water Quality 2/18

Students may need to fill out forms regarding their progress and needs for clarity on procedures.
Emphasize the importance of ensuring everyone understands the required actions for form completion.

A lawsuit regarding illegal sewer overflows has been recently filed.
Documented illegal sewer overflows include 76 cases in Charleston due to older infrastructure.
Infiltration: Rainwater seeps into cracked sewer pipes, leading to pressure build-up.
- Result: Raw sewage is ejected through manholes.
A major incident occurred in December 2023, releasing 40,000 gallons of untreated sewage into Charleston Harbor.
Charleston Water Keeper has criticized local authorities for neglecting the infrastructure issues related to sewer systems for decades.
Proposed solutions include:
- Slip lining: Technique to extend the life of pipes by coating them with a protective polymer.
- Smoke testing: Involves injecting smoke into pipes to locate breaks or trouble areas.
- Difficulty in repairs stems from the age (some pipes are over 200 years old) and lack of mapping information regarding existing sewer systems.

Introduction to the IDEXX E. Coli method
- Single reagent container used for detecting bacteria in fecal samples.
- Nutrient indicators change color and fluoresce under specific conditions.
Measurement specifics: down to 1 colony-forming unit in 100 mL sample within 18 hours.
Distinction between E. coli and total fecal coliforms:
- Both detected but yellow coloration indicates presence of total coliforms; further analysis needed for specific identification.
Issues of specificity and potential false positives noted in marine waters.
- Importance of further testing for confirmation.

Most Probable Number (MPN): A statistical estimate of bacteria concentration based on sample data.
Discussions around detection limits and statistical probability in relation to water sample testing were highlighted.
- Must report as less than one if no colonies are detected.
Understanding precision and control limits in testing:
- Relative Percent Difference (RPD) used to assess duplicates in lab results.
- Various acceptable RPD thresholds are discussed for different concentrations.

Sampling technique employing field duplicates to check for precision in non-homogeneous water samples.
Comparison between lab duplicate and field duplicate results reveals insights into measurement consistency under field conditions.
Discussion of factors leading to high RPD observed in field measurements, such as settling of bacteria in water.

Procedures should be followed as per SOP to ensure proper corrective actions when duplicates exceed control limits.
Communication with clients regarding unusual results and potential risks is essential.

Initial Demonstration of Capability (IDOC) for students involves precise control over measurements to demonstrate lab analytical skills.
Each testing run incorporates calibration checks using secondary standards.
Importance of understanding and correctly using significant figures in laboratory measurements and calculations.

Students encouraged to analyze lab reports from GEL to familiarize themselves with quality control measures.
Future lessons will include deeper dives into equipment functioning and methods of analysis for different environmental samples.