King County Road Services - Low Impact Development (LID) for Roads - Military Road S. at S. 272nd St. Project - Water quality monitoring data

ISCO Equipment information

Bioretention facility water quality and inflow/outflow velocities will be monitored throughout the first three years of operation. All water-related field measurements will utilize Teledyne ISCO equipment.

ISCO 6712 Series Auto-Sampler

Water quality samples will be collected using the ISCO 6712 series auto-sampler equipped with 22 one-liter high density polyethylene (HDPE) sample bottles and two glass 350 mL bottles. The HDPE bottles will house samples for testing metals and suspended solids, and the glass bottles will house samples for testing trace organics and diesel fuels. Volumes collected by the ISCO 6712 will be proportional to flows of the facility’s influent and effluent.

Collection will consist of 22 sequential samples per sampling period. Each sample line will be fitted with a custom, pre-cleaned, non-contaminating screen to prevent large material from entering the 6712’s containers. Inflow samples will be collected during “trigger” storm events—when adequate volumes for sampling are likely to be generated—and properly sequenced to ensure samples represent the range of contaminant concentrations throughout the duration of the storm event. All samples will be held on ice and transported to a King County laboratory.

The 6712 sampler requires no volumetric calibration, although manual volume calibration can be performed were sample volumes to vary from programmed volumes. A routine maintenance checklist will be followed biannually to ensure proper operation: once prior to wet season sampling and once prior to dry season sampling.

For ISCO 6712 specifications, please see the 6712 Portable Samplers Installation and Operation Guide (5MB .pdf) on the ISCO Web site.

ISCO 4250 Area Velocity Flow Meter

Water velocities of bioretention facility inflows and outflows, as well as the depths of standing water in the facility, will be measured by an ISCO 4250 Area Velocity Flow Meter attached to the 6712 auto-sampler.

The ISCO 4250 will be programmed to continually monitor water elevations and velocities whenever stormwater is flowing into and/or out of the bioretention facility. To ensure accuracy in measuring flows, readings from the 4250 will be verified against a separate flow meter prior to installation. To ensure accuracy in measuring pond depth, readings from the 4250 will be verified manually using a ruler. Corrections will be made as necessary.

The 4250 Area Velocity Flow Meter requires no calibration before or during use. Cleaning will be performed per the Teledyne ISCO recommendations and procedures.

For ISCO 4250 specifications, please see the 4250 Area Velocity Flow Meter Installation and Operation Guide (5MB .pdf) on the ISCO Web site.