Sampling Requirements for NPDES Compliance

The purpose of this module is to help those who operate facilities and do their own stormwater sampling. The results of sampling will be helpful for developing a facility’s Stormwater Pollution Prevention Plan (SWPPP), determining if facility’s existing plan is adequate, and implementing or assessing Best Management Practices (BMPs). To have a representative and valid stormwater monitoring data, it is critical to have well prepared sampling plan and to follow it through step-by-step.

To develop a comprehensive sampling plan all personnel involvd in sample collection, sample analysis, data analysis, process engineers, and quality assurance need to be included Through the meeting, a document that describes sampling objectives, lists the individual tasks, and identifies how those tasks will be performed will be developed. The following contents need to be included in a sampling plan:

• Background information about the outfalls to be sampled

• Appropriate sampling equipment, containers, preservatives need to be selected

• The number, volume, and sampling sites need to be decided

Sampling Plan

• Developing a stormwater sampling plan

• Sampling point selection

• Type of sampling method needed

• Industrial stormwater discharge parameters

• Special consideration when collecting oil and grease samples

• Alternate Sampling Methods

• Laboratory selection and questions for the lab

• Sampling Related Health and Safety Issues

Sampling Procedures

• Sampling Preparation

• How to Fill the Sampling Bottle

• Selecting a Storm Event for Sampling

• Sampling a Snowmelt Event

• Chain-of-custody procedures

• Sample documentation

• Recording field notebook

• Sample Identification and Labeling

• Sample packaging and shipping

The detailed sampling procedure for stormwater is published by the EPA’s NPDES Storm Water Sampling Guidance Document, EPA 833-8-92-001.

Copyright @ January,2005 Prepared by Transportation Environmental Resource Center (TERC)