Stormwater Chemistry and Water Quality Georgetown County Stormwater Division Tracy Jones, P.E. – Division Manager Zollie Green, P.E. – Senior Engineer.

Stormwater Chemistry and Water Quality

Georgetown County Stormwater Division

Tracy Jones, P.E. – Division ManagerZollie Green, P.E. – Senior Engineer

Shelly Jordan – Quality/Billing CoordinatorChris Allen – Inspector

What we do?

Plan Reviews Inspections Capital Projects Drainage Complaints Utility Fee

Funds our division

What is Stormwater?

Rain or snow that falls on streets, parking areas, rooftops and other developed land and either flows directly into nearby streams or travels through drainage systems.

The flows are then discharged, untreated, into Georgetown County’s drainage ways.

An area of land that drains to a single outlet.

WHAT IS A WATERSHED?WHAT IS A WATERSHED?

Pee Dee Basin (HUC4-0304)

Impervious Surfaces

Materials like cement, asphalt, roofing, and compacted soil that prevent percolation of runoff into the ground.

Components of Impervious Cover in the Urban LandscapeComponents of Impervious Cover in the Urban Landscape

Roads

ParkingParking

BuildingsBuildings

SidewalksSidewalks

DrivewaysDriveways

Center for Watershed Protection

Point Source Pollution

Nonpoint SourcePollution

Where does this go?Industrial/Commercial – each discharge has its own permitNPDES TRI & PCS

What is an Illicit Discharge?

Georgetown County Stormwater Ordinance defines an Illicit Discharge as: “Any activity which results in a

discharge to the Georgetown County Storm Water System or receiving waters that is not composed entirely of storm water, except a discharge pursuant to an NPDES permit and other allowable discharges as defined in this Ordinance.”

Allowable Discharges-Unless a significant contributor of pollutants

Water line flushing Landscape irrigation Diverted stream flows Rising ground water Uncontaminated

ground water infiltration

Uncontaminated pumped ground water

Discharges from potable water sources

Foundation drains Air conditioning

condensation Irrigation water Springs Water from crawl

space pumps

“Uncontaminated” is the key word!

Sources of Stormwater Pollution

Street Pavement Components of road surface degradation are

common constituents of urban runoff. Motor Vehicles

Contribute a wide variety of materials to runoff flow.

Fuels, lubricants, particles from tires or brake lining, exhaust emissions which collect on the roadway surface, corrosion products, parts which fall from vehicles.

Organics, nutrients and suspended solids which have become attached to the vehicle are washed onto the roadway by the action of the rain or splashing from street runoff.

Sources (cont’d)

Atmospheric Fallout Air pollution such as dust and particles from

industrial practices, acid particles, heavy metals from fossil fuel power plants, emissions from automobiles and planes, and from exposed land.

Vegetation Waste matter is an important source of organic

and nutrient pollutants in urban stormwater. Leaves, grass, and other plant material

that fall or become deposited in urban areas may become part of the stormwater runoff flows.

Sources (cont’d)

Land Surface The type of ground cover found in a drainage

basin as well as the amount of vehicular and pedestrian traffic is a function of land use and will have a direct effect on the quality of stormwater runoff in that area.

Litter Consists of various kinds of discarded material

such as food containers, packaging material and animal waste.

In some areas, animal waste has been shown to be a major contributor of both nutrients and bacterial contamination in runoff

Anti-Skid Compounds and Chemicals Governments in cold weather regions deploy

large amounts of salts, sand, and ash to provide better traction and to melt ice.

These materials accumulate along the roadway during the winter months and become part of the snow melt when spring arrives.

Fertilizers, insecticides and herbicides are often used for maintenance of roadside areas.

Sources (cont’d)

Construction Sites Erosion of soil from land disturbing

during construction activities is a highly visible source of suspended matter in stormwater runoff.

Soil erosion is a major source of stormwater solids for both urban and suburban areas.

Sources (cont’d)

Components of Stormwater Runoff

Suspended Solids (Sediment)Nutrients MetalsOxygen Demanding Substances Oils, Greases and HydrocarbonsPathogens

Material such as sand, silt, clay and organic matter with a particle size larger than dissolved molecules or ions.

The largest contributor by volume to nonpoint source pollution in the U.S.

Studies indicate that other pollutants are often bound or adsorbed onto suspended particles, such as phosphorous, heavy metals and organic compounds.

Suspended Solids (Sediment)

Suspended Solids (Sediment)

Nonpoint Sources

Agriculture Silviculture Urban Runoff Construction Mining

Impacts Causes a decrease in transmission of light through water

Decreases primary productivity of aquatic plants and phytoplankton upon which other species feed

Obscures sources of food, habitat, hiding places, and nesting sites

Interferes with mating activities that rely on sight and delays reproductive timing

Effects on respiration and digestion of aquatic species Decreases survival rates of fish eggs and sizes of fish

populations which may alter species composition Increases temperature of surface water which increases

stratification and reduces oxygen in the lower layers May affect surface water sources for drinking water

Increases drinking water costs Deposition can clog conveyance systems and reduce water

storage Decreases value for recreational and commercial activities

Reduced aesthetic value, sport and commercial fish populations

Decreased boating and swimming activities Interference with navigation

Nutrients

Plant nutrient such as nitrogen and phosphorous, are common constituents of nonpoint source runoff.

Stimulates growth of algae and other aquatic plants and accelerates the process of eutrophication.

Enter runoff through fertilizers, plant matter, detergents and washing fluids, soil leeching, animal wastes, and seepage from septic tanks.

Nutrients

Nonpoint Sources

Agriculture Silviculture Urban Runoff Construction Septic Tanks

Impacts Nutrients promote premature aging of lakes and

estuaries (eutrophication) Algal blooms caused by nutrients and the resulting

decay of organic materials create turbid conditions that eliminate submerged aquatic vegetation and destroy habitat and food sources for aquatic animals and waterfowl

Blooms of toxic algae, such as blue-green species, can affect health of swimmers and aesthetic qualities of waterbodies

Excess algal growth favors survival of less desirable fish species over more desirable/sensitive species

Interference with boating and fishing activities Reduced quality of water supplies, including addition

of tastes and odors Reduced dissolved oxygen levels can suffocate fish

species Reduction of waterfront property value

Heavy Metals

Originate from the operation of motor vehicles, direct fallout and the degradation of highway materials.

Gasoline (Pb), diesel fuel (Cd), exhaust emissions (Pi,Ni), crankcase and lubricating oils (Pb, Ni, Zn), grease (Zn, Pb), tire wear (Cd,Zn).

The most abundant are lead, zinc and copper which account for 90% of dissolved heavy metals.

Most metals are present in particulate form

Heavy Metals

Nonpoint Sources

Agriculture Transportation Urban Runoff Construction Mining

Impacts Dissolved metals can create short term

and long term toxic impacts to receiving waters.

Accumulate in bottom sediments, posing risks to bottom-feeding organisms and their predators

Affect reproduction rates and life spans of aquatic species

Disrupt food chains in aquatic systems Affect recreational and commercial

fishing Affect water supplies

Oxygen Demanding Substances

Include numerous organic materials which are decomposed by microorganisms thereby creating a need for oxygen.

This biochemical reaction results in the use of dissolved oxygen in the water. Imposes a BOD (biochemical oxygen demand)

on the limited oxygen resources available in waterbodies.

Oxygen used can be replenished through Photosynthetic production by algae and other green plants.

Oxygen Demanding Substances

Nonpoint Sources

Agriculture Urban Runoff Silviculture Septic Tanks

Impacts May cause oxygen depletion and fish

kills if introduced in high concentrations

May alter species composition to make them more tolerant of low D.O. conditions.

Increase growth of anaerobic microorganisms which produce by-products responsible for odors in water

Low oxygen levels may increase solubility of phosphorous and heavy metals in the water column.

Oils, Greases and Hydrocarbons

Organic chemicals cause concern because they cannot be easily decomposed through biological action and may persist for long periods.

Hydrocarbons come from fractions of oils and greases resulting from transportation and industrial sources, benzene from gasoline, synthetic detergents, pesticides, herbicides, wood preservatives, a wide range of industrial chemicals.

Because there is no mechanism by which nature can rapidly cleanse itself of these compounds, even low concentrations can accumulate in the environment and reach dangerous concentrations.

Oils, Greases and Hydrocarbons

Nonpoint Sources

Agriculture Urban Runoff Silviculture Construction

Impacts All compounds can hinder photosynthesis in

plants Can affect reproduction, respiration, growth

and development in aquatic species as well as reduce food supply and destroy habitat for aquatic species

If released to the aquatic environment before degradation, many compounds can kill non-target fish and other species.

Pesticides/herbicides bioaccumulate in tissues of fish

Health hazard from human consumption of contaminated fish/water

Pathogens

Includes a wide variety of organisms such as bacteria, fungi, viruses, protozoans capable of transmitting disease and having an adverse impact on human health.

Primary sources include, animal wastes, illegal wastewater connections into stormsewer lines, seepage of groundwater containing pathogens into sewer lines and septic tanks.

The principle indicator of pathogen contamination is coliform bacteria.

Murrells Inlet shellfish beds close after a heavy rain due to high counts of fecal.

Pathogens

Nonpoint Sources

Agriculture Urban Runoff Septic Tanks

Impacts Introduction of disease-bearing

organisms to surface waters Reduced recreational usage Increase in treatment costs for drinking

water Human health hazards

Removal of Pollutants

Particulate Pollutants Unhindered settling of particles

Dissolved Pollutants Wide variety of chemical, physical and

biological processes are responsible Chemical precipitation, adsorption onto

plant surfaces, suspended solids, biological uptake by algae, bacterial decomposition

Removal (cont’d)

Oxygen Demanding Wastes Occurs through simple oxidation of

organic matter by aerobic bacteria and fungi.

Generally complete within 3-5 days. Heavy Metals

Deposition of metals into sediments pH must be kept at 6-8 to keep metals

bound to sediments

Pathogens Die off, coagulation, predation by zooplankton,

and adsorption onto suspended matter with deposition into the bottom sediments.

Best treatment is to investigate and reduce the sources within the watershed.

Oils, Greases, and Hydrocarbons Retain by using oil skimmers at the discharge

point Reducing pesticides by controlling the sources

of these compounds Hydrocarbons often float on water surface and

are removed by volatilization.

Removal (cont’d)

What you can do to help

Recycle Pick up pet waste Beach sweep Volunteer Raingardens & Bioretention Get Involved!

SW Contact

Stormwater office can be reached at: (843) 545-3524 [email protected] www.georgetowncountysc.org www.GeorgetownCountyCleanWater.com

–Coming Soon

Downstream pollution leads to upstream source