Nitrogen in Barnegat Bay:

Transcription

1 Nitrogen in Barnegat Bay: Issues, Problems & Solutions September 27, 2011 RCE of Ocean County Christopher Obropta, Ph.D., P.E. Rutgers Cooperative Extension Water Resources Program

2 Introduction Barnegat Bay, like many coastal areas in the country, is undergoing water quality problems that t affect both its use and ecology. The most pressing issue affecting the Bay is overih tby nutrients, ti t primarily il nitrogen, from surface runoff. enrichment Approximately half (~50%) of the nitrogen loads to Barnegat Bay originate from surface runoff (Kennish et al. 2007). Increased nitrogen can lead to a variety of water quality problems: eutrophication and hypoxia (lowered dissolved oxygen), increased harmful algal blooms, loss of submerged aquatic habitat, altered benthic communities, and loss of fisheries.

3 What is Stormwater or Runoff? Stormwater is the water from rain or melting snows that can become runoff, flowing over the ground surface and returning to lakes and streams.

4 The Hydrologic Cycle

5 Meteorological Factors Affecting Runoff Type of precipitation (e.g., rain, snow, sleet, etc.) yp p p ( g,,,, ) Rainfall intensity Rainfall amount Rainfall duration Distribution of rainfall over the drainage basin Direction of storm movement Proceeding precipitation and soil moisture Temperature, wind, relative humidity (i.e., factors that affect evapotranspiration)

6 Physical Characteristics Affecting Runoff Land use Vegetation Soil type Drainage area Basin shape Elevation Slope Topography Direction i of orientation i Drainage network patterns Presence of waterbodies (ponds, lakes, reservoirs, etc.)

7 Hydrologic Implications of fland duse Urban land uses lead to impervious surfaces Commercial Industrial Residential Low Density Medium density High density Other Agriculture leads to land alteration that might lead to erosion

8 Barnegat Bay Watershed covers 660 square miles in 37 municipalities in Ocean and Monmouth Counties Approximately 25% of the land use is Urban

9 Linking Land Use to Waterway Condition More Impervious Cover = More Water

10 What Is Impervious Cover? Roads, rooftops, parking lots, and other hard surfaces that do not allow stormwater to soak into the ground Even disturbed/constructed open spaces (such as parks) have become impervious due to compaction The predominant American vegetation

11 Impacts from a Changing Landscape Hydrologic Effects Disruption of natural water balance Increased flood peaks Increased stormwater runoff More frequent flooding Increased bankfull flows Lower dry weather flows

12 Impacts from Development on Stormwatert Natural Conditions

13 Impacts from Development on Stormwatert Low Density Development

14 Impacts from Development on Stormwatert Medium Density Development

15 Impacts from Development on Stormwatert Urban Development

16 Flooding Riverine Slow kinds: runoff from sustained rainfall or rapid snow melt exceeding the capacity of a river's channel. Fast kinds: flash flood as a result of e.g. an intense thunderstorm. DOWNSTREAM communities are always affected by the cumulative effect from UPSTREAM. Examples Hurricane Irene Delaware River at Trenton, NJ Multiple communities along the Mississippi River over the last few years.

17 Flooding Estuarine/Coastal Storm surge: Estuarine floods can result from sea tidal surges caused by stormforce winds or a storm surge from a hurricane. Overtopping of a barrier: The barrier may be natural or human engineered and overtopping occurs due to swell conditions during storm or high tides. The height of the waves exceeds the height of the barrier and water flows over the top of the barrier to flood the land behind it. Breaching of a barrier: Breaching occurs on open coasts exposed to large waves. Breaching is where the barrier is broken down by waves allowing the sea water to extend inland. Examples Hurricane Irene Tsunami in Japan

18 Impervious Cover & Stream Quality At 10% impervious cover, stream degradation (e.g., changes in the aquatic biological i l community) is detectable. t At >25% impervious cover, streams no longer support biological/human uses. Relationship between Impervious Cover and Stream Quality 70 Watershed Im mpervious Cov ver (%) Good Non-supporting (>25%) Fair Impacted (11 to 25%) Sensitive (0 to 10%) Poor Level of Stream Quality

19 Pollutants Found in Runoff Sediment Soil particles transported from their source Toxics Pesticides Herbicides Fungicides Insecticides Metals (naturally occurring in soil, automotive emissions/ tires) Lead Zinc Mercury Petroleum Hydrocarbons (automotive exhaust and fuel/oil) Biochemical Oxygen Demand (BOD) Oxygen depleting material Leaves Organic material Nutrients Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material): Nitrogen (N) Phosphorus (P) Bacteria/ Pathogens Originating from: Pets Waterfowl Failing septic systems Debris Litter and illegal dumping Thermal Stress Heated runoff, removal of streamside vegetation

20 Pollutants Found in Runoff Sediment Soil particles transported from their source Toxics Pesticides Herbicides Fungicides Insecticides Metals (naturally occurring in soil, automotive emissions/ tires) Lead Zinc Mercury Petroleum Hydrocarbons (automotive exhaust and fuel/oil) Biochemical Oxygen Demand (BOD) Oxygen depleting material Leaves Organic material Nutrients Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material): Nitrogen (N) Phosphorus (P) Bacteria/ Pathogens Originating from: Pets Waterfowl Failing septic systems Debris Litter and illegal dumping Thermal Stress Heated runoff, removal of streamside vegetation

21 Stormwater Management ONNEC CTION C Traditional Dams, dikes and levees Hydraulic alterations (straighten, channelize, piped, etc.) Combined sewer systems Curb/gutter or open channel gutters Next generation Separate storm sewer systems (MS4s) Detention systems (minimize peak flows and volumes) Concrete flow-flow channel Fill and release slowly over time Low Impact Development

22 Connected Impervious Surfaces (MS4) No chance for GW recharge for stream base flow No chance for infiltration/plant uptake for improved water quality Peak flow rates and volumes can be too high for stream carrying capacity

23 Newer MS4s are Centralized

24 Detention Basins &P Ponds

25 Goals of Low Impact Development (LID) Mimic natural conditions and water balance Decentralization/ disconnection Uniform distribution of small-scale controls Older NJ Municipalities are already at/near build-out Unique approach to watershed management Requires retrofits Incorporate natural systems as a feature that complements the existing urban design

26 Efforts to Solve Nitrogen Problems in Barnegat Bay Rain Gardens Gravel Wetlands Detention Basin Retrofits Fertilizer Law as part of the Barnegat Bay Action Plan

27 Rain Gardens A rain garden is a landscaped, shallow depression that is designed to intercept, treat, and infiltrate stormwater at the source before it becomes runoff. The plants used in the rain garden are native to the region and help retain pollutants that could otherwise harm nearby waterways.

28 Rain Gardens Benefits Rain gardens provide extremely high levels of storm water treatment for some types of pollutants. The plant material (trees and shrubs) within the basins will provide diversity in the landscape and wildlife habitat. Storm water treatment t t requirements may be satisfied using rain gardens and bioretention basins. They are aesthetically pleasing and easily incorporated into the landscape.

29 Pollutant Removal Rate Comparison PARAMETER SOURCE Suspended Solids Total Phosphorus Total Nitrogen NJDEP Stormwater BMP Manual 90% 60% 30% Davis et al % to 99% -240% to 99% 32% to 99% Lucas & Greenway 2008 N/A 6% to 36% 34% to 58% Dietz & Clausen 2006 N/A -117% to -98% 31% to 51% Hunt et al N/A -240% to 65% 40%

30 Pollutant Removal Rate Comparison PARAMETER SOURCE Suspended Solids Total Phosphorus Total Nitrogen NJDEP Stormwater BMP Manual 90% 60% 30% Davis et al % to 99% -240% to 99% 32% to 99% Lucas & Greenway 2008 N/A 6% to 36% 34% to 58% Dietz & Clausen 2006 N/A -117% to -98% 31% to 51% Hunt et al N/A -240% to 65% 40%

31 The Nitrogen Cycle

32 Pollutant Removal Mechanisms Absorption to soil particles Removes dissolved d metals and soluble phosphorus h Plant uptake Removes small amounts of nutrients Microbial processes Removes organics and pathogens Exposure to sunlight and dryness Removes pathogens Infiltration of runoff Provides flood control, groundwater recharge, and nutrient removal Sedimentation and filtration Removes total suspended solids, floating debris, trash, soilbound phosphorus, some soil-bound pathogens

33 Georgian Court University it Rain Garden Place rain garden next to dining hall to capture roof runoff. Include a monitoring components to evaluate rain gardens ability to remove nitrogen. Additional research opportunities and partnerships between Rutgers & Georgian Court University (GCU).

34 GCU Rain Garden Our project involves alteration of the traditional rain garden design in order to maximize removal of nitrogen from stormwater runoff. Maintaining saturated conditions in the rain garden increases nitrogen removal.

35 Nitrogen Removal from Rain Gardens From: Kim et al. 2003

36 Subsurface Gravel Wetland The University of New Hampshire s s Stormwater Center (UNHSC) has established guidelines for the design of subsurface gravel wetlands as a BMP. Results from their work indicate that such gravel wetlands can achieve a median annual removal of at least 95% of nitrate-nitrogen, t and TP removal was 55% (UNHSC 2010). This design is a very promising candidate for use in the Barnegat Bay Watershed.

37 GCU Subsurface Gravel Wetland Install a series of four subsurface gravel wetlands with different designs to evaluate design alternatives ti for Barnegat Bay.

38 Subsurface Gravel Wetland Concept From: UNHSC 2010

39 Detention Basins Basins whose outlets have been designed to detain stormwater runoff for some minimum time to prevent downstream flooding. Provide quantity control, mowed regularly l with concrete low-flow channels, dry except during and immediately following a storm event (typically 48 hours). Basins can treat stormwater runoff through settling of particles.

40 Detention Basins

41 Types of Retrofits 1. Extended Detention Basin 2. Outlet Modification 3. Water Quality

42 Retrofit: Extended Detention ti Basin Extended detention can address both the stormwater runoff quantity and quality impacts of land development. The lower stages of an extended detention basin can detain runoff from the Stormwater Quality Storm for extended periods of time, thereby promoting pollutant removal through sedimentation. Higher stages in the basin can also attenuate the peak rates of runoff from larger storms for flood and erosion control. Extended detention basins are designed for complete evacuation of runoff and normally remain dry between storm events. To enhance soluble pollutant t removal, the lower stages of an extended detention basin may also be designed with a permanent pool and partially function as either a wetland or retention basin.

43 Keys for Extended Detention ti Basin The basic design parameters for an extended detention basin are its storage volume and detention time. An extended detention basin must have the correct combination of storage volume and outflow capacity to contain and slowly discharge the design runoff volume over a prescribed period of time.

44 Extended Detention Basin Concept From: NJDEP 2004

45 Retrofit: Outlet t Modification

46 Retrofit: Outlet t Modification

47 Retrofit: Outlet t Modification

48 Retrofit: Water Quality Basins Vegetate with Native Species Remove Concrete Low Flow Channels Install Permeable Weirs Storm Inlet Filtering Devices Manufactured Treatment Devices Disconnect Impervious Surfaces Capturing, treating and infiltrating the runoff generated by the water quality storm.

49 Fertilizer Legislation On January 5, 2011, Governor Christie signed legislation restricting ti nitrogen content t in fertilizer and reducing application rates for use. These standards will reduce nutrient pollution in all of New Jersey s water bodies. Establishes new content standards for fertilizer that will reduce excess nutrient runoff into the Bay by decreasing the total amount of nitrogen in fertilizer and increasing the amount of slow release nitrogen. The law also creates a fertilizer application i certification i program for professional fertilizer applicators, through the New Jersey Agricultural Experiment Station at Rutgers University and in consultation with the NJDEP. The NJDEP, in consultation with environmental groups and industry, will provide public education for homeowners on the effects of fertilizer runoff into Barnegat Bay.

50 References Davis, A.P., W.F. Hunt, R.G. Traver, and M. Clar Bioretention Technology: Overview of Current Practice and Future Needs. Journal of Environmental Engineering. 135(3): Dietz, M.E. and J.C. Clausen Saturation to Improve Pollutant Retention in a Rain Garden. Environmental Science & Technology. 40: Hunt, W.F., A.R. Jarrett, J.T. Smith, and L.J. Sharkey Evaluating Bioretention Hydrology and Nutrient Removal at Three Field Sites in North Carolina. Journal of Irrigation and Drainage Engineering. 132(6): Kennish, M.J., S.B. Bricker, W.C. Dennison, P.M. Glibert, R.J. Livingston, K.A. Moore, R.T. Noble, H.W. Paerl, J.M. Ramstack, S. Seitzinger, D.A. Tomasko, and I. Valiela Barnegat Bay-Little Egg Harbor Estuary: Case Study of a Highly Eutrophic Coastal Bay System. Ecological Applications. 17(5)Supplement:S3-S16. Kim, H., E.A. Seagren, and A.P. Davis Engineered Bioretention for Removal of Nitrate from Stormwater Runoff. Water Environment Research. 75(4): Lucas, W.C. and M. Greenway Nutrient Retention in Vegetated and Nonvegetated Bioretention Mesocosms. Journal of Irrigation and Drainage Engineering. 134(5): New Jersey Department of Environmental Protection (NJDEP) New Jersey Stormwater Best Management Practices Manual. Division of Watershed Management. Trenton, NJ. University of New Hampshire Stormwater Center (UNHSC) and New England Interstate Water Pollution Control Commission Investigation of Nutrient Removal Mechanisms of a Constructed Gravel Wetland Used for Stormwater Control in a Northern Climate: Final Report. UNHSC. Durham, NH.

51 Christopher h C. Obropta, Ph.D., P.E. Rutgers Cooperative Extension Water Resources Program 14 College Farm Road New Brunswick, NJ Phone: obropta@envsci.rutgers.edu water.rutgers.edu