Under Pressure: Monitoring, Controlling, and Assessing Groundwater Level Elevations in a Tidally Influenced Aquifer

Oral Presentation

Prepared by B. Johnson1, J. Edwards1, M. Riley1, J. Renda1, B. Wyatt2
1 - Anchor QEA, 6650 SW Redwood Ln, Suite #333, Portland, OR, 97224, United States
2 - NW Natural, 220 NW 2nd Avenue, Portland, OR, 97209, United States


Contact Information: bjohnson@anchorqea.com; 503-679-4543


ABSTRACT

Monitoring, controlling, and assessing groundwater level elevations are fundamental components of a Hydraulic Control and Containment (HC&C) system installed along 0.45mi of the Willamette River at a former manufactured gas plant in Portland, Oregon. To achieve project goals a network of 102 extraction wells, control wells, monitoring wells and piezometers have been installed. Each of these system components has been outfitted with a pressure transducer designed to collect high resolution groundwater level elevation data in-situ. Data from transducers connected to the HC&C system are channeled through Programmable Logic Controls that manage extraction well pumping rates thereby preventing groundwater discharge to the river. Hydraulic control is maintained over the full range of tidal and stage conditions in the Willamette River. Confirmation of the HC&C systems performance is being assessed through extensive field testing. Groundwater level elevation data collected from connected wells during the tests are channeled through Excel Reporter to a server database from which queries and analyses can be executed. To assist in the assessment of these data a series of analyses have been programmed in MODFLOW and IDL using water level data uploaded to the server. Outputs including potentiometric surface maps, vertical gradient maps, and particle tracking analysis are being used to assess hydraulic control site wide.