Since the first dye trace was performed in 1877 to trace the sinking
portions of the upper Danube river, fluorescent dyes have remained the
best and most used tools for determining groundwater flow. Very low toxicity
and extremely low detection limits combine to make fluorescent dye tracing
a standard tool for development of a site hydrogeologic model, particularly
in the area of risk assessment.
The methods that Crawford Hydrology Laboratory have developed are the
result of 25 years of scientific research and practical field experience.
As dye tracing has grown into a high-tech science, our methods have set
new standards. Regulators from 8 states, the US EPA and the USGS, as well
as consultants from many Environmental Consulting Firms, have our field
and laboratory procedures on-file for use as reference when working in
areas of carbonate bedrock.
The Crawford Hydrology Laboratory
m provides the following services:
- Extraction, classification and quantification of fluorescent dyes
from activated charcoal or carbon samples
- Classification and quantification of fluorescent dyes in water samples
- Matrix interference investigations
- Analysis for 10 different fluorescent dyes
|
A small waterfall flowing
over a carpet
of moss is turned red by Rhodamine WT dye. |
Dye Trace Analysis
The Lab uses a Shimadzu's RF-5301PC Spectrofluorophotometer that is capable of detecting fluorescent dyes at
concentrations as low as 5 parts per trillion. This instrument meets ISO-9001 certification with
signal-to-noise ratios over 4 times that of Shimadzu's previous models
(RF5000U and RF540). The instrument is covered by a comprehensive service contract that provides for 24 hour
repair or replacement in the event of a malfunction.
Multiple Traces
Through utilization of non-linear, curve-fitting software, samples can be analyzed for 10 different fluorescent dyes (6 on charcoal, 3 on cotton, 9 in water). In a situation requiring multiple tracers, up to 10 dyes are available (of which 6 can be injected into the same location simultaneously).
Dye Tracing Supplies
large part of any Quality Assurance/Quality Control plan is control
of the materials used during the study. The same high-quality supplies
used in our own investigations are available for purchase at reasonable
prices. Supplies include but are not limited to:
