ONSITE WASTEWATER TREATMENT SYSTEMS IN THE WALLSBURG WATERSHED

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1 ONSITE WASTEWATER TREATMENT SYSTEMS IN THE WALLSBURG WATERSHED Generated for the Wasatch Conservation District By the Wasatch County Health Department October 2011 A compilation of information regarding use and management of onsite wastewater systems and recommendations for future water quality issues related to such systems in the Wallsburg watershed

2 Onsite Wastewater Treatment Systems in the Wallsburg Watershed Onsite wastewater treatment systems (OWTS) are now viewed as a permanent solution to wastewater management. Whenever a centralized municipal or community sewage treatment plant is not an option, as is typically in rural areas, an onsite wastewater treatment system is usually installed to manage household wastewater. A conventional OWTS is an onsite individual sewage management system typically consisting of a septic tank followed by a soil absorption field (Figure 1). It s the ability of an OWTS to remove solids, oils and greases, nutrients, and pathogens from wastewater which shows their importance in protecting human health and the environment, especially in rural areas. A properly designed and installed OWTS can effectively dispose and treat wastewater discharges in a manner that will protect public health and the environment. In its 1997 Report to Congress, the EPA stated that adequately managed decentralized wastewater systems are a cost-effective and long-term option for meeting public health and water quality goals, particularly in less densely populated areas. (USEPA, 2010) Figure 1. Conventional onsite wastewater treatment system Source (USEPA, 2005): OWTS are designed to safely treat and dispose of wastewater generated from toilets, shower, bathtub, sinks, kitchen, and laundry facilities. The primary components of a standard conventional OWTS are the septic tank and the soil absorption field, also referred to as the subsurface wastewater infiltration system (SWIS). (USEPA, 2002) Wastewater flowing from the home is collected and contained in a septic tank designed to retain the wastewater for a period long enough to allow separation and decomposition of some of the wastewater constituents, i.e. waste solids, liquids, and fats, oils, and greases (FOGs), to occur. This tank must be constructed of durable material, typically rebar reinforced concrete, plastic 1

3 with fiber reinforcement, fiberglass, or polyethylene. It should be able to resist corrosion and/or decay and must be water tight. Inside the tank are inlet and outlet baffles or compartments which are designed to keep the wastewater from flowing across the top and out into the absorption system. The inlet baffle forces the wastewater down into the tank allowing the wastewater to separate into three separate layers. With sufficient retention time the solids will settle out of the wastewater onto the bottom of the tank to form a sludge layer and the FOGs will float to the surface to form a scum layer. (USEPA, 1999) The middle or segregated liquid layer is a relatively clear liquid which is the layer that fills the outlet baffle and exits the tank, and is called the effluent. The outlet baffle is designed to prevent the sludge and scum layers from exiting the tank and migrate to the absorption field. Additionally, this retention time within the tank allows for anaerobic bacteria to partially digest some of the suspended solids/wastes and start the treatment of the wastewater. This is a natural process of microbial digestion/decomposition, so no chemicals, enzymes, yeast or other additives should be added to the tanks. Normal household chemicals and occasional use of drain cleaners will not significantly affect tank operations. (Hammond & Tyson, 1991) Figure 2. Typical single-compartment septic tank Source: (USEPA, 2005) As wastewater enters the tank, an equal volume of the effluent flows from the septic tank thru distribution pipes to a distribution box. From the distribution box the effluent is dispersed to perforated pipes in the SWIS, otherwise called the drain field, leach field, or absorption field. The EPA states the SWIS is the interface between the engineered system components and the receiving groundwater environment. It is important to note that the performance of conventional systems relies primarily on treatment of the wastewater effluent in the soil horizon(s) below the dispersal and infiltration components of the SWIS. (USEPA, 2002) Therefore, the soil is the most critical component of an OWTS and can be the most problematic. An effective conventional OWTS will have a good soil component that can absorb all the effluent generated, provide a high level of treatment, and have a long, useful life. (Canter & Knox, 1985) For a conventional OWTS the infiltrative soils must be permeable and remain unsaturated for several feet below the system depth. (USEPA, 1999) It is in the infiltrative soils where disposal and most importantly 2

4 the treatment of the effluent is completed. As the effluent percolates through the soil, treatment occurs through a variety of physical, biologic/biochemical, and chemical process and reactions. It is the combination of these processes acting on the effluent as it passes through the soils that produces an acceptable quality of discharge to groundwater. (USEPA, 1980) Effluent is physically treated as it migrates through the pores of the soil where many microorganisms and suspended solids are captured and, thus, strained or filtered out of the effluent. The natural filtering process of the effluent as it moves through the soil is enhanced by biochemical and chemical processes in the soil. Most soil particles and organic matter in the soil are negatively charged. This is important because the negative charged soils attract and hold the positively charged wastewater components. The charged sites in the soil are able to absorb the principal wastewater components of concern, i.e. bacteria, viruses, ammonium, nitrogen, and phosphorus. Sufficient retention of bacteria and viruses allows for their die-off or destruction by predation by other soil microorganisms. Ammonium and other nitrogen compounds can be adsorbed and retained onto clay particles in the soil or be changed into a less insidious forms. Phosphorous is generally chemisorbed onto mineral surfaces like iron, aluminum, or calcium which are naturally present in most soils. (USEPA, 1980) The filtering and retention action of the soil is most efficient in unsaturated soils. Studies have shown that typically two to four feet of unsaturated soils are sufficient to remove bacteria, viruses, and phosphorous. Also, unsaturated soils are necessary to allow oxygen to be present for soil bacteria to nitrify ammonium to nitrate, which is soluble and more readily leachable into the groundwater. In saturated conditions the natural filtering, biochemical, and chemical processes may be short circuited because wastewater will flow through the larger pores and not be retained for sufficient time to allow the processes to work. (USEPA, 1980) In the appropriate soils a properly designed and installed conventional OWTS can operate indefinitely if they are regularly maintained. However, this combination does not typically exist; specifically most 3

5 households do not maintain their systems, so the functioning life of a conventional OWTS is typically 20 years or less. (USEPA, 1999) There are many advantages and disadvantages to a conventional OWTS. Because they treat and dispose household wastewater onsite, a conventional OWTS is typically more economical, especially in rural areas where lot sizes are larger and houses are spaced widely apart. Prior to the 1980 s, it was generally assumed that a conventional OWTS was a short-term measure until every household was connected to a centralized wastewater treatment plant. It s ironic that the large centralized treatment plant systems were planned for and designed to provide service over the plant s life expectancy of approximately 20 years, approximately the same life expectancy of a conventional OWTS. Today it is obvious that we can t install miles of sewer lines and disrupt the environment to service a few, widely spaced households. (Eddy, 2004) Besides cost there are other advantages to a conventional OWTS. They are simple to install compared to a centralized system. They are generally reliable and long lasting, especially if designed, installed, and properly maintained. Environmentally, they have a smaller impact and are less disruptive than a large centralized system. Nutrients in the waste are returned to the soil and, when functioning properly, they can help replenish groundwater. (Eddy, 2004) (USEPA, 1999) There are also disadvantages to a conventional OWTS that need to be considered. There are on-going costs for inspecting the system and routinely pumping the septic tank, generally once every three to seven years depending on usage patterns. Property owners need to be aware that not every lot is acceptable for an OWTS. There are site limitations like natural soil type, permeability, bedrock and groundwater elevations, site topography, and regulations that require and OWTS to be set-back from features like open water, water supply lines, drains, property and easement lines, and steep slopes. Another disadvantage is homeowners must take responsibility for their OWTS. This includes using water efficiently and restricting water usage so they don t hydraulically overload the system. It is recommended that homeowners use high-efficiency toilets, clothes washers, dishwashers, showerheads, and faucets to help conserve and minimize water flow. Personal habits may need to be altered; like taking long showers or big baths, washing clothes or dishes when the machine is not full, or even washing many loads of laundry a day. Additionally, homeowners need maintain plumbing fixtures so that they work properly. Items like a water softener and hot tubs should not be connected to an OWTS as they will create excessive flows. Maintenance of household fixtures is very important. A dripping faucet or a leaking flapper valve in the toilet can potentially add hundreds of gallons a day of unnecessary water to the absorption field. Most individuals on a large centralized system don t really pay attention to what they flush or dispose through their sewer. On a conventional OWTS, the homeowner needs to be cognizant of what is flushed or disposed into their system. An OWTS does not handle clogging things that don t easily break down, 4

6 items like diapers, cat litter, cigarette filters, coffee grinds, feminine hygiene and personal care products, dental floss, condoms, paper towels, and excessive scrap foods and fats/oils. In addition to clogging items are those items that will kill off the natural microorganism that are present to treat the wastewater. These include, but are not limited to, household chemicals, pesticides, antifreeze, paints, paint thinners, and petroleum products like gasoline, oils, and diesel fuels. Although an OWTS can manage normal amounts of household cleaning products, excessive amounts of those products, especially those labeled anti-bacterial, will also kill off a system. Other items that should not be disposed through an OWTS include over-the-counter medications and prescription medicines. An OWTS cannot treat these items so they pass through and impact groundwater and the environment. (Eddy, 2004) (USEPA, 2005) (USEPA, 1999) Unlike large centralized sewer systems, the homeowner needs to take an active role in the operation and maintenance of their OWTS. Most OWTS failures occur because the proper care during design, installation, and operation of the system was not taken. The homeowner doesn t have much control over the design and installation of their system, but they can manage and operate their OWTS appropriately. OWTS FAILURE Most homeowners mistakenly believes that their OWTS is working properly so long as the toilet flushes properly, there is no water backing up into the tub, and/or there is no sewer smell in the yard. Failures of an OWTS can be classified into one of four basic categories: Sewage Backflow typically manifests when sewage is backing up into the home. This is the most commonly reported failure category and the one that gets corrected quickly. Hydraulic failure generally seen as improperly/partially treated wastewater pooling on the ground surface causing marshy areas or breaking out on hill slopes. Decline in Water Quality not as easily recognizable as the previous two failure categories because it doesn t normally manifests on the property where the failure is occurring. Decline in water quality is generally found by sampling ground and surface water hydraulically down gradient of the property where a system is failing. The decline in water quality is most likely the result of pathogens or higher nitrate levels, but also can result in taste and odor problems. However, some decline in water quality can occur because solvents, excessive household chemicals, and other toxic substances like paints, thinners, pesticides, waste oils, and other hazardous chemicals are disposed of into an OWTS. Many chemicals disposed into a system are toxic to the naturally occurring bacteria that treat the wastewater, thus killing them off and resulting in untreated wastewater potentially entering waters. Additionally, many chemical substances cannot be treated by those naturally occurring microorganisms so they pass through the system and into the environment. 5

7 Gradual Environmental Degradation again, not as easily recognizable as the first two categories and usually results from several failures and as the name implies it is a gradual change in an ecosystem. This also is more difficult to identify as failing OWTS as it most likely occurs in water downstream of the failures and is more of a long-term impact. Gradual environmental degradation occurs because nutrients from the wastewater are not being filtered and captured by the soil absorption system and they enter the waterways. As nutrient levels increase in the waterways, more aquatic plant production and algae blooms occur which lead to low dissolved oxygen concentrations in the waterways. (California Wastewater Training & Research Center, 2003) (Lee, Jones, & Peterson) There are four general reasons OWTS fail; three of which are controllable and a fourth, system age, that is not. The three controllable factors include the following: Improper installation this includes proper siting, design, application of technology, and the actual construction of the system. The selection of the proper site of an OWTS is critical o the operation and longevity of the system. Each proposed OWTS site should be evaluated to determine if it is feasible for an OWTS to properly function. Factors that are assessed include topography; distance to steep slopes, water features, and other setback features; current and proposed landscaping; depth to limiting factors like groundwater, bedrock, and impermeable soils; and especially soil conditions (type, depth, structure, stratification, etc.) as they are critical to the operation and functionality of any OWTS. A percolation test maybe used to help determine the permeability of the soils and its hydraulic conductivity, the rate at which the soil will accept and move water. It is important that the soils can accept water and move it away from the distribution system fast enough so that extended saturated conditions don t occur, but not too fast so that treatment of the wastewater can take place. After the site has been evaluated and determined feasible for an OWTS, a design of appropriate size and layout is completed to be compatible with the findings of the assessment. The design should be based on the intended use of the system (residential, commercial, industrial, etc.); the expected hydraulic and organic loading; and state and local regulations. Once the site has been evaluated and a system designed, the last step is the installation of the system components. The use of the correct materials as specified by the design is important to the longevity and functionality of the system. Care should be taken to use construction practices that do not compromise the site, soil conditions, or the integrity of the system components. Practices like not installing a system under wet conditions; smearing the soil interface so soil pores and water pathways are closed; not compacting the soil in the absorption area; compacting soils under non-drainfield components, i.e. tank, sewer lines, distribution/drop 6

8 boxes to prevent settling; installing drainfield lines level; and keeping soil particles from failing down into the clean drain rock of the trenches and potentially clogging the absorption field. Improper operation OWTS should be designed to operate properly based on the anticipated waste volume (hydraulic loading), type of waste (residential or commercial), and waste strength (organic load). Each component of an OWTS is sized based on those anticipated loads, but if those loads are greater than anticipated or change, then the system may malfunction or fail more rapidly than it would under normal operations. Hydraulic overloading may occur when more water enters the system that the soil absorption system can process. This is likely to happen when one or more of the following is true: system over use (high washing frequency, more people than design anticipated); leaking plumbing fixtures; surface water run on; or high groundwater leaking back into the system because components are not watertight. Organic overload can occur if the organic material in the wastewater is too high for a system component or process, thus causing clogging of the infiltrative surface (i.e. septic rock or other media filter) or the soil absorption system. High organic overloading will often cause the septic tank to fill with system clogging suspended solids more quickly so that it would need to be cleaned more frequently. Also, failure can occur because incompatible materials, i.e. chemicals, are introduced or disposed into the OWTS that disrupt the biological, chemical, or physical processes. Inadequate maintenance- Failure to maintain systems can lead to clogging and poor performance. For a conventional OWTS, maintenance is generally limited to routine inspection of the system and regularly pumping the septic tank. If the system has any floats and pumps, filters, or is an alternative system, then regular inspection and servicing of the mechanical parts and operations should occur. If any mechanical parts or filters fail, then the system will malfunction and sewage can back up into the home or surface above ground. System Age- The fourth reason systems fail is system age. The system will eventually go into failure because the soil conditions slowly change, or solids particles and/or fats have worked their way and have clogged the pores, or a biomat forms that naturally builds up and causes plugging of the system. Typical OWTS Pollutants Many of the constituents of typical residential wastewater can potentially pollute localized and regional groundwater. The typical residential wastewater characteristics and the general range in which the constituents are found has been listed in Table 1. (Burks & Minnis, 1994) 7

9 Table 1. Composition of Typical Residential Untreated Wastewater Constituent Unit Range Typical Total Solids mg/l Dissolved Solids mg/l Suspended Solids mg/l Biochemical Oxygen Demand (BOD 5 ) mg/l Total Organic Carbon (TOC) mg/l Chemical Oxygen Demand (COD) mg/l 200-1, Total Nitrogen mg/l Organic Nitrogen mg/l Ammonia mg/l Nitrite mg/l 0 0 Nitrate mg/l 0 0 Total Phosphorous mg/l Organic Phosphorous mg/l Inorganic Phosphorous mg/l Chloride mg/l Sulfate mg/l Alkalinity mg/l Grease mg/l Total Coliform colonies/100 ml VOCs µg/l These wastewater characteristics can be grouped into the five general categories of potential groundwater pollutants. Each of these potential contaminates are discussed and examined in regard to their potential impacts and mechanisms of attenuation in the soil. 8

10 Pathogens Pathogens are biological contaminates in the form of microorganisms, typically bacteria and viruses. These pathogenic microorganisms can potential migrate from an OWTS into the groundwater if there is insufficient soil, insufficient retention time in the soil or if the soil becomes saturated. However, if an OWTS is properly designed, installed and maintained the pathogens are primarily removed by filtration, sedimentation, and adsorption. Much of the pathogenic bacteria is removed from the wastewater in the septic tank, but none of the protozoan cysts and only about half of the helminth eggs are removed. The remaining microorganisms in the effluent can be efficiently removed through the physical straining or filtration of the wastewater as it moves through the soil. The effectiveness of the soil to filter these pathogens is generally inversely proportional to the soil particle size, i.e. the smaller the size the more effective it filters the percolating effluent. However, the smaller the particle is in size the potential increases for soil clogging which can eventually lead to hydraulic failure. Therefore, there is a delicate balance to install OWTS in soils that can filter the effluent, but also allow it to migrate. Studies have shown that one to three feet of soil beneath the soil absorption system is adequate for complete removal of pathogenic bacteria provided the soils has a the ability to allow unsaturated flow while providing enough restrictiveness to form a filtration zone. Adsorption, the process of bonding the microorganisms to soil particles, can also play a big part in bacterial removal. Soils with increased clay content and organic fraction are the most effective in bonding bacteria. The organic fraction of a soil profile is greatest near the surface, thus adsorption is most effective in systems with near-surface disposal methods. Once retained in the soil, the pathogenic bacteria will eventually die off. The rate of the die off is dependent on the moisture content, moisture holding capacity, temperature, ph, presence of organic matter, and antagonism form other soil microflora. Survival of the bacteria is enhanced by higher moisture content, low temperatures, high organic matter content, and lack of antagonism of competing microflora. Because of evapotranspiration and increase in antagonistic microflora in near surface soils, OWTS with the soil absorption system installed as shallow as possible is generally the most effective placement for removal of pathogenic bacteria. Another important factor to the effectiveness is the loading rate to which the wastewater is applied to the soils. High loading rates decrease the travel and contact time between the bacteria and the soil which reduces the removal efficiency of the system Pathogenic viruses have a longer life span in soils than bacteria and constitute a significant threat to public health. Because of viruses smaller size than other microorganisms, the removal of viruses are almost totally dependent on adsorption. Factors that impact the removal of viruses include flow rate, 9

11 soil characteristics, ph, cations present, characteristics of the virus, and the content of soluble organic matter in the water. Lower flow rates are important to provide longer and better contact between the percolating water and potential adsorption sites in the soils. Important soil characteristics that influence virus movement and adsorption are clay content, cation exchange capacity, chemical composition, and organic matter. High clay content is more effective in removing viruses due to the higher cation exchange capacity and larger surface area per volume than other soil particles. Soils with higher metal complexes like iron oxides and soils with higher exchangeable aluminum readily adsorb viruses to their surfaces. Organic matter is particularly important in soils that lack the adsorption capacity provided by clays because it offers a larger number of active sites for adsorption to occur. However, the presence of soluble organic matter in the water competes with viruses for adsorption sites on soil particles and therefore hinders the adsorption of viruses. Lower ph also favors virus adsorption due to its impact on the net charge of viruses and soil components. Soils with neutral or high ph can hinder virus adsorption and can cause elution of viruses already adsorbed. (Venhuizen, 1995) (Luce, Hansen, & Poole, 1994) Nitrogen Nitrogen compounds, generally in the form of ammonia, nitrate, and organic nitrogen, are probably the most problematic and difficult to treat in conventional OWTS. Nitrogen entering the septic tank is mostly organic nitrogen, approximately 70%, and the remainder is mostly ammonia. The anoxic conditions in the tank allow anaerobic bacteria to convert approximately 75% of the organic nitrogen to ammonia so that only 25% organic nitrogen and 75% ammonia are exiting the septic tank. In a properly functioning soil absorption system, aerobic conditions should predominate beneath the trench which allows for aerobic bacteria to convert the ammonia to a nitrate form of nitrogen in a process called nitrification. Unless conditions are favorable for de-nitrification (an anaerobic environment to convert nitrate to nitrogen gas), nitrates can readily migrate with the percolating water resulting in the potential of nitrate impacting and polluting ground and surface waters. Some nitrogen removal can occur in the soil absorption systems through adsorption, fixation, volatilization, biological uptake, and denitrification, unfortunately not enough. Most of these nitrogen removal processes occur more readily in the upper or near surface layers of the soil. The Figures on the next pages illustrates these treatment processes and the fate of nitrogen as it passes through an OWTS. (Venhuizen, 1995) (Luce, Hansen, & Poole, 1994) 10

12 Source: (Luce, Hansen, & Poole, 1994) 11

13 Phosphorous Phosphorous is not generally a concern to groundwater pollution because it is readily removed by the soil. However, it is of great concern in surface waters because as a nutrient it can increase algae growths or blooms and decrease water quality. The removal and immobilization of phosphorus in a septic system is dependent upon the availability of sorption sites where negatively charged phosphate ions can attach to positively charged cations present in soil minerals. These sorption sites are provided by clay and organic fractions of the soil. A soils sorption capacity is finite, once those sorption sites are occupied movement of phosphorous increases. The rate of phosphorous movement is dependent upon the application rate, percolation rate, and the ph of the soil. Other mechanisms of removing phosphorous in soils include plant uptake and biological immobilization. (Luce, Hansen, & Poole, 1994) (Venhuizen, 1995) Trace Organics Organic compounds are increasingly being found in trace concentrations in wastewater effluent and thus have the potential to pollute groundwater. Trace organic compounds are synthetic organic chemicals that are potentially toxic and/or carcinogenic. These substances can be introduced into the wastewater through household cleaners and common chemicals used around the residence. Many can be pesticides, herbicides, or other volatile organics. Concern regarding these compounds has increased as improved analytical methods have been able to detect their presence in waters in concentrations on 12

14 the order of parts per trillion. Many of these trace organics can be removed from the effluent by soils through sorption, volatilization, and biological degradation or attenuation. These removal mechanisms generally perform most efficiently in the near surface soil. Trace Inorganics Inorganic compounds are the minerals and metals that are found in wastewater, such as sodium, potassium, calcium, magnesium, cadmium, copper, lead, nickel, and zinc. These metals can enter into the wastewater from a variety of sources, but the most common is from leaching of aging pipes. Most of the inorganic compounds are stable and aren t readily broken down or degraded by organisms in wastewater and so flow through to the soil absorption system. Whatever the amount of inorganics in the wastewater, it is expected that the soil will be the primary removal mechanism. Similar to organics and phosphorous, the sorption sites on fine grained soil particles are responsible for this process. Also, this process is most efficient in the near-surface soil horizons. Some studies do indicate that some filtration of inorganics can occur as water percolates through the soils. Large amounts of inorganic compounds can potential contaminate soil and water, but such concentrations are not typical of residential wastewater. The long-term accumulation of inorganics to a degree where they potentially could become a toxic hazard to animals and humans is very unlikely to result from residential wastewater, but potentially could occur from some industrial processes. (College of Engineering, Forestry, and Natural Sciences, 2011) (Venhuizen, 1995) Historic Impacts of OWTS Use on Groundwater Quality Currently, the Wasatch County Health Department is unaware of any ongoing studies or sampling of groundwater in the Wallsburg watershed area. Historically, there is limited documentation of groundwater sampling data from wells and springs in the area as well. A 1991 study entitled Hydrology of Heber and Round Valleys, Wasatch County, Utah, with emphasis on simulation of ground-water flow in Heber Valley was published by the Utah Department of Natural Resources. (Roark, Holems, & Sholsar, 1991) This report contained chemical analysis data from fourteen wells and springs in Round Valley. One data point was from a sample collected in 1941 and the remaining data points were from samples collected in The samples were analyzed for 25 inorganic properties, not all of which had reported analytical data. The table below is a summary of those analytes typically found in wastewater. Based on the reported data summarized below, at that point in time, it does not appear that groundwater in the Wallsburg watershed had been significantly or adversely impacted by the use of OWTS in the area. Constituent Unit Analysis Range Mean ph Alkalinity mg/l

15 Solids, dissolved mg/l Nitrogen, NO 2 + NO 3 mg/l < Nitrogen, Ammonia mg/l < Phosphorus mg/l < Present Status of OWTS Usage The Wasatch County Health Department (WCHD) does maintain files for properties where OWTS have been installed and operated. However, records only extend back into the 1980 s and sometimes into the 1970 s. A survey was conducted in 2005 in attempts to identify parcels with OWTS and to locate the components of the systems. According to the data collected from WCHD s files and the results of the survey there were 289 onsite wastewater treatment systems in operation in the Wallsburg watershed. To take into account systems that may have been missed and the permits issued since that time, it is estimated that there are 320 systems within the Wallsburg watershed. Map 1 in Appendix A shows the location of the OWTS from the survey of Failures of OWTS On average there are approximately one to two failing systems a year in the area that are reported to WCHD. A wastewater permit is required for all failures, repairs and replacements of OWTS. Unfortunately, not everybody reports a failure, repair or replacement of their OWTS as required by WCHD wastewater rules. One of the most common causes of an OWTS failing is the failure to pump the tank so solids and other materials flow out of the tank and cause the piping to clog or cause the soil interface to plug so that water cannot be transported away from the distribution pipe. To avoid failures, WCHD recommends that an OWTS is inspected every year and that the septic tank is pumped every three to seven years depending upon usage and the amount sludge/scum build up in the tank. This small amount of preventative maintenance will extend the life of a system and reduce the large costs associated with replacing the system. Once an OWTS fails because of age, improper installation, or lack of maintenance the typical response is to replace the absorption field with an equivalent field. Ideally, the failed soil absorption system (SAS) should be left in place and allowed to relax and recover. Thus, allowing for the old SAS to be used again after it has recovered. During the installation of the new SAS, a diversion valve can be installed so that effluent can be directed to either the old or new SAS as needed. By alternating SAS fields, a septic system can be virtually sustainable as long as there is regular maintenance of the system and repairs as needed. 14

16 Generally, the old systems that were installed prior to any regulations or real enforcement of the regulations are not in compliance with current standards. At the time of failure, it is WCHD s goal to bring the system, as much as possible, into compliance with current rules and regulations. The objective requiring compliance with the more restrictive code is to increase groundwater protection, ensure a healthier environment, and protect public health. Management of OWTS The USEPA in their Onsite Wastewater Treatment Systems Manual said Effective management is the key to ensure in the requisite level of environmental and public health protection for any given community is achieved. One of the most important issues relating to septic tank use is an effective management program. Effective management programs involve many partners but most importantly are the homeowners and local regulators. The homeowner is the most important factor in an effective OWTS management program. One of the most basic things the property owner can to is to modify their behavior. By watching what they introduce into their system and use in their house, they can improve the likelihood of the system functioning properly. Homeowners must not flush items that don t easily breakdown like diapers, dental floss, feminine hygiene products, cigarette butts, coffee grounds, condoms, cat litter, chemicals, petroleum products, paints, medicines, or any items that could potentially clog the system. Simply being aware of what they dispose of can prolong the life of the system. Also, the property owners should conduct routine or annual inspections of their systems. They should check, fix or replace plumbing fixtures that may allow excessive amounts of water into the system and cause it to hydraulically fail. They can also check the soil absorption area for unusual smells, wet or soggy areas, areas of unusual vegetation growth, and especially any surfacing water. The most important thing the property owner can do is check their septic tanks annually and have it pumped as need or at least every three to seven years. The homeowner can check their tank by sticking a rod or other measuring device and determine the depth of the scum and sludge layers. Typically, if the scum layer is greater than 12 inches or the sludge layer is greater than 20 inches, the tank should be pumped. Additionally, regulators need to be conscientious in their approach to the program starting with ensuring that the site is adequate for an OWTS. At a minimum, features should be looked at that will affect the performance of the system such as water features, depth to groundwater, depth to bedrock or impermeable layers and most importantly the suitability of the soil to conduct water away from the distribution system. Besides ensuring that the site is suitable for a system, the regulator should review the design of the OWTS to determine if it meets all the requirements of the regulations and more importantly is appropriate for the proposed site. Next, the regulator should inspect the installation of the systems to verify that they are installed in accordance with the approved designs and current 15

17 regulations. The regulator should also work with and educate the property owner to help them understand their system and what they can do to get the most out of it. Current regulations Onsite wastewater treatment systems in Wasatch County are regulated under the Utah Administrative Code R317-4 and Wasatch County Health Department Rules. The general purpose of the rules is to provide guidance to and establish minimum requirements for the design, installation and operation of onsite wastewater treatment systems in a manner that will not significantly affect human health or the environment. Copies of R317-4 and local rules applicable to OWTS are provided in Appendix B. Water Quality Study In 1993 Wasatch County contracted Hansen, Allen & Luce, Inc. to prepare a Hydrogeologic/Water Quality Study to address some of the County s most pressing water quality issues. Wasatch County has sensitive watersheds which provide a significant portion of the culinary water supply to large population areas downstream. Throughout the years Wasatch County has made significant efforts to protect the quality of the vulnerable water resources. The stated purpose of the study was to asses the adequacy of current County water quality protection measures and to prepare or strengthen guidelines in the following three areas as needed: Drinking water source protection; Septic system usage; Surface water quality protection. The study is significant to this report as it reviewed, collated, and summarized significant data specific to Wasatch County including Round Valley. Maps 2 and 3 in Appendix A respectively show general groundwater elevation levels in Round Valley and groundwater velocity and flow direction in the valley. Most significantly, the Hansen, Allen & Luce report provided recommendations which Wasatch County has acted upon, including the area within the Wallsburg watershed, to reduce potential impacts on water quality. Specifically, Wasatch County increased the minimum size of new parcels to the recommended five acres as an attempt to reduce water quality issues potential caused by OWTS densities. Additionally, the report made recommendations regarding improving site evaluation and monitoring depths to groundwater. The report also reaffirmed Wasatch County s rule requiring a 4 foot minimum separation to ground water from the soil absorption system, replacing the 2 foot minimum separation requirement in R Map 4 in Appendix A shows the Utah Geologic Survey feasibility determination for OWTS as it relates to the depth of groundwater. 16

18 Recommendations To understand the water quality and potential issues of the Wallsburg Watershed, the Wasatch County Health Department recommends that an expanded study similar to the Hansen, Allen, Luce study conducted in 1994, be considered specifically for this area. This study could better evaluate the actual and future impacts to ground and surface water resources in the area of not only OWTS, but of agricultural and residential practices, change of irrigation patterns, and use of pesticides and fertilizers. Regarding the use of OWTS within the Wallsburg watershed, the following recommendations are presented from least expensive and most achievable to most expensive and least achievable: Because it is private citizens who own and operate these systems there is limited ability to ensure the proper operation and maintenance. As such, steps should be taken to initiate an educational campaign for property owners to help them understand how to operate and maintain their systems in a manner which minimizes impacts. Develop and institute a maintenance program for all OWTS in the area. This program could be voluntary or with the oversight of an onsite wastewater management district. The program could require all system owners to obtain an operating permit which would require the submission of annual inspections of the entire system for renewal; or those participating could just be required to pump the septic tank and inspect all components of the system every three to five years of operation. For all new construction and repair/replacement of existing systems, design techniques should be considered that allow for better treatment of wastewater and sustainability of the OWTS. Such techniques include but are not limited to, over sizing the tank and drainfield, providing convenient access to the tank and drainfield for inspection purposes, use of alternating drainfields, dosing the effluent throughout the drainfield through a pressurized system, using alternative technologies that treat the effluent prior to disposal for water quality s sake, not just to overcome limitations. The concept of the formation of a sewer district should also be taken into consideration. A sewer district could be used to convert existing systems that are within the Wallsburg Watershed to a modified centralized sewer system or even a traditional centralized sewer system. Feasibility of using a STEP system (septic tank effluent pumping system that moves wastewater to a centralized disposal area) and the traditional centralized sewer system (central collection of sewage with treatment and disposal off-site), should be investigated. 17

19 APPENDIX A MAPS 18

20 Map 1 Round Valley Septic System Locations 19

21 Map 2 Round Valley Hydrogeology Source: (Luce, Hansen, & Poole, 1994) 20

22 Map 3 Round Valley Ground Water Velocity and Direction Source: (Luce, Hansen, & Poole, 1994) 21

23 Map 4 USGS OWTS Suitability Depth to Ground Water Source: (Utah Geologic Survey Open File Report 319) 22

24 APPENDIX B STATE RULE R317-4 AND LOCAL RULES 23

25 R Onsite Wastewater Systems. R Definitions. RULE R317-4 Onsite Wastewater Systems 1.1. "Absorption bed" means an absorption system consisting of a covered, gravel-filled bed into which septic tank effluent is discharged through specially designed distribution pipes for seepage into the soil "Absorption system" means a device constructed to receive and to distribute effluent in such a manner that the effluent is effectively filtered and retained below ground surface "Absorption trench" means standard trenches, shallow trenches with capping fill, and chambered trenches constructed to receive and to distribute effluent in such a manner that the effluent is effectively filtered and retained below ground surface "Alternative onsite wastewater system" means a system for treatment and disposal of domestic wastewater or wastes which consists of a building sewer, a septic tank or other sewage treatment or storage unit, and a disposal facility or method which is not a conventional system; but not including a surface discharge to the waters of the state "At-Grade" System means an alternative type of onsite wastewater system where the bottom of the absorption system is placed at or below the elevation of the existing site grade, and the top of the distribution pipe is above the elevation of existing site grade, and the absorption system is contained within a fill body that extends above that grade "Bedrock" means the rock, usually solid, that underlies soil or other unconsolidated, superficial material "Bedroom" means any portion of a dwelling which is so designed as to furnish the minimum isolation necessary for use as a sleeping area. It may include, but is not limited to, a den, study, sewing room, sleeping loft, or enclosed porch. Unfinished basements shall be counted as a minimum of one additional bedroom "Building sewer" means the pipe which carries wastewater from the building drain to a public sewer, an onsite wastewater system or other point of disposal. It is synonymous with "house sewer" "Chambered trench" means a type of absorption system where the media consists of an open bottom, chamber structure of an approved material and design, which may be used as a substitute for the gravel media with a perforated distribution pipe "Condominium" means the ownership of a single unit in a multi-unit project together with an undivided interest in common, in the common areas and facilities of the property "Conventional system" means an onsite wastewater system which consists of a building sewer, a septic tank, and an absorption system consisting of a standard trench, a shallow trench with capping fill, a chambered trench, a deep wall trench, a seepage pit, or an absorption bed. 24

26 1.12. "Curtain drain" means any ground water interceptor or drainage system that is gravel backfilled and is intended to interrupt or divert the course of shallow ground water or surface water away from the onsite wastewater system "Deep wall trench" means an absorption system consisting of deep trenches filled with clean, coarse filter material, with a minimum sidewall absorption depth of 24 inches of suitable soil formation below the distribution pipe, into which septic tank effluent is discharged for seepage into the soil "Division" means the Utah Division of Water Quality "Disposal area" means the entire area used for the subsurface treatment and dispersion of septic tank effluent by an absorption system "Distribution box" means a watertight structure which receives septic tank effluent and distributes it concurrently, in essentially equal portions, into two or more distribution pipes leading to an absorption system "Distribution pipe" means approved perforated pipe used in the dispersion of septic tank effluent into an absorption system "Domestic wastewater" means a combination of the liquid or water-carried wastes from residences, business buildings, institutions, and other establishments with installed plumbing facilities, together with those from industrial establishments, excluding non-domestic wastewater. It is synonymous with the term "sewage" "Domestic septage" means the semi-liquid material that is pumped out of septic tanks receiving domestic wastewater. It consists of the sludge, the liquid, and the scum layer of the septic tank "Drainage system" means all the piping within public or private premises, which conveys sewage or other liquid wastes to a legal point of treatment and disposal, but does not include the mains of a public sewer system or a public sewage treatment or disposal plant "Drop box" means a watertight structure which receives septic tank effluent and distributes it into one or more distribution pipes, and into an overflow leading to another drop box and absorption system located at a lower elevation "Dry Wash" means the dry bed of an intermittent stream that flows only after heavy rains and is often found at the bottom of a canyon "Dwelling" means any structure, building, or any portion thereof which is used, intended, or designed to be occupied for human living purposes including, but not limited to, houses, mobile homes, hotels, motels, apartments, business, and industrial establishments "Earth fill" means an excavated or otherwise disturbed suitable soil which is imported and placed over the native soil. It is characterized by having no distinct horizons or color patterns, as found in naturally developed undisturbed soils "Effluent lift pump" means a pump used to lift septic tank effluent to a disposal area at a higher elevation than the septic tank. 25

27 1.26. "Ejector pump" means a device to elevate or pump untreated sewage to a septic tank, public sewer, or other means of disposal "Experimental onsite wastewater system" means an onsite wastewater treatment and disposal system which is still in experimental use and requires further testing in order to provide sufficient information to determine its acceptance "Final local health department approval" means, for the purposes of the grandfather provisions in R (Table 1, footnote a) and R , the approval given by a local health department which would allow construction and installation of subdivision improvements. Note: Even though final local health department approval may have been given for a subdivision, individual lot approval would still be required for issuance of a building permit on each lot "Ground water" means that portion of subsurface water that is in the zone of soil saturation "Ground water table" means the surface of a body of unconfined ground water in which the pressure is equal to that of the atmosphere "Ground water table, perched" means unconfined ground water separated from an underlying body of ground water by an unsaturated zone. Its water table is a perched water table. It is underlain by a restrictive strata or impervious layer. Perched ground water may be either permanent, where recharge is frequent enough to maintain a saturated zone above the perching bed, or temporary, where intermittent recharge is not great or frequent enough to prevent the perched water from disappearing from time to time as a result of drainage over the edge of or through the perching bed "Gulch" is a small rocky ravine or a narrow gorge, especially one with a stream running through it "Gully" is a channel or small valley, especially one carved out by persistent heavy rainfall or one holding water for brief periods of time after a rain storm or snow melt "Impervious strata" means a layer which prevents water or root penetration. In addition, it shall be defined as having a percolation rate greater than 60 minutes per inch "Invert" is the lowest portion of the internal cross section of a pipe or fitting "Liquid waste operation" means any business activity or solicitation by which liquid wastes are collected, transported, stored, or disposed of by a collection vehicle. This shall include, but not be limited to, the cleaning out of septic tanks, sewage holding tanks, chemical toilets, and vault privies "Liquid waste pumper" means any person who conducts a liquid waste operation business "Local health department" means a city-county or multi-county local health department established under Title 26A "Lot" means a portion of a subdivision, or any other parcel of land intended as a unit for transfer of ownership or for development or both and shall not include any part of the right-of-way of a street or road. 26