Runoff Quality/Peak Rate Control

Runoff Quality/Peak Rate Control SCMs function by retaining/retarding runoff to reduce the peak flow and improve the water quality. Many of these SCMs allow time for evapotranspiration and infiltration during the process.

Peak Rate Control

Hydrology Sampling

In a residential, suburban, urban and ultra-urban SCM, minimal equipment is needed to reach compliance. Storms should be monitored on a seasonal basis to determine the effectiveness of reducing the volume and peak discharge. Data can be compared to precipitation data from a nearby raingage using NOAA-ATLAS 14 (National Weather Service 2007). Storms should be monitored for: 

  • Water Elevation

  • Overflow

Water elevation calculations can help in calculating the overflow. Especially at this type of SCM where there is no probability of completely eliminating overflow, there is a better chance of reducing the peak flow.

Quality Sampling & Quality Parameters

Samples should be acquired on a seasonal basis to assure the SCM is functioning as appropriate quality control. Storms should be monitored for:

  • Physical Properties

Physical properties are important because they can indicate the potential for other pollutants and whether these pollutants are being eliminated between entry and exit, especially TDS because contaminants stick to solids. 

Ecology

Ecology monitoring is not required for Quality Control/Peak Reduction SCMs at this monitoring level.

Hydrology Sampling

Hydrologic monitoring is important at a commercial site because of the potential spills that may increase and contaminate flow through the SCM. Therefore at a compliance level, information other than overflow must be reviewed on a monthly basis for:

  • Water Elevation

  • Storage Volume

  • Overflow

Water elevation calculations can help in calculating the overflow. Especially at this type of SCM where there is no probability of completely eliminating overflow, there is a better chance of reducing the peak flow.  Knowing the storage volume, can give a better understanding of the capacity of the SCM to retain water while reducing the peak flow.

Quality Sampling & Quality Parameters

Quality is important on industrial and commercial sites because of the potential for contaminant spills. Samples should be collected on a monthly basis and tested for site specific chemical contamination including:

  • Physical Properties

  • Nutrients/Ionic Species

  • Total Recoverable Metals

Physical properties are important because they can indicate whether other pollutants potentially contaminate the water source and whether they are being eliminated between entry and exit, especially TDS. Nutrients and ionic species should be reviewed because of their effects on eutrophication. Increased levels of nutrients and metals lead to detrimental effects on aquatic life. 

Ecology

Ecology can be important in determining if there are high levels of toxins in runoff. Various toxins can lead to a noticeable decline in plant life or invertebrates. Tests should be completed on a seasonal basis for:

  • Diversity Coverage

  • Invertebrates

A review of diversity and coverage can help determine which plants thrive better in the environment. Additional plants can be introduced to increase evapotranspiration. Invertebrate studies can determine if the toxin levels are increasing or decreasing based on indicator species results.

Hydrology Sampling

At research and educational facilities, the manpower and utilities are available to monitor all hydrological aspects. Therefore data should be recorded on a storm by storm basis with baseflow hydrology being monitored monthly for:

  • Total Precipitation

  • Water Elevation

  • Soil Moisture Content

  • Infiltration Rate

  • Storage Volume

  • Overflow

Water elevation calculations can help in calculating the overflow. Especially at this type of SCM where the probability of completely eliminating overflow is negligible, there is a better chance of a better reduction in peak flow. Additional precipitation readings can help determine the amount of water being introduced to the site while soil moisture content helps determine the storage volume. Knowing the storage volume, can give a better understanding of the capacity the SCM to retain water while reducing the peak flow. 

Quality Sampling & Quality Parameters

At research and educational facilities, the manpower and utilities are available to monitor all quality parameters. Therefore data should be recorded on a monthly basis including sample of baseflow during periods of dry time for:

  • Physical Properties

  • Nutrients/Ionic Species

  • Total Recoverable Metals

Physical properties are important because they can tell indicate whether other pollutants potentially contaminate the water source and whether they are being eliminated between entry and exit, especially TDS. Nutrients and ionic species should be reviewed because of their effects on eutrophication. Increased levels of nutrients and metals lead to detrimental effects on aquatic life. 

Ecology

At research and educational facilities, the manpower and utilities are available to monitor all ecology parameters. Therefore data should be recorded on a seasonal basis for:

  • Diversity/Coverate

  • Nutrient Uptake

  • Invertebrates

  • Vertebrates

A review of diversity and coverage can help determine which plants thrive better in the environment. Additional plants can be introduced to increase evapotranspiration. Nutrient uptake will help determine plants ability to absorb excess nutrients and which plants are more conducive to nutrient uptake. Invertebrate studies can determine if the toxin levels are increasing or decreasing based on indicator species results. Vertebrate studies should be completed because of the possible effects of animals of eating the vegetation and the potential for tampering with equipment.

SCMs

Constructed Wetlands

Wet Pond Retention Basin

Dry Extended Detention Basin