Planning and Technical Services - Pahrump Non-Attainment
The Town of Pahrump is located in the Pahrump Valley of Southern Nevada (hydrographic area 162) approximately 60 miles west of Las Vegas and 60 miles east of Death Valley. Pahrump is an unincorporated town governed by a five-member, elected Town Board, a Town Manager and staff. Located in Nye County, it borders the California state line. The word Pahrump is a Paiute Indian expression interpreted to mean "water rock" or "place where big waters flow".
In Pahrump the population increased by about 18,000 people during the '90s to its current 33,000 [2005 estimate]. The annual growth rate in Pahrump is between 12 and 15% and it has become a "bedroom community" of Las Vegas. It's estimated that 60 percent of the workforce in Pahrump commutes to Las Vegas and retirees comprise the majority of the population.
The Problem: Fugitive Dust
The recent population growth has created intensive development. Large parcels of land have been cleared of vegetation, subdivided and prepared for housing construction. Dirt and gravel roads were constructed. Many of the planned housing developments never materialized and the lots are now disturbed, vacant areas.
Former farm land continues to be developed for housing at the highest rate in the state. Several major housing developments are currently under construction and will eventually provide over 10,000 new homes in the valley. As a result of the disturbed, vacant land and the number of dirt and gravel roads, fugitive dust (Particulate Matter less than 10 microns or PM10) became a problem. The Pahrump valley is subject to high winds and these winds often create dust storms. Even the slightest wind can pick up dust from the disturbed areas, where it can become a health hazard.
Citizen complaints in the late 90's led to the installation of an ambient air monitor in the downtown area. The Bureau of Air Quality Planning (BAQP) has been monitoring the ambient air quality in the Town of Pahrump since January 2001. The monitor records ambient air data continuously and can be downloaded to the BAQP office in Carson City. Twenty seven (27) exceedances of the National 24-hour ambient air standard were recorded during 2001, 2002 and 2003. Under the Federal Clean Air Act (CAA), these exceedances mean that Pahrump is no longer attaining the 24-hour standard (the Federal and State ambient air quality standard for PM10 is 150 ug/m3 and the annual standard is 50 ug/m3.)
Particulate matter (PM)
Particulate matter are very small airborne particles, less than 10 microns in diameter. Major sources of particulate matter are burning fuels, such as wood in woodstoves and fireplaces, or diesel in motor vehicles; crushing or grinding, such as dust from unpaved roads and construction sites; and from industrial processes. Breathing high levels of particulate matter is harmful to lung tissue and aggravates asthma symptoms.
- FAQ's — General Air Quality Information
- Particulate Matter Fact Sheet
- Health Effects of Wood Smoke
- Burn Barrels: A Burning Health Problem
The Options
fter exceedances are monitored and an area is determined to be in nonattainment, the Governor typically submits a letter to the US EPA requesting designation of the area to non-attainment. EPA then promulgates this designation in the Federal Register and gives the state and local government three years to prepare and submit a State Implementation Plan (SIP). The SIP will bring the area back into attainment with the standard within five years of designation.
BAQP has discussed possible options with the US EPA and Nye County. The US EPA is willing to allow BAQP and Nye county the opportunity to address the problem through a Memorandum of Understanding (MOU). The MOU would allow significantly more local control of the process and significantly less federal involvement.
However, because this is a more informal approach, BAQP and Nye county must be able to demonstrate to the US EPA that there is an environmental benefit to addressing this problem through an MOU. BAQP and Nye county need to show that this approach would be more effective and/or produce results faster.
Preferred Option
The US EPA, the State, the Pahrump Town Board and Nye County have agreed to use the MOU approach instead of the SIP submittal. Once the MOU is signed, Nye County will have until 2009 to bring the area back into attainment. Control strategies must be in place by 2006 and must remain in place to ensure that the Pahrump Valley will continue to attain the standards in the future.
The state and local agencies are volunteering to work under the MOU to expedite air cleanup for future public health and welfare. The MOU process will have two components:
- The Memorandum of Understanding (MOU) - The MOU is an agreement to prepare and implement a Clean Air Action Plan (CAAP) for the Pahrump Valley. More specifically, the MOU sets measurable enforceable milestones for developing and implementing the Clean Air Action Plan;
- Clean Air Action Plan (CAAP) - The CAAP serves as the areas official air quality improvement plan, with quantified emission-reduction measures. The CAAP will include all necessary elements of a comprehensive air quality plan, but will be tailored to local needs and driven by local decisions. Moreover, the CAAP will be incorporated into the formal SIP and the state will be legally required to carry out this plan just as in nonattainment areas. For example, development of the CAAP will require the same scientific diligence and undergo the same scrutiny as the nonattainment area's SIPs, so that the emission reduction strategies selected will be adequate to ensure the area stays in attainment of the PM10 standards.
The Memorandum of Understanding [PDF] was signed in September 2003 by the US Environmental Protection Agency (Region IX Administrator), the Nevada Division of Environmental Protection Administrator, the Nye County Board of Commissioners and the Pahrump Town Board. For the purpose of the MOU, the Pahrump Regional Planning District boundaries [PDF] were used to generate the emission inventories. More information on the MOU can be found in the briefing document [PDF], and in the list of definitions [PDF].
Control Measures
Several types of control measures are being looked at to minimize fugitive dust in the valley. This document "Pahrump Valley Air Quality Management; Control Measures Assessment" [PDF] has a list of possible control measures (this list in this document is not all conclusive).
Emissions Inventory
BAQP staff have surveyed the Pahrump Valley to identify land, road and source types. Staff also compiled a 2001 base year emissions inventory [PDF] for:
|
|
|
The emissions inventory will be submitted to US EPA as part of the MOU. Best Available Control Measures (BACM) must be implemented in the Pahrump Valley to minimize the generation of fugitive dust. BACMs may include paving of roads and stabilizing disturbed vacant lands. Projected future year (2009) emission inventories will be used to calculate reductions.
Monitoring Network in Pahrump
All monitors monitor PM continuously, and will be co-located with a weather station capable of measuring maximum wind speed, wind direction and temperature. Each monitor is a Beta Attenuation Monitor (BAM) and has been shown to correlate well with the federal reference method (FRM). BAQP will have the capability of downloading data hourly via cell phone from each of the monitors. The map of the network [PDF] shows the locations of the monitoring sites in relation to each other and also shows the location of the meteorological tower.
| |||||||||||||||
The Bureau of Air Quality Planning (BAQP) has been monitoring the ambient air quality in the Town of Pahrump since January 2001. Citizen complaints in the late 90's led to the installation of an ambient air monitor near the Municipal Pool in the downtown area. Since last year, BAQP expanded the monitoring network in the Pahrump Valley to four sites: the Municipal Pool site downtown, the Willow Creek Golf Course, the "Our Lady of the Valley Roman Catholic Church" on Gamebird and a background site on Linda Street.
Over the last couple of years, BAQP received several requests, from local elected officials and citizens of Pahrump, to post the monitoring data on the internet in real time. The goal is to display the monitoring data from all four monitoring sites on the internet. The first phase of the project was completed in late April. The data from the Municipal Pool became available on the internet on April 28, 2004. As of September 22, 2004, the Willow Creek Golf Course, Church and Linda Street sites are also on-line. On December 6, 2005, the monitoring data of a fourth monitor site came on-line: in late November a fourth monitoring station near the Manse Elementary School became operational.
The ambient air monitoring data is posted on the internet in near-real time: the data is downloaded from the monitor four times a day, every six hours, starting at 3:00 am (however, due to equipment setup the time shown on the web is off by two hours), and uploaded to the internet. The air quality data is color-coded according to EPA's Air Quality Index (AQI). This index is a yardstick for air quality, the higher the AQI value, the greater the level of air pollution and the greater the health danger. The index ranges from 0 - 500. The scale is subdivided into six categories, ranging from good to hazardous.
For example, an AQI value of 50 represents good air quality and little potential to affect public health, while an AQI value over 300 represents hazardous air quality. An AQI value of 100 generally corresponds to the national air quality standard for the pollutant, which is the level EPA has set to protect public health. So, AQI values below 100 are generally thought of as satisfactory. When AQI values are above 100, air quality is considered to be unhealthy at first for certain sensitive groups of people, then for everyone as AQI values get higher. More information on the AQI can be found in the following document "Air Quality Index - A Guide to Air Quality and Your Health" [PDF]. Although Pahrump does not qualify as a large metropolitan area, the AQI for Pahrump was calculated for educational purposes only.
County Commissioners Approve Air Quality Ordinance.
The proposed air quality bill was approved by the Nye County Commissioners during the August 17 Board meeting. Of note, the Nye County Ordinance 289 became effective on January 1, 2005. Finally, the Natural Events Action Plan [PDF] is posted here and addresses health and environmental effects of smoke and dust.