Vt denitrifying bioreactor design

Abstract Excess nutrients, primarily nitrogen (N) and phosphorus (P), underlie a suite of environmental problems including eutrophication and can be human health hazards at high concentrations. Managing the natural microbial process of denitrification is advocated as a promising avenue to reduce excess N, and denitrifying bioreactors (DNBRs) are an emerging technology harnessing this process. Recent research has shown that DNBRs can remediate other contaminants as well, including P. DNBRs support microbial processing of N and P by providing a suitable microbial habitat and an energy source (carbon) in a periodically saturated environment. The objective of this project is to design a DNBR for the Virginia Tech Stream Research, Education, and Management (VT StREAM) lab at the College of Agriculture and Life Sciences (CALS) farm. The DNBR will be designed to treat spring exfiltrated groundwater with high levels of N and P. The primary cause of nutrient excess in the project area is manure and fertilizer application in the contributing watershed. Using data from a previous Research Experience for Undergraduates (REU) team, a spring with average nitrate-N (NO3-) and phosphate (PO43-) concentrations of 9.8 mg L-1 and 0.02 mg L-1, respectively was deemed most appropriate for DNBR implementation. In order to determine design constraints, the spring flow rate was determined using data obtained from a flume and capacitance probe installed at the site. An average flow rate of 3218 ft3 d-1 was calculated from a capacitance probe installed in the flume. Scientific literature was consulted to determine that a 4 hour retention time was needed to achieve 50% removal rate for N and 35% removal rate for P. The DNBR will be a lined excavation 40 ft long, 4 ft wide and 4 ft deep, with the carbon substrate being 90% woodchips and 10% biochar. Engineering drawings were created in AutoCAD Civil 3D as shown in Appendix C. Acknowledgements The team would like to thank the following for assistance during the project process: Dr. Zach Easton, Faculty Advisor Dr. Joshua Faulkner, Professional Mentor Dr. Cully Hession, Professor, Senior Design Laura Lehmann, Environmental/Agricultural Research Manager, Department of Biological Systems Engineering Kelly Peeler, Water Quality Laboratory Manager, Department of Biological Systems Engineering Denton L. Yoder, Computer Systems Engineer, Department of Biological Systems Engineering

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Table of Contents Abstract .................................................................................................................................................. 2 Acknowledgements ................................................................................................................................. 2 Introduction ............................................................................................................................................ 4 Design Constraints, Criteria and Goals ..................................................................................................... 5 Design Process ........................................................................................................................................ 6 Site Selection ....................................................................................................................................... 6 Flow Analysis ....................................................................................................................................... 6 Sampling.............................................................................................................................................. 7 Surveying............................................................................................................................................. 7 Design Alternatives .............................................................................................................................. 9 Bioreactor Type ............................................................................................................................... 9 Carbon Substrate ........................................................................................................................... 11 Bioreactor Sizing ................................................................................................................................ 12 CAD Design ........................................................................................................................................ 12 Final Design Summary ........................................................................................................................... 13 Environmental Impact ....................................................................................................................... 13 Economic Analysis ............................................................................................................................. 14 References ............................................................................................................................................ 14 Appendix A: Final Design Calculations .................................................................................................... 16 Appendix B: Nutrient Analysis Results.................................................................................................... 18 Appendix C: Engineering Drawings ........................................................................................................ 19

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Introduction There is a current need to improve water quality by reducing nutrient loading in surface and groundwater. Compared to pre-industrial loadings, the input of reactive N into the environment has almost doubled due to the usage of fertilizers, fossil fuels and soil cultivation (Christianson et al., 2012). NO3- and P are two critical water pollutants, that when found in excess, can cause significant water quality problems. (Cheikh et al., 2013). The US Environmental Protection Agency (EPA) estimates that 48% of N and 45% of P originate from agriculture. Concentrations of NO3- exiting subsurface drains in agriculturally intensive areas frequently exceed 15 mg L-1 in spring and early summer (Moorman et al., 2010). Some estimates have shown that nearly 65% N applied on farms is lost to the environment though runoff, leaching or as N gas is lost to the atmosphere (Schmidt and Clark, 2011). High levels of P resulting from agriculture can likewise harm surface waters and accelerate eutrophication.

DNBRs are an emerging technology for N attenuation that function by supporting ubiquitous soil denitrifiers in a favorable habitat consisting of an organic carbon medium that is sufficiently saturated to allow anoxic conditions to develop. The goal of this design project is to design a DNBR to reduce the N and P loadings from a spring as shown in Figure 1.

DNBRs can be used to reduce the amount of N and P in waters by converting reactive NO3 into N2, which is released into the air. Denitrification occurs naturally when bacteria use NO3- as the terminal electron acceptor in their respiratory process (Torrent贸 et al). P can also be absorbed to exchange sites in the carbon substrate, precipitated in an insoluble form, as well as incorporated into microbial biomass (Bock et al., 2014). DNBRs contain carbon substrates, such as woodchips, which serve as carbon sources for denitrifying microbes. As established by the problem statement, this project aims to reduce N loading by 50% and P loading by 35% to improve water quality in Stroubles Creek.

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Figure 1 Aerial View of DNBR Location Design Constraints, Criteria and Goals The overall goal of this project is to reduce nutrient levels in the groundwater without harming surrounding land and ecosystems. A site assessment was initially conducted to locate areas of high sources of N and P based on REU data.

The following constraints are important to the final design:  

The DNBR will be implemented in Blacksburg, Virginia so the design must be in compliance with all local, state and federal regulatory requirements.

The DNBR must comply with the following Standards: o NRCS (interim) Conservation Practice Standard Code 747: DNBR o ASCE Comprehensive Transboundary Water Quality Management Agreement (33-09) o NRCS Conservation Practice Standard Code 554: Drainage Water Management o Dept. of Conservation and Recreation and Division of Soil and Water Conservation: Virginia Nutrient Management Standards and Criteria

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   

o ASTM F449-02: Standard Practice for Subsurface Installation of Corrugated Polyethylene Pipe for Agricultural Drainage or Water Table Control The DNBR must reduce N by 50% and P by 35% on average.

The total cost of design implementation must be less than $5,000.

Future annual maintenance and operating costs must be less than $100.

There must be minimal impact on surrounding lands and ecosystems.

Design Process The team began the design process by analyzing nutrient data that was previously collected from springs in the CALS farm area by an REU team. A literature review detailed the history of nutrient loading and the accompanying concerns, the process of denitrification, DNBR types and substrate combinations. Reviewing past DNBR field and lab experiments in the literature guided the project and provided equations and constants used in final calculations.

Site Selection The site of the DNBR was determined based on data from Andruzkiewicz et al. (2013) and a site visit with project mentors. The concentration of NO3- in six springs surrounding the CALS farm area is shown in Figure 2 below. As can be observed, the highest NO3- loadings are present in springs 6 and 3. Springs 3, 6 and 5 were assessed during the trip with Dr. Hession, Dr. Easton and team members. Spring 3 had a good water level and was not too difficult to access, but it was located near a wetland. Constructing a DNBR near protected land may pose additional difficulties, so this spring was not ideal for DNBR installation. Spring 6 seemed to be the best possible location for the design and construction of the DNBR and exhibited the greatest NO3- concentrations. Therefore, Spring 6 was chosen as the ideal location for a DNBR.

Figure 2 Concentration of Nitrate by Spring (Andruzkiewicz et al., 2013) Flow Analysis 6

The first step in the design process was to obtain flow information from the spring. To obtain this information, a 0.5-ft H-flume was installed at the site directly downstream of the spring. Two thin metal barriers were placed on either side of the flume, to direct surface flow into the flume. The flume contained a capacitance probe that provided water level and temperature data in 15-minute increments from December through April. A stage discharge formula from the flume manufacturer was used to calculate daily flow. A graph of this is shown in Figure 3 below, and sample calculations are included in Appendix A. The average daily flow rate over the measurement period was 3218 ft3 d-1.

Figure 3 Calculated Discharge from Spring Sampling In order to further develop the nutrient concentration time series to determine the needed reductions, grab samples from the spring were taken twice a week for three months.

The samples were analyzed for NO3- and total dissolved P (TDP) by the BSE Water Quality Lab, and the results of these tests are included in Appendix B. Based on the mean concentrations calculated, a target concentration of 4.90 mg L-1 NO3- and 0.01 mg L-1 P after DNBR installation was established.

Surveying A survey was conducted to quantify relative elevations and distances of points around the spring. Before surveying, major cross sections by the spring were marked with flags, and a control point elevation of 1993 feet was established. The team used a survey laser level and rod 7

to survey the spring and surrounding areas. A total of 22 points were surveyed, including the back-sited control point. Points were measured at the stream bank and in the streambed, which establishes the maximum elevation difference between the spring and the streambed, and sets the maximum depth of the DNBR.

Figure 4 Survey Points with Elevation Once the survey was complete, the team created a field book. The field book is a .fbk file that contains horizontal angle, vertical angle and angle from the rod. The approximate location of the spring was inserted from GPS coordinates provided by Google Maps. The location had an 8

estimated Northing of 3604507.82 and an Easting of 10917488.83. A correction to the vertical distance of two points by the stream was also made to account for changes in rod height.

A topographic map of the CALS farm area was obtained and imported into AutoCAD Civil 3D Imperial from the Blacksburg GIS website. The coordinate system of the topography map was NAD 83 Virginia South zone feet. The topography map was imported first, and the field book was imported on top using import survey data. The points were made into a point group and a surface was created. The coarser contour lines from the topography map were interpolated to provide more apparent elevation changes. The survey point map was overlaid on the topography map of the CALS farm and is shown in Figure 5.

Figure 5 Survey Surface and Blacksburg Topography Map

Design Alternatives Bioreactor Type Various experiments in literature have created and tested DNBRs. The four most common DNBR types are bed, wall, lined bed and in-stream as shown in Figure 6, below. The project site is a fairly small spring with a comparatively low flow rate; thus, some of the DNBR designs are not feasible to implement at the site. Thus, the bed and lined bed were considered most appropriate of all available alternatives because they are simple, do not require high flow volumes, and are low maintenance.

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Figure 6 Types of Denitrifying Bioreactors (clockwise from top left: bed, lined bed, denitrification wall, and in-stream bioreactor) Denitrification beds are containers filled with carbon substrates that receive NO 3- from focused flow paths that resemble the high flux conditions associated with point sources (Cameron et al., 2011). Compared to a simple bed, the lined bed adds a layer of impermeable fabric to this bed to contain flow and prevent interaction with the surrounding environment (Schipper et al., 2010). Although the bed DNBR is easiest to install based on topography, channel size and flume type, a lined bed is recommended to contain the substrate and prevent soil from clogging the system. Comparing the designs by ease of installation, cost, environmental impact, aesthetics, effectiveness and longevity, the lined bed was the best possible design solution for the scope of this project as seen in Table 1 below.

Table 1 Decision Matrix for DNBR Design. The weight indicates the level of importance of each criteria, and each criteria value was multiplied by its corresponding weight to calculate total score for each alternative.

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Criteria Ease of Installation Cost Environmental Impact Aesthetics Effectiveness Longevity Total

Weight 15 25 20

Bed 5 3 4

Wall 2 3 3

Lined Bed 4 3 4

In-Stream 1 2 3

5 25 10 500

5 3 4 370

4 3 4 300

4 4 5 385

2 1 3 190

Carbon Substrate Carbon substrates in DNBRs are responsible for the removal of N and P in the waterway.

The criteria considered when choosing a substrate was cost, N and P removal, longevity and ecological impact due to such factors as production of greenhouse gas, chemical oxygen demand or export of dissolved organic carbon. Literature indicates that combinations of carbon substrates are more effective than individual substrates alone. For example, woodchips combined with pond sediment, biochar, and sawdust resulted in more effective denitrification and enhanced P removal than woodchips alone (Schipper et al., 2010; Bock et al., 2014).

In Table 2 the main source substrates evaluated were woodchips, cardboard, biochar, pond sediment, and sawdust. Similar to Table 1, the weight indicates the level of importance of each criteria, and each criteria score was multiplied by its corresponding weight to calculate total score for each substrate alternative. As indicated by Table 2, woodchips and biochar seem to be the best carbon substrates to be placed in the DNBR. Woodchips are durable, effective at N removal, provide ample carbon and minimal ecological impact, all of which are favorable characteristics (Schipper et al., 2010). In the majority of studies conducted, woodchips have been the primary denitrification substrate. Biochar is a charcoal or activated carbon-like substrate that can increase the microbial activity and enhance the rate of denitrification as well as P removal (Lassister and Easton, 2013; Bock et al., 2014). Thus biochar offers excellent N and P removal efficiency, but comes with added cost. Sawdust, although similar to woodchips, was thought to not to be as effective and long lasting due to it being light and porous (Schipper et al., 2010). Sawdust is likely more effective in the short run, since the finer particle size creates a larger surface area, making it more labile. Cardboard is least favorable due to various concerns with cardboard being stuck in the stream, not being able to withstand significant flow rates and being washed out over time. Pond sediment has the potential to reduce the hydraulic conductivity of the system thus reducing overall treatment efficacy. Therefore, pond sediment, sawdust and cardboard are not viable alternatives for this DNBR. Woodchips and biochar are the most effective carbon substrates for use in the DNBR, and it was decided to utilize a mixed substrate of the two based on recent literature (Bock et al., 2014).

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Table 2 Decision Matrix for Carbon Substrate Type Types of Weight Woodchips Cardboard Biochar Substrate Effectiveness 30 5 4 5 Cost 20 3 2 4 Ecological Impact 30 3 2 2 GHG 2 1 1 COD 2 3 3 Longevity 20 5 3 4 Totals 100 400 280 370

Pond Sawdust Sediment 2 3 5 3 5 3 5 3 5 3 2 2 350 280

Bioreactor Sizing Specifying the dimensions of the DNBR was the final step in the design process. It would be designed to treat 80% of the average daily flow, which is 2574 ft3 d-1. The designed depth of the DNBR was based on the elevation difference between the spring and bed of the stream. The elevation differential was determined by the surveying to be 6 ft. The team decided that a maximum DNBR depth of 4 ft was a conservative depth to allow the DNBR to fully drain into the stream.

Darcy’s Law (Appendix A Equation 1) was used to solve for DNBR length in terms of hydraulic head, hydraulic conductivity and design residence time (Appendix A Equation 2). We used an iterative approach to determine the DNBR dimensions. First we approximated the DNBR area by solving Eq 1 for A (area). Then plugging into Eq 2, we solved the DNBR length, which was determined to be 86.4 ft. The width of the DNBR was calculated using the retention time equation (Appendix A Equation 3). Substituting in the known length and depth into the volume and converting flow in terms of ft3 hr-1, the width was calculated to be 2.22 ft. The calculated dimensions of the DNBR were 86.4 ft x 2.22 ft x 4 ft. Evaluating the dimensions the team determined that length of the DNBR was to great for the site and the the width of 2.22 ft would be too narrow and result in reduced treatment due to the surface area to volume ratio.

A long and narrow DNBR could cause reduced treatment due to a shortened less interaction with the substrate matrix. Adjusting the variables, the team shortened the length to 40 ft, which allowed for the width to be adjusted to 4 ft. The changes in dimensions did not affect the ideal retention time of 4 hrs as seen in Appendix A. The final dimensions of the DNBR were 40 ft x 4 ft x 4 ft.

CAD Design The final step of the design process was to create engineering drawings. AutoCAD Civil 3D was used to create a drawing of the designed DNBR (Appendix C) along with a 2D crosssection view. A drainage control unit was added to the end of the DNBR to allow water to flow 12

out after the specific retention time of 4.2 hours. The cross-sectional view contains two levels to represent the woodchips/biochar substrate matrix and the soil fill that will be placed on top.

The geotextile material that will be on top of the substrate, along with the sides and bottom liner are shown in the cross-sectional view.

Final Design Summary After the team gathered flow, nutrient and survey data, the final dimensions and material were finalized for the DNBR. For implementation, the DNBR size will be 40 ft long, 4 ft wide and 4 ft deep. Survey points were taken in order to calculate the grading of the area around the spring to determine land slope and location of the DNBR. With a land slope of 4% and an N removal rate of 50%, a retention time of 4.2 hours was determined. The carbon substrate to be placed in the DNBR is 90% woodchips and 10% biochar. An engineering fabric will be used to line the sides and bottom of the DNBR, with a geotextile placed on top of the carbon substrate. AutoCAD design drawings of the DNBR as shown in Appendix C were then created.

Environmental Impact There are several potential environmental concerns to using a DNBR for NO3- removal.

Greenhouse emissions are a concern due to the potential production of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) during the denitrification process. This is an example of pollution swapping, a process that results in an increase in one pollutant due to a measure implemented to reduce another pollutant (Healy et al., 2012). So far there are only a few cases whereof N2O fluxes from DNBRs were quantified (Bock et al., 2014). The amount of N2O produced is related to the completeness of the denitrifying process—if NO3- removal is complete, there is less N2O released (Schipper et al., 2010).

Other chemical emission concerns include CO2 and CH4 caused by the decaying of organic matter. The leaching of dissolved organic carbons (DOC) can occur from fresh organic material of the carbon substrate. DOC spikes are typical during the initial phase of operation so a solution could be to pre-leach the substrate before use; however this would add to costs and has yet to be attempted (Schipper et al., 2010).

Despite these concerns, the proposed DNBR is expected to be environmentally benign.

Although a small quantity of greenhouse gases will be invariably produced, the DNBR uses organic materials to facilitate a natural process. Installation of monitoring equipment is recommended to monitor emissions and other downstream environmental concerns, so DNBR performance may be adjusted appropriately.

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Economic Analysis The DNBR outlined above is economically feasible and meets the given construction budget of $5,000. A breakdown of expected costs is listed below: Table 3 Cost Analysis Component Cost 1 Wood Chips 426.60 Total woodchips volume: 23.7 yd3 Engineering Fabric liner2 85.50 2 2 Total Surface Area: 512 ft or 57 yd Cost : $1.50 per yd2 Geotextile cover3 30.32 2 Total surface area: 160 ft Cost: $15.16 for 150 ft2 Water table control structure 1600.00 Lab work 107.77 4 Trenching and installation 1,500.00 Additional expenses 549.81 Total $ 4,300.00 The total project estimate of $4,300 is less than the project budget of $5,000. Further monitoring and construction costs may be added to this, since the StREAM Lab intends to monitor this DNBR for performance.

References Andruszkiewicz, E., Bick, I., & Wiklund, C. (n.d.). Designing the next generation of denitrifying bioreactors: Coupled biological and physiochemical processes to resubstrate nitrogen and phosphorus. StREAM Lab REU. Retrieved April 29, 2014, from http://streamlabreudnbr.weebly.com/index.html.

Bock, E., Smith, N., Rogers, M., Colemn, B., Reiter, M., Benham, B. & Z.M. Easton. (2014).

Nitrate and phosphate removal and nitrous oxide production in lab-scale denitrifying bioreactors. Journal of Environmental Quality (In Press).

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Reference bulk price from JKE Enterprise Landscape Supply Reference price from AgriDrain Corporation 3 Reference price from T. Christy Enterprises, Inc. 4 Estimate from Ellingson Companies 2

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Cameron, S. G., & Schipper, L. A. (2012). Hydraulic properties, hydraulic efficiency and nitrate removal of organic carbon media for use in denitrification beds. Ecological Engineering, 41, 1-7.

Cheikh, A., Yala, A., Drouiche, N., Abdi, N., Lounici, H., & Mameri, N. (2013). Denitrification of water in packed beds using bacterial biomass immobilized on waste plastics as supports.

Ecological Engineering, 53, 329-334.

Christianson, L., Castell贸, A., Christianson, R., Helmers, M., & Bhandari, A. (2010). Technical Note: Hydraulic Property Determination of Denitrifying Bioreactor Fill Media. Applied Engineering in Agriculture, 26(5), 849-854.

Christianson, L., Helmers, M., Bhandari, A., & Moorman, T. (2013). Internal hydraulics of an agricultural drainage denitrification bioreactor. Ecological Engineering, 52, 298-307.

Healy, M. G., Ibrahim, T. G., Lanigan, G. J., Serrenho, A. J., & Fenton, O. (2012). Nitrate removal rate, efficiency and pollution swapping potential of different organic carbon media in laboratory denitrification bioreactors. Ecological Engineering, 40, 198-209.

Lassister, E., & Easton, Z. (2013). DNBRs: An Emerging Best Management Practice to Improve Water Quality. Virginia Cooperative Extension. Retrieved October 16, 2013, from http://pubs.ext.vt.edu/BSE/BSE-55/BSE-55-PDF.pdf.

Moorman, T. B., Parkin, T. B., Kaspar, T. C., & Jaynes, D. B. (2010). Denitrification activity, wood oss, and N2O emissions over 9 years from a wood chip bioreactor. Ecological Engineering, 36(11), 1567-1574.

Schipper, L. A., Robertson, W. D., Gold, A. J., Jaynes, D. B., & Cameron, S. C. (2010). Denitrifying Bioreactors: An Approach For Reducing Nitrate Loads To Receiving Waters. Ecological Engineering, 36(11), 1532-1543.

Schmidt, C. A., & Clark, M. W. (2012). Efficacy of a denitrification wall to treat continuously high nitrate loads. Ecological Engineering, 42, 203-211.

Torrent贸, C., Urmeneta, J., Otero, N., Soler, A., Vi帽as, M., & Cama, J. (2011). Enhanced denitrification in groundwater and sediments from a nitrate-contaminated aquifer after addition of pyrite. Chemical Geology, 287(1-2), 90-101.

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Appendix A: Final Design Calculations Assumptions for the calculations were made based on literature, survey data and the flow calculations provided earlier as seen in Table 4. The porosity of the woodchips was stated to be 0.7 or 70% and the hydraulic conductivity was 0.15 ft s-1 in (Bock et al., 2014). The hydraulic head was based on land slope from the right edge of the flume down to the streambed. The calculations were done in AutoCAD Civil 3D Imperial based on the elevation and distance to the stream.

Table 4 Original Assumptions Specification Porosity of carbon substrate (p) Hydraulic conductivity (K) Hydraulic head (i) Treated Flow (Q) Minimum Retention Time (t) Depth of bioreactor (D)

Measurement 0.7 (70%) 0.15 ft s-1 0.04 ft ft-1 2574 ft3d-1 4 hrs 4 ft

Source Christianson et al., 2010 Christianson et al., 2010 Survey Flow Calculations Bock et al., 2014 Survey (1)

Where

Q is flow ft3 s-1 K is hydraulic conductivity ft s-1 i is hydraulic head ft ft-1 A is area ft2 (2)

Where

L is length ft i is hydraulic head ft ft-1 K is hydraulic conductivity ft s-1 t is minimum retention time s

Using Equation 2, L = (0.15ft s-1)*(0.04ft f-1t)*(4 hr)*(3600s) = 86.4 ft

(3) Where

T is retention time s ÎĄ is porosity ft ft-1 V is volume ft3 Q is flow ft3 s-1 16

Using Equation 3, 4 hrs =

so w = 2.22 ft

Original dimensions: 86.4 x 2.22 x 4, and the calculated dimensions were w = 2.22 ft. This was too narrow, therefore, the original dimensions were adjusted to depth = 4 ft, w = 4 ft, and L = 40 ft.

Calculated new retention time based on new dimensions:

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Appendix B: Nutrient Analysis Results Report Date:

4/21/14

Water Quality Laboratory Virginia Tech Department of Biological Systems Engineering 106 Seitz Hall, Blacksburg, Virginia 24061 Final Report

Client Name: Email:

Lauren Smith laurs91@vt.edu

Project: Matrix: Quantity:

DNBR Spring water 13

Sample ID DNBR Spring Sample, 2/4/14, 1:30pm DNBR Drop Sample 1, 2/4/14, 1:30pm DNBR Drop Sample 2, 2/4/14, 1:30pm DNBR sample, 2/25/14, 1:17pm DNBR sample, 2/27/14, 3:52pm DNBR sample, 3/4/14, 2:24pm DNBR sample, 3/6/14, 1:07pm DNBR sample, 3/18/14, 3:05pm DNBR sample, 3/20/14, 12:26pm DNBR sample, 3/26/14, 12:50pm DNBR sample, 4/4/14, 2:45pm DNBR sample, 4/8/14, 12:54pm DNBR sample, 4/10/14, (no time on bottle)

Analyst Name: Email: Sample Information Preparation: Arrival: Storage:

Kelly Peeler, Laboratory Manager kapeeler@gmail.com

Filtered and frozen 4/10/14 Freezer

RESULTS Dissolved Phosphorus (mg/L) Sample ID DNBR Spring Sample, 2/4/14, 0.03 1:30pm DNBR Drop Sample 1, 2/4/14, 0.02 1:30pm DNBR Drop Sample 2, 2/4/14, 0.02 1:30pm 0.02 DNBR sample, 2/25/14, 1:17pm 0.03 DNBR sample, 2/27/14, 3:52pm 0.02 DNBR sample, 3/4/14, 2:24pm 0.02 DNBR sample, 3/6/14, 1:07pm 0.02 DNBR sample, 3/18/14, 3:05pm 0.02 DNBR sample, 3/20/14, 12:26pm 0.02 DNBR sample, 3/26/14, 12:50pm 0.03 DNBR sample, 4/4/14, 2:45pm 0.03 DNBR sample, 4/8/14, 12:54pm DNBR sample, 4/10/14, (no time 0.02 on bottle)

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Nitrate (mg/L) 8.9 9.0 9.1 12.8 12.8 10.4 9.8 10.4 9.9 9.4 8.7 8.0 8.3

Appendix C: Engineering Drawings

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