Spring- Time to Flush the Pipes

 As part of the annual maintenance program for the regional water distribution systems in Virginia and Washington DC, on March 21st , 2022 Fairfax Water, the Washington Aqueduct, Loudoun Water and the City of Manassas will switch from chloramine to chlorine to disinfect their water. During this time, Arlington Department of Environmental Services, DC Water, the Prince William Service Authority, Loudoun Water and Fairfax Water will begin flushing their water distribution systems. Each spring these water distribution companies flush their water mains by opening fire hydrants and allowing them to flow freely for a short period of time.

Fairfax Water will disinfect with chlorine from March 21st  to June 13th and the water systems the flushing of the water mains in Fairfax and Prince William will occur during that time. Crews from the Service Authority and Fairfax Water will open hydrants throughout their service area in brief intervals in order to draw water more forcefully through the distribution system and scrub out the pipes. This helps to dislodge sediment that may have collected in water mains over the past year. In DC, Arlington and  Falls Church, the flushing will occur from March 23 through May 9th , 2022. Those jurisdictions purchase treated drinking water from the Washington Aqueduct. Loudoun Water also announced they will be starting their program on March 21st.

For most of the year, chloramines, also known as combined chlorine, is added to the water as the primary disinfectant. During the spring the water treatment plants for Fairfax Water, Loudoun Water and the Washington Aqueduct switch back to chlorine in an uncombined state, commonly referred to as free chlorine. This free chlorine reacts with sediments suspended during flushing and kills bacteria that may be in the bio-film that forms on the pipe walls. Many water chemistry experts believe this short exposure to a different type of disinfectant maintains a low microbial growth in the bio-film and improves the quality and safety of the water.

This change in disinfection is an annual program to clean the water distribution pipes and maintain high water quality throughout the year. The U.S. Army Corps of Engineers Washington Aqueduct provides water to the District of Columbia, Arlington County, and other areas in Virginia. Fairfax Water provides water to Fairfax County and parts of both Loudoun and Prince William County. WSSC does not switch their disinfectant.

You may notice a slight chlorine taste and smell in your drinking water during this time, this is not harmful and the water remains safe to drink. Depending on your location within the distribution system, it could take up to a week for your drinking water to transition from combined to free chlorine at the beginning of the flushing program, or from free chlorine to combined chlorine at the conclusion of the flushing program. You may want to use filtered water to drink or leave an open container of water in the refrigerator for a couple of hours to allow the smell to dissipate. Refrigerator filters remove chlorine so you do not have to worry about ice. Water customers who normally take special precautions to remove chloramine from tap water, such as dialysis centers, medical facilities and aquarium owners, should continue to take the same precautions during the temporary switch to chlorine. Most methods for removing chloramine from tap water are effective in removing chlorine. The annual chlorination is important step to remove residue from the water distribution system. Free chlorine is better suited to remove residue that may have collected in the pipes than chloramine and a coordinated opening of fire hydrants serves to flush the system and scrub the pipes.

Occoquan Watershed

Recently, the Prince William County Board of Supervisors approved the development of the Preserve at Long Branch, rezoning a portion of the Rural Crescent. No analysis was done as to the potential impact of this development to the hydrology of the Occoquan Watershed.  There is no understanding what the impact this might have to the sustainability of the drinking water supply of adjacent property well owners and the quality of the Occoquan Reservoir itself. 

Occoquan Watershed

The Occoquan Reservoir is an important part of our drinking water supply. The Occoquan supplies about 40% of the clean drinking water for around 2 million people and, in an emergency, can supply all for a short period of time. The reservoir’s current storage capacity is estimated by ICPRB to be 8.3 billion gallons. Prince William land accounts for 40% of the Occoquan watershed which contains 1,300 stream miles, Lake Jackson and Lake Manassas as well as the Occoquan Reservoir.  Water from the Occoquan Reservoir is distributed to customers in Fairfax and Prince William Counties. This water is essential. 

Development impacts water quality. Minimizing impervious surface cover and maintaining the tree canopy is critical to the protection of the County’s streams which flow to the Occoquan and other reservoirs. There is a direct correlation between stream health and impervious surface cover and tree canopy. According to the Northern Virginia Regional Commission, watersheds with impervious surface cover of 10 to 15% show clear signs of degradation, while watersheds with impervious surface cover greater than 25% typically do not support a diverse stream ecology and are dying.

During development the primary impact is erosion and sediment that are carried by stormwater into the streams. The primary post-development impact is increased stormwater volume and velocity that is caused by the removal of tree canopy cover and the replacement of pervious surfaces of plants and grass with the impervious surfaces such as roads, parking lots, rooftops, driveways, patios, etc.

Development increases impervious surface area, and this has created in the past and will in the future create a host of concerns for managing the Occoquan Watershed. For instance, the physical condition of the Watershed's tributaries has been measured to fall with development. Increased stormwater runoff from impervious surfaces flows into streams and creeks at a higher volume and velocity. The result is increased erosion of stream banks that leaves a degraded ecosystem.

The Occoquan Watershed is more than just a source of water for the Reservoir. In addition to its role as an essential portion of the drinking water system for approximately 1.2 million Northern Virginians, the Reservoir and the Watershed also serves to improve water quality:

• The Reservoir is an essential element in meeting the Chesapeake Bay TMDL by trapping sediments and nutrients. According to the Occoquan Watershed Monitoring Lab (OWML) the Reservoir captured 34% of total nitrogen, 56% of total phosphorus, and 83% of total sediment.
• The downzoned portion of the Watershed within Fairfax and the Rural Crescent serve as a natural water treatment system and high quality ecological habitat.
• The Reservoir is a regional recreational asset.

Prince William has ignored its responsibility to best manage the Occoquan watershed in conjunction with Fairfax County’s management of Occoquan Reservoir (and their side of the Watershed) maintaining the primary benefit of the Reservoir as an essential and reliable source of safe, clean drinking water for Prince William County and the importance of the Reservoir as an integrated ecological and hydrological system with multiple uses.

Fairfax Water Annual Water Quality Report

Every year public water suppliers are required to issue an annual drinking water quality report to their customers before July first of the following year. In June Fairfax Water released their report which can be found in its entirety at this link. Fairfax Water owns and operates the James J. Corbalis Jr. and the Frederick P. Griffith Jr. treatment plants. These plants are the primary source of water for most of Fairfax County and portions of Loudoun county and Prince William County. Fairfax Water acquired the City of Falls Church water distribution system (the green areas) as well as a tiny area (orange area) that serve approximately 120,000 people and obtain their water from the Dalecarlia and McMillan treatment plants, part of the Washington Aqueduct which is owned and operated by the U.S. Army Corps of Engineers.

The result is that now Fairfax Water provides water to county residents from their two water treatment plants and buy water from the Washington Aqueduct to supply residents in and around the City of Falls Church. These were historic systems that were once town owned. The newer developments around Merrifield and the Dunn Loring Metro Station are supplied water from the Fairfax Water owned plants. Thus, they are required to report on the water quality of all these sources. 

Both the Washington Aqueduct and Fairfax Water run excellent water treatment plants. All four plants use advanced technologies and practices in drinking-water treatment, which is the process of cleaning raw water to make it safe to drink. Fairfax Water reports that their water consistently surpasses all federal (US EPA Safe Drinking Water Act) and state standards. Of the 182 compounds that are required to be tested for, very few were found in the finished drinking water. Those found were in concentrations well below the EPA’s maximum contaminant levels under the Safe Drinking Water Act. Fairfax Water’s state-certified Water Quality Laboratory performs or manages the testing required by federal and state regulations. The Washington Aqueduct does the testing for the water they supply. 

Over the years as the county grew Fairfax Water expanded its infrastructure. They built the Frederick P. Griffith Jr. Treatment Plant first and then the James J. Corbalis Jr. plant and expanded their distribution system which today serves over 1.7 million people with the lowest water rates in the region.

In order to ensure that tap water is safe to drink, the EPA limits the amount of certain contaminants (a list of more than 90 contaminants) that can be in the water provided by public water systems under the Safe Drinking Water Act. When untreated water enters the treatment plants, coagulants are added to cause small particles to adhere to one another and settle in a sedimentation basin. The water is then filtered through activated carbon and sand to remove remaining fine particles. This produces water with extremely low turbidity and provides excellent barrier against pathogens such as Cryptosporidium and Giardia. 

Next, the water is disinfected with chlorine to kill harmful bacteria and viruses. A corrosion inhibitor is added to help prevent leaching of lead and copper that might be in household plumbing (Fairfax Water reports that all lead containing service laterals were removed from the system). Fluoride is added to protect teeth. Powdered activated carbon and potassium permanganate may also be added to the treatment process to remove taste or odor-causing compounds. In addition to these treatment steps, the Corbalis and Griffith plants use ozone to further reduce odors and organic material. Fairfax Water’s state-certified Water Quality Laboratory performs or manages the testing required by federal and state regulations. The Washington Aqueduct does the testing for the water they supply.

Fairfax Water and the Washington Aqueduct continually monitor and test the water during the treatment process and the finished drinking water as it leaves the plant and in customer homes a part of the Lead and Copper Rule testing. The Virginia Department of Health performs, source-water assessments for the watersheds. The assessment consists of maps of the evaluated watershed area, an inventory of known land-use activities, and documentation of any known source-water contamination within the last five years. Based on the criteria developed by the VDH, the Potomac River and the Occoquan Reservoir were determined to be of high susceptibility to contamination.

Nonetheless, the quality of the finished drinking water being produced at Washington Aqueduct and Fairfax Water is excellent. It meets or exceeds all United States Environmental Protection Agency (US EPA) standards and requirements. The water quality report released in June covers the sampling done during calendar year 2019. There were no violations of the U.S. EPA’s Safe Drinking Water Act. The full report is at this link. 

Arlington Board Approves the Connection to Fairfax Water

At last week’s Arlington Board of Supervisors meeting the under the consent agenda the Board authorized the County Manager to execute the Agreement for Construction of Water Facilities and Emergency Use of Water with Fairfax County Water Authority, subject to legal review by the County Attorney.

Arlington obtains their water from the Washington Aqueduct, a federally owned and operated by the Army Corp of Engineers and dates back to 1853. The Aqueduct produces an average of 155 million gallons of water per day and sells that water to the District of Columbia (about 75% of the finished water), Arlington County, Virginia (about 15%), and the City of Falls Church, Virginia (10%). The Washington Aqueduct consists of the Dalecarlia Reservoir and Water Treatment Plant, the Georgetown Reservoir, and the McMillan Reservoir and Water Treatment Plant. The Washington Aqueduct draws water from the Potomac River and treats it to provide finished drinking water to the water distribution companies that buy water from them.

The maximum capacity of the Aqueduct is 320 million gallons of water per day much more than even the peak demand for drinking water and fire fighting for their customers. Water use peaked at an average of 180 million of gallons a day nearly 20 years ago, the system was expanded in the 1950’s anticipating serving Montgomery and Prince George counties, but the Washington Suburban Sanitary Commission (WSSC) instead built what is today the WSSC's principal water supply facility, the Potomac River Filtration Plant in western Montgomery County to supply their needs. Despite the excess capacity, the water supply remains vulnerable to a chemical spill or other disruption in the Potomac River upstream from the Aqueduct’s intake.

This deal with Fairfax Water is an insurance policy. Fairfax Water has two water treatment plants. The Corbalis Water Treatment Plant, the newer of the two also draw water from the Potomac River. However, the older Griffith plant draws from the Occoquan Reservoir. Fairfax Water produces 160 million gallons of water per day from both the Corbalis plant and the Griffith plant, but the combined total capacity of both plants is 345 million gallons/day. In an emergency when intake from the Potomac River is not possible for an extended period of time this water main could supply water to Arlington and Falls Church balancing the use of the regions Reservoirs and water supply by the ICPRB.

There is already a half mile water main connecting Falls Church to the Fairfax Water system. This project would extend that by another three quarters of a mile to Arlington along North Powhatan Street for emergency use purposes. This project provides redundancy for Arlington County’s water supply in case of an emergency. Currently, its sole water supply is from the Washington Aqueduct. Fairfax Water estimates that the Powhatan Street Main Cost will equal $2,875,000. The Arlington County portion is 70%, currently estimated at $2,012,500. Fairfax Water will build, maintain and operate the water main.

The quality of the water being produced at Washington Aqueduct and Fairfax Water is excellent. It meets or exceeds all United States Environmental Protection Agency (US EPA) standards and requirements. The water quality report release at the end of 2019 covers the sampling done during calendar year 2018. There were no violations of the U.S. EPA’s Safe Drinking Water Act and you can view the report here. The Aqueduct report can be viewed here.

Uranium Mining in Virginia a Threat to Our Water Resources

Last week the winter session of the Virginia General Assembly was called to order. Scheduled to be decided this winter is whether or not to lift a 30-year-old moratorium on uranium mining within the state. Senator John Watkins has introduced a proposal to require the state to draft uranium-mining regulations, essentially ending the 30 year moratorium on Uranium mining in the Commonwealth. Senator Watkins, from Powhatan and Senator Richard Saslaw, from Fairfax will carry the legislation in the Senate, and Delegate Jackson Miller, from Manassas, will introduce similar legislation in the House of Delegates. Now is the time to make your voice heard.

In 1978 a particularly rich deposit of Uranium was discovered at Cole's Hill in Pittsylvania County in south central Virginia. This was followed by a flurry of exploration for uranium deposits in Virginia. In 1982 the Commonwealth placed a moratorium on uranium mining. In recent years, as the price of uranium reached $140 around 2007, and two families living in the vicinity of Cole's Hill formed a company called Virginia Uranium, Inc. to begin exploring the uranium deposit once again. Though the uranium spot price has fallen to around $40, that is still more than twice the historical price, and Virginia Uranium and their supporters have called for the Virginia legislature to lift the uranium mining moratorium for now just on Cole's Hill. As this was all percolating in state politics, in 2009 the Virginia Coal and Energy Commission requested that the National Research Council convene an independent committee of experts to review all the literature and develop a report to identify the scientific, environmental, human health and safety, and regulatory aspects of mining and processing Virginia’s uranium resources. In addition, Fairfax Water commissioned a white paper on uranium mining and ended up with the Fairfax County Water Authority opposing uranium mining in Virginia and supporting the continuation of the moratorium on uranium mining in the Commonwealth.  

After reviewing these reports and as a voting member of the Potomac Watershed Roundtable I voted with the majority to maintain the moratorium on uranium mining. The Virginia Association of Soil and Water Conservation Districts with which I am also affiliated (through my volunteer work at the PWSWCD) also supports maintaining the moratorium. The Virginia Municipal League, the Virginia Association of Counties, the Virginia Farm Bureau, the Fauquier Water Authority, and local governments from Halifax and Virginia Beach, oppose lifting the ban. Last week Lt. Gov. Bill Bolling, who serves as the tie-breaking vote in the Senate if the vote falls to party lines (Sen Watkins is a Republican and Senator Saslaw is a Democrat so that does not seem likely), announced that he supports maintaining the moratorium on uranium mining. Let me tell you why I do not want to see the moratorium lifted at this time.

From the Fairfax Water White Paper

Geological exploration has identified more than 55 locations within the Piedmont and Blue Ridge regions of Virginia where uranium is found.  Uranium occurs in the Lovingston rock formation at a fraction of a percent.  In order for a uranium occurrence to be considered a commercially exploitable source of uranium ore, it must be of sufficient size, be at least 0.1% uranium to the other rock components in the deposit and be able to be mined and processed with current technology. So far only the uranium deposits at Cole Hill have been proven to meet these requirements. Even the “rich deposits” at Cole hill will produce 1,000 pounds of waste called tailing for every pound of uranium extracted. The waste, the mine tailings, is the problem.

There are several methods to mine and process uranium. The choice of mining method depends on the quality and quantity of the ore, the shape and depth of the ore deposit, the type of rock, and a wide range of site-specific environmental conditions. Because of the geology in the Commonwealth of Virginia, it is likely that only open pit or underground mining would be viable. While there are risks inherent in mining to worker the uranium miners would also face the additional risk of dust containing radiation.

After the millions of pounds of rock are removed from the ground by conventional mining methods, the uranium must be separated from the rock and minerals and other radioactive materials, impurities removed and yellowcake produced. Yellowcake is a concentrated form of uranium oxide made in a combination of crushing and/or grinding the rock and chemical processes to dissolve the uranium from the rest of the rock using acids or bases to leach the uranium from the rock dust. The yellowcake then needs to be separated, dried, and packaged. There is more than one type of processing and the choice depends on the nature of the uranium ore, the composition of the rock in the formation as well as environmental, safety, and economic factors. During uranium ore processing, several waste products are created, including tailings, leached residue and waste water. Tailings consist of everything that was in the ore except the extracted uranium. Tailings from uranium mining and processing operations contain radioactive materials remaining from the radioactive decay of uranium, such as thorium and radium as well as heavy metals also present in the rock. The real risks to Virginia are the risks of contamination to our water resources from the waste water and tailings. Uranium tailings are a source of radioactive contamination for thousands of years, and therefore must be controlled and stored carefully away from water which will erode and carry the radioactive materials into the ground and surface water.

Over the past few decades, improvements have been made to tailings management systems to isolate tailings from the environment. The long term effectiveness of these management systems has not been tested and uranium mining is typically carried out in arid environments. Virginia is subject to relatively frequent storms that produce intense rainfall. Natural events such as hurricanes, earthquakes, intense rainfall, or drought could lead to the release of contaminants into the waters of Virginia. It is questionable whether modern-engineered tailings containment could be expected to prevent erosion and surface and groundwater contamination for as long as 1,000 years. In Coles Hill alone the tailings waste will amount to over 118,888,000,000 pounds of pulverized rock with radioactive materials that can slowly leach into our groundwater through failure to prevent percolation of precipitation into the tailings containment or through accidents be released from impoundments to surface waters. Though Virginia’s rainfall averages 42 inches a year in past few years alone rainfall has varied from under 30 inches to a high of 82 inches of rain a year. Water is a great solvent and in Virginia it would seem impossible to keep such vast quantities of tailings permanently isolated from water.  

The only use for uranium is for weapons and nuclear powered reactors. The United States currently has 104 nuclear reactors in operation supplying about 20% of U.S. electricity, and in 2011 these reactors required 20,256 short tons of concentrated enriched uranium and this is not expected to change significantly in the future. In 2010, the United States imported 92 % of the uranium that it needed to fuel its nuclear power reactors. There appears to be adequate world supply for our limited number of nuclear power plants at this time. Uranium mining and processing represents unique risks to source water supplies from toxic and radioactive byproducts. The half-life of the uranium 238 and its isotopes is thousands of years. A containment failure will risk the groundwater and surface water supply of the Commonwealth, and for Cole's Hill will endanger the drinking water supply of Virginia Beach if there is a breach in containment. With current technology, the risk is too great.  The uranium will still be there when our knowledge of how to stabilize for hundreds of year the mine tailings increases to the point we can safely mine the uranium without endangering our water resources.

The formation the contains uranium in Virginia from Fairfax Water

The Rural Crescent, the Occoquan and the Water Supply

The Board of Supervisors of Prince William County have allocated $60,000 to engage a study to examine if the goals desired from the creation of the Rural Area of the county have been met through the implementation and management of the Rural Crescent. In addition, the study is to identify other rural preservation tools that would allow the elimination of the Rural Crescent restrictions on development density. This is a direct result of a motion by Supervisor Martin Nohe at the regular March meeting of the Prince William County Board of Supervisors.

The Rural Crescent was created in 1998 and originally intended as an urban growth boundary for the county designed to preserve the agricultural heritage and force redevelopment along the Route 1 corridor rather than development in the remaining rural areas. This was to be accomplished by limiting development to one home per 10 acres with no access to public sewers. The Rural Crescent has been chipped away at for years, but still contains 80,000-acres; however, active farming in Prince William continues to decrease.  To adequately judge the utility of the Rural Crescent the study must consider its impact on water resources and water ecology. While the Rural Crescent may have been the wrong policy to preserve our agricultural heritage, it has been a success at preserving water resources, protecting our groundwater and supporting the ecosystem of our estuary. In addition, continued redevelopment of areas with preexisting infrastructure will allow Prince William County to improve storm water management in those areas and score nutrient points for the EPA mandated TMDL as well as revitalize older areas of the county and support of sustainable development. The Rural Crescent is about water, specifically groundwater.

The Rural Crescent in Prince William aligns roughly with the Culpeper groundwater basin, one of the more important watersheds in Virginia and essential to the health of the Occoquan Reservoir which in turn is an essential element in the drinking water supply of Fairfax Water - Prince William Service Authority, PWSA, obtains most of the drinking water they distribute in the county wholesale from Fairfax Water. Besides purchased water from Fairfax Water, PWSA operates the Evergreen water wells that draw water directly from the Culpeper Basin and thousands of home owners have private wells that also draw from the aquifer. The Virginia-American Water Company also distributes water purchased from Fairfax Water. Any changes in land use have the potential to negatively impact groundwater, the watershed and the Occoquan Reservoir and should be considered in the study of “other preservation tools.”  

The Rural Crescent is located within the northeast quadrant and eastern quadrant of the Culpeper basin and consists of an interbedded sequence of sedimentary and basaltic that is highly fractured and overlain by a thin cover of overburden. While ground water flows generally speaking west to east, the fractures within the rock run predominately north south. Contaminants can enter the groundwater at these fractures and zigzag through the aquifer, but these fractures also serve as recharge areas. Groundwater is typically protected against contamination from the surface by the soils and rock layers covering the aquifer, but there is inadequate overburden in much of the Rural Crescent. Once contaminated, groundwater is very difficult to clean and in a fractured rock system there is limited if any natural attenuation and the aquifer could be polluted beyond our ability to remediate.

Generally, groundwater in the Culpeper Basin is replenished each year through precipitation. Groundwater recharge through precipitation requires adequate area for infiltration of rainwater, control of sheet flow created by roads and paved areas, as well as protecting the most geologically favorable infiltration points. Precipitation and snow melt flows over the ground as surface runoff. Not all runoff flows into rivers, much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes the saturated subsurface rock of the aquifer, which store huge amounts of freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into rivers, creeks, and ponds as base flow for the rivers, and some ground water finds openings in the land surface and emerges as fresh water springs.

According to the U.S. Environmental Protection Agency, impervious cover levels of 10% can significantly impact watershed health increasing stormwater runoff. When runoff volume increases, runoff velocity increases, and peak storm flows causes flooding and erosion.  Increased stormwater velocity increase soil erosion, increases nutrient contamination and reduces water infiltration into groundwater. The groundwater is essential as the base flow to the streams and rivers that feed the Occoquan Reservoir during the dry months. The groundwater stored in the watershed can supply adequate water to maintain river flow during droughts. Maintaining open areas provides areas of groundwater recharge and controls runoff. Decisions about the fate and management of the Rural Crescent will impact groundwater quantity and quality and in turn will impact water flows to the Occoquan Reservoir during dry periods.  Flow to the Occoquan Reservoir is essential in managing the drinking water withdrawals from the Potomac River.  The Interstate Commission on the Potomac River Basin, ICPRB, manages the Potomac River drinking water allocations for the entire region by “suggesting” the quantity that Fairfax Water draw from the Occoquan and Potomac daily.  Prince William County’s decision on the fate of the Rural Crescent could impact drinking water supplies in Fairfax, Maryland, and DC as well as our own county.

 

The “rural preservation tools” to be investigated as part of the study are sustainable community concepts, high density communities utilizing the strategies of Low Impact Development, LID, which include dedicated open space. While high density communities built adjacent to dedicated open space of cute community farms as is being done in Loudoun might preserve our agricultural heritage, it will not guarantee the preservation of our ecosystem and water. When development disturbs more than 10% of the natural land by covering surfaces with roads, driveways, walkways, patios, and homes the natural hydrology of the land is disturbed, irreparably disturbed. These developments while much better than traditional developments still disturb more than half the land area by significantly increasing building density. 

The lack of overburden limits natural protection to the aquifer, but has allowed easy infiltration. The sedimentary rocks of the Rural Crescent are productive aquifers and feed not only the groundwater wells that provide drinking water to Evergreen and other communities, but also feeds the tributaries to Bull Run assuring the base flow to the rivers and streams that feed the Occoquan. Our freshwater resources need to be managed as a whole. Development that will impair the recharge of the aquifer can result in impacts to the entire region, including the decrease in water level and aquifer storage, reductions in stream base flow and lake levels, loss of wetland and riparian ecosystems, saltwater intrusion and changes in groundwater quality. Our future and our children’s future is our water. We can’t allow it to be destroyed  in paving roads and building houses for short term gain.

Sharing Our Water in the Potomac Watershed

The May 1st Potomac Basin Drought Monitor indicated that most (96.8%) of the Potomac River Basin was abnormally dry (D0). Stream flows measured at Point of Rocks and Little Falls were below median levels.  Precipitation levels in the Basin were below normal in April by 1.2 inches. Most of the groundwater monitoring wells were normal to low across the Basin.  I was not the only one wondering if this would be the beginning of a drought, and worried about my own water supply. Then the rains came.

For the past two weeks as thunder storms have rolled through the region, I checked the water level in the nearby U.S. Geological Survey (USGS) well 49 V1 almost daily and watched as the water level has risen. For two weeks the regular downpours have kept my 15 new trees well watered while the groundwater level has risen 3 feet in the USGS well 49 V1! My drinking water well is undoubtedly as flush as 49 V1 and I’m relieved. The water level has gone from the 10th percentile to the 90th in two fairly wet and stormy weeks. My garden is beautiful, and I can with a clear conscience plan to fill the “gator bags” on my new trees during the dry days of summer. I’ve seen first-hand how immediately rainfall and its percolation into the ground directly impact groundwater.

The groundwater and rain also feed the river at the bottom of my land. That water flows into Bull Run at Sudley Springs and onto the Occoquan River. The rain also feeds the tributaries to the Potomac River.  The Washington metropolitan area gets nearly 90% of its drinking water from the Potomac River. The remaining 10% of the region’s supply is from the Patuxent and Occoquan rivers, Goose Creek (a Potomac Tributary that runs through Loudoun County), Lake Manassas (which feeds the Occoquan), the Jennings Randolph and Little Seneca Reservoirs and groundwater resources that serve small community supplies and private wells like mine. Though I fixate on the water resources in my little corner of the region which I have no ability to supplement, the Potomac River is truly the lifeblood of the region. The Potomac is the region’s major source of drinking water, accepts the clean effluent from waste treatment plants, cools power generation plants, and with the C&O Canal, Lake Manassas, and the Occoquan Reservoir provides water recreation and breath taking scenery to our communities.

The Washington Aqueduct Division of the U.S. Army Corps of Engineers (WAD), the Fairfax County Water Authority (FCWA) and the Washington Suburban Sanitary Commission (WSSC) furnish about 95% of the metropolitan region's water. A number of distribution agencies like Prince William Service Authority purchase some or most all of their water wholesale from the big three and distribute that water in their communities. A number of smaller agencies and self-supply portions of distribution agencies supply the remaining 5% of the water.

For more than two centuries the waters of the Potomac seemed unlimited so that the region is not hampered and tied by water allocation agreements created centuries ago that bind many areas of the arid west to fixed and rigid allocations. Instead, the Interstate Commission on the Potomac River Basin, ICPRB, which was authorized by congress in 1940 to address the pollution of the river facilitated the creation of the Potomac River Low Flow Allocation Agreement in 1978 in response to the droughts of the 1960’s and 1970’s.  Back in the days when the ICPRB was formed, raw sewage flowed directly into Four Mile Run, Hunting Creek, Hooffs Run, and the Potomac River. The river tributaries were putrid and clogged, a foul mix of bubbling, decomposing human waste in brown waters. Shorelines were devoid of wildlife, and tests showed dozens of disease-causing pathogens. Water pollution was so bad that propeller airplane passengers from D.C. (filled with the members of congress) could look down and see the sludge. The extent of the problem was documented in 1949 by the Izaak Walton League, one of the first conservation organizations in the U.S., in a film showing water conditions in Alexandria.

The ICPRB was one of the first organizations with a congressional mandate to consider water resources on a watershed basis, rather than along political boundaries. However, now, the focus of the ICPRB has changed. Sewage is not released into the Potomac (unless the combined sewer systems in Baltimore or Washington overflow).  We have reached the point in population density and development that during times of drought, natural flows on the Potomac are not always sufficient to allow water withdrawals by the utilities (including power generation which takes an awesome amount of water) while still maintaining a minimum flow in the river for sustaining aquatic resources. ICPRB allocates and manages water resources of the river through the management of the jointly owned Jennings Randolph Reservoir (built in 1981), Potomac River Low Flow Allocation Agreement (1978) and the Water Supply Coordination Agreement in 1982 which designated a section of the ICPRB as responsible for allocating water resources during times of low flow. These steps improved reliability of the water supply and ensured maintenance of in-stream flows to meet minimum aquatic habitat requirements as defined by the Maryland Potomac River study in 1981. The section of ICPRB responsible for all this is known as the Section for Cooperative Water Supply Operations on the Potomac (CO-OP), and is formally empowered in its duty by the Water Supply Coordination Agreement of 1982.

This ICPRB is intended to coordinate all the political entities, Maryland, Virginia, Fairfax Water, Washington DC, the federal government and counties and cities within and dependent on the watershed to address the basin’s major challenges, including water quality impairments, water supply and restrictions, flooding, groundwater use, nonpoint source pollution and emerging contaminates. The ICPRB role has been somewhat overshadowed by the recent EPA mandated Chesapeake Bay TMDL, but the ICPRB remains primary in coordinating water supply management and spearheading coordination of effluent water quality issues as they impact drinking water supplies. In their most recent water supply update on June 4th ICPRB assures us that “there is sufficient flow in the Potomac River to meet Washington metropolitan area’s water demands without augmentation from upstream reservoirs.”  After the recent rains it appears unlikely that the Washington metropolitan area’s back up water supply- primarily the Jennings Randolph reservoir helped in by the smaller supply at Little Seneca reservoir will be needed during the summer of 2012.  ICPRB also brings you the Potomac River Watch.
Thanks to Curtis Dalpra Communications Manager at CO-OP for his help.

The Fairfax County James J. Corbalis Jr. Water Treatment Plant

On Thursday, April 26, 2012 I went up to Fairfax County near Herndon to see the Corbalis Water Treatment Plant, the newer of the two Fairfax Water treatment plants and visit with Melissa Billman, the Water Quality Laboratory & Regulatory Compliance Manager and Jeanne Bailey, the Public Affairs Officer for Fairfax Water. Combined they have more than half a century experience in Water Treatment Pants and Compliance and were kind enough to take the time to share their knowledge and experience. Fairfax Water is one of the 25 largest water supply companies in the nation supplying drinking water to 1.7 million Virginians, 900,000 of whom reside in Fairfax County. Twenty percent of all Virginians who are served by public water get their water either directly or indirectly from Fairfax Water. Loudoun Water, Prince William Service Authority, Virginia American Water, the town of Herndon, Fort Belvoir, and Dulles airport all obtain some or all of their water from Fairfax Water.

The Corbalis Water Treatment Plant also houses the Fairfax Water Quality Laboratory built in 2005 and using the state-of-the-art gas chromatography and laboratory equipment that reminded me that I studied chemistry in the Stone Age. The Water Quality Laboratory tests 15,000 samples of water each year and tested for 67,000 parameters including 3,240 samples tested throughout the year for coliform bacteria alone. Each and every month 270 samples are tested for coliform bacteria for the Virginia Department of Health, VDH.  All this testing is done to ensure that the water delivered to  their customers meets or exceeds all regulatory standards and that the water supply delivered to their 1.7 million customers is the best possible drinking water with today’s knowledge and technology.

The Water Quality Laboratory monitors the water from the Potomac River and Occoquan Reservoir throughout the water treatment process and at various points in the distribution system for almost 300 parameters including the Federal Safe Drinking Water Act, SDWA primary and secondary contaminants for which there exist maximum contaminants limits and also for a list of emerging contaminants such as Endocrine Disrupting Compounds (EDCs), Pharmaceuticals, and Personal Care Products (PPCPs) that have been found in water nationally. Fairfax Water tests their source and treated waters for a list of 25 substances, hexavalent chromium and perchlorate have recently been added to the list. In 2011 Fairfax water found minuscule traces (parts per billion or parts per trillion) of 2,4-D, TCEP, DEET, Monensin, Simazine, Atrazine,hexavalent chromium and perchlorate in the finished water.

The technology used for chemical analysis has advanced to the point that it is possible to detect and quantify nearly any compound known to man down to less than a nanogram per liter or parts per trillion (1/1,000,000,000,000). The guiding principal of toxicology is that there is always a dose below which no response occurs or can be measured. So if the concentration of the contaminant was low enough there would be no toxic reaction and a trace amount of a substance does not necessarily represent a health risk. Fairfax Water as one of the largest (top 25) water utilities in the nation gathers and provides some data to federal and state regulators that may determine the future changes in the SDWA. In the meantime, research has shown that using the combination of ozone and granular activated carbon filtration that is used by Fairfax Water is very effective in removing broad categories of personal care products and pharmaceuticals as well as the more dangerous Cryptosporidium organism from the source water. Though, no method of filtration is 100% effective all the time.

  

After Melissa Billman showed us the laboratories and their equipment, Jeanne Bailey led the plant tour. Ms. Bailey once worked in this plant, starting when the plant was brand new and delivered 50 million gallons of water a day in 1982. Now the Corbalis Water Treatment Plant can deliver 225 million gallons of water a day and is planned to be expanded to 300 million gallons a day years from now when the fourth and final phase of the plant is finally built. The plant was conceived and planned to be built in phases.  The Corbalis plant is the newer of the two Fairfax Water Treatment Plants. Water from Fairfax Water is distributed through approximately 3,200 miles of water mains to the county’s homes and businesses. On average, Fairfax Water produces 160 million gallons of water per day from both the Corbalis plant and the Griffith plant. The combined total capacity of both plants is 345 million gallons/day. The system must be sized to deliver the peak demand on a 100 degree day when everyone is doing laundry and watering their lawns and everything else we do with water on hot summer days.  To ensure the continuation of water supply during droughts, Fairfax finalized a regional drought response plan in 2001 that included a low flow allocation agreement with the members of the Interstate Commission on the Potomac River Basin, ICPRB. In addition, Fairfax bought the rights to 14 billion gallons of water from the Jennings Randolph Reservoir. 

The Corbalis Plant draws its water from the Potomac River four and a half miles away. There are two water intakes-one near the shore and the other mid-stream, which ever intake has better water quality is the one that is used.  Bars and giant screens on the pipes are used to prevent the intake of trash, debris and fish. Potassium permanganate (KMnO4) is added to the water at the intake to control taste and odors, remove color, prevent biological growth within the water treatment plant, and remove iron and manganese. The raw water is then pumped to the Corbalis plant where is treated in a series of slow and elegantly simple steps to produce clean and clear drinking water. 

  

Once at the plant the water is pumped to the first of a series of water chambers where the pH is adjusted by adding either caustic soda or sulfuric acid and the primary coagulant, polyaluminum chloride. This coagulant is used to remove small particles of dirt suspended in the water by causing them to stick to one another aided by the coagulant polymer. The water moves from the first water chamber where it is well mixed through a series of chambers (which are really just a series of open rectangular water pools) with slower and slower mixing to allow the particles to coagulate into larger and larger particles until dirt floc is formed. Finally, the water arrives in the sedimentation basins that are not mixed at all and the floc is allowed to settle to the bottom of basins by gravity where they are removed. The floc is thickened by the addition of a polymer, filtered, dewatered by pressure and ultimately used as a lovely agricultural soil amendment.

The next step in the water treatment process is ozonation, the infusing of the water with ozone gas and the first of two disinfection steps. This step was added at the Corbalis plant in 2000 and used this way is still very much leading edge in water treatment technology. Ozone is highly effective in eliminating the Cryptosporidium bacteria and other naturally occurring microorganisms present in water. Unlike ultraviolet and chlorine disinfection systems, there is no re-growth of microbes after ozonation. This step improves the taste and smell of the water. Ozonation also reduces the formation of trihalomethanes (chlorine breakdown products) because of the reduction of organic materials in the water before chlorination. Fairfax water converts liquid oxygen to ozone by an electrical discharge field created within a series of tanks. Viewed just right, you should be able to see the purple corona during the process, but I did not see it.

Ozonation is followed by filtration through granular activated carbon and sand. One cup of GAC has the surface area of about 25 football fields (1,300,000 square feet). Billions of pores in GAC absorb the organic substances removing them from the water and is very effective in removing biological and physical impurities that occur in broad categories of personal care products and pharmaceuticals as well as the more dangerous Cryptosporidium organisms from the water. Slow flow through the filter tanks improves the effectiveness of the filtration. The filter water wash, all runoff from the plant and the water from the dewatering process are reclaimed and returned to the raw water control chamber.

The final steps in the water treatment process is the second disinfection, fluoridation and the addition of a ammonium hydroxide to adjust the pH slightly to prevent corrosion of piping and fixtures in customer  homes to prevent the leaching of lead into water. Nine months of the year Fairfax Water uses chloramine as the final disinfection step. However, during April, May and June of every year Fairfax Water flushes the entire 3,200 miles of water main and uses chlorine during that time to disinfect the delivery network. Flushing the water system entails sending a rapid flow of water through the water mains. As part of the flushing program, fire hydrants and valves are checked and cleaned. Flushing of the water distribution system is performed to remove sediment in pipes and helps to keep fresh and clear water throughout the distribution system. Chlorine is used as the disinfectant during this time so that after the system is flushed, a chlorine residual is maintained in the distribution system to provide a persistent disinfectant to prevent the re-contamination of water before your water tap.

Building the plant in phases has allowed Fairfax water to modify their water treatment process and stay in the forefront of water treatment. Yet, Fairfax Water delivers water to their customers significantly below the national average cost of water, has the lowest retail water rates in the region and has a repair and replacement program that responds not only to the water main breaks, but is designed to replace the entire water supply and distribution system ever 75 years. Many thanks to Melissa and Jeanne for their time and a very interesting afternoon.