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If unusually high water flows occur in the water mains to due a main break, firefighting efforts, or during system flushing, then a customer’s water may be brown or orange in color. In this case, the water should clear up within several hours. Please not that the discolored water is still safe to drink. The City of Longview Utility Department conducts a flushing program to remove sediment that accumulates in the water main to minimize these causes of discolored water.
The Fisher’s Lane water treatment plant was constructed in 1946. Despite capacity upgrades in 1960 and 1980 and a regulatory upgrade in 1998, the facility was aged and failing. Several concrete structures had deteriorated to the point that it was not practical to rebuild. The plant struggled to keep up with demand due to frequent mechanical and structural failures. Eleven filters failed over a period of ten years, including three catastrophic failures which were declared emergencies in order to expedite repair.
If the existing water treatment plant were to have been rehabilitated, it would have been necessary to keep the plant in operation throughout construction. To do that, construction would have had to be phased to meet water demand year-round while constructing improvements. Three phases of construction were expected to require roughly nine years and $52.6 Million to complete – approximately $18 million more than the cost of the new groundwater supply.
Volcanic debris continues to wash down the Toutle and Cowlitz Rivers from Mount Saint Helens. In spring and winter, high turbidity caused by suspended sediment significantly reduced plant capacity. Turbidity in the river can exceed 2,000 Nephelometric Turbidity Units (NTU) during spring run-off and winter storms. Turbid raw water significantly slows the treatment process in order to produce finished water less than 5 NTU to meet drinking water standards.
In the summer, rising sand bars and low water levels threatened to leave the intake dry. In 1986, the U.S. Army Corps of Engineers (USACE) constructed a dam on the Toutle River to capture sediment before it reached the Cowlitz.
By 1998, the dam was full and water began coming over the spillway, bringing silt, sand and sediment with it. In 2002, the USACE projected the Cowlitz River bottom would raise 9-feet at the City’s intake structure by 2034. But four years later, the river had already filled in roughly 12-feet at the mouth of the Cowlitz.
In 2005, the City constructed its own 8-foot sediment dam in front of the intake to keep it from being silted in but the dam was overtopped the next year. The USACE dredged the lower Cowlitz but funds are not available to dredge far enough upriver to reach the intake structure.
The City’s dredging permit to maintain a sump in front of the intake structure and keep it clear of sediment has expired; renewal will require the intake to be upgraded to meet current fish code. The size of the openings in the intake screens is too large to keep out smelt larvae and recently hatched fish. The structure also lacks a fish return to send entrained fish back out to the river, and the flow velocity at the face of the intake screening is too high. Screen failures due to sediment build-up against the screens were already problematic; smaller screen openings would create more plugging problems because coarser sediment would not be able to pass through.
High rate pump testing conducted during pre-design indicated there was an abundant supply of water available from the aquifer. Little draw down has been observed in the deep aquifer since the Mint Farm Regional Water Treatment Plant started producing water, further confirmation the aquifer is a sustainable supply. Static water level is continuously recorded in the deep monitoring wells which surround the Mint Farm wellfield and the data confirms the aquifer is continuously recharged during pumping.
To meet current demand, approximately 5 million gallons per day are pumped from the aquifer and we are confident the aquifer will easily continue to meet our needs as demand grows to 20 million gallons per day, in the future.
No. It is not uncommon for groundwater in the Longview-Kelso area to contain some amount of iron and manganese.
Left untreated, raw water containing iron and manganese will oxidize when exposed to air (as it leaves the tap) and these minerals will change from a colorless, dissolved form to red-brown (iron) or brownish-black (manganese) particles. If not removed from the water, iron can cause reddish-brown staining of:
Manganese acts similarly but causes a brownish-black stain. Soaps and detergents do not remove these stains, and use of chlorine bleach can intensify the stains.
The City treats for iron and manganese removal in order to prevent the problems associated with staining and to prevent the build-up of iron and manganese deposits which can collect in pipes, pressure tanks, water heaters, and water softeners. Temporary water quality issues including discolored water have been experienced in some areas of Longview, particularly in older areas of town where the distribution system is made up of cast iron and galvanized water main pipe. The City is actively working to resolve this problem and continues to flush areas of concern on a regular basis until a long term solution can be implemented.
The problems in the Cowlitz River with moving sandbars and turbid water are not specific to the location of the intake structure at River Mile 5.2. Moving the location of the intake structure to a wider or deeper section or a bend in the river that historically seems to stay scoured out does not address the larger problem of sediment transport. River training structures such as rock dike fields, submerged pile dikes and Iowa vanes have been suggested as a way to improve water flow but all of these would require extensive modeling evaluation and there is disagreement amongst river experts about whether or not it would work. Rock vanes installed in front of the intake structure in 2005 to promote flushing flows across the face of the intake were buried by sediment within the first year of operation.
The Cowlitz River and Columbia River are federally defined as navigable waterways and fall under the jurisdiction of the U.S. Army Corps of Engineers. Construction in or over the river, excavation or discharge of material into the river, or any work which affects the course, location, condition, or capacity of the river requires approval and permitting from multiple state and federal agencies. The permitting process to construct a new intake structure on the Cowlitz River or Columbia River is expected to be lengthy, difficult and expensive.
To further complicate the situation, NOAA Fisheries is taking a close look at adding Pacific Smelt to the list of Endangered Species in response to a recent petition from the Cowlitz Tribe urging smelt protection in the Columbia River and its tributaries. Salmon and steelhead fish are already listed as endangered species, making the process and conditions of any permit to construct and operate a new intake very complex, if it is possible at all.
Finally, the cost of a relocating the intake to a presumed better location on the Cowlitz River or to the Columbia River, together with rehabilitating the existing water treatment plant, was evaluated early on in the planning process and determined to be not cost effective. In order to avoid similar sedimentation problems at a new intake on the Cowlitz River, the intake would need to be located upstream of the confluence of the Toutle River (the primary source of the sediment).
The distance from an intake structure at either location to the water treatment plant on Fisher’s Lane and the need for a river crossing in order to route a raw water main back to the plant make the total project cost prohibitive. In 2007, the cost to install an intake structure upstream on the Cowlitz River and rehabilitate the existing water treatment plant was estimated at $66 Million. And the cost to install a Columbia River intake and rehabilitate the existing water treatment plant was estimated at $72 Million.
The groundwater contains small amounts of naturally occurring iron, manganese and arsenic. Iron and manganese are not considered a risk to human health and federal regulations do not require treatment to remove them from drinking water. Many people take vitamin and mineral supplements containing iron and manganese, and when ingested in small concentrations, both can provide a health benefit. However, at the concentrations found in the Mint Farm aquifer, state regulations do require treatment because iron and manganese cause objectionable aesthetic issues like taste, odor, color and a tendency to stain. The City plans to treat for iron and manganese removal in order to produce high quality drinking water and prevent those types of problems.
The groundwater also contains trace amounts of naturally occurring arsenic. For many years, the drinking water standard for arsenic was 50 parts per billion (ppb). In 2004, regulations tightened the drinking water standard for arsenic from 50 to 10 ppb to lessen people's long-term exposure.
The groundwater at the Mint Farm contains approximately 6 ppb of arsenic, roughly one-half the allowable limit. At that concentration, drinking water regulations only require that we notify our customers that arsenic exists above the specified reporting level. Our current water source, the Cowlitz River, also contains arsenic but at lower levels. Although not required, the City plans to treat for further arsenic removal and reduce the arsenic concentration to approximately 2 to 3 ppb.
Our testing indicates there is an abundant supply of water available from the aquifer which will ensure a safe and sustainable water supply for years to come.
In the fall of 2009, we constructed and pumped a test production well continuously at a rate of 5.5 million gallons per day for 36 days. While it is typical to pump a test well for only a few days, we pumped for an extended period of time to capture any changes in groundwater quality caused by pumping and confirm the viability of the aquifer as our municipal water supply. Using our network of 17 monitoring wells in and around the Mint Farm, along with sampling from other water sources, we collected and analyzed water quality and flow data.
Our test pumping showed very little effect on the aquifer, and that it recharged continuously during our pumping. We are confident the aquifer will easily meet our needs and remain sustainable when we begin pumping 10 to 20 million gallons per day from the aquifer.
An extensive sampling program collected numerous soil and water samples from multiple locations and performed more than 14,500 analytical tests to identify any potential contaminants in the groundwater. In addition to contaminants that are regulated by the State for drinking water, we also tested for non-regulated contaminants, emerging contaminants (pharmaceuticals and personal care products) that may be of concern in the future, and compounds specific to local industry. In all of these tests, naturally occurring iron, manganese and arsenic were the only contaminants detected at levels which warrant treatment.
In addition, a network of monitoring wells (or sentry wells) has been constructed around the perimeter of the Mint Farm and proposed well field. These monitoring wells will become a critical part of a Well Head Protection Program and will be regularly monitored for changes in water quality. They are intended to safeguard the well field by providing early detection of potential contaminant migration, allowing the City several years advance notice to install additional treatment equipment or implement an alternative solution.
While drilling the first 17 shallow and deep monitoring wells, soil samples were collected to confirm that a confining layer exists which is very resistant to water seepage, and that confining layer protects the deep aquifer from potential contamination at the surface.
In addition, the deep aquifer is under pressure, which prevents potential shallow contamination from migrating into the deep aquifer. We constructed a full size production well and tested the well by pumping it at 5.5 million gallons per day continuously for 36 days and the pressure in the aquifer dropped only the equivalent of 3-feet (less that 2 pouinds per square inch), confirming that the aquifer will remain under pressure after our plant begins operation. We collected water samples before, during, and after test pumping, specifically looking for indications of migration of potential contaminants, and actually found that the water quality improved slightly during pump testing.
The deep aquifer has a strong hydraulic connection to the Columbia River. The deep wells show a clear tidal response and the fluctuation of the static water level inside the well column correlates closely with changes in tide. Isotope analysis is a way to match water chemistry signatures of different water sources and draw inferences about where it is coming from.
Although the actual water chemistry is different between the Columbia River and the deep aquifer due to filtration through thick layers sand, silt and gravel, the isotope analysis indicates the deep aquifer is recharged by the Columbia River.
No. The pH targets for river water and groundwater sources are the same, approximately 7.6 to 7.7 leaving the plant. Upon startup of the groundwater plant, the pH was a bit lower, so it was increased to meet the established target.
Some customers have reported their tap water smells like chlorine, blood, or metal. The City is committed to providing water that looks, tastes, and smells good, but it is important to note these types of odors are aesthetic and usually do not pose a public health threat. In order to correct the problem, it is first necessary to determine whether the odor originates from the water supply or your household plumbing.
If the odor occurs at every water faucet at the residence, it is probably the main water supply. If it only occurs in certain faucets, the problem is the household plumbing. In most cases, the best way to reduce odor caused by household plumbing is to run the faucet for several minutes. If the smell persists or you have concerns, contact the City of Longview Utility Operations Center at 360-442-5700.
To prevent illness, a small amount of chlorine is added during the water treatment process to kill any bacteria or microorganisms that might be present in the raw water. The chlorine concentration in the finished water supply leaving the Mint Farm Water Treatment Plant is closely monitored, but the amount of chlorine in the water at your home or business varies slightly depending on location. Chlorine is virtually odorless at the proper concentration to maintain a slight residual, but you may detect its odor if the level is too low or too high.
The finished water leaving the Mint Farm Water Treatment Plant has been treated to remove iron, manganese and arsenic from the raw groundwater. However, as the water moves through the distribution system and interacts with the scale build-up inside the water mains, some minerals are dissolved into the water. Iron has been determined to be the most common cause of these odors, but other metals such as copper, zinc, and manganese may also be found.
Bacteria living on food, soap, hair, and other organic matter in the drain / hot water heater can form gases which produce a sulfur or rotten egg small. The bacteria is not a health hazard and it is common to associate the smell with the water because it is most noticeable when the water is turned on.
To confirm the odor is gas pushed out of the drain by the water rather than the water itself, take a glass of cold water into another room to smell it. If the water has no odor, the problem is in the drain and can likely be eliminated by disinfecting the drain to kill the bacteria. If the problem is isolated to the hot water systems, contact a licensed plumber or consult your owner’s manual to evaluate the heating element and/or temperature setting.
Installation of a private water softener is a matter of personal preference. Because residential softening systems replace the calcium and magnesium with sodium, consumers will experience increased salt intake. You are encouraged to research any water softener product, particularly customers with sodium-restricted diets. Water softened by private softening systems tends to be more corrosive to household plumbing than hard water, and it is not recommended for watering plants, lawns and gardens due to higher sodium content.
This information was developed with input from the following sources:
Here are some helpful hints for dealing with hard water:
Hard water minerals may result in the following:
Public water supplies are not typically softened unless the hardness value exceeds 200 milligram per liter. However, in response to hard water complaints, the City Council recently authorized staff to investigate softening alternatives.
The City has teamed with Confluence Engineering to review current and historical hardness and develop a softening treatment goal, evaluate potential softening treatment processes, identify potential health effects, and estimate the cost to construct and operate softening treatment at the Mint Farm Regional Water Treatment Plant. The results of the evaluation will be presented to the City Council to decide whether softening treatment will be implemented.
Prior to making the transition to groundwater wells, the treated surface water from the Cowlitz River was historically “soft”, with a hardness level of approximately 27 milligrams per liter. Groundwater hardness from the Mint Farm aquifer varies slightly among each of the four production wells, ranging from 69 to 91 milligrams per liter. Although the difference in hardness is a change from what our customers are accustomed to, the City of Longview groundwater is similar in hardness to other local water systems.
The City of Longview has permanently switched to groundwater wells for its water supply instead of using water from the Cowlitz River. The wells are drilled deep underground to extract water from a deep aquifer. As the water moves through the underground aquifer, it dissolves and absorbs traces of rock and soil minerals which contain calcium and magnesium, resulting in moderately water hard.
Yes. Hard water is safe for drinking, cooking, and other household uses. Hard water tends to leave white calcium deposits and can make soap more difficult to lather, but it is not dangerous. The State of Washington Department of Health and the federal Environmental Protection Agency do not require treatment to reduce water hardness. Calcium and magnesium are essential nutrients that do not pose a public health hazard and may contribute some health benefit.
Hardness is a measure of naturally occurring calcium and magnesium minerals dissolved in water, the higher the mineral content, the harder the water. The following table classifies hardness by category based on mineral content in milligrams per liter. City of Longview groundwater hardness ranges from 69 to 91 milligrams per liter and is considered to be “moderate”. According to the U.S. Geologic Survey, more than 85% of the United States has hard water.
0 to 60
61 to 120
121 to 180
Greater than 180