T his section focuses on air quality and

Transcription

1 T his section focuses on air quality and water quality. In considering air quality, concentrations ozone are used as the primary parameters. Air quality is regional because of air s properties of dispersal. There are no ozone monitors in Chapel Hill. Therefore, we use ozone concentration values from the Triangle ozone forecast area. AIR QUALITY The Clean Air Act requires the Environmental Protection Agency (EPA) to set National Ambient Air Quality Standards (NAAQS) for wide-spread pollutants from numerous and diverse sources considered harmful to public health and the environment. EPA has set NAAQS for six principal pollutants, which are called "criteria" pollutants. These pollutants are: ozone (ground-level), particulate matter, carbon monoxide, sulfur dioxide, nitrogen oxides, and lead. The -hour ozone NAAQS is. parts per million (ppm). An exceedance of the -hour ozone NAAQS occurs when a monitor measures ozone above. ppm on average for an eight-hour period. A violation of this NAAQS occurs when the average of the annual fourth highest daily maximum -hour ozone values over three consecutive years is greater than or equal to.5 ppm. This three-year average is termed the design value for the monitor. The design value for a nonattainment area is the highest monitor design value in the area. The Triangle region was designated as in 7 CHAPEL HILL DATA BOOK nonattainment for the -hour ozone NAAQS on April 3,. The Triangle nonattainment area includes Durham, Franklin, Granville, Johnston, Orange, Person and Wake Counties and Baldwin, Center, New Hope and Williams Townships in Chatham County. The EPA took this action based on data from 1-3. Ground-level ozone is a principal ingredient in smog, which can lead to health problems such as respiratory illnesses. Ozone formation is affected by emissions of nitrogen oxides (NO x) and Volatile Organic Compounds (VOCs). Ozone control measures in this region typically focus on industrial and transportation-related emissions. However, weather conditions also impact ozone production, meaning that ozone concentrations measured in one area may be due in part to emissions in that area, as well as emissions that travel from other regions. While air quality is monitored and managed regionally, local policies can affect local emissions of air pollutants. AIR QUALITY HIGHLIGHTS There are currently eight ozone monitors located throughout the Triangle nonattainment area. The latest ozone design value (through August ) shows the Triangle in attainment of the -hour ozone NAAQS, and eligible to be considered for redesignation to attainment. The North Carolina Division of Air Quality is currently working on a redesignation/maintenance plan to submit to USEPA..1

2 Based on monitoring of ground-level ozone, air quality in the Triangle area has improved in recent years. The Raleigh-Durham-Chapel Hill area experienced zero unhealthful days in the summer of compared to seven in the summer of. Twenty nine percent of the days sampled in the summer of were moderate, compared to 5% of days sampled in the summer or. The improvements to regional air quality are likely due to multiple factors, including: * New EPA rules for nitrogen oxides emissions (potentially related to much of the improved air quality all across the southeast) * The Clean Smokestacks rule (NC) * Meteorological factors (temperature, humidity, wind patterns, etc) It is important to note, however, that the trends in recent years are not necessarily predictive of patterns that we may see in the near future. The Triangle region had moderate ozone ratings compared with other areas in the state, in the summer of. The Charlotte, Triad, and Hickory regions had more unhealthy for sensitive populations days. WATER QUALITY Water quality samples are collected at monitoring sites in Chapel Hill and Carrboro (see Map) at low-flow conditions. Thirteen water quality parameters are measured, but only those that have statutory or recommended standards defined by the North Carolina Division of Environmental Management are presented here. There are limitations to the use of these data. Collection methods do not conform to the North Carolina state sampling methodology or frequency recommendations. Only approximate comparisons can be made to NC state water quality standards. The standards used in the three-year summary charts are shown on the following below. Dissolved Oxygen Temperature ph Turbidity Dissolved Solids Fecal Coliforms Phosphorus Nitrite & Nitrate Ammonia Lead Zinc maximum 5mg/L maximum 3 degrees Celsius between and 9 ph units maximum 5 NTU maximum 5mg/L maximum count /ml recommended maximum.5mg/l maximum mg/l recommended maximum mg/l maximum 5µg/L maximum 5 µg/l WATER QUALITY HIGHLIGHTS Water quality standards for temperature, zinc, and lead have not been exceeded in the past 3 years. Zinc and lead in water are indicators of automobile-related pollution, specifically from gasoline and car batteries. Both are very rarely detected in surface water in the past three years, and have not exceeded the standard in that time. There were no dissolved oxygen measurements in 5 and few in due. 7 CHAPEL HILL DATA BOOK

3 to a malfunctioning dissolved oxygen probe. There were fewer measurements of ph, temperature, and dissolved solids as well for the year for this reason. Water temperatures generally follow air temperature through the year, though it only very rarely dips below freezing. Summer temperatures are moderated by shade, and most streams in Chapel Hill retain a small forested buffer. Water quality samples above the standard for fecal coliforms are frequent among all sites, and show no strong trend over the past three years. Fecal coliform sources include leaking sewer lines, feces of domestic and wild animals, and resuspension of in-stream sediments where bacteria may incubate. The source of these organisms can be better traced through concurrent measurement of ammonia, which can help to differentiate between human and animal sources. Measurements of nitrite and nitrate are generally low for most sites. Site 3, Morgan Creek at the Ford, has a history of elevated nitrogen levels. This is to be expected because the OWASA treatment plant is upstream of this site. However, too few samples are taken for most sites (except for Carrboro sites) to detect any exceedances of standards or to determine any trends in phosphorus or nitrate and nitrite. More frequent sampling of nutrients would be necessary to determine base levels and trends. Understanding of nutrient sources and transport may become important for the Town as more strict nutrient standards are developed to maintain water quality for Jordan Lake as a drinking water source. Turbidity of water quality samples is generally low, as would be expected dur- 7 CHAPEL HILL DATA BOOK ing low-flow sampling, and very few exceedances of standards were detected in 5. Suspended solids were also measured and were consistently low, exceeding the low end of the standard for most samples. Suspended solids include both soil and organic materials, and low amounts may be indicative of erosive conditions. Sampling after storms or during other high-flow events would better indicate the degree of bank erosion and sediment transport occurring in area streams. Evidence of low solids in some stream segments and sedimentation in other stream segments indicates that this may be one of the more important characteristics impairing stream health in Chapel Hill. Hydrologic factors affecting erosion and sedimentation, such as velocity and the discharge profile, are important for determining the cause of sediment problems. A model of stream scour in the Chapel Hill area is being developed as part of the Town s involvement in the Little and Morgan Creeks Watershed Planning Initiative. The Town of Chapel Hill is undertaking programs to manage stormwater and related water resources issues within its jurisdiction. For more information, visit: stormwater/ In, the Town adopted an ordinance which established a Stormwater Management Utility, and appointed a Stormwater Management Utility Advisory Board..3

4 Map 1: Raleigh-Durham-Chapel Hill Ozone Monitoring Sites Key H - Rte., Pittsboro O - 7 N. Duke St., Durham V - 31 S. Hillsborough St., Franklinton AA - 3 Jack Road, Clayton AB - Highway 31 & SR 11 AR - 1 N. Broad St., Fuquay- Varina AS TV Tower Road, Garner AT - North State St. Raleigh AU - 31 Spring Forest Road, Raleigh Figure 1: Annual Ozone Exceedance Days in Raleigh-Durham-Chapel Hill Days Annual Ozone Exceedance Days. 7 CHAPEL HILL DATA BOOK

5 Figure : Triangle Area Ozone Monitor Data for Summer Months - % 7% % % days sampled 5% % 3% % % % year Good Moderate Unhealthy for Sensitive Populations Unhealthy Table 1: Triangle Area Ozone Monitor Data for Summer Months - Ozone Rating Good Moderate Unhealthy for Sensitive Populations Unhealthy Total Source: NC Department of Environment and Natural Resources, Monitors collect data for May-September, when highest ozone concentrations are found 7 CHAPEL HILL DATA BOOK.5

6 Table : Ozone Monitoring in North Carolina, Summer Ozone Rating Triangle Number of Days with each Ozone Rating Recorded Asheville Ridge Tops Asheville Valleys Hickory Charlotte Fayetteville Rocky Mount Triad Good Moderate Unhealthy for Sensitive Populations 3 17 Unhealthy Total Source: NCDENR, 7 Table 3: Estimated Emissions Inventory for the Triangle 1 (tons/day) Source Pollutant NO X VOCs Point (Factories & Utilities) 11.. Mobile (Cars & Trucks) Nonroad Mobile (Heavy Equipment) Area (Gas Stations, Dry Cleaners, etc.). 7.7 Biogenic (Plants, trees, vegetation) 7.1. Total 37. 1,. Source: North Carolina Department of Environment and Natural Resources, Air Quality Division 1 includes Chatham, Durham, Franklin, Granville, Johnston, Orange, Person, Wake Counties Note: Estimates for typical summer conditions Nitrogen-Oxygen compounds (NO x) and Volatile Organic Compounds (VOCs) are the two most important precursors for ozone formation. Because the vast majority of VOC emissions in the Southeastern United States come from biogenic sources, such as pine trees, ozone reduction strategies in this area mostly focus on reducing NO x emissions.. 7 CHAPEL HILL DATA BOOK

7 Map : Water Quality Monitoring Sites 7 CHAPEL HILL DATA BOOK.7

8 Figure 3 Water Quality Samples Exceeding NC Standard for Dissolved Oxygen site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site There were few measurements in due to a malfunctioning dissolved oxygen probe. Legend Samples Exceeding NC Standard Figure Total Water Quality Samples Exceeding NC Standard for ph site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site. 7 CHAPEL HILL DATA BOOK

9 Figure 5 Water Quality Samples Exceeding NC Standard for Turbidity site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site Legend Samples Exceeding NC Standard Figure Total Water Quality Samples Exceeding NC Standard for Dissolved Solids site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site 7 CHAPEL HILL DATA BOOK.9

10 Figure 7 Water Quality Samples Exceeding NC Standard for Fecal Coliforms site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site Legend Samples Exceeding NC Standard Figure Total Water Quality Samples Exceeding NC Standard for Phosphorus site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site. 7 CHAPEL HILL DATA BOOK

11 Figure 9 1 Water Quality Samples Exceeding NC Standards for Nitrite and Nitrate site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site Legend Samples Exceeding NC Standard Figure Total Water Quality Samples Exceeding NC Standard for Ammonia site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site 7 CHAPEL HILL DATA BOOK.11

12 Figure 11 Water Quality Samples Exceeding NC Standard for Suspended Solids site 1 site site 3 site site 5 site site 7 site site 9 site site 11 site 1 site Legend Samples Exceeding NC Standard Total ABOUT THE WATER QUALITY DATA Chapel Hill's water quality sampling program does not conform to the NC State sampling methodology or frequency, therefore results are only an approximation compared to NC water quality standards. Water quality samples were generally taken at one month intervals and were not correlated to flow. The sources for all water quality data (Figures through 1) are the Chapel Hill Engineering Department, DENR Division of Water Quality, state Fresh Surface Water Standards, and the Chapel Hill Planning Department..1 7 CHAPEL HILL DATA BOOK

13 Table : Exceedances of Fecal Coliform, Dissolved Oxygen, and Total Suspended Solids Fecal Coliform Dissolved Oxygen Total Suspended Solids Units #/ml mg/l mg/l NC Standard Year # Exceedances Not < 3-mg/l Samples Taken % Exceed # Exceedances Samples Taken % Exceed # Exceedances Samples Taken % Exceed % 1 1 1% 1 9% % % 1 1 % % 11 % % % 1 3 % 5 9% % % 79 99% % 7 3% 77 9% % 13 3% % % 1 3% % % % % % 1 1 % % % % % % % % 7 CHAPEL HILL DATA BOOK.

14 Table 5: Chapel Hill Bioclassification Summary According to NC Benthic Macroinvertebrate Stream Survey Bioclassification NC Benthic Macroinvertebrate Sampling Site Site CH WQ Monitoring Apr- Feb-93 Apr-93 Feb-9 Mar-9 Trend Morgan Creek at NC Botonic. Garden Site 1 NS.5. NS.5 Inconclusive Meeting of the Waters Creek Site NS NS 1. NS 1. Neutral at Laurel Hill Road Bolin Creek at Umstead Park Site NS NS.5 3. NS Positive Bolin Creek at East Franklin Site 5.5. NS 1.. Negative St. Little Creek at Pinehurst Site NS. NS 1. NS Negative Drive Morgan Creek at NC 5 Site 7 NS. NS 3.5 NS Negative Booker Creek at Piney Site NS NS NS NS. NA Mountain. Road Morgan Creek below Site 3 NS. NS NS. Neutral OWASA Wastewater Plant Bolin Creek at Homestead Rd. NA NS NS 3. NS 3. Neutral Source: Chapel Hill Engineering Department, DEHNR Division of Water Quality; NC Fresh Surface Water Standards, Chapel Hill Planning Department Bioclassification: = Excellent, 3.5 = Excellent/Good, 3 = Good,.5 = Good/Fair, = Fair, 1.5 = Fair/ Poor, 1 = Poor, NS = No Sample. In June 3 North Carolina Department of Environment and Natural Resources Division of Water Quality published an assessment report: Biological Impairment in the Little Creek Watershed which includes some samples for the above listed sites. For more information please visit stormwater/wtr_quality.html.1 7 CHAPEL HILL DATA BOOK