Pore Water Sampling Procedure

Samples of pore water will be collected by the methods described below. Samples from water more than three feet deep may be collected from a boat or sampling barge. Pore water samples will be collected from the top six inches of sediment, which is typically the zone of maximum biological activity. Samples will be collected by means of the sampling device illustrated in Figure 1. The pore water sample device consists of a steel drive point with a 6-inch-long screen at the end. Attached to the drive point will be a metal or PVC stopper plate, which will prevent the drive point from being driven into the sediment beyond the desired depth. The pore water samples will be collected using a peristaltic pump and a length of PVC tubing inserted to the depth of the screen. The sampling device will be pushed into the sediment to the desired depth and then the peristaltic pump will be turned on. Field parameters (e.g., DO, ORP, pH, temperature, turbidity, and conductivity) may also be measured and recorded. Purging will be considered complete when DO, turbidity, conductivity, and pH have approached the stabilization goals provided below, for three consecutive readings taken at intervals of approximately five minutes: • DO and turbidity: 10