Stormwater Effects. Stormwater Management Steps. Major Receiving Water Beneficial Uses

Transcription

1 Stormwater Effects Robert Pitt, P.E., Ph.D., DEE Department of Civil and Environmental Engineering The University of Alabama Presentation based on material further discussed in: Burton, G.A. Jr., and R. Pitt. Stormwater Effects Handbook: A Tool Box for Watershed Managers, Scientists, and Engineers. ISBN CRC Press, Inc., Boca Raton, FL pages. Stormwater Management Steps Identify beneficial use impairments Identify causes of impairments Identify sources (magnitude, seasonality, flow phases, etc.) of problem constituents Identify, select, and design controls suitable for problem pollutants and locations Implement controls, conduct validation monitoring, modify controls as needed Photo by Lovena, Harrisburg, PA Major Receiving Water Beneficial Uses Stormwater Conveyance (flood prevention) Recreation (non-water contact) Uses Biological Uses (Warm water fishery, aquatic life use, biological integrity, etc.) Human Health Related Uses (Swimming, Fishing, and Water Supply) WI DNR photo 1

2 Basic Goals for Urban Streams Stormwater conveyance and aesthetics should be the basic beneficial use goals for all urban waters. Biological integrity should also be a goal, but with the realization that the natural stream ecosystem will be severely modified with urbanization. Biological integrity is the capacity to support and maintain a balanced, integrated and adaptive biological system having the full range of elements [the form] and process [the function] expected in a region s habitat. James Karr 1991, modified Certain basic stormwater controls at the time of development, plus protection of stream habitat, may enable partial use of some of these goals in urbanized watersheds. Water contact recreation, consumptive fisheries, and water supplies are not appropriate goals for most heavily urbanized watersheds. Receiving Water Effects of Water Pollutant Discharges Sediment (amount and quality) Habitat destruction (mostly through high flows [energy] and sedimentation) Eutrophication (nutrient enrichment) Low dissolved oxygen (from organic materials) Pathogens (mostly from municipal wastewater and agricultural runoff) Toxicants (heavy metals and organic toxicants) Temperature Debris and unsafe conditions etc. Historical concerns focused on increased flows during rains and associated flooding. However, decreased flows during dry periods are now seen to also cause receiving water problems. WI DNR photo 2

3 Sediment transported in stormwater causes significant receiving water impacts. WI DNR photo WI DNR photos Bank instability and habitat destruction due to increased flows R. Bannerman photo One Early Method of Getting Rid of Wastewater Wastewater treatment has only been around since the late 1800s. People dumped wastes into gutters and ditches, or sometimes out an open window. Wastes then flowed into nearest stream or pond. Coombs and Boucher 3

4 Polluted New York Harbor in 1883 Coombs and Boucher Gross floatables most important wet weather flow pollutant in many urban areas. Basic Wastewater Conveyance in Sanitary Condition not Always Achieved McKinney and Schoch 4

5 Sewage contamination of storm drainage system Beach Closings in the US in 1994 (Water Envir. & Tech. 1995) Sanitary Sewer Overflows (SSOs) Stormwater Runoff Combined Sewer Overflows (CSOs) Agricultural Runoff Wastewater Treatment Plant Malfunctions 584 (43%) 345 (25%) 194 (14%) 136 (10%) 106 (7.8%) Public swimming beach located in utility right-of-way adjacent to stormwater outfall (not uncommon) Children frequently play in urban creeks, irrespective of their designation as water contact recreation waters WI DNR photo 5

6 Fishing in urban waters also occurs, both for recreation and for food. Historical approach to urban drainage has been devastating to environment and recharge of groundwaters WI DNR photo WI DNR photo WI DNR photo 6

7 WI DNR photos Eutrophication dramatically detracts from recreational uses, along with affecting aquatic life Inappropriate discharges, including accidental hazardous material releases, into storm drainage can cause acute receiving water effects. Cuyahoga River in Cleveland Often Caught on Fire Between 1952 and 1969 Coombs and Boucher 7

8 Fire from 200,000 gallons of spilled gasoline in residential area from pipeline rupture (June 1999) Whatcom Creek, Bellingham, WA, fire-fighting foam Bellingham Herald (Washington) Alabama has about 200 transportation accidents a year involving hazardous materials. This is typical for most states. Groundwater Contamination The potential for groundwater contamination associated with stormwater infiltration is often asked. Road cut showing direct recharge of Edwards Aquifer, Austin, TX Birmingham News (Alabama) Book published by Ann Arbor Press/CRC, 219 pages. 1996, based on EPA research and NRC committee work. Groundwater%20EPA%20report.pdf 8

9 Barton Springs, Austin, TX Example Weak-Link Model Influencing Factors Constituent Nitrates Abundance in Stormwater low/moderate Mobility (sandy/low organic soils) mobile Filterable Fraction (treatability high Chlordane moderate intermediate very low Anthracene low intermediate moderate Pyrene high intermediate high Lead moderate very low very low Links Depend on Infiltration Method (contamination potential is the lowest rating of the influencing factors) Surface infiltration with no pretreatment (grass swales or roof disconnections) Mobility and abundance most critical Surface infiltration with sedimentation pretreatment (treatment train: percolation pond after wet detention pond) Mobility, abundance, and treatability all important Subsurface injection with minimal pretreatment (infiltration trench in parking lot or dry well) Abundance most critical Moderate to High Groundwater Contamination Potential Surface Infiltration with no Pretreatment Lindane, chlordane Benzo (a) anthracene, bis (2-ethylhexl phthalate), fluoranthene, pentachlorophenol, phenanthrene, pyrene Enteroviruses Chloride Surface Infiltration after Sedimentation Fluoranthene, pyrene Enteroviruses Chloride Injection after Minimal Pretreatment Lindane, chlordane 1,3-dichlorobenzene, benzo (a) anthracene, bis (2-ethylhexl phthalate), fluoranthene, pentachlorophenol, phenanthrene, pyrene Enteroviruses, some bacteria and protozoa Nickel, chromium, lead, zinc Chloride 9

10 Basic Premise for Receiving Water Assessments one single approach can be routinely used to accurately determine or predict ecosystem health and beneficial use impairment. Each assessment approach or component has associated strengths and weaknesses. Major Components of Receiving Water Assessments Chemical (major impairments and uses) Biological (community tolerance) Physical/habitat (ecological integrity) Toxicity (availability of chemical contaminants) The complexity of ecosystems require that these assessment tools be used in an integrated manner. Selection of Components Based on Site Specific Conditions At sites of extensive chemical pollution, extreme habitat destruction, or absence of desirable aquatic organisms, the impact can be clearly established with only one or two components, or simply qualitative measures. However, at most study sites, there will be gray areas where the ecosystem s integrity is less clear and should be measured via multiple components, using a weight-ofevidence approach. Reported State s Bioassessment Tools macroinvertebrate surveys (almost all programs, but with varying identification and sampling efforts) habitat surveys (almost all programs) some simple water quality analyses some watershed characterizations few fish surveys limited sediment quality analyses limited stream flow analyses hardly any toxicity testing hardly any comprehensive water quality analyses 10

11 The study design must be developed based on: study objectives, preliminary site-problem assessments, regulatory mandates, and available resources. The main objectives of most monitoring studies may be divided into two general categories: Characterization (quantifying a few simple attributes of the parameter of interest ), and/or comparisons (to standards or reference conditions). Other common objectives include identifying hot spots, examining trends, etc. Typical Urban Receiving Water Problems and Key Parameters of Concern Flooding and drainage: debris and obstructions affecting flow conveyance. Biological integrity: habitat destruction, high/low flows, inappropriate discharges, polluted sediment (SOD and toxicants), benthic macroinvertebrate and fish species impairment (toxicity and bioaccumulation of contaminants) and wet weather quality (toxicants, nutrients, DO). Typical Urban Receiving Water Problems and Key Parameters of Concern (cont.) n-contact recreation: odors, trash, high/low flows, aesthetics, and public access. Swimming and other contact recreation: pathogens, and above listed non-contact parameters. Water supply: water quality standards (especially pathogens and toxicants). Shellfish harvesting and other consumptive fishing: pathogens, toxicants, and those listed under biological integrity. 11

12 Selection of Biological Endpoints for Monitoring The most commonly used biological groups in aquatic assessments are fish, benthic macroinvertebrates, zooplankton and algae. In streams and rivers, fish and benthic macroinvertebrates are often chosen as the major monitoring tools. Macroinvertebrates Macroinvertebrates are organisms larger than 0.3 to 0.5 mm. They include a wide range of invertebrates, such as worms, insect larvae, snails, and bivalves. Excellent indicators of water quality because they are relatively sedentary and do not move between different parts of a stream or lake, as fish do. In addition, a great deal is known about their life histories and pollution sensitivity. Other Common Biological Indicators Algae, zooplankton, and fish are used more in lake environments. Of these, fish are most often used. Fish are transient, moving between sites, therefore it is more difficult to determine their source of exposure to stressors; however, they are excellent indicators of water quality and provide a direct link to human health and wildlife consumption advisories. Selection of Multiple Biological Endpoints In order to effectively and accurately evaluate ecosystem integrity, biosurveys should use two to three types of organisms which have different roles (functions) in the ecosystem. This same approach should be used in toxicity testing 12

13 Experimental Design Issues Budget Basic Study Approach Duration Sampling Effort Sampling Locations Data Analyses Quality Control/Quality Assurance 13

14 Basic Study Approach Experimental designs can be organized in one of the following basic patterns: Parallel Stream Study (urban and rural stream) (Bellevue, WA) 1. Parallel watersheds (developed and undeveloped) 2. Upstream and downstream of a city 3. Long-term trend Preferably, most elements of all of the above approaches can be combined in a staged approach Large Rain rural urban Small Rain rural urban Longitudinal Trend Study (above and below city) (San Jose, CA) Long-Term Trend Study (Sweden) 14

15 Likely Follow-up Testing Short-term chronic toxicity testing with additional species (lab and in situ), Increased testing of toxicants, Characterizing fish, plankton, periphyton, or mussel populations, Measuring assimilative capacity via long term BOD and SOD testing, and/or Measuring productivity with light/dark bottle BOD in situ tests. Stormwater Discharge Characterization Monitoring Data needed to calculate expected mass discharges to receiving waters. Also needed to calibrate and validate stormwater runoff quality models. Much data collected over past 25 years, but not easily accessible. Main historical nationwide database is the NURP information (EPA 1983). NPDES Phase 1 stormwater permit monitoring data since early 1990s. Univ. of Alabama and the Center for Watershed Protection are being funded by EPA to gather and present this data. 15

16 WI DNR photo WI DNR photo Stormwater quality can vary greatly, even at a single site. Variations between events is greater than variations within events. WI DNR photo 16

17 Comparison of NURP with Phase 1 Data (median and COV) TSS COD Pb Zn NURP NSQD 1.1 NURP NSQD 1.1 NURP NSQD 1.1 NURP NSQD 1.1 Resid. 101 (1) 49 (1.8) 73 (0.6) 55 (0.93) 144 (0.8) 12 (1.9) 135 (0.8) 73 (1.3) Commer. 69 (0.9) 42 (2) 57 (0.4) 60 (1) 104 (0.7) 18 (1.6) 226 (1) 150 (1.2) Open Space 70 (3) 49 (1.5) 40 (0.5) 42 (1.5) 30 (2) 10 (1.7) 195 (0.7) 40 (1.3) Comparison of National Stormwater Quality Database with NURP Data Database Years of Data Collection NURP NSQD Ver Number of Monitoring Stations Number of Metropolitan Areas WI DNR data and slide Number of Station-Storm Events

18 Median (COV) SS (mg/l) COD (mg/l) Fecal colif. (#/100mL) TKN (mg/l) P (mg/l) Communities Included in Database (EPA Rain Zones) All data combined (3,770 events) Residential (1069 events) 58 (1.8) 48 (1.8) 53 (1.2) 55 (1.1) 5080 (4.6) 7750 (5.1) 1.4 (1.4) 1.42 (1.3) 0.27 (1.5) 0.30 (1.1) Zone 7 Zone 8 Zone 9 Zone 1 Open Space (68 events) 51 (1.9) 21 (1.8) 3100 (2.9) 0.6 (1.0) 0.25 (3.6) Zone 2 Commercial (497 events) Industrial (524 events) 43 (2.0) 77 (1.5) 63 (1.0) 60 (1.2) 4500 (2.8) 2500 (5.6) 1.6 (0.9) 1.4 (1.2) 0.22 (1.2) 0.26 (1.4) Zone 6 Zone 5 Zone 4 Zone 3 Institutional (18 events) Freeways (185 events) 17 (0.83) 99 (2.5) 50 (0.9) 100 (1.1) n/a 1700 (1.9) 1.4 (0.5) 2.0 (1.4) 0.18 (1.0) 0.25 (1.8) These grouped box-whisker plots sort all of the data by land use. Kruskal-Wallis analyses indicate that all constituents have at least one significantly different category from the others. Heavy metal differences are most obvious. Residential area concentrations grouped by EPA rain zones. Zones 1-4 are eastern half of country, zones 5-9 are western half of country. Zones 3 and 7 are the wettest zones. 18

19 Plots of expected relationships are being used to identify data redundancies that can reduce future analytical costs. Plots of concentrations vs. rain depth typically show random patterns. Mean Suspended Solids Concentrations (mg/l) for Different Rain Zones and Land Uses Open Space Commercial Residential Industrial Freeways 1 (NE and mid west) 34 (1) 132 (25) 37 (3) 50 (13) 2 (mid Atlantic) 160 (28) 76 (631) 80 (287) 78 (212) 47 (3) 3 (SE) 149 (55) 61 (24) 124 (41) 4 (S central) 225 (13) 229 (89) 317 (54) 206 (62) 5 (Texas) 104 (87) 44 (22) 245 (43) 6 (SW) 126 (25) 177 (11) 296 (19) 183 (104) 7 (coastal NW) 62 (51) 84 (40) 183 (24) 151 (26) 8 (N mtns) 97 (7) 9 (N central) 232 (7) 188 (9) 502 (9) Seasonal data are well distributed at each site, and did not statistically influence TSS In-Stream and Laboratory Biological and Toxicity Assessments needed to Identify and Quantify Actual Receiving Water Problems 19

20 Contaminated sediments in urban receiving waters likely much more responsible for biological impacts than contaminated water. Fish surveys in urban streams typically find similar biomass as in control streams, but sensitive native fish displaced by hardy exotics WI DNR photo Benthic macroinvertebrate populations on natural and artificial substrates have been extensively used to indicate receiving water effects. Toxicity tests using stormwater find much of the toxicity associated with small particulates, not just filtered portions of the water EXCELLENT GOOD FAIR POOR Riparian Integrity Biotic Integrity Benthic Index of Biotic Integrity (B-IBI) Watershed Urbanization (%TIA) C. May

21 Interstitial water in urban sediments highly contaminated and directly affected by contaminated sediment Side-stream bioassay tests show chronic toxicity after about 1 to 2 weeks of exposure to urban stream water, and no 96- hr toxicity WI DNR and USGS tests WI DNR and USGS tests Side-stream bioassay tests demonstrated the benefits of stormwater controls for the removal of fine particulates. Residual toxicity remains, however. Conclusions We can learn from the past several decades of receiving water investigations Problems are site specific and require sequential investigations Must use combination of study components, including: - habitat evaluations, - rain and flow monitoring, - chemical, and biological monitoring, and - toxicity investigations 21

22 Conclusions (continued) Must evaluate both sediment and water in most cases All flow phases (dry and wet weather) and seasons (including snowmelt) may be important May require extensive and long-term effort to obtain data with small uncertainty Need to balance resources with study objectives 22