A. Sampling Plan
A sampling plan should be conducted before any sampling has begun. The following are special considerations that should be taken into account when formulating an Optical Brightener Sampling Plan.
1. Combining Optical Brightener sampling with other data
One should be very careful in drawing conclusions from Optical Brightener sampling alone. Optical Brightener sampling is infinitely more accurate and therefore much more useful when it is part of a larger sampling program. When conducting Optical Brightener sampling for marginal or failing septic systems, it is recommended that the monitoring plan also include information on:
a.) Rainfall - Quite obviously, there are fewer potential sources of contamination during dry weather than during wet weather. Rainfall data is therefore vital in being able to pin-point a source(s).
b.) Bacterial Sampling- Because Optical Brightener sampling only provides presence/ absence data, it is important to remember that in many instances, bacterial sampling is necessary to provide quantitative results about a pollution source. Quantitative results are required to determine the concentration of pollutants in a water sample to evaluate the relative contribution of a pollution source to water quality problems and to help guide pollution remediation and enforcement decisions.
c.) Flow data - Flow data is vital information in monitoring as well as in remediation because:
- Without water as a transport vehicle, waste water has no way of reaching and then impacting receiving waters from upland sources.
- Volume flows are needed when calculating bacterial loading. Bacterial loading is calculated by measuring flow in gallons per minute, the number of bacteria in a 100 ml portion taken from that source, and entering this information into the formula: Bac/day = bac x Q x 54800 (where bac= bacterial concentration per 100ml of water and Q is gallons per minute) Kittrell, 1969. Bacterial loading calculations are used to figure the total number of bacteria per day that is being contributed by a source (or sources) to receiving waters and is critical in being able to compare the relative contribution of pollution sources. (As an example: a site which has a bacterial count of 240/100ml and a volume of 100 gallons per minute would have ten times the bacterial loading as a site that has a count of 2,400/100ml and a volume flow of only 1 gallon per minute.)
- Sometimes rainfall and high groundwater can dilute Optical Brightener dye to such a degree that it can not be detected through qualitative sampling.
- By profiling dry weather flow data, one is able to calculate periods of seasonally high and seasonally low groundwater tables.
- Because a high water table can sometimes cause substandard on-site septic systems to fail, there are instances where a sample will be repeatedly negative during low groundwater periods and yet positive during periods of high groundwater.
- It is advantageous to take flow measurements just prior to placement of the rigid O.B. sampling device.
d.) Field Observations- Probably the most essential of all monitoring programs as well as the most difficult to quantify into a database. Some of the more common field observations are :
2. Optical Brightener Data Sheet (see Appendix A)
It is essential that all pertinent information be written on the Optical Brightener Data Sheet, at the time of placement, at the time of retrieval, and immediately after reading the results. Information as to total rainfall and the total number of days the sample was in place can be entered at a more convenient time if it is so desired. It should also be noted (because the O.B. pad remains on site for a period of time) that the total amount of rain that has fallen while the sample is in place is more appropriate than when the last rainfall occurred. For purposes of simplicity, it is sufficient to note total rainfall in one-half inch increments.
3. Proper handling
When handling samples that have been exposed to waters that might contain waste-water, it is always advisable to wear plastic or rubber gloves while handling these samples and to wash ones hands very thoroughly afterwards.
All rigid sampling devices should be rinsed thoroughly in a strong stream of tap water before reuse to prevent potential cross contamination.
It is also a good precaution to avoid direct contact with laundry soaps and detergents for 24 hrs. prior to handling any sampling equipment.
4. Quality Control
Although the analysis is relatively simple and straight forward, the reading of these samples should be done by people who have been trained in the reading of Optical Brightener results or at least involved in other forms of qualitative sampling.
As a quality control check, it is recommended that 10 to 20% of all O.B. pads be re-read by properly trained personnel. One source of obtaining this quality control check is the Gloucester Shellfish Department at (978) 281-9741
Another quality control check for monitoring groups is to have a designated portion of their retrieved samples quantitatively sampled. One source for obtaining quantitative results for a fee is:
Ozark Underground Laboratory
Rt. 1, Box 62
It should be noted that some laboratories require different protocol for the retrieving and handling of samples that will be tested for quantitative results. This information is best obtained by contacting the laboratory that will be conducting those tests.
1. Because Optical Brightener is so pervasive when dealing with cotton products, the first hurdle a would-be monitor must overcome is to find a reliable source of untreated cotton pads.
One source for purchasing untreated cotton pads is:
V.W.R. Scientific Products
200 Center Square Rd.
Bridgeport, New Jersey 08014
All cotton pads, regardless of their source, should be checked under a long wave Ultra Violet fluorescent light to make sure they do not contain Optical Brightener before they are used.
Optical Brightener Sampling Devices
2. It is necessary to have a rigid sampling device that will hold the cotton pad securely in place while allowing water to easily pass through it.
In open pipe or stream sampling it is recommended that the rigid sampling device be non-metal plastic or a vinyl coated black 1/2 wire cage that consists of two hinged pieces that measure approximately 5 by 5. This cage should be fabricated so that it will rest at approximately a 30 to 45 degree angle. The open end of this cage is closed with an elastic band.
In sampling catch basins it is recommended that the sampling device be constructed from 1/2 mesh black plastic netting that is closed at the bottom to create a bag. Small stones are placed in the bottom of the bag so that it will not float. The cotton pad sampler is then stapled above these stones to the plastic netting.
One source for purchasing sampling devices is:
Winchester Fishing Co.
18 Washington St.
Gloucester, Mass. 01930
(978) 281-1619, 283-0757
3. A long wave 4-6 watt fluorescent Ultra Violet (U.V.) light should be used for analysis. Although the most costly component of O.B. sampling, this is critical as the U.V. light must be of sufficient strength and quality to make definitive results possible.
One source for purchasing a long wave U.V. 4-6 watt fluorescent light is:
200 Center Square Rd.
Bridgeport, New Jersey 08014
Next: Step 2