Evaluation of Approaches for Managing Nitrate Loading from On-Site Wastewater Systems near La Pine, Oregon

Morgan, David S.; Hinkle, Stephen R.; Weick, Rodney J.

doi:10.3133/sir20075237

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…Annual per capita N loading rates to groundwater at the LT and YG sites are lower than other estimates of 4.5 kg N yr −1 (Cox and Kahle, 1999), which would yield 9 and 13.5 kg N yr −1 for households with two and three people, respectively. Based on septic tank studies in central Florida (Sherman and Anderson, 1991) and Oregon (Morgan et al, 2007), about 9.5 to 9.7 kg N yr −1 per home are released to the drainfield, and it is estimated that an additional 25% reduction in N occurs beneath the drainfield (Anderson et al, 1994; Morgan et al, 2007). The annual N loading for the HK site (6.6–12 kg N yr −1 ) also is lower than the estimated loading to groundwater of 18 kg N yr −1 based on per capita N loading (Anderson et al, 1994; Cox and Kahle, 1999).…”

Section: Resultsmentioning

confidence: 99%

Fate of Effluent‐Borne Contaminants beneath Septic Tank Drainfields Overlying a Karst Aquifer

et al. 2010

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Groundwater quality effects from septic tanks were investigated in the Woodville Karst Plain, an area that contains numerous sinkholes and a thin veneer of sands and clays overlying the Upper Floridan aquifer (UFA). Concerns have emerged about elevated nitrate concentrations in the UFA, which is the source of water supply in this area of northern Florida. At three sites during dry and wet periods in 2007-2008, water samples were collected from the septic tank, shallow and deep lysimeters, and drainfield and background wells in the UFA and analyzed for multiple chemical indicators including nutrients, nitrate isotopes, organic wastewater compounds (OWCs), pharmaceutical compounds, and microbiological indicators (bacteria and viruses). Median NO3-N concentration in groundwater beneath the septic tank drainfields was 20 mg L(-1) (8.0-26 mg L(-1)). After adjusting for dilution, about 25 to 40% N loss (from denitrification, ammonium sorption, and ammonia volatilization) occurs as septic tank effluent moves through the unsaturated zone to the water table. Nitrogen loading rates to groundwater were highly variable at each site (3.9-12 kg N yr(-1)), as were N and chloride depth profiles in the unsaturated zone. Most OWCs and pharmaceutical compounds were highly attenuated beneath the drainfields; however, five Cs (caffeine, 1,7-dimethylxanthine, phenol, galaxolide, and tris(dichloroisotopropyl)phosphate) and two pharmaceutical compounds (acetaminophen and sulfamethoxazole) were detected in groundwater samples. Indicator bacteria and human enteric viruses were detected in septic tank effluent samples but only intermittently in soil water and groundwater. Contaminant movement to groundwater beneath each septic tank system also was related to water use and differences in lithology at each site.

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Section: Resultsmentioning

confidence: 99%

Fate of Effluent‐Borne Contaminants beneath Septic Tank Drainfields Overlying a Karst Aquifer

et al. 2010

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“…where: C PEN1 is a coefficient for adjusting Pen1 values to reach the order of magnitude of other penalty items in the total penalty function (see Equation (17); here, C PEN1 = 1,000,000); N adW is the number of AWs (nominal); X j and Y j are the abscissa (number of column in the 80 × 80 Modflow top view grid) and the ordinate (number of rows in the Modflow grid) of AW j (j = 3, 4), respectively (nominal); maxX and maxY are the max physical values of X j and Υ j , respectively (nominal). C4: The EWs (W 1 , W 2 ) must not pump pollution during the study period of 300 d. Thus, the pollutant concentration in the respective cell must remain equal to zero.…”

Section: Constraint Handlingmentioning

confidence: 99%

“…It is assumed that aerobic conditions apply in the aquifer, with dissolved oxygen concentrations DOC > 0.5 mg/L (oxic groundwater; similar to [17]), which do not favor the denitrification process (as described in [18,19]).…”

mentioning

confidence: 99%

Optimal Pollution Control and Pump-and-Fertilize Strategies in a Nitro-Polluted Aquifer, Using Genetic Algorithms and Modflow

Kontos,

Rompis,

Karpouzos

2023

Agronomy

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Nitro-pollution in a confined aquifer may originate from its recharge area, e.g., agricultural sites, animal feedlots, septic tanks, and other waste disposal sites or from treated wastewater recharge wells. The latter case is studied. Existing water supply pumping wells should be protected for a given period. Instead of typically investigating optimal pump-and-treat or hydrodynamic pollution control management/remediation strategies, a novel combined pollution control and pump-and-fertilize (PAF) approach is proposed: protect existing wells with additional wells, considering pumped nitro-polluted groundwater as profitable reusable fertilizer rather than a pollutant to be remediated; convey pumped polluted water to an irrigation reservoir, considering nitrogen (N) uptake by irrigated crops in nearby farmlands and proportional decrease in fertilizer application, meaning profit. Optimization entails the operation of optimally located additional pumping wells with optimal flow rates, minimizing the sum of (i) annual pumping cost, (ii) pipe network (connecting additional wells and reservoir) amortization cost, and (iii) profit from retrieved N reuse. Modflow simulates a 3D flow field and advection-dispersion mass transport, while Genetic Algorithms (GAs) handle optimization. Various scenarios are simulated concerning crops’ retrieved N root uptake percentage, fertilizer, and energy market prices. The paper provides a data-ready optimization/decision support tool that creates a pool of alternative (sub)optimal management solutions/strategies.

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“…Seven landscape-scale variables that describe the hydrogeologic and landscape settings of the springs and that may influence spring discharge type, discharge amount, and water chemistry were derived from other spatial datasets and summarized for each spring. These Gannett, 1984;Gonthier, 1985 Early Tertiary volcanic, volcaniclastic, and volcanic sediment deposits of the Clarno and John Day Formations 5-140 0.003-0.3 Low Gannett, 1984;Gonthier, 1985 Basalt flows of the Miocene Columbia River Basalt Group 5-900 0.3-40 Medium Ely et al, 2014;Gannett, 1984;Gonthier, 1985;Vaccaro et al, 2015 Quaternary surficial deposits 9-1,400 8-46 Medium Gannett, 1984;Gonthier, 1985;Morgan, Hinkle, & Weick, 2007 Late Tertiary volcanic, volcaniclastic, and volcanic sediment deposits of the Deschutes Formation (and their age equivalents) 20-23,000 3-680 High Gannett et al, 2001;Gannett, Lite, Risley, Pischel, & La Marche, 2017;Gonthier, 1985 Quaternary volcanic deposits of the Cascade Range and Newberry Volcano 50-74,000 1-300 High Gannett et al, 2001Gannett et al, , 2017Gates & Gannett, 1996;Manga, 1997, Saar & Manga, 2004 Note. Transmissivity and hydraulic conductivity values were estimated in the cited sources using a variety of methods including analysis of specific capacity data from well logs, published aquifer tests, and model analysis.…”

Section: Landscape Variablesmentioning

confidence: 99%

Landscape controls on the distribution and ecohydrology of central Oregon springs

2019

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Small springs in semiarid landscapes are essential for maintaining aquatic biodiversity and supporting livestock grazing operations. However, little is known about controls on the distribution and physical characteristics of small springs, the aquatic species they support, or their sensitivity to disturbance. We address this information gap in the Crooked River subbasin, a tributary of the Deschutes River in Oregon. We conducted spatial analyses on 2,519 mapped springs to investigate the influence of landscape controls (precipitation and bedrock permeability) on spring density in the Crooked River subbasin and the adjacent Upper Deschutes subbasin. Spring density was highest in areas of low bedrock permeability (P < 0.0001) and high annual precipitation (P < 0.0001). We suggest that the high density of small springs on low‐permeability bedrock indicates that these springs generally have short, shallow flow paths and thus may be susceptible to forecasted climate changes. A survey of 137 springs in the Crooked River subbasin revealed the hydrogeologic setting affects spring discharge type (P = 0.017), temperature (P = 0.011), and pH (P = 0.026). We found a high frequency of anthropogenic impacts on springs: 95% of diffuse‐discharge springs and 79% of discrete‐discharge springs were disturbed by livestock grazing. Species inventories at 10 of the most intact surveyed springs confirm that small springs are biologically diverse, with 151 total species of plants and 135 total taxa of macroinvertebrates. Springs in the Crooked River subbasin are ecologically important habitats but require careful management to protect against livestock disturbance and development.

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Evaluation of Approaches for Managing Nitrate Loading from On-Site Wastewater Systems near La Pine, Oregon

Cited by 11 publications

References 13 publications

Fate of Effluent‐Borne Contaminants beneath Septic Tank Drainfields Overlying a Karst Aquifer

Fate of Effluent‐Borne Contaminants beneath Septic Tank Drainfields Overlying a Karst Aquifer

Optimal Pollution Control and Pump-and-Fertilize Strategies in a Nitro-Polluted Aquifer, Using Genetic Algorithms and Modflow

Landscape controls on the distribution and ecohydrology of central Oregon springs

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