Otter Tail Water

Management District

Septic System Use

and Maintenance

Evaluation

2017

Onsite Sewage Treatment ProgramWater Resources Center University of Minnesota Taylor Nelson, Sara Heger

173 McNeal Hall

1985 Buford Avenue

St. Paul, MN 55108

800-322-8642

septic.umn.edu

Table of Contents Introduction ................................................................................................................................... 3

Methods .......................................................................................................................................... 7

Results and Discussion .................................................................................................................. 8

References .................................................................................................................................... 17

Appendix A ..................................................................................................................................... i

List of Figures Figure 1. The three basic components of a subsurface sewage treatment system: plumbing, septic

tank, and soil treatment area. .......................................................................................................... 3

Figure 2. Cross-section of a septic tank. ......................................................................................... 4

Figure 3. Study area in Otter Tail County, Minnesota, in the townships of Amor, Everts, Girard,

and Otter Tail. ................................................................................................................................. 5

Figure 4. Example of a two-compartment tank. ............................................................................. 6

Figure 5. Breakdown of the residence type of survey respondents ................................................ 8

Figure 6. Excessive wastewater discharge to a septic tank results in the disruption of wastewater

treatment due to turbulence. .......................................................................................................... 12

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List of Tables Table 1. Property use factors and the influence on septic tank cleaning. ....................................... 9

Table 2. Occupancy factors and the influence on septic tank cleaning. ......................................... 9

Table 3. Home characteristic factors and the influence on septic tank cleaning. ......................... 10

Table 4. Standard household appliance factors and the influence on septic tank cleaning. ......... 11

Table 5. Extra household appliance factors and the influence on septic tank cleaning. ............... 13

Table 6. Household chemical use factors and the influence on septic tank cleaning. .................. 14

Table 7. Factors that were found to have an impact on septic tank cleaning frequency and

average time between tank cleanings. ........................................................................................... 15

Table 8. Factors that did not have an impact septic tank cleaning frequency or average time

between septic tank cleanings. ...................................................................................................... 16

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Executive Summary Subsurface sewage treatment systems (SSTS - commonly referred to as septic systems) protect human health and the environment. When SSTS fail, partially treated wastewater is released into the environment, putting others at risk. Proper design, installation, operation, and maintenance of SSTS ensures wastewater is treated efficiently and effectively, while also helping to prevent costly repairs and/or replacement. Better understanding of the impact of household practices is needed for more specific SSTS maintenance recommendations. While it is known proper maintenance directly affects the function and longevity of a septic system, further analysis of the impact that household practices have on maintenance is needed. A water management district in West Central Minnesota, the Otter Tail Water Management District (OTWMD), provided a unique study opportunity for the analysis of household practices and maintenance needs of septic systems. The OTWMD, formed in 1981, is responsible for maintaining septic systems to ensure proper sewage treatment and dispersal at an affordable long-term cost for the community. In 1984, the U.S. Environmental Protection Agency (EPA) initiated and funded a large portion of a project to upgrade and inspect the existing 1,250 SSTS, resulting in the installation of 837 new individual SSTS and 13 cluster SSTS. Since the establishment of the OTWMD, only 40 of the 1,680 SSTS have been replaced (failure rate of only 2.4%). This study looked for correlations between household practices and the functioning of individual wastewater treatment systems in order to identify factors contributing to successful septic system performance. Homeowner surveys were coupled with septic tank inspection and monitoring records kept by the OTWMD. The majority of survey respondents were part-time residents. The following two data sets were of interest: the frequency at which septic tank pumping occurred and the average length of time between septic pumping events. A Kruskal-Wallis Test was used to identify factors that had significant impact on septic tank cleaning frequency. There were 28 household factors, which were tested against the two cleaning categories. Of the 56 factors tested (28 household factors and two cleaning categories), 17 were found to have an impact on septic tank cleaning. Septic tank cleaning frequency and average time between septic tank cleanings were both impacted by the presence of a water softener, washing machine, hot tub, dishwasher, property use (i.e. seasonal/all-year), and fixture leaks. These factors contribute additional solid waste and/or water to the septic system. The result is a need for more frequent cleaning due higher solid content and higher potential for disruption of the treatment process from turbulence. Average time between septic tank cleanings was impacted by having well water, the number of adults and children at the residence, having a sump pump, and the use of long-term prescription medications. Finally, several ideas for increasing survey response rates and response effectiveness have also been developed.

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Introduction

Subsurface Sewage Treatment Systems Subsurface sewage treatment systems (SSTS - commonly referred to as septic systems) protect human health and the environment by recycling wastewater back into the natural environment. Over 25% of Minnesota’s households treat their wastewater using septic systems (Onsite Sewage Treatment Program, 2011). These SSTS utilize physical, chemical, and biological processes for treatment and are composed of three basic parts: plumbing, a septic tank, and a soil treatment area. Plumbing delivers raw sewage from the home to the septic tank, where settling and decomposition of solids occurs. The partially treated wastewater is then delivered from the septic tank to the soil treatment area (STA), where treatment is completed and the water is dispersed (Figure 1, (Onsite Sewage Treatment Program, 2011)).

Figure 1. The three basic components of a subsurface sewage treatment system: plumbing, septic tank, and soil treatment area.

Proper design, installation, operation, and maintenance of SSTS ensures wastewater is treated efficiently and thoroughly, while also helping to prevent costly repairs and replacement. Improper maintenance, overuse of water, or the improper design or installation of a septic system can lead to system concerns and/or failures. During a failure, people and the natural environment are at risk of coming into contact with insufficiently treated wastewater. Signs of a septic system failure may be obvious, such as sewage backup into a house or surfacing in the yard, or the signs are subtler, like the deterioration of water quality in nearby waterbodies.

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Figure 2. Cross-section of a septic tank.

Better understanding of the impact household practices is needed for more specific SSTS maintenance recommendations. While we know proper maintenance directly affects the function and longevity of a septic system, we need further analysis of the impact that household practices have on maintenance needs. For example, proper maintenance includes evaluating the septic tank at least every three years, which is required by MN Rules Chapter 7080.2450, Subp.2. A tank should be cleaned when: ¼ of the initial liquid capacity is occupied by floating and settled solids, when the top of the sludge layer reaches twelve inches below the outlet baffle, or when the bottom of the scum layer reaches three inches above the outlet baffle (Onsite Sewage Treatment Program, 2011; MN Rules Chapter 7080.2450). The specific cleaning frequency depends on many factors, with four major factors being household size, total wastewater generated, volume of solids in wastewater, and septic tank size (U.S. E.P.A., n.d.). General recommendations regarding septic system maintenance exist and include using toilet paper recommended for septic systems, conservation of household water to allow for longer retention times, using liquid laundry detergents as some powdered detergents contain filler material that may plug the drain field, more frequent tank cleaning if a garbage disposal is used, no use of additives, and do not dispose of non-biodegradable materials, petroleum-based products, or latex-based products (Derickson, 2002). Additionally, septic tank cleaning intervals must be properly determined, as cleaning a septic tank too frequent does not allow for the establishment of necessary microbial communities responsible for thorough digestion (Bounds, 1997). As previously stated, better understanding of the impact of specific household practices is needed for improved septic system maintenance recommendations and a water management district in northwestern Minnesota provided a unique study opportunity for such analysis.

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Otter Tail Water Management District The Otter Tail Water Management District (OTWMD) in Otter Tail County, Minnesota is responsible for maintaining approximately 1,700 septic systems for residences in a 55-square mile area, which includes portions of the City of Ottertail, the townships of Amor, Everts, Girard, and Otter Tail, and six lakes (Figure 3).

Figure 3. Study area in Otter Tail County, Minnesota, in the townships of Amor, Everts, Girard, and Otter Tail.

The OTWMD was formed in 1981 to ensure proper sewage treatment at an affordable long-term cost for the community, in response to declining lake water quality and anticipated population growth. The chief water quality concerns included elevated levels of nitrate in groundwater, and lakes with decreased water clarity and elevated levels of phosphorus (Christopherson & Anderson, 2004). If septic systems are not functioning properly, untreated sewage containing high levels of nutrients can be released into the environment. In 1984, the U.S. Environmental Protection Agency (EPA) initiated and funded a large portion of a project to upgrade and inspect the existing 1,250 SSTS. Eight hundred and fifty SSTS were replaced the following year. All new systems are required to have a two-compartment tank (Figure 4, (Onsite Sewage Treatment Program, 2011)), resulting in most new systems consisting of a 1,000-gallon first compartment followed by a 500-gallon second compartment. There are different types of SSTS systems found

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throughout the District, including on-site mounds, pressure beds, gravity trenches, gravity beds, and community cluster drainfields. The OTWMD assumed responsibility of the SSTS and cluster systems. There are now 1,680 SSTS in the OTWMD. Since the establishment of the OTWMD, only 40 of the 1,680 STSS have been replaced (failure rate of only 2.4%), with additional replacement or upgrade of 120 older pre-District systems.

Figure 4. Example of a two-compartment tank.

The District has been recognized as a success story for proper management of SSTS, with an effective inspection and maintenance program. There are two management options for those in the OTWMD, active or passive. The inspection frequencies are the same for both active and passive, with inspections occurring every two years for SSTS that are used year-round, while seasonally used SSTS are inspected every three years. OTWMD assumes responsibility for maintenance and repairs of active SSTS, while maintenance and repairs for passive SSTS remain the homeowner’s responsibility. All properties pay a yearly administrative fee to the OTWMD. Since 2012, all new systems have been required to be on active management.

When implementing a SSTS management plan, the OTWMD recommends establishing an accurate account of what the district would be taking over, segmenting the district, determine basic home characteristics (e.g. number of bedrooms, seasonal vs. permanent use), establishing and adherence to an inspection timeline, determining a standard inspection procedure with detailed documentation of system conditions, and the employment of a licensed SSTS professional who is familiar with your systems and equipment.

This study looked for correlations between household practices and the function of individual wastewater treatment systems in order to identify factors contributing to achieving such a high septic system success rate. Homeowner surveys were coupled with septic tank inspection and monitoring records kept by the District in an attempt to identify correlations.

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Methods The District has kept records of septic system inspections and monitoring details for each residence. These records included type of management plan (active or passive), residence type (permanent or seasonal), inspection date, scum measurement, sludge measurement, years tank cleaned, installation date, system type, drainfield size, and years pump tank cleaned, as well as comments from inspections. Surveys were sent to all homeowners, with a 27% response rate (443 responded out of 1618 sent). The homeowner surveys were created by the authors and included questions pertaining to property use frequency, average number of visitors, the presence and use of water-related household appliances (garbage disposal, dishwasher, etc.), the presence of water-related activities and/or equipment (hot tub, sump pump, outdoor drains, etc.) and if the outputs are sent to the septic tank, use of antibacterial products, and use of medications (Appendix A). The surveys were sent in early August 2014. There was no date deadline to return the surveys, but almost all the responses received came back within two months.

Cleaning events for the septic tank were obtained from the District’s septic inspection and maintenance records. These records specified the year that a pumping event occurred. Septic tanks were cleaned when: ¼ of the initial liquid capacity was occupied by floating and settled solids, when the top of the sludge layer reached twelve inches below the outlet baffle, or when the bottom of the scum layer reached three inches above the outlet (MN Rules Chapter 7080.2450). A sludge judge was used to visually inspect sludge and scum levels within the septic tank. According to the District, pump tanks were cleaned every three years, as well as at the time of septic tank cleaning. The average length of time between septic tank cleanings was determined by manually averaging the years between the recorded years.

The following two data sets were of interest: the frequency at which septic tank pumping occurred (i.e. the total number of pumping events) and the average length of time between septic pumping events (i.e. the average number of years between each pumping event). The data were first statistically analyzed for normality. Many statistical tests require the dependent variable to be normally distributed (bell curve distribution). Tank cleaning frequency and time between tank cleanings were found to significantly deviate from a normal distribution (as reported by a Shapiro-Wilk Test of Normality); meaning nonparametric statistical tests had to be used to analyze the data. Nonparametric statistical tests often analyze data based on ranks.

The Kruskal-Wallis Test was used to test for significant differences of a dependent variable with grouping of the independent variable and rank assignment. Independent variable groups were required to have at least five samples when possible (for sample sizes see Appendix B). When the sample size for a group was less than five, groups were combined and assigned the weighted average for a new group value to ensure adequate sample size (denoted by *). The null hypothesis assumed the samples (in groups) are from identical populations, meaning we would expect no significant difference between ranks. If the null hypothesis is rejected, we accept the alternative hypothesis, that the samples come from different populations, meaning the factor by which groups were sorted is shown to influence the reported value (i.e. in this case tank cleaning frequency). We used a 0.05 significance level.

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Results and Discussion

Response Overview The majority of homeowner-survey respondents were warm-months part-time residents (60%), followed by full time residents (34%), all season part-time residents (5%), and 1% did not specify residence type (Figure 5). The District is comprised of approximately 440 (26%) permanent residents, and 1260 (74%) seasonal residents, however many of the seasonal residents are present over half of the year (breakdown of seasonal was not available). The survey results were sufficient in number and composition to draw conclusions, as the proportions of resident-type between homeowner-survey respondents and actual District statistics are relatively similar.

This study highlighted certain household practices that affect septic system cleaning frequency and others that did not. However, this study was limited due to the low survey response rate (27%), incomplete or unclear responses, and small sample size per group. A low survey response rate ultimately means the survey results are not representative of the population being studied. A 50%-60% response rate is an appropriate benchmark (Baruch & Holtom, 2008; Punch, 2003).

Septic tank cleaning frequency and average time between tank cleanings were found to be significantly different based on property use type (e.g. full vs. part-time) (Table 1), meaning those who lived in a home full-time had their septic tanks pumped more frequently (Table 1). The average frequencies for septic tank cleanings between property use categories were 2.4 for warm-month part-time residents, 3.2 for full time residents and 2.7 for all season part-time residents. The average of average time between septic tank cleanings between property uses categories were: 8.9 years for warm-month part-time residents, 4.9 years for full time residents, and 7.9 for all season part-time residents.

All Seasons Part-time5% N/A

1%

Warm Months Part-time

60%

Full-time34%

Residence Type

Figure 5. Breakdown of the residence type of survey respondents (n = 443).

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Table 1. Property use factors and the influence on septic tank cleaning. Significant impact from a factor on septic tank cleaning is indicated by The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Property Use

Household Factor (response options)

Septic Tank Cleaning Frequency

Average Time Between Septic Tank

Cleanings Use

(permanent/seasonal-summer/seasonal-all year)

Average time between septic tank cleanings was found to be impacted based on the average number of adults and the average number of children currently occupying a residence (Table 2). More people results in more waste generation and the subsequent need for more frequent septic tank cleaning. The number of bedrooms in a residence did not have an impact on septic tank cleaning (Table 2). The average septic tank cleaning frequency based on number of adults were: 3.0 for 1 adult, 2.8 for 2 adults, 3.1 for 3 adults, 2.6 for 4 adults, 2.0 for 5 adults, and 1.9 for 6 adults. Tank cleaning frequencies may be fewer with higher numbers of adults due to the potential part-time nature of properties. The small number of samples for certain groups may also be limiting.

Table 2. Occupancy factors and the influence on septic tank cleaning. Significant impact from a factor on septic tank cleaning is indicated by . The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Occupancy

Household Factor (response options)

Septic Tank

Cleaning Frequency

Average Time Between Septic Tank Cleanings

Adults* (#) 0.08

Children* (#) 0.07

Bedrooms (#) 0.78 0.79

*groups with weighted averages (see Methods for explanation)

Well water use was found to have an impact on average time between septic tank cleanings (Table 3). This may be due to increased awareness of water usage if paying for city-water, unlike well water where there is no city fee. The occurrence of a water quality test or a sewer backup did not have any effect on cleaning frequency (Table 3).

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Table 3. Home characteristic factors and the influence on septic tank cleaning. Significant impact from a factor on tank/pump tank cleaning is indicated by . The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Home Characteristics

Household Factor (response options)

Septic Tank

Cleaning Frequency

Average Time Between Septic Tank Cleanings

Well Water (yes/no)

0.26

Water Quality Test (yes/no)

0.09 0.71

Sewer Backups (yes/no)

0.20 0.99

Septic tank cleaning frequency and average time between septic tank cleanings were found to be impacted by the presence of a dishwasher or washing machine. This is likely due to increased water usage associated with dishwashers and washing machines. To ensure maximum water efficiency, washing machines and dishwashers should be set on proper load cycles. Additionally, washing machine use should be spread throughout the week, so as to avoid septic tank overloading due to inadequate residence time for wastewater treatment (U.S. E.P.A., n.d.). Lint traps can help to prevent drainfield clogging from lint (Hygnstrom, Skipton, & Woldt, 2010).

Garbage disposals may result in increased cleaning frequency or even the need for a larger or additional tank, as this appliance results in the addition of more solids to the septic system in the form of food waste. Fruit and vegetable peels that have been ground in a garbage disposal tend to float or remain suspended in the septic tank, resulting in easier transportation to the drainfield and subsequent clogging (Ziebarth, Merrill, & Peterson, 2006). One study found that the use of garbage disposals increased the rate of scum accumulation by 34%, but only increased the rate of sludge accumulation by 2% (Bounds, 1988). Instead, homeowners could consider composting food scraps. It is surprising the presence of a garbage disposal was not shown to have an impact on septic tank cleaning.

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Table 4. Standard household appliance factors and the influence on septic tank cleaning. Significant impact from a factor on septic tank cleaning is indicated by . The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Standard Household Appliances

Household Factor (response options)

Septic Tank

Cleaning Frequency

Average Time Between Septic Tank Cleanings

Garbage Disposal (yes/no)

0.90 0.31

Garbage Disposal Use (often/rare/never) 0.13 0.38

Dishwasher (yes/no)

Dishwasher Weekly Loads* (#) 0.51 0.74

Washing Machine (yes/no)

Washing Machine Weekly Loads* (#)

0.57 0.91

Detergent Type (liquid/powder/both) 0.90 0.62

*groups with weighted averages

Septic tank cleaning frequency and average time between septic tank cleanings were impacted by the presence of a water softener, hot tub, or fixture leaks. Average time between septic tank cleanings was additionally found to be impacted by the presence of a sump pump. No impact was found based on the presence of a water softener with discharge to the septic system, a hot tub with discharge to the septic system, a sump pump with discharge to the septic system, drains, drain discharge to the septic system, other water treatment device, and other water treatment device discharge to the septic system. The discrepancy between a water softener and water softener to septic may be due to survey confusion or incompleteness. See Table 5.

All appliances listed use water, and would likely result in more frequent cleaning needs if discharged to the septic system. Roof/floor drains, sump pumps, and other drainage systems should discharge to areas away from the drainfield so as not to interfere with the wastewater treatment process (U.S. E.P.A., n.d.). Adjusting water softeners to recharge based on the use of a specific volume of water can also decrease water discharge to the septic tank, compared to time-specific recharge (Ziebarth et al., 2006). There has been some concern regarding the discharge of water softener recharge, which contains sodium (the water softening salt), to the septic tank (Ferrero, 2010). One study found that water softeners increase sodium content in wastewater discharge resulting in a negative, but undramatic, impact on effluent quality, where effluent quality was defined by the amount of solids reaching the drainfield. Recharge wastewater that

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were subjected to them minimal sodium loads actually produced better quality effluent, while recharge wastewater subjected to high sodium concentrations had a negative effect on effluent quality. Overall it was determined that water softeners may have an effect on wastewater discharge, but the level of impact will depend on the hardness of the water and amount of excess sodium in the recharge water (Hogan, Novak, Little, & Cox, 2012). Water is relatively hard in the Otter Tail area, meaning there is a higher potential for excess sodium loading in water

softener discharge. Hot tubs or whirlpool tubs can result in higher water usage if discharged to the septic system and can result in turbulence in the septic tank, disrupting the wastewater treatment process (Figure 6, (Onsite Sewage Treatment Program, 2011)) (Anderson, 2012).

Figure 6. Excessive wastewater discharge to a septic tank results in the disruption of wastewater treatment due to turbulence.

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Table 5. Extra household appliance factors and the influence on septic tank cleaning. Significant impact from a factor on septic tank cleaning is indicated by . The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Extra Household Appliances

Household Factor (response options)

Septic Tank

Cleaning Frequency

Average Time Between Septic Tank Cleanings

Water Softener (yes/no)

Water Softener to Septic

(yes/no) 0.94 0.78

Hot Tub (yes/no)

Hot Tub to Septic (yes/no)

0.14 0.71

Sump Pump (yes/no)

0.92

Sump Pump to Septic (yes/no)

0.59 0.72

Floor/Roof Drains (yes/no)

0.09 0.25

Floor/Roof Drains to Septic

(yes/no) 0.64 0.41

Other Water Treatment Device

(yes/no) 0.07 0.10

Other Water Treatment Device to

Septic (yes/no)

0.79 0.90

Fixture Leaks (yes/no)

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Average time between septic tank cleanings was impacted by the use of long-term prescription medications. Medications and antibacterial products, along with bleach and drain cleaners, can disturb the bacteriologic balance in a septic tank, resulting in decreased breakdown of solid waste and a more frequent need for cleaning (Anderson, 2012; Onsite Sewage Treatment Program, 2011). There was no impact due to the use of septic system additives, which supports the principle that additives cannot be used in place of tank cleaning. Furthermore, additives have not been shown to improve septic tank efficiency and are considered an unnecessary expense (Ziebarth et al., 2006). It is important to note that tank cleaning also provides the opportunity for inspection to identify potential problems of need for repair (Onsite Sewage Treatment Program, 2011). Antibacterial products may not have had a significant impact on septic tank cleaning due the majority of people using properties part-time.

Table 6. Household chemical use factors and the influence on septic tank cleaning. Significant impact from a factor on septic tank cleaning is indicated by . The number listed is the p-value, which signifies a statistically significant factor is less than 0.05.

Household Chemical Use

Household Factor (response options)

Septic Tank

Cleaning Frequency

Average Time Between Septic Tank Cleanings

Additives to Septic (yes/no)

0.58 0.34

Antibacterial Products (yes/no)

0.40 0.26

Long Term Prescription Medications

(yes/no)

0.20

This study sought to identify household factors that had an impact on septic system cleaning frequency. There were 29 household factors, which were tested against two cleaning categories: tank cleaning frequency and average time between tank cleanings. Of the 56 factors tested (28 household factors and two cleaning categories), 17 were found to have an impact on septic tank cleaning. Significance/impact is defined as: a Kruskal-Wallis H statistical test showed means were significantly different between factors within the category (e.g. tank cleaning frequencies were found to be significantly different based on the category of property use (with the factors of property use being permanent residence or seasonal residence)), with a p-value of 0.05 (meaning any category with p<0.05 is considered significant). All factors found to impact tank cleaning frequency and average time between tank cleanings can be found in Table 7.

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Table 7. Factors that were found to have an impact on septic tank cleaning frequency and average time between tank cleanings. The different response options for each factor are listed in parenthesis. The lower the p-value, the more significant the impact of the factors. The factors are listed in descending order of impact.

Septic Tank Cleaning Frequency Average Time Between Septic Tank

Cleanings Water softener

(yes/no) p<0.01

Water softener (yes/no) p<0.01

Use (permanent/seasonal-summer/season-all year)

p<0.01

Use (permanent/seasonal-summer/season-all year)

p<0.01

Washing machine (yes/no) p=0.02

Washing machine (yes/no) p<0.01

Fixture leaks (yes/no) p=0.02

Fixture leaks (yes/no) p<0.01

Hot tub (yes/no) p=0.03

Hot tub (yes/no) p<0.01

Dishwasher (yes/no) p=0.04

Dishwasher (yes/no) p<0.01

Well water (yes/no) p=0.01

Adults (yes/no) p=0.02

Sump pump (yes/no) p=0.03

Long term prescription medications (yes/no) p=0.05

Children (#)

p=0.05

The factors that had no measureable impact on either tank cleaning frequency or average time between tank cleanings can be found in Table 8. However, while the data did not show an impact from these factors, we cannot say with certainty that they do not have an impact, particularly due to incomplete or unclear survey responses.

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Table 8. Factors that did not have an impact septic tank cleaning frequency or average time between septic tank cleanings.

No Impact on Maintenance Bedrooms Water Softener to Septic

Water Quality Test Hot Tub to Septic

Sewer Backups Sump Pump to Septic

Garbage Disposal Floor/Roof Drains

Garbage Disposal Use Floor/Roof Drains to Septic

Dishwasher Weekly Loads Other Water Treatment Device

Washing Machine Weekly Loads Other Water Treatment Device to Septic

Detergent Type Additives to Septic

Antibacterial Products

If possible, future research should modify the survey, specifically with questions and answer boxes that limit the potential for open-ended answers. The presence of blank lines next to questions often resulted in qualitative responses, rather than the originally intended check on the line to indicate yes or no. Additionally, a page with descriptive definitions regarding the questions being asked would aid homeowners when completing the survey, as there were many question marks left as responses. Another possibility would be to conduct a homeowner survey at the time of septic inspection. Finally, it would be beneficial to study a population where the majority of residents are permanent to limit the variables.

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References Anderson, J. (2012). Life in the Septic Tank. Retrieved January 31, 2017, from

http://www.pumper.com/editorial/2012/04/life_in_the_septic_tank

Baruch, Y., & Holtom, B. C. (2008). Survey response rate levels and trends in organizational

research. Human Relations, 61. http://doi.org/10.1177/0018726708094863

Bounds, T. R. (1988). Summary of Sludge and Scum Accumulation Rates. Glide Audit 1986-

1987.

Bounds, T. R. (1997). Design and Performance of Septic Tanks. American Society for Testing

Materials. Retrieved from http://www.microseptec.com/images/Greywater/Other

studies/TR Bounds Septic Tanks.pdf

Christopherson (Heger), S., & Anderson, J. (2004). Twenty Years of Successful Onsite

Wastewater Management - The Otter Tail Water Management District.

Derickson, R. (2002). Septic System Maintenance. South Dakota State University Extension

Extra.

Ferrero, T. (2010). Measuring Water Softener Impact on Septic Systems. Retrieved January 30,

2017, from http://www.pumper.com/editorial/2010/01/measuring-water-softener-impact-on-

septic-systems

Hogan, P. L., Novak, J. T., Little, J. C., & Cox, S. S. (2012). Changes in Septic Tank Effluent

due to Water Softener Use. Virginia Polytechnic Institute and State University. Retrieved

from https://theses.lib.vt.edu/theses/available/etd-10082012-

232446/unrestricted/Hogan_PL_T_2012.pdf

Hygnstrom, J., Skipton, S., & Woldt, W. (2010). Residential Onsite Wastewater Treatment:

Septic Tank Maintenance. Retrieved January 30, 2017, from

http://extensionpublications.unl.edu/assets/html/g1424/build/g1424.htm

Onsite Sewage Treatment Program. (2011). Manual for Septic Professionals in Minnesota (2nd

ed.). St. Paul, MN: University of Minnesota.

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Punch, K. (2003). Survey research : the basics. Sage Publications.

U.S. E.P.A. (n.d.). How to Care for Your Septic System. Retrieved January 30, 2017, from

https://www.epa.gov/septic/how-care-your-septic-system

Ziebarth, A., Merrill, J., & Peterson, J. (2006). Care & Maintenance of Residential Septic

Systems. Retrieved from http://learningstore.uwex.edu/assets/pdfs/B3583.pdf

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Appendix A Homeowner Survey

Answering these questions to the best of your knowledge will provide valuable information to the University of Minnesota. Your information is very important to us and will be kept strictly confidential (used only for the purposes of research for this project).

Name_________________________________________________________ Phone Number__________ Address______________________________________________________________________________ Parcel ID Septic Permit No._______ 1. Information about the home and residents: 1. The house/cabin is used:

full time, year-round

seasonal or part-time, which seasons:______________________________________________

How many days per typical week? How many weeks per typical year? How many days per typical year?

2. Number of people living in the home: (peak) adults children

3. Number of bedrooms

4. Do you have an in-home business? If yes – what is it?

5. Do you have a water well? yes no shared

a. Has your well ever been tested for water quality? yes no

b. If yes to c, did the results indicate any concerns? No yes, (what)

2. Household product and use information:

1. Garbage disposal: no yes, and use it __ often rarely never

2. Dishwasher: no yes, typical loads per week ________________

3. Clothes washer: no yes, typical loads per week _______________

Detergent Type: Liquid_____ Powder_____

4. Water softener: no yes, and it discharges to the septic system yes no

5. Whirlpool or hot tub: no yes, and it discharges to the septic system yes no

6. Sump pump: no yes, and it discharges to the septic system yes no

7. Floor, roof or other drains no yes, and it discharges to the septic system yes no

8. Other water treatment device: what: , and it discharges to the septic system yes no

9. Do you use septic tank or system additives? ___ no ___yes, we have added

10. Do you have any hobbies that add extra water or waste to the system? no yes, _________

11. Do you use antibacterial products? ________no yes, (what) ____________________

12. Is anyone in the home on long term prescription medications? ___ no ___yes, (what) _________

13. Do any of the toilets are faucets leak or drip? ___ no ___yes, (what) ___________________

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Appendix B Number of Samples

Factor Categories Septic Tank Cleaning Frequency

Categories Average Time Between Septic Cleanings

Home Business Yes 323 Yes 284

No 9 No 7

Well Water Yes 318 Yes 281

No 29 No 5

Water Quality Test Yes 254 Yes 220

No 64 No 58

Sewer Backups Yes 36 Yes 32

No 316 No 277

Garbage Disposal Yes 116 Yes 103

No 238 No 208

Garbage Disposal Use Often 49 Often 44

Rarely 53 Rarely 48

Never 6 Never 6

Dishwasher Yes 215 Yes 188

No 139 No 123

Dishwasher Weekly Loads 1 42 1 34

2 28 2 32

3 48 3 40

4 21 4 20

5 16 5 15

7 21 7 21

Clothes washer Yes 279 Yes 244

No 76 No 68

Clothes washer Use 1 37 1 30

2 60 2 55

ii

3 52 3 45

4 34 4 29

5 29 5 27

6 19 6 16

7 5 7 3

10 19 10 18

Detergent Liquid 219 Liquid 192

Powder 36 Powder 31

Both 12 Both 11

Water Softener Yes 231 Yes 201

No 124 No 111

Water Softener to Septic Yes 179 Yes 159

No 19 No 14

Hot Tub Yes 54 Yes 50

No 301 No 262

Hot Tub to Septic Yes 37 Yes 34

No 14 No 13

Sump Pump Yes 74 Yes 62

No 280 No 249

Sump Pump to Septic Yes 36 Yes 31

No 31 No 31

Drains Yes 90 Yes 77

No 262 No 233

Drains to Septic Yes 38 Yes 33

No 47 No 41

Other Water Treatment

Device

Yes 23 Yes 20

No 130 No 118

Other Water Treatment

Device to Septic

Yes 16 Yes 15

iii

No 6 No 5

Additives Yes 16 Yes 14

No 333 No 296

Antibacterial Products Yes 98 Yes 90

No 246 No 212

Medications Yes 161 Yes 150

No 183 No 153

Leaking Fixtures Yes 21 Yes 17

No 327 No 288

Property Use Full Time 132 Full Time 120

Part-time

all seasons

15 Part-time

all seasons

14

Part-time

warm

seasons

206 Part-time

warm

seasons

176

Adults 1 32 1 28

2 200 2 175

3 60 3 55

5 40 5 33

7 12 7 10

11 6 11 7

Kids 0 231 0 202

1 11 1 11

2 49 2 42

3 24 3 22

4 18 4 15

5 5 5 5

6 6 6 5

11 6 11 6

Beds 1 11 1 10

iv

2 105 2 94

3 152 3 127

4 65 4 61

5 11 5 10

6 8 6 7