Stormwater Management and Testing Basics

As our communities grow and living spaces become denser, stormwater management is becoming more critical. Local, county and the national government are becoming increasingly focused on stormwater management as it offers solutions to problems like water quality, water scarcity, flooding and pollution. This article will help you understand the basics of stormwater management and the critical step of stormwater testing.

What is Stormwater?

Stormwater is water that originates from precipitation like snow or rain. This precipitation lands on the earth and can either be absorbed into the ground and become groundwater or move along a surface and become runoff. Runoff is the primary concern of stormwater management. Stormwater needs to be guided safely to bodies of water to prevent flooding and minimise pollution. While all precipitation is technically stormwater, the term is most commonly used to refer to runoff.

What is Stormwater Management?

In the UK, stormwater drains typically lead directly into canals, streams, rivers or the sea without any type of water treatment. Modern drainage systems have separate pipes for stormwater and wastewater, with wastewater going to sewage wastewater treatment works (WWTWs). Areas with older infrastructure may use a ‘combined sewer system’ where rainwater mixes with wastewater which goes to a treatment plant. However, during heavy rain, these combined systems often overflow from stormwater overflows (SWOs), releasing untreated sewage into local waterways. Storm drains, culverts, and retention ponds are all used to manage stormwater.

Stormwater management programs (SWMPs) utilise methods like constructing stormwater infrastructure, increasing green spaces and testing stormwater for quality to prevent erosion, reduce flooding, increase water quality, protect the environment, and turn stormwater into a usable resource for the community. Storm drains, culverts to direct stormwater under roads or railways, and retention ponds are all used to manage stormwater on local government maintained land and private land. On private land at high risk of oil contamination, oil interceptors use gravity separation of suspended solids and oil or fuel, allowing cleaner water to be discharged into stormwater system. In areas subject to flooding or where the stormwater system can be easily overwhelmed, attenuation tanks may be used to temporarily store rainwater and release it at a controlled rate.

As our communities and industrial areas grow the amount of pavement, asphalt and other impermeable surface area enlarges which increases the amount of runoff that needs to be managed. When rainwater lands on impermeable surfaces like pavement, it runs across those surfaces picking up contaminants. It will eventually carry these contaminants into a body of natural water. When stormwater is not managed it can cause erosion, flooding, and groundwater or river pollution.

Who is Responsible for Stormwater Management?

Stormwater management is usually the focus of three different groups: government entities, private owners, and environmental groups.

The Government in Stormwater Management

Stormwater is managed in the UK by the Environment Agency, through the use of Water Discharge Activity Permits (WDAPs) which are required to release contaminated water, including surface runoff that may contain pollutants, into watercourses or the ground, in order to prevent pollution. This may include industrial sites, construction sites (managing silt/runoff), as well as water companies. Active management of surface water runoff on construction sites is required to prevent silt/sediment being carried into water courses. Water companies must manage storm and emergency overflows of stormwater and wastewater during periods of heavy rain. Uncontaminated rainwater run off such as in clean roof water soakaways or road runoff may be exempt. Permits are mandatory unless an exemption applies, requiring risk assessments, monitoring, and compliance. The permit is specific to the site or location and sets parameters for the water, including the maximum flow rate, pH, temperature and chemical composition. The permit requires the operator to manage its activities to minimise pollution risk, including mitigation measures and to perform routine sampling and testing of key parameters to ensure compliance.

Stormwater permits in Ireland are regulated by the Environmental Protection Agency (EPA) and local authorities, and are required for the release of contamined water into water courses and groundwater. High emissions activities require an Industrial Emissions (IE) licence and lower emissions activities require an Integrated Pollution Control (IPC) Licences. These require specific controls on stormwater runoff from non-process areas, such as roofs and yards.

In the USA, municipal separate storm sewer systems, or MS4s, are permitted by local authorities who have been authorised by the USEPA. These are a type of National Pollutant Discharge Elimination System (NPDES) permit and are often just referred to as MS4 permits. Government entities are also responsible for finding and confirming violations of these permits.

Private Owners in Stormwater Management

The owners, managers, and employees of industrial sites, construction sites, and other permit holders are responsible for enacting stormwater management programs. They will be managing infrastructure, performing stormwater quality testing, and working to meet regulations.

Environmental Groups in Stormwater Management

Many environmental groups and participatory science groups monitor stormwater. These groups track water quality in their community and help identify where illicit discharges originate from. They often utilise field test kits to get rapid water quality results and work to educate the public about stormwater.

The Benefits of Testing Stormwater

A major aspect of stormwater management is testing stormwater quality. Stormwater testing helps determine the impact stormwater has when it enters waterways. Stormwater monitoring is a requirement of a WDAP, IPC or MS4 permit and can potentially be one of the most expensive requirements of an MS4 program, according to the US National Association of Clean Water Agencies (NACWA). Implementing an appropriate testing regime is critical to the success of a SWMP.

Proper monitoring of stormwater can hold many benefits for the community and the permit holder. Permit holders will prevent costly fines and poor public image in the community. It can also prevent unnecessary damage to equipment and infrastructure. Everyone within the community will benefit from a healthier environment with cleaner waterways.

Figure 1: Stormwater monitoring has many benefits besides reducing the risk of fines.

Sampling

Regardless of the testing method you use you will need to follow specific sampling rules. Stormwater sampling requires consistent documentation and planning. To successfully gather a stormwater sample there needs to be a rain event with 0.1 inches of rain with no rain 24 hours prior to the event. You will also need to be sampling from specific sites in your system. Follow your sampling requirements closely and document accurately. Include information like when the rain started, when you collected your samples, and anything that stood out to you.

Stormwater Testing Methods

Stormwater testing is done in one of two ways, field testing or lab analysis.

Common Stormwater Testing Parameters

While every situation is different, the common tests you will see for stormwater include:

• pH – to determine if the water is acidic or basic.
• Turbidity – measures the haziness of water by measuring ability of light to pass through the sample.
• Total suspended solids (TSS) – is a measurement of the dry weight of non-dissolved particles that can trapped by a filter per given water volume, typically silt, clay, algae and other organic matter.
• Biochemical oxygen demand (BOD) – measures how much dissolved oxygen is consumed by microorganisms.
• Chemical oxygen demand (COD) – measures how much dissolved oxygen is consumed by chemical oxidation of organic matter.
• Hardness - measures amount of dissolved metals in the water, typically calcium and magnesium.

Other stormwater tests include tests for heavy metals, chemicals, or microbes may be done as well depending on the situation.

Stormwater Testing with Aquaphoenix and CHEMetrics

AquaPhoenix and CHEMetrics understand the challenges that come with stormwater testing and have created the AquaPhoenix Stormwater MS4 Test Kit (TKIDDEMS4-STD) to make field testing simpler.

Figure 2: The AquaPhoenix Stormwater MS4 Test Kit lets you protect your waterways with confidence!

The standard MS4 test kit comes with the following CHEMetrics test kits and AquaPhoenix meter.

These tests can also be purchased separately. The test kit is also customisable with optional addon CHEMetrics and AquaPhoenix tests and meters for additional parameters including but not limited to:

• Chlorine
• Colour
• Copper
• Nitrate
• Nitrite
• Oxygen (Dissolved)
• Phenols
• Potassium
• Phosphate (Ortho)
• Turbidity

If you need an analyte not listed, check the list of parameters on the parameters page or contact us for further customisation. The kit comes in a secure plastic case that is foam lined, perfect for carrying out into rainy weather. Don’t be fooled by the name, the AquaPhoenix Stormwater MS4 Test Kit is great for participatory science, environmental groups, or anyone trying to track down an illicit discharge location. No MS4 permit required!