project is still on-schedule to be completed by the end of 2018.

Background:  During excavation earlier in the winter, a significant amount of contaminated groundwater was discovered in the area just east of U.S. 101 and south of the slough.  Heavy and consistent rainfall throughout the winter and spring have added much more water to the site and further complicated the treatment process.   The contractor and ODOT needed to determine how to address the problem, and the contractor has been forced to concentrate resources on this issue, thereby putting the bridge construction behind schedule.

A company that specializes in treatment of contaminated water has provided a treatment system approved by the Department of Environmental Quality.  At the construction site, two 20,000 gallon tanks are used to pump out the contaminated water, filter and treat it and discharge it back in to the slough.  The system only treats the water.  It is not designed to clean up the site.

Prior to the start of construction, ODOT drilled test holes at the construction site and suspected that there might be contamination issues.   The history of the site included an old sawmill and
other businesses that could have been the source of the contamination over time.  However, ODOT did not expect the extent of and the quantity of contaminated water that was discovered.

Once the site has a chance to dry out this summer excavation activities should get back to normal and there will be much less contaminated water to treat.

ODOT is working with the contractor on a plan that will accelerate work and minimize any additional schedule impacts.   There is enough time in the overall schedule to get all the necessary work done by the end of 2018, as originally planned.

The Oregon Transportation Commission (OTC) has approved an additional $2.5 million of mostly unexpended Jobs and Transportation Act funds for treatment of the contaminated water and for accelerating the work.

ODOT and the contractor will make attempts to open the extra lanes as soon as possible.

When the project is finished, travelers on U.S. 101 through downtown Tillamook will experience wider streets, a safer and more intuitive U.S. 101/OR 6 intersection, a new four-lane bridge that will include bike lanes, wider sidewalks, viewing platforms and other aesthetic enhancements.