Low Flow Sampling

1. What is low-flow sampling?
In low-flow sampling a well is purged at a very low rate to minimize drawdown and avoid disturbance in the well, rather than purging a well at a high rate and removing 3-5 volumes of the casing.

2. What are the advantages of low-flow sampling?
Low-flow sampling has a number of important advantages, but they all boil down to better samples at a lower cost. Low-Flow Sampling minimizes drawdown, turbidity and purge volume. Proactive’s™ dedicated pumps will not disturb well water.

Here’s Why:
Less well disturbance leads to lower sample turbidity, which in turn reduces the variability in the sampling results. Purge volume reduced up to 95%; can reduce purge time/labor in most cases. Reduces problems related to excessive drawdown and pumped volumes. Dedicated equipment for low-flow sampling saves even more field time and eliminates contamination from other wells and equipment handling.

Did You Know…
Traditional Sampling or High-flow pumping increases drawdown, turbidity and purge volume. Bailer movement surges and mixes well, thus, increases turbidity.

3. What equipment do I need to low-flow sample?
* A sampling device capable of consistently providing low flow rates without agitating the water in the well or altering sample quality.
* A flow cell to determine completion of purging.
* A water level measurement device to measure drawdown.
* With any of Proactive™ pumps the field technician can now low flow sample in an easy and cost effective way!

Portable sampling devices can be used for low-flow sampling, but their use can require more time and extra procedures. First, lowering a portable device into the well mixes the water column between the upper, more stagnant zone, and the screened zone, adding significantly to the time required to complete purging. Second, portable equipment requires cleaning, handling and setup steps; dedicated systems do not.

How do I Low-Flow Sample?
1. What purge flow rate?
Determine a purge flow rate which will minimize drawdown, commonly less than 1 liter/min.

2. How long to purge?
Passing the purge flow through a flow cell measures key water quality parameters, allowing observation of the point when the readings become stable. This commonly occurs within 10-20 minutes, but depends on the well. Sample collection can begin at this point.

3. How much will it cost?
Dedicated PVC pumps from Proactive™ normally reduce costs enough to pay for itself in usually around the first round of sampling! Yes, you read that right, usually within the first round of sampling! Proactive™ manufacturers over 10 pumps all with specific depth capabilities. For example we design pumps that can sample from 25 feet all the way down to 200 feet! A small addition cost is the purchase or rental of a Flow cell.

4. How will low-flow sampling affect regulatory approval of my existing sampling program?
State and federal acceptance of low-flow sampling has been very good, Proactive™ has currently hundreds of sites using our pumps for low-flow sampling . Most of the time, local agencies require only a simple letter for switching over to low-flow sampling. For situations where questions or complexities arise, call Proactive™ for assistance.

5. How can I get started?
Call Proactive™ today at 1.941.322.8504 for immediate, no-obligation assistance.
Or email us at: techsupport@gopronow.biz