wastewater treatment wetland in pilot mountain state park

Wastewater Treatment Wetland in Pilot

Mountain State Park

Authors:

E. M. Bennett

J. H. Guthrie

M. K. Harper

R. R. Moore

B. T. Smith

Advisor: Dr. Michael Burchell

April 29, 2011

of 52

Abstract:

The Pilot Mountain State Park in western North Carolina is open year round to tourists, campers,

and hikers. To treat the municipal waste produced, the park has an on-site wastewater treatment

plant permitted to treat 10,000 gallons per day. The effluent from the package treatment plant

currently discharges into Grassy Creek, which is classified as a Water Supply IV stream that

connects to Winston-Salem’s drinking supply. The pollutant and nutrient levels of the treated

waste meet state requirements, but the park would like to reduce them further to set an example

and be good stewards to the environment. Of greatest concern are the nitrate levels being

released which have been observed to be up to 30 times greater than that of the receiving body of

water. The design team was asked to design a tertiary treatment system to further treat the

effluent before being introduced to Grassy Creek. To address this issue, the team designed a

wastewater treatment wetland which utilizes the maximum amount of available space and made

design decisions to minimize cost. Three designs were created in order to select one design that

best balanced pollutant removal and cost. For the selected design candidate, design candidate 1,

the maximum observed influent concentration of 31 mg/l is expected to be reduced to 7 mg/l, a

reduction of 78%. Additionally, nitrate reduction is expected to be as high as 99% in the warmest

month and 48% in the coldest month. With an estimated average influent nitrate concentration of

9 mg/l, the nitrate concentration will be reduced to an annual average of 2 mg/l, a reduction of

77%. The total estimated cost of this design is $50,000.

of 52

Table of Contents

Abstract: .......................................................................................................................................... 1

Introduction: .................................................................................................................................... 4

Problem Statement ...................................................................................................................... 4

Background Information ............................................................................................................. 4

Objective ..................................................................................................................................... 8

Materials and Methods:................................................................................................................... 8

Site Visits and Surveys ............................................................................................................... 8

Feasibility Analysis ..................................................................................................................... 9

k-C* Model for Nitrate Reduction .......................................................................................... 9

Nitrate Loading Analysis ...................................................................................................... 10

Theoretical Efficiency ........................................................................................................... 11

Hydraulic Retention Time ..................................................................................................... 11

Water Balance ....................................................................................................................... 11

Soils....................................................................................................................................... 12

Design ....................................................................................................................................... 12

Vegetation ............................................................................................................................. 15

Results and Discussion: ................................................................................................................ 15

Site Visits and Surveys ............................................................................................................. 15

Feasibility Analysis ................................................................................................................... 17

Water Balance ....................................................................................................................... 22

Soils....................................................................................................................................... 23

Design ....................................................................................................................................... 24

Vegetation ............................................................................................................................. 26

Permitting .............................................................................................................................. 27

Cost ....................................................................................................................................... 27

Conclusions: .................................................................................................................................. 27

Acknowledgments: ....................................................................................................................... 28

List of References: ........................................................................................................................ 29

Figures........................................................................................................................................... 31

Appendices .................................................................................................................................... 33

Appendix 1: Construction Scope of Work ................................................................................ 33

Appendix 2: Maintenance Plan ................................................................................................. 35

of 52

Appendix 3: Planting Instructions ............................................................................................ 37

Appendix 4: Calculation Package ............................................................................................. 38

1 Key ..................................................................................................................................... 38

2 Pilot Mountain ................................................................................................................... 39

2.1 Stormwater Calculations ................................................................................................. 39

2.2 Clean Water Diversion .................................................................................................... 39

2.3 Inlet Pipe ......................................................................................................................... 40

2.4 Pipe Outlet Protection ..................................................................................................... 40

2.5 Flashboard ....................................................................................................................... 40

2.6 Planting ........................................................................................................................... 41

Appendix 5: Budget .................................................................................................................. 43

Design Candidate 1 ............................................................................................................... 43



Appendix 6: Derivation ............................................................................................................ 49

Appendix 7: Gantt Chart ........................................................................................................... 51

of 52

Introduction:

Problem Statement

Pilot Mountain State Park, in western North Carolina, recently installed a new package

wastewater treatment plant on-site (Figure 20) to treat the municipal waste from the park’s

facilities. The park is open year round to tourists, campers, and hikers and is permitted to treat

10,000 gallons per day. The effluent from the wastewater treatment plant currently discharges

into a Water Supply IV stream, Grassy Creek. The monthly allowable ammonium concentration

of the effluent is 11.1 mg/L. The pollutant and nutrient levels of the treated waste meet state

requirements, but the park would like to reduce them further to set an example and be good

stewards of the environment. Currently the system uses a two stage package system implemented

by The Smith Sinnet Associates, PA. To ensure the health of the stream and further minimize

discharge levels, a tertiary wastewater treatment method is needed. Nutrient levels are of the

greatest concern, thus the denitrification capacity of a wastewater treatment wetland makes it an

appropriate design selection. Area is available for the construction of a wetland on the site of the

wastewater treatment plant, but space is limited. The budget for the project is expected to be low,

so keeping costs low will be a major design constraint.

Background Information

There are many widely accepted definitions for wetlands. According the Section 404 of the

Clean Water Act a wetland is defined as:

Those areas that are inundated or saturated by the surface or ground water (hydrology) at

a frequency and duration sufficient to support, and that under normal circumstances do

support, a prevalence of vegetation (hydrophytes) typically adapted for life in saturated

soil conditions (hydric soils). Wetlands generally include swamps, marshes, bogs and

similar areas. (Fangmeier, Elliot, Workman, Huffman, & Schwab, 2006, p. 272)

Jurisdictional wetlands, as regulated by the U.S. Army Corp of Engineers under Section 404,

must exhibit all three characteristics: hydrology, hydrophytes, and hydric soils. The U.S. Fish

and Wildlife Service define wetlands as having one or more of the following three attributes:

1. At least periodically, the land supports predominately hydrophytes;

2. The substrate is predominately undrained hydric soils; and,

3. The substrate is non-soil and is saturated with water or covered by shallow water at

some time during the growing season of each year. (Fangmeier et. al, 2006, p. 271)

All these definitions combine three factors: hydrology, soils and vegetation. Hydrophytes are

plants which thrive where water is at or near the surface. Hydric soils are saturated for long

intervals during the growing season to develop anaerobic conditions near the surface (Fangmeier

et. al. 271).

of 52

Constructed wetlands are built to treat wastewater or stormwater and are controlled by inlet and

outlet conditions. Wastewater can have high biochemical oxygen demand (BOD), total

suspended solids (TSS), nitrogen, phosphorous, and fecal coliform bacteria. Wastewater

treatment wetlands can be classified as surface flow or subsurface flow wetlands. The

disadvantage of subsurface flow wetlands is their tendency to clog (Fangmeier et. al, 2006, p.

283-284). Figure 1 depicts a surface flow wastewater treatment wetland that treats the waste of

Richmond Hill, a community in Georgia.

Figure 1. Richmond Hill community wastewater treatment wetland (City of Richmond Hill Georgia, 2011)

Nitrogen can occur in many forms in wetlands depending on oxidation-reduction state, several of

which are important in a wetland’s biogeochemistry. Nitrogen transformation in wetlands

involves several microbial processes which are displayed in Figure 2. A wetland serves as a

bioreactor because it is an engineered environment that supports biological activity. With the

presence of anoxic conditions in wetlands, microbial denitrification transforms nitrate to gaseous

forms of nitrogen which are released into the atmosphere. Nitrate serves as an electron acceptor

in wetland soils that are depleted of oxygen. Humans release excess nitrogen into the system

through activities such as fertilizer manufacturing, increased use of nitrogen-fixing crops, and

fossil fuel burning. Wetlands serve as potential “sinks” for nitrogen (Mitsch & Gosselink, 2000,

p. 171).

of 52

Figure 2: Nitrogen transformations in wetland (Mitsch and Gosselink, 2000)

Nitrogen mineralization converts organically bound nitrogen to ammonium nitrogen as the

organic matter is being decomposed and degraded. The pathway can occur in both aerobic and

anaerobic conditions and is referred to as ammonification. Mineralization of simple soluble

organic nitrogen is given as:

NH2CONH2 + H2O → 2 NH3 +CO2

NH3 + H20 →NH4+ + OH-

When the ammonium ion (NH4+) is formed it can be absorbed by plants through their root

systems or by anaerobic microorganisms and converted back to organic matter. Under high- pH

conditions (pH > 8), excessive algal blooms can form and the ammonium ion can be converted to

NH3, which is then released in to the atmosphere through volatilization. The ammonium ion can

also be immobilized through ion exchange onto negatively charged soil particles. With the

anaerobic conditions of wetlands, ammonium is normally restricted from further oxidation. The

gradient of high concentrations of ammonium in the reduced soils and low concentration in

oxidized layers causes an upward diffusion of ammonium to the oxidized layer. In an aerobic

environment, ammonium nitrogen can be oxidized through the process of nitrification in two

steps. The first step is facilitated by Nitrosomonas bacteria while the second step is facilitated by

Nitrobacter bacteria:

2NH4+ + 3O2 →2NO2

- + 2H2O + 4H+ + energy

2NO2- + O2 →2NO3

- + energy

Nitrate (NO3-) is more mobile in solution. Denitrification occurs in anaerobic conditions where

nitrate acts as a terminal electron acceptor. The reduction of oxygen yields the most energy but

when oxygen is absent, nitrate has the highest reduction potential and many microorganisms can

utilize the nitrate instead of oxygen

represented in Figure 3. This process results in the loss of nitrogen because it is converted to

gaseous nitrous oxide (N2O) and molecular nitrogen (N

C6H

Denitrification is inhibited in acidic soils. Nitrogen fixation

nitrogen starting the cycle over again. This can

wetlands. In wetlands, nitrogen fixation can occur in overlying waters, in the aerobic soil layer,

in the anaerobic soil layer, in the oxidized rhizosphere of plants, and on the leaf and stem

surfaces of plants (Mitsch & Gosselink, 2000, p. 172

Figure

(

Vegetation plays an important role in the chemical processes that take place in wetlands.

submerged plant matter provides surface area for the growth of bacteria, algae, and protozoa

which break down dissolved organic matter and utilize nutrients in the wetland for

oxidation/reduction reactions, as described above (Cronk & Fennessy, 2001, p

sustaining microbial activity the wetland becomes more effective at removing wastewater

contaminants. The vegetation has many other roles which contribute to the effectiveness of

treatment wetlands. Plants increase sedimentation by dissipating en

column, which prevents re-suspension of solids and they provide shade to the water column,

keeping algae growth under control (Kadlec & Wallace, 2009, p.96). An essential function of

decomposing vegetation is to provide a carbon s

source acts as an electron donor which is essential for the dentrification process to take place. As

the microorganisms break down the carbon source the donated electrons are accepted by nitrate

whose reduction yields energy (Kadlec & Wallace, 2009, p.149)

utilize the nitrate instead of oxygen (Kadlec & Wallace, 2009, p.149). This pathway is

. This process results in the loss of nitrogen because it is converted to

O) and molecular nitrogen (N2):

H12O6 + 4NO3 → 6CO2 + 6H2O +2N2

ted in acidic soils. Nitrogen fixation can convert N2 gas to organic

starting the cycle over again. This can be a significant source of nitrogen for some



(Mitsch & Gosselink, 2000, p. 172-173).

Figure 3: Nitrification and denitrification in wetlands

(NRCS, 2007 and I.M. Hagenbuch, 2007)

Vegetation plays an important role in the chemical processes that take place in wetlands.



oxidation/reduction reactions, as described above (Cronk & Fennessy, 2001, p.341). By



treatment wetlands. Plants increase sedimentation by dissipating energy throughout the water

suspension of solids and they provide shade to the water column,


decomposing vegetation is to provide a carbon source for the denitrifying bacteria. A carbon



(Kadlec & Wallace, 2009, p.149).

Page 7 of 52

. This pathway is

. This process results in the loss of nitrogen because it is converted to

gas to organic

be a significant source of nitrogen for some



Vegetation plays an important role in the chemical processes that take place in wetlands. The



.341). By



ergy throughout the water

suspension of solids and they provide shade to the water column,


ource for the denitrifying bacteria. A carbon



of 52

Denitrification is the main mechanism for nitrate removal in wetlands, and it is the only

mechanism that completely removes nitrate from the system (Birgand et al., 2007).

Denitrification occurs predominately at the soil-water interface, called the hyporheic zone. The

rate of denitrification is affected by the presence of oxygen, pH, organic carbon supply, water

temperature, nitrate supply, and the population of denitrifying bacteria (Tisdale et al., 1993).

Most of the factors will stay relatively constant or will vary at a slow rate. However, temperature

can vary often and rather significantly. Denitrification rates have been observed to increase more

than ten times with a temperature increase from 5 °C to 27 °C (Dawson and Murphy, 1972).

Accordingly, research shows that nitrogen removal rates are greatest in the summer and lowest in

the winter (Birgand et al., 2007). Because water temperature plays a very large role in the rate of

denitfication and the fact that water temperature is likely to fluctuate often, it is important to

model the denitrification rate as a function of water temperature to get the most accurate analysis

of nitrate removal.

Objective

The overall goal of the designed wetland is to lower nutrient and pollutant levels of the

wastewater discharged into Grassy Creek. Implementing a wetland will also reduce the volume

of water entering the stream due to losses through infiltration and evapotranspiration and,

therefore, decrease the loading of these nutrients and pollutants. While designing the wetland, the

design team would like to optimize the function of the wetland as well as reduce the cost of

implementing the wetland to satisfy the client’s needs. The wetland will need to maximize the

removal of nitrogen from the wastewater. This will be achieved through the denitrification of

nitrate in the anaerobic conditions that occur in the saturated wetland soils. To provide more

treatment of the effluent, hydraulic retention time will be taken into consideration in the design.

The design also needs to be low maintenance in order to reduce continuing costs. These

objectives will be considered to design the wastewater treatment wetland.

Materials and Methods:

Site Visits and Surveys

Two site visits were taken during the course of this design project. During the first site visit, a

land and soil survey of the area of interest (Figure 21) around the package wastewater treatment

plant was conducted. A total station, tripod, rod, prism, and data collector were used for the land

survey. A 3-inch hand soil auger was used to describe several soil profiles to a depth of 5-feet

below the surface in multiple areas. Soil samples were analyzed on site for soil texture and depth

of water table. Important locations that were necessary for creating a design were surveyed:

bench marks, the stream, the gravel road, soil sample locations, the fence line, pipe inverts, the

wastewater treatment plant and other structures in the waste treatment area. Ideas were discussed

of 52

with the client and the proposed area for the wetland was analyzed for possible places to

discharge the wetland.

The main purpose of the second site visit was to acquire GPS data points. The bench mark

locations and points along the wastewater treatment structures were re-surveyed in order to

increase the precision of the survey data. Point elevations were used to create surfaces for cut/fill

calculations and pipe invert elevations aided in pipe design. A macroinvertebrate survey was

conducted as well. Water samples were taken above and below the wastewater treatment outlet

and also from an unaffected tributary that connects upstream.

Feasibility Analysis

After the site visits, a feasibility analysis was performed on the areas delineated by the site

survey and initial design candidates in order to determine if levels of denitrification could be met

that would deem building a treatment wetland practical. Several methods of estimating nitrate

removal and wetland hydrology were used in the analysis.

k-C* Model for Nitrate Reduction

The k-C* first-order area-based degradation model (Kadlec and Knight, 1996, p. 436) was used

to analyze each design candidate for expected post-treatment nitrate concentration.

� = � ∗ ln �� − �∗� − �∗

��

Where:

A= Area of wetland, m2 Q= Inflow, m3/yr kT= Nirate rate constant for temp T, m/yr Ci= Input concentration, mg/l Co= Output concentration, mg/l C*= Background concentration, mg/l

The effective area of each wetland design candidate was known while the output concentration

was unknown, so the model was rearranged to solve for Co given the area:

� = �� − �∗

�∗��+ �∗

The nitrate removal rate constant, kT, was found using a modified Arrhenius relationship (Kadlec

and Knight, 1996, p. 403) to correct for water temperature.

�� = ��(��)

of 52

Where:

kT= Temperature-dependant nitrate removal rate constant, m/yr k20= Nitrate removal rate constant @ 20 °C, m/yr T= Water temperature, °C θ= empirical temperature factor for nitrate reduction, dimensionless

An estimated temperature factor for nitrate reduction of 1.09 was used (Kadlec and Knight,

1996, p. 406). In order to increase the accuracy of the design candidate analysis, a reference

wetland in Lakeland, Florida, was selected to determine the appropriate nitrate removal rate

constant, kT, to use. The Lakeland wetland is located in a region with a climate similar to Surry

County, NC, and has similar hydrologic and nutrient loading characteristics to the design

candidates. Data from the Lakeland wetland gave an average nitrate removal rate constant of

23.8 m/yr at an average water temperature of 22.6 °C (NADB, 1993). Adjusted using the

modified Arrhenius relationship, the k20 used was 19.02 m/yr.

Determining the appropriate input nitrate concentration was difficult as the site operator does not

sample for nitrate concentration monthly. Only four data points were provided. Using the data

points and other knowledge of the site, a typical input nitrate concentration was assumed to be 10

mg/l. An appropriate background nitrate concentration was determined to be 0.1 mg/l through

discussion with Dr. Burchell, an Assistant Professor and Extension Specialist in Ecosystem

Restoration in the Biological and Agricultural Engineering Department at North Carolina State

University (personal communication, March 27, 2011).

The area for each design candidate was determined using the CAD drawings for each wetland.

The effective area was measured at the 0.5’ water depth of the wetland.

Maximum, average, and minimum daily inflow and water temperature values are monthly

averages taken from the NPDES Permit Compliance System (EPA, 2011). Records were only

available from between March 2009 and June 2010. Data from overlapping months was

averaged.

Nitrate Loading Analysis

The nitrate loading rate was determined for each design candidate.

�� !�" = � ∗ �

Where:

Loading Rate= Nitrate loading rate, kg-NO3 /day C= Nitrate concentration, kg-NO3 /m

3 Q= Outflow, m3/day

of 52

For each design candidate, the estimated nitrate concentration of the effluent from k-C* model

analysis was converted to units of kg-NO3 /m3. Outflow data used in k-C* model analysis was

converted to m3/day.

Theoretical Efficiency

The theoretical nitrate removal efficiency was determined for each design candidate. The

equation for theoretical nitrate removal efficiency was derived (personal communication,

Birgand, 2011). The derivation for theoretical nitrate removal efficiency is shown in Appendix 6:

Derivation. The equation is shown below: %$%% = &1 − � ��()*+ ∗ 100

Where: %Eff= Theoretical nitrate removal efficiency, % kT= Temperature-dependant nitrate removal rate constant, m/day HLR= Hydraulic loading rate, m/day The kT used is the same rate constant used for k-C* model analysis, converted to units of meters per day. The Hydraulic Loading Rate is:

-�! = 100 ∗ �

�

Where: Q= Inflow, m3/day A= Wetland area, m2

Hydraulic Retention Time

The theoretical hydraulic retention time of the wastewater within the wetland indicates how much contact time the wastewater will have with denitrifying bacteria. This equation assumes plug flow through the wetland:

" = . ∗ /�

Where; t= hydraulic retention time, days V= volume of wetland basin, m3 p= porosity, 1.0 for surface-flow wetlands Q= flow rate through wetland, m3/day

Water Balance

A general water balance for a wetland was constructed and can be viewed in Figure 4. The

balance accounts for the treatment plant inflow, surface run-off, precipitation, evapotranspiration

(ET), soil infiltration, groundwater discharge, and wetland outflow.

for both precipitation and ET. Precipitation data was collected from the State Climate Office of

North Carolina as the 30-yr normal for a local weather station in Mount Airy, NC.

was obtained from the NC Climate Retrieval and Observat

Database (NC CRONOS) as a 10

pan evaporation data was multiplied by 75% for assumed ET rates, as recommended by the EPA

(2000, p. 76).

Soils

To determine if a liner should be implemented to prevent water los

surface of the wetland, the saturated hydraulic conductivity (K

must be determined. EPA recommen

adequate as an infiltration barrier (2000, p. 93).

to the sandy loam horizons. Figure 618.88 of the NRCS National

describes a sandy loam soil of high bulk density (1.72 g/cm

of the wetland bottom) to have a K

Design

The survey points from the site visit

database was created. With this data, the points were

description and an elevation. A raster

obtained from the North Carolina State’s Geographic Information Systems database and added to

the current drawing in AutoCAD.

(ET), soil infiltration, groundwater discharge, and wetland outflow. Climate data was

Precipitation data was collected from the State Climate Office of

yr normal for a local weather station in Mount Airy, NC.

was obtained from the NC Climate Retrieval and Observations Network of the Sout

10-year average pan evaporation from a local weather station.


Figure 4. Water balance

To determine if a liner should be implemented to prevent water loss or gain through the bottom

, the saturated hydraulic conductivity (Ksat) of the bottom wetland material

EPA recommends that soils with Ksat values less than 10-6

adequate as an infiltration barrier (2000, p. 93). The bottom of the wetland will be graded down

Figure 618.88 of the NRCS National Soil Survey Handbook

loam soil of high bulk density (1.72 g/cm3, representing compacted conditions

of the wetland bottom) to have a Ksat value of 10-4 to 10-3 cm/s (2011).

from the site visit were imported into AutoCAD Civil 3D 2010 and a survey

With this data, the points were placed into point groups and labeled with a

A raster image of the location of the wastewater treatment was

rom the North Carolina State’s Geographic Information Systems database and added to

the current drawing in AutoCAD. With this raster data, the survey points were translated to

Page 12 of 52

Climate data was obtained

Precipitation data was collected from the State Climate Office of

yr normal for a local weather station in Mount Airy, NC. The ET data

ions Network of the Southeast

year average pan evaporation from a local weather station. The


s or gain through the bottom

) of the bottom wetland material

cm/s are

The bottom of the wetland will be graded down

Survey Handbook

representing compacted conditions

were imported into AutoCAD Civil 3D 2010 and a survey

to point groups and labeled with a

image of the location of the wastewater treatment was

rom the North Carolina State’s Geographic Information Systems database and added to

With this raster data, the survey points were translated to

of 52

North Carolina State Plane US Feet Coordinates. These points were then used to delineate the

existing structures, wastewater treatment plant, tree line, Grassy Creek, fence, and roads. Once

the points were translated, the LIDAR contour data of Surry County for two foot intervals from

the North Carolina Department of Transportation was downloaded and incorporated with the

supplemental topographical survey data to create a digital surface of the area of interest.

Three design candidates were created for the client. These candidates can be found in the design

documents. The first design candidate will maximize all available area and will discharge in to a

clean water diversion. The second design candidate will maximize all available area, not

incorporate a bentonite liner, and discharge in to the riparian buffer next to the stream. The third

design candidate will have less area in order to not take out the existing fence and will discharge

in to a clean water diversion.

Once the existing surface was created, a design surface was created for each wetland of the

design candidate. Grading on AutoCAD Civil 3D 2010 was completed from the existing surface.

The grading process was repeated for each design candidates with the only difference being the

size and shape of the initial wetland base feature line as well as the starting elevations of the

wetland base. With the grading for all the design candidates, the design wetland surface was

created to display existing and design contour lines. A wetland design surface can be seen below

in Figure 5.

Figure 5. Wetland design surface, design candidate 1

Currently the piping between the waste water treatment plant, flow meter, and dechlorinator is 6”

PVC. The size of inlet pipe was determined using the capacity equation found in Soil and Water

Conservation Engineering (Fangmeier et. al, 2006, p. 196)

to be the elevation difference between the pipe inlet and the pipe outlet.

coefficients were determined based upon components used for each design.

The outlet structure is crucial to keep an effective water depth in the wetland.

structure that will be implemented is a flashboard riser.

and orifice equations as shown in

The clean water diversion in the design

guidelines for non-critical areas (2000, p.92)

seen in Appendix 4: Calculation Package.

and Water Conservation Engineering

Erosion control measures were developed

acre and a site plan and E&S Protection plan

submittals. In order to implement this

tree line, silt fence outside the tree protection fence to capture sediment, and wattles every 100

in the clean water diversion to decrease the velocity in the diversion to facilitate the settling of

sediments. Four alignments were created to allow stationing and

of the design candidates. These profiles consist of the existing and design surface.

representative profile is shown below i

A budget was made for all the design candidates to give to

Figure

(Fangmeier et. al, 2006, p. 196) The head causing flow was

levation difference between the pipe inlet and the pipe outlet. The friction loss

were determined based upon components used for each design.

to keep an effective water depth in the wetland. The outlet

structure that will be implemented is a flashboard riser. The flashboard riser was sized using

in Appendix 4: Calculation Package.

in the design was sized for a 10 year storm according to the EPA

(2000, p.92). Calculations for the clean water diversion can be

Appendix 4: Calculation Package. These equations and coefficients were taken from

and Water Conservation Engineering.

developed for the design even though the project is less than one

otection plans are not expected to be required as separate

In order to implement this, all design candidates have tree protection fence along the

line, silt fence outside the tree protection fence to capture sediment, and wattles every 100

decrease the velocity in the diversion to facilitate the settling of

Four alignments were created to allow stationing and to create four profiles for each

profiles consist of the existing and design surface.

tative profile is shown below in Figure 6. A budget was created in Appendix 5: Budget

e for all the design candidates to give to the client.

Figure 6. Representative profile – design candidate 1

Page 14 of 52

The head causing flow was assumed

The friction loss

The outlet

The flashboard riser was sized using weir

was sized for a 10 year storm according to the EPA

Calculations for the clean water diversion can be

These equations and coefficients were taken from Soil

project is less than one

not expected to be required as separate

tree protection fence along the

line, silt fence outside the tree protection fence to capture sediment, and wattles every 100’

decrease the velocity in the diversion to facilitate the settling of

create four profiles for each

profiles consist of the existing and design surface. A

Appendix 5: Budget.

of 52

Plans were then created for the client. For this a title block was created and added to all sheets

which consisted of the sheet number, sheet title, client, designers’ name and information, scale,

north arrow, and date. A cover sheet was created which consisted of a vicinity map, county

location, site coordinates, surveyors, and engineers. A table of contents was created to guide the

client and contractor through the plans. Details are provided in the design plans to provide more

information on the components of the design. The plans were plotted to Arch D sheets

(24”X36”) and to PDF files to be presented to the client. These three different proposed plans

will be delivered to the client for the final design selection.

Vegetation

Wetland vegetation was researched in order to determine which species would be most

appropriate for the designed wastewater wetland. The plants are divided into four groups based

on their growth form: emergent, submerged, floating leaved and floating (Cronk & Fennessy,

2001, p.13). Emergent plants have stalks and leaves that emerge from the water surface while

submerged plants remained entirely submerged beneath the water surface. Floating leaf plants

have leaves that float on the water with roots that are anchored in the soil while floating plants

float unattached to the soil bed. It has been shown through research that only a few plants can

thrive in high-nutrient treatment wetlands; those plants include bulrushes (Schoenoplectus,

Scirpus) and cattails (Typha) (Mitsch & Gosselink, 2000, p. 713).

Results and Discussion:

Site Visits and Surveys

The survey points taken during the first site visit can be seen on Figure 19. The results water

samples taken on October 27, 2010 are shown below in Table 1:

Table 1. Water samples at wastewater treatment plant outlet in October

Pollutant Concentration

Nitrate (NO3-) 30.6 mg/l

Total Suspended Solids (TSS) 3.33 mg/l

Biological Oxygen Demand

(BOD)

<2 mg/l

Ammonium (NH4+) 0.177 mg/l

of 52

Fecal Coliform <1 col/100 ml

From these samples it can be concluded that the pollutant that needs to be reduced is nitrate at

30.6 mg/L and ammonium is not of concern. With the macroinvertebrate study during the second

site visit, the health of the stream was confirmed upon finding water pennies, gilled snails, an

amphipod, and a salamander (EPA, 2011). Water samples taken during the second site visit are

seen below in Table 2:

Table 2. Water samples taken in january above and below the outlet and a tributary

TKN

(mg/L) NO3-N/NO2-N (mg/L) TP (mg/L)

ABOVE 0.33 0.25 0.144

BELOW 0.08 0.23 0.09

TRIBUTARY 0.15 0.11 0.09

With the water samples it can be concluded that the outlet contributes no significant source of

pollutants during the colder off season of Pilot Mountain State Park.

A typical soil profile was developed for the area and is shown in Figure 7. The profile consisted

of a loam surface (0-10”) transitioning to a sandy loam in the next 2 horizons (10-34”), and

finally to a loamy sand (34-60+”). Evidence of the seasonal high water table was seen at 34” as

indicated by the low chroma color (chroma less than or equal to 2). No restrictive layers of rock,

clay, or saprolite were encountered on any of the sampled sites. It was noted that a good portion

of the topsoil in the desired area of the wetland was fill material placed during the removal of an

existing dry bed used with the previous waste system so topsoil will need to be imported for the

wetland.

Figure 7. Typical soil profile

Feasibility Analysis

Nitrate reduction analysis was performed for each design candidate using the k

(Kadlec and Knight, 1996, p.436) assuming an average input nitrate concentration of 10 mg/l.

The average nitrate loading expected from each wetland was determined as shown in

Figure 8. Comparison of expected nitrate loading rate of each wetland design candidate

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140

Jan Feb Mar Apr

Nit

rate

Lo

ad

ing

(k

g-N

O3

/da

y)

Average Output Nitrate Loading Rate for each Wetland Design

rofile

Profile Description A (0-10”): Reddish-Brown LoamBw1 (10-24”): Reddish-Brown Sandy LoamBw2 (24-34”): Yellowish-Brown Sandy LoamBg (34-60”+): Gray Loamy Sand

Nitrate reduction analysis was performed for each design candidate using the k-C* model

and Knight, 1996, p.436) assuming an average input nitrate concentration of 10 mg/l.

The average nitrate loading expected from each wetland was determined as shown in

. Comparison of expected nitrate loading rate of each wetland design candidate

Apr May Jun Jul Aug Sept Oct Nov Dec

Month


Candidate

Page 17 of 52

Brown Loam Brown Sandy Loam

Brown Sandy Loam Gray Loamy Sand

C* model

and Knight, 1996, p.436) assuming an average input nitrate concentration of 10 mg/l.

The average nitrate loading expected from each wetland was determined as shown in Figure 8.

. Comparison of expected nitrate loading rate of each wetland design candidate


Input Load

Wetland 1

Output

Load

Wetland 2

Output

LoadWetland 3

Output

Load

of 52

Wetlands 1 and 2 show similar nitrate loading due to their similar size. During the summer, all

three wetlands reach very low nitrate loading rates. Significant nitrate loading rate reduction is

achieved by all design candidates, but wetland 1 and 2 perform better year-round than wetland 3

due to the size differential.

Figure 9. Theoretical nitrate removal efficiency expected for each wetland design candidate

The theoretical nitrate removal efficiency was determined for each design candidate as shown in

Figure 9. The results for removal efficiency are similar to the results for nitrate loading; wetlands

1 and 2 have very similar removal efficiencies. Each wetland design candidate is expected to

approach 100% nitrate removal during the warm summer months as the water temperature rises

and biological activity increases. Again, wetlands 1 and 2 out-performed wetland 3 on a yearly

basis.

Due to the superior expected nitrate removal efficiency over wetland 3 and the necessity for a

liner (which will be discussed later in the results), wetland 1 is the design candidate that is

recommended to Pilot Mountain State Park. Further analysis of wetland 1 was performed to give

the client more detailed performance expectations.

30

35

40

45

50

55

60

65

70

75

80

0

10

20

30

40

50

60

70

80

90

100

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Av

g. W

ate

r Te

mp

era

ture

(°F)

Nit

rate

Re

mo

va

l (%

)

Month

Theoretical Nitrate Removal Efficiency for each Wetland Design

Candidate vs. Average Monthly Water Temperature

Wetland 1

Wetland 2

Wetland 3

Avg Water

Temp

of 52

Figure 10. Theoretical nitrate reduction efficiency expected for Wetland 1 given certain conditions

As shown in Figure 10, the minimum expected nitrate reduction efficiency (average observed

inflow, minimum nitrate removal rate constant) is expected to be above 90% during the warmest

summer months. The low spike in nitrate reduction during September is due to the increased

hydraulic loading experienced during the park’s busiest time, the autumn leaf season. Wetland 1

is expected to maintain at least 20% nitrate reduction efficiency during the coldest winter

months, with the possibility of seeing up to 50% reduction efficiency.

Figure 11. Comparison of input and output nitrate loading rates for Wetland 1

As shown in Figure 11, the reduction in nitrate loading rates provided by wetland 1 are

significant year-round, especially as the water temperature warms and denitrifying bacteria

0

20

40

60

80

100Ja

n

Feb

Ma

r

Ap

r

Ma

y

Jun

Jul

Au

g

Sep

t

Oct

No

v

De

c

Nit

rate

Re

du

ctio

n (

%)

Month

Theoretical Nitrate Reduction Efficiency in Wetland 1

Max

Avg

Min

Min (@Max

Permitted Q)

0.00

1.00

2.00

3.00

4.00

5.00

6.00

0.000

0.020

0.040

0.060

0.080

0.100

0.120

0.140


Nit

rate

Co

nce

ntr

ati

on

(m

g/l

)

Nit

rate

Lo

ad

ing

(k

g-N

O3

/da

y)

Month

Input Nitrate Loading vs. Ouptut Nitrate Loading and Concentration for

Wetland 1

Load (Max

Reduction)

Input Load

Concentration

(Max Reduction)

of 52

become more active. With an expected average input nitrate concentration of 10 mg/l, wetland 1

is expected to provide nitrate removal to a concentration of as little as around 5 mg/l in the

coldest months and very close to the background concentration of 0.1 mg/l during the warmest

months.

Figure 12. Comparison of output loading rates dependant on input nitrate concentration for Wetland 1 with a

hydrograph

Figure 12 illustrates the nitrate loading rates that wetland 1 is expected to provide given 5 mg/l,

10 mg/l, 20 mg/l, and 35 mg/l input nitrate concentration. Based on the sample data provided by

the site operator and other local considerations, the input concentration is likely to be within the

10-20 mg/l range on average. Again, as denitrifying bacteria become more active during the

warm months, nitrate loading rates are reduced to near-zero for even the highest input nitrate

concentrations that are expected. The hydraulic loading stays relatively constant through the

year, so it will not make a big difference on the nitrate loading rate.

0

500

1000

1500

2000

2500

3000

3500

4000

0.000

0.050

0.100

0.150

0.200

0.250

0.300


Inflo

w (g

allo

ns/d

ay

)

Nit

rate

Lo

ad

ing

Ra

te (

kg

-NO

3/d

ay

)

Month

Output Loading vs Input Nitrate Concentration for Wetland 1

35 mg/l

20 mg/l

10 mg/l

5 mg/l

Avg Inflow

of 52

0

5

10

15

20

25


Re

tne

tio

n T

ime

(d

ays

)

Month

Min, Avg, and Max Hydraulic Retention Time for Wetland 1

HRT, Avg Observed Q

HRT, Max Observed Q

HRT, Max Permitted Q

Figure 13. Minimum, average, and maximum hydraulic retention time for Wetland 1

A hydraulic retention time of between 5 and 14 days is recommended for wastewater treatment

wetlands (Mitsch & Gosselink, 2000, p. 701). As shown in Figure 13, the average HRT of

wetland 1 is expected to stay well above the minimum recommended HRT. This indicates that

there will be ample time for wastewater to be treated within the wetland. If the wetland receives

the maximum permitted 10,000 gpd, then the HRT will still be very close to 5 days.

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0


Hy

dra

ulic

Lo

ad

ing

Ra

te (

cm/

day

)

Month

Min, Avg, and Max Hydraulic Loading Rate for Wetland 1

Max Permitted

Max Observed

Avg Observed

Figure 14. Minimum, average, and maximum hydraulic loading rate for Wetland 1

As Figure 14 shows, an analysis of the expected hydraulic loading rate of wetland 1 indicates

that with average inflows, wetland 1 will remain within the recommended HLR for treatment

wetlands of 2.5 - 5.0 cm/day (Mitsch & Gosselink

inflows, the wetland will remain within the recommended range for 10 months out

The hydraulic loading rate and hydraulic retention time and closely tied together. The results

from these analyses indicate that the wetland will be able to handle the expected

loading while providing the desired

Water Balance

As shown in Figure 15, the surface runoff can be controlled by use of

It was determined that a clean water diversion will

runoff from surrounding areas awa

discharge is controlled by the permeability of the soil surface.

eliminate these two factors. With the use of a diversion and a clay liner, a simplified

balance would include all factors but surface runoff, infiltration, and groundwater discharge.

Both the inflow and outflow to the wetland can be controlled by inlet and outlet structures.

only factors that cannot be controlled within the balance are precipitati

Figure 15. Water balance that incorporates a clay liner to eliminate infiltration and groundwater d

The precipitation and ET data was compiled

shown in Table 3. The max monthly

as observed in June. These changes in water level are not expected to adversely affect wetland

vegetation; the wetland will neither dry

n analysis of the expected hydraulic loading rate of wetland 1 indicates

with average inflows, wetland 1 will remain within the recommended HLR for treatment

Mitsch & Gosselink, 2000, p. 699). With the maximum observed

inflows, the wetland will remain within the recommended range for 10 months out


indicate that the wetland will be able to handle the expected

the desired performance.

he surface runoff can be controlled by use of the clean water

clean water diversion will be placed next to the wetland to divert any

runoff from surrounding areas away from the wetland. The soil infiltration and groundwater

discharge is controlled by the permeability of the soil surface. A clay liner could be used to

With the use of a diversion and a clay liner, a simplified

ould include all factors but surface runoff, infiltration, and groundwater discharge.

Both the inflow and outflow to the wetland can be controlled by inlet and outlet structures.

only factors that cannot be controlled within the balance are precipitation and ET.

. Water balance that incorporates a clay liner to eliminate infiltration and groundwater d

data was compiled and the net gains and losses were computed as

monthly gain is 2.9” as observed in January and the max loss is 1.21

These changes in water level are not expected to adversely affect wetland

the wetland will neither dry-up nor flood under these conditions.

Page 22 of 52

n analysis of the expected hydraulic loading rate of wetland 1 indicates

with average inflows, wetland 1 will remain within the recommended HLR for treatment

. With the maximum observed

inflows, the wetland will remain within the recommended range for 10 months out of the year.


indicate that the wetland will be able to handle the expected hydraulic

the clean water diversion.

next to the wetland to divert any

The soil infiltration and groundwater

A clay liner could be used to

With the use of a diversion and a clay liner, a simplified water

ould include all factors but surface runoff, infiltration, and groundwater discharge.

Both the inflow and outflow to the wetland can be controlled by inlet and outlet structures. The

on and ET.

. Water balance that incorporates a clay liner to eliminate infiltration and groundwater discharge

ins and losses were computed as

max loss is 1.21

These changes in water level are not expected to adversely affect wetland

of 52

Table 3. Precipitation and evapotranspiration data

Month Precipitation 75% ET Net

(in) (in) (in)

January 4.0 1.1 2.9

February 3.4 1.3 2.0

March 4.4 2.8 1.7

April 3.9 4.0 (0.1)

May 4.7 4.8 (0.1)

June 4.0 5.2 (1.2)

July 4.4 5.1 (0.7)

August 3.8 4.6 (0.8)

September 4.3 3.5 0.8

October 3.4 2.1 1.3

November 3.5 1.3 2.2

December 3.3 0.9 2.4

Total 47.0 36.5 10.4

*Precipitation Data obtained from NC Climate Office for weather station 315890-Mt Airy 2 W

(COOP).

*ET Data obtained from NC CRONOS for weather station KMWK- Surry County Airport.

Soils

The Ksat value (10-4 to 10-3 cm/s) indicates current soil conditions are inadequate to serve as an

infiltration barrier. A clay liner will be recommended for this wetland so that failure of the

system will not occur. Bentonite, a high shrink-swell clay material, should be applied to the

graded surface at a rate 1.5 lb/ft2 and incorporated into the graded surface by tillage (NRCS,

1997, p. 521C-2). After incorporation, this layer should be compacted lightly.

Additionally, a clay liner is recommended because it would be advantages for the wetland to

hold water 100% of the time to maintain anaerobic conditions at the soil-water interface. If the

wetland were to become completely dry, then oxygen would be introduced into previous-

anaerobic zones that were hosting denitrifying processes. Anaerobic conditions would have to be

restored which would reduced the nitrate removal efficiency of the wetland until the soil-water

interface returned to its anaerobic state. Additionally, the wetland will not perform as predicted if

it is allowed to dry out because the nitrate removal models assume saturated conditions 100% of

the time.

A 6-inch layer of topsoil should be added on top of the soil/bentonite mixture so the wastewater

treatment wetland can optimize its treatment. This will provide media to support plant growth as

well as a protection barrier for the clay liner. The topsoil should be rich in nutrients to ensure

proper growth and health of the wetland vegetation. It is recommended that topsoil be hauled in

for this layer because much of the current topsoil is fill material of unknown origin. This layer

of 52

should be graded with a generally undulating surface to increase surface area and microbial

activity.

Design

The grading of the wetland was completed based on recommendations by the EPA Manual and

NOAA precipitation depth. The base of the wetland was created as a feature line with a 0.5%

slope in order that the base of the wetland would have a 0.5% slope as recommended by the EPA

Manual. From this feature line, the surface was graded up to a relative elevation of 2.7’ with 3:1

side slopes. The 2.7’ was graded to account for 0.2’ of bentonite to inhibit exfiltration, 0.5’ of

topsoil, 1’ of water depth and 1’ of freeboard. The 1’ water depth is recommended per Dr.

Burchell (personal communication, 2011). 3:1 side slopes are recommended by the EPA. The

EPA generally recommends having a freeboard depth of 2’. Because of the use of a diversion

ditch, no stormwater runoff enters the wetland. Therefore, 1’ of freeboard will be sufficient for

storing the precipitation for storm events. Additionally, occasional flooding will not harm

wetland vegetation and the structure exists in a flood-plain and is down-grade from any

structures. Once this grading was completed, the design surface was graded back to the original

surface with a 3:1 side slope. An infill was created in the bottom of the wetland and an 18” deep

pool was added in the area adjacent to the flashboard riser to complete the grading for the design

surface. (EPA, 2000, p. 92)

Based on the capacity equation found in Soil and Water Conservation Engineering (Fangmeier

et. al, 2006, p. 196) 6” PVC was determined to be adequate for the inlet pipe to the wetland as

shown in Appendix 4: Calculation Package. 6-inch Schedule-40 PVC pipe was chosen to be used

with accompanying components for the design candidates. The outlet of the wetland inlet pipe

will be composed of a 6”x4”x4” double wye with two spans of 4” PVC connecting. The wye will

be capped at the end, allowing a simple cleanout method if needed. The water will be split

between the two 4-inch pipes, delivering it to two separate areas of the wetland. This is intended

to decrease dead zones, and normalize flow across the width. The design for the inlet pipe can be

seen in the design documents and in Figure 16 below:

A flashboard riser was chosen because it is economical and adjustable.

consists of 6” flashboards which

adjustability of the wetland water depth is beneficial because the wetland can be drained in case

of an emergency or if the system is breached.

establishing new vegetation after planting.

design documents and in Figure 17

Figure

Figure 16. Inlet detail

A flashboard riser was chosen because it is economical and adjustable. The flashboard riser

can be added or removed to control water depth. The


of an emergency or if the system is breached. Additionally, varying water-level is important for

w vegetation after planting. The design of the flashboard riser can be seen

17 below:

Figure 17. Flashboard riser outlet structure

Page 25 of 52

The flashboard riser

added or removed to control water depth. The


level is important for

The design of the flashboard riser can be seen in the

of 52

A clean water diversion was added to the east side of the wetland in order to capture any

stormwater runoff before it entered the wetland. Aluminum diversions covered with railroad

ballast were added throughout the wetland with spacing of 14’-20’. These diversions were

created to decrease dead zones and increase retention time by lengthening flow path as

recommended by the EPA (EPA, 2000, p. 92). The design for these diversions is shown below in

Figure 18. Benches are often used to control flow path, the aluminum diversions were designed

to have a smaller footprint and allow more space for vegetation.

Figure 18. Aluminum Diversion

After treatment analysis and designing, certain factors about the design candidates were

observed. The first design candidate has higher treatment potential due to a larger surface area.

The second design candidate has the largest surface area for treatment but does not have a

bentonite liner to inhibit exfiltration and is set deeper into the existing surface resulting in larger

net volume of soil cut. The lower elevation is important so that water sits below existing grade so

that any exfiltration is into the soil below the wetland and not through berms. Design candidate 3

has less surface area for treatment. Construction sequence and maintenance plans can be found in

Appendix 1: Construction Scope of Work and Appendix 2: Maintenance Plan.

Vegetation

The final selection of wetland species to be planted in the designed wetland is bulrush, cattail,

and pickerelweed. Bulrush and cattail are to be planted in alternating section throughout the

water depth in the wetland. The pickerelweed will be planted around the 6 inch water depth.

Pickerelweed is a wetland plant that blooms large purple flowers. The primary purpose of this

species is to add to the aesthetics of the wetland, as requested by the client. Grasses are also

going to be purchased and planted on the berm surrounding the wetland and diversion ditch. The

planting plans and instructions are located in Appendix 3: Planting Instructions and in the design

documents.

of 52

Permitting

One consideration for the wetland design is permit requirements. The specific permit

requirements necessary will depend on where the effluent water from the wetland is discharged.

A National Pollutant Discharge Elimination System (NPDES) wastewater treatment and disposal

permit is needed for any direct discharges of wastewater to surface waters of the state to be in

compliance with Section 402 of the Clean Water Act as well as state regulations. The Division of

Water Quality (DWQ) issues NPDES permits for discharges of treated wastewater to surface

waters. Because the treatment wetland is changing the process of the treatment system, a major

modification of the existing NPDES permit will be needed. A major modification uses the same

forms as a new permit application and can be obtained from DWQ. After obtaining an NPDES

permit, an Authorization to Construct (ATC) permit may be obtained from the Construction

Grants and Loans Section of the DWQ. To remain in compliance with section 401 and 404 of the

Clean Water Act additional permits and certifications may be needed, often referred to

collectively as 401/404 permits.

The US Army Corps of Engineers is responsible for issuing 404 permits and the NCDWQ is the

state agency responsible for issuing 401 water quality certifications (WQC). A 401 WQC is

required to ensure and certify that a project will not violate any water standards and is needed for

any projects that impact wetlands or waters. Depending on where the effluent of the water is

discharged, an Isolated and Other Non-404 Jurisdictional Wetlands and Waters Permit may be

needed. To remain in compliance with section 401 and 404 of the Clean Water Act the design

candidates avoid areas that may be delineated as jurisdictional wetlands.

Cost

Of the three budgets, represented in Appendix 5: Budget, design candidate 3, is the least costly.

This is to be expected since it is the smallest wetland and would require less earthwork. Design

candidate 1 is slightly more expensive than design candidate 3 due to a larger surface area

resulting in more earthwork. Design candidate 2 is the most expensive design candidate due to

the lower base elevations which results in the largest amount of earthwork.

Conclusions:

Of the three designs, Design Candidate 1 was selected as the best wastewater treatment solution.

This design accomplishes all objectives stated for this project. This conclusion was reached after

considering many factors. The major differences between design 1 and design 2 are the clay liner

and method of water dispersal from the flashboard riser. It was determined the sandy loam soil

was not suitable as an infiltration barrier; therefore, a clay liner is recommended if the client does

not want the system to fail. Design 2 also would require disturbance of the riparian buffer,

whereas design 1 will not disturb any of the riparian buffer. Due to these factors, design

candidate 2 is not a recommended option. The major difference between design 1 and design 3 is

of 52

the size of the wetland. Design 3 has less surface area which, in turn, will provide less treatment

of nitrate. Design candidate 1 should be implemented on a treatment, design and economic basis;

design candidate 1 was selected as the best solution. The next step will be to present the client

with the design candidates for their evaluation.

Acknowledgments:

This project has been supported by the client, Mr. Windsor, Pilot Mountain State Park

Superintendent. We acknowledge the Blue Ridge Environmental Consultants, P.A and ACH

Constructors, LLC for providing guidance in design and material selection. This paper draws on

the knowledge of many groups and individuals who have been involved in research of treatment

wetlands. We express gratitude to them all with special thanks to Dr. Michael Burchell, our

senior design advisor, and Dr. François Birgand. We are grateful to Dr. Michael Boyette, our

senior design professor, for his assistance and direction during the project development.

of 52

List of References:

Birgand, F., R. W. Skaggs, G.M. Cheschier, and J. W. Gilliam. (2007). Nitrogen removal in

streams of agricultural catchments: A literature review. Critical Reviews in Environ. Sci.

and Tech. 37(5): 381-487.

City of Richmond Hill, Georgia (site creator). (2011). Wetlands 1 [photograph], Retrieved April

25, 2011, from: http://www.richmondhill-

ga.gov/PublicWorksDepartment/WaterWastewaterSystems/tabid/100/Default.aspx

Cronk, J. K., & Fennessy, M. S. (2001). Wetland Plants Biology and Ecology. Boca Raton, FL:

CRC Press LLC.

Dawson, R. N., and K. L. Murphy. 1972. The temperature dependency of biological

denitrification. Water Res. 6(1): 71-83

Fangmeier, D. D., Elliot, W. J., Workman, S. R., Huffman, R. L., & Schwab, G. O. (2006). Soil

and Water Conservation Engineering (5th ed.). Clifton Park, NY: Thomson Delmar

Learning.

Garbisch, E. W. (1986). Highways and wetlands, compensating wetland losses. U.S. Department

of Transportation, Federal Highway Administration. U.S. Government Printing Office,

1987.

Hagenbuch, I.M. (creator). (2007). Nitrification.Denitrification [flow chart], Retrieved March 30,

2011, from: http://www.nano-reef.com/articles/?article=17

Kadlec, J. A., and Wentz, W. A. (1974). “State-of-the-art survey and evaluation of marsh plant

establishment techniques: Induced and natural Volume I: Report of research,” Contract

Report D-74-9, U.S. Army Engineer Waterways Experiment Station, Environmental

Laboratory, Vicksburg, MS.

Kadlec, R. H., & Knight, R. L. (1996). Treatment Wetlands. Boca Raton, FL : Lewis Publishers.

Kadlec, R. H., & Wallace, S. D., (2009). Treatment Wetlands (2nd ed.). Boca Raton, FL: Taylor

& Francis Group, LLC.

Mitsch, W. J., & Gosselink, J. G. (2000). Wetlands. New York, NY: John Wiley & Sons, Inc.

NADB (North American Treatment Database). 1993. Electronic database created by R. Knight,

R. Ruble, R. Kadlec, and S. Reed for the U.S. Environmental Protection Agency. Copies

available from Don Brown, U.S. EPA, (513) 569-7630.

of 52

NRCS-Natural Resources Conservation Service (site creator). Drawing of threesquare bulrush

plant with roots [drawing]. (2007). Retrieved March 30, 2011, from: http://www.mt.nrc

s.usda.gov/technical/ecs/plants/technotes/pmtechnotemt37/threesquare.html

Olin, T. J., Fischenich, C., & Palermo, M. R. (2000). Wetlands Engineering Handbook.

Retrieved from http://el.erdc.usace.army.mil/elpubs/pdf/wrpre21/wrpre21.pdf

U.S. Environmental Protection Agency. (2011, January 31). Biological Indications of Watershed

Health. Retrieved February 8, 2011, from: http://www.epa.gov/bioiweb1/html/invertebr

ate.html

U.S. Environmental Protection Agency. (2000). Constructed Wetlands-Treatment of Municipal

Wastewaters Manual. Cincinati, Ohio: Office of Research and Development.

US Natural Resource Conservation Services. (2011). National Soil Survey Handbook.

Washington, DC: US Department of Agriculture. Retrieved from

http://soils.usda.gov/technical/handbook/contents/part618ex.html.

US Natural Resource Conservation Services. (1997). Field Office Technical Guide: Pond

Sealing or Lining, Bentonite Sealing (No.) Code 521C. Georgia: US Department of

Agriculture.

of 52

Figures

Figure 19. GIS data and original survey points

Figure 20. Wastewater treatment plant

Figure 21. Proposed area for wetland

Page 32 of 52

of 52

Appendices

Appendix 1: Construction Scope of Work

The scope of work is intended to cover all work contained in this and all other applicable design

documents. The scope of work includes, but may not necessarily be limited to, all labor,

materials, and supervision to complete the work in accordance to the design documents. It shall

be the bidder’s responsibility to review all design documents and fully understand the project and

scope of work. For the purposes of this document, “Subcontractor” refers to this bidder and

“Owner” refers to Pilot Mountain State Park and related agencies and “EOR” refers to the

engineer on record for the project. All work shall be in strict accordance with all Local, State,

and Federal laws, regulations, and guidelines. All construction shall be in accordance to 29 CFR

1926 “Safety and Health Regulations for Construction.” A construction start date in March is

recommended so that planting can begin in April.

Project Scope and Sequence

1. The Subcontractor shall review all design documents and related reports.

2. Subcontractor shall coordinate all permitting with Owner, DENR, and DWQ.

3. Subcontractor shall be responsible for coordinating with all other contractors and for

supervising their lower tier subcontractors if applicable.

4. The Subcontractor shall keep the work areas clean and is responsible for protecting all

work and materials stored on site.

5. Any construction track out must be cleaned and kept clear from the main road at all

times.

6. Any deviation from design documents shall be allowed only at the approval of the EOR

and Owner.

7. The scope of work includes installing tree protection, erosion and sediment controls,

fencing, rough and fine grading, piping, wetland structures, seeding, and planting.

8. The Subcontractor is responsible for developing and submitting a site-specific Health and

Safety Plan and shall designate a safety representative.

9. Subcontractor will layout, supply, install, maintain, and remove all erosion control and

tree protection systems in accordance to the design documents.

10. Subcontractor will excavate diversion ditch and install wattles per the design documents

before any other grading is to continue.

11. Diversion ditch shall be immediately seeded according to the seeding instructions in the

design documents.

12. Subcontractor is responsible for all construction dewatering and shall ensure that all

sediment is controlled and that no effluent from construction dewatering is pumped into

the stream or riparian buffer.

13. The fence in the area of the wetland should be removed and temporary fencing installed

to protect the existing treatment plant until permanent fencing is installed. The

of 52

Subcontractor shall submit to the Owner a report outlining how much, if any, of the

existing fence the Subcontractor intends to reuse.

14. The excavation work includes, but may not be limited to, excavation, stockpiling,

protection and relocation of excavated soils as well as loading soils into vehicles for

hauling when necessary.

15. The location of all temporary stockpiles should be approved by the EOR and Owner and

stockpiles must be protected to prevent erosion and sediment runoff.

16. Any excavations of trenching deeper than 4’ shall be considered a confined space and

shall follow the requirements for trenching in 29 CFR 1926.

17. The subcontractor shall provide fencing, signs, and/or flagging to warn of any open

ditches to protect site personnel.

18. Include all labor, equipment, and materials to complete all piping.

19. All piping work shall comply with all applicable codes and standards of the Plastic Pipe

Institute (PPI).

20. The Subcontractor shall be responsible for receiving, moving, securing, and storing all

piping required for the project.

21. The Subcontractor shall submit manufacturer’s technical data for all equipment used.

22. Coordinate with surveyor to complete as-built surveys including the location of all

piping.

23. Some deviation from the piping layout may be allowed with the approval of the EOR.

24. When backfilling trenches, the backfill level be placed evenly along the entire length. No

backfill materials shall be placed over frozen earth.

25. Bentonite shall be added at a rate of 1.5 lb/ sq ft and incorporated into the soil in a 0.2 ft

layer and topsoil shall be added in a 0.5ft layer across the entire wetland.

26. Wetland structures shall be installed concurrently with rough and fine grading in the most

logical order as determined by this subcontractor.

27. Flashboard Riser structure shall be constructed and installed per the design documents.

28. Sheet diversions shall be installed by driving galvanized sign post into ground so 2 ft

remain above the topsoil layer and spaced no more than 12 ft apart. Corrugated sheeting

shall be attached with bolts that may be removed for any future wetland maintenance.

29. Corrugated sheeting shall be installed along the grade and topsoil shall be backfilled

against them.

30. Topsoil shall be finely graded and stabilized; the wetland base may have a generally

undulating surface in accordance to design specifications.

31. After topsoil has been properly compacted and stabilized, wetland shall be planted

according to design documents as soon as seasonal conditions allow.

of 52

Appendix 2: Maintenance Plan

A maintenance plan is important for the performance of the wetland and prevents the conditions

of the wetland vegetation from being changed. Problems from not developing and following a

wetland can include: invasion of unwanted plant species resulting in a major alteration of the

vegetation and its effectiveness, insufficient vegetation cover to prevent erosion and loss of

substrate, changes to topography, colonization by exotic plant species and other pest organisms,

and an increased time for the wetland to reach peak effectiveness (Olin, Fischenich , & Palermo,

2000, p. 7-97). It is particularly important for the maintenance plan to be followed through the

first growing season as the vegetation is becoming established (Garbisch, 1986), but the wetland

should be monitored and maintained throughout the life of the wetland. The wetland should be

monitored to determine if any vegetation needs to be replaced, if any damage needs to be

repaired, to determine if any additional controls are needed, and during and after winter months

to determine if freezing has caused any damage to vegetation or wetland topography.

To determine the need for supplemental or replacement vegetation a visual assessment of the

wetland should be made. For this treatment wetland a vigorous stand of wetland vegetation is

desired in all areas except for the deep pool adjacent to the flashboard riser. The deep pool depth

ahead of the flashboard riser is intended to prevent encroachment by wetland vegetation. Any

vegetation found in this deep pool should be removed and discarded or removed and replanted

into any under vegetated areas of the wetland. Any vegetation that needs to be removed shall be

done through hand removal and not by any mechanical harvesting or herbicides. For this

wetland, either standardized vegetation sampling or a photographic record should be used to

compare vegetation to previous seasons. For a wetland of this size, a photographic record can

assist with making a determination of any replanting needs from a visual assessment. Litter and

debris can also damage the wetland and should be removed anytime they are scene in or adjacent

to the wetland. Whenever possible planting should be conducted with the wetland is drained; the

wetland can be drained by removing flashboards and directing flow to the existing outlet.

Mowing is an important part of the maintenance plan for seeded areas on the outside of wetland

banks and inside the grassed diversion ditch. Mowing can help to reduce weeds and weed seed

production as well as preventing the invasion of woody plants in areas where they are not desired

(Olin et al, 2000, p. 7-106). Mowing should be to a height of approximately 4 inches. Grass

should not be mowed in a manner such that more than one quarter of their height is cut during

any single mowing event, this will reduce the stress on grass. Having established grass is

important to maintain the topography of the wetland and protect wetland berms. The Tall Fescue

species called for in the design documents may go dormant during the summer; during these

times mowing is still important to prevent infiltration by weeds and woody plants. During the

late fall and early winter the fescue may also go dormant, an overseeding with rye grass as

mentioned in the planting instructions can continue grass cover into later seasons.

of 52

Maintaining grass on all banks and diversion ditches is important to maintain site topography and

prevent erosion. The wetland should be periodically inspected for any evidence of erosion such

as sediment deposit or erosion rills. If any evidence of erosion is found immediate steps should

be taken to control and repair the damage. Animals can also cause damage to the wetland,

beavers and burrowing animals can have negative impacts on the performance of the wetland and

steps should be taken to control them at the first sign of damage. After planting, wetland

vegetation can be susceptible to waterfowl and other small mammals (Kadlec and Wentz, 1974).

The interior of the wetland in design candidates one and three utilize a bentonite liner. If any

seepage is indicated through the wetland berms, the topsoil in the area may need to be stripped

and bentonite reincorporated into the soil in the area to prevent damage to the berms and to

maintain water level. Water level in the wetland needs to be maintained to encourage vegetation,

after planting particular care must be made to follow the water level instructions in the planting

guidelines. Water level manipulation can be used to encourage or discourage vegetation (Olin et

al, 2000, p. 7-109).

Wetland vegetation needs to be continually monitored for signs of plant disease. Diseases affect

different plants in different ways and are often of greatest concern when plants are stressed due

to climatic conditions such as high temperatures and humidity (Olin et al, 2000, p. 7-110). Dead

or diseased plants should be removed to discourage the spreading of any fungi or disease

organisms. In cases where only parts of plants are affected, pruning can simulate new growth to

compensate for the damage (Olin et al, 2000, p. 7-111).

of 52

Appendix 3: Planting Instructions

The site is ready for planting after all soils have been properly compacted and as soon as

seasonal conditions allow. Planting should be done at least six weeks prior to filling with water

and following the design documents. For sites subjected to high physical stresses, transplantation

has a higher success rate than seeding so plants should be transplanted (Olin et al, 2000, p. 7-43).

Plants may be stressed from being packed shipped and stored so post nursery cares are important.

Keep plants watered and shaded. Losses from heat stress and drought occur when planted in

summertime. Plants should be ordered at least six months in advance to ensure availability of

species. Ensure that temperatures will remain above forty (40) degrees Fahrenheit before

planting. All planting should be in accordance to any instructions provided by the supplier and

all supplier information should be retained for future planting needs. Seedlings should be

handled with care and planted as soon as possible after arriving. Seedling roots should not be

exposed to direct sun or wind and root moisture may be maintained by submerging them in

buckets or using a wet burlap sack (Olin et al, 2000, p. 7-66). The planting hole should be sized

appropriately to provide space for seedling roots. Seedling roots should be no less than a half

inch deep but not so deep that roots are bent within the hole. Root depth is critical for the

survival of the plant (Olin et al, 2000, p. 7-66). Any soil plugs shall be place in stabilized soils

and gently tamped to ensure good contact between soil and plug. After planting, the wetland

should be saturated with 1 inch of water for 4 to 5 weeks. After the sixth week, or when plants

show new growth, water levels should be gradually increased to support erect upright forms.

Stems and leaves must be above water level to prevent drowning. If after six weeks the plants do

not take hold, replant new plants in between existing plants in the same row fashion. If planting

cannot take place six weeks prior to hard frost, postpone until spring. Refer to design plans for

further information.

of 52

Appendix 4: Calculation Package

1 Key

1. 0� = 01�� 1 �

2. "2 = 3�4 �% ��5 �"1�"��

3. �67 = �� 8" 9:�; <�"ℎ �� 01�� 1 �

4. -67 = $: >�"�� 0�%% 1 �5 �:�� 8" 9:�; <�"ℎ, �

5. � = !��%�:: @�" �8�"A

6. � = !B��%% �� %%�5� �"

7. ��CDE = �1 � �% 31�/ F��: �ℎ�� : 8. � = G��H8!�B�ℎ� 88 �� %%�5� �"

9. ! = -A�1�B:�5 !��B8

10. I = I:�/

11. J = J�8 �% �ℎ�� : 12. 3KLMCLE�EL = 3�/ �% �ℎ�� : N %�1 9:�8ℎN��1� !�8 1 <�/ $�" 18

13. 3DM6LCE�EL = 3�/ �% �ℎ�� : �%" 1 9:�8ℎN��1� !�8 1 <�/ $�" 18

14. �KLMCLE�EL = 0 /"ℎ �% �ℎ�� : N %�1 9:�8ℎN��1� !�8 1 <�/ $�" 18

15. �DM6LCE�EL = 0 /"ℎ �% �ℎ�� : �%" 1 9:�8ℎN��1� !�8 1 <�/ $�" 18

16. �O6CPLQLR6 = 9:�; ;�"ℎ �ℎ�� : S �4 "1A ;�"ℎ�B" 9:�8ℎN��1� !�8 1 <�/

17. �O6CPLQLR6TE�EL = 9:�; ;�"ℎ �ℎ�� : S �4 "1A ;�"ℎ 9:�8ℎN��1� !�8 1 <�/

18. �2DU2KLMCL E�EL = ��:5B:�" � 9:�; ;�"ℎ�B" 9:�8ℎN��1� !�8 1 <�/

19. �2DU2DM6LC E�EL = ��:5B:�" � 9:�; ;�"ℎ 9:�8ℎN��1� !�8 1 <�/

20. �E�EL = �1 � �% <�/

21. - = - �� 5�B8�� %:�;

22. VL = $�"1��5 ��88 �� %%�5� �"

23. VK = J �� 88 �� %%�5� �"

24. V2 = ��B�" ��88 �� %%�5� �"

25. �E�EL = � ��"ℎ �% <�/

26. �D = WB": " <1�" 5"�� /1�� "ℎ

27. XD = WB": " <1�" 5"�� /1�� X��"ℎ

28. � = � ��"ℎ �% X �1

29. �Y = X �1 �� %%�5� �"

30. - = - ��ℎ" �% X�" 1 W> 1 � �" 1 �% W1�%�5

31. �Z = W1�%�5 �� %%�5� �"

32. -Y = - ��ℎ" �% X�" 1 J %�1 X �1

33. � = 0��4 " 1 �% W1�%�5

34. � = I"��1� S1�>�"A

35. � = �1 � �% W1�%�5

36. I� = IB1%�5 �1 �

of 52

37. � = � ��"ℎ

2 Pilot Mountain

2.1 Stormwater Calculations

0� = 3.34

"2 =^�67

_-62 `

�._ab

128 = e130.416 g�._ab

128 < 5 4��B" 8 → B8 "2 = 5 4��B" 8

� = 6.80 ��ℎ1 ; 10 l �1 I"�14

� = 0.150

�m� = ��0� = (0.150)(6.80)(3.34) = 3.41 %"_8

2.2 Clean Water Diversion

G��′8 $oB�"��: �2DU2 = � � !�_Im�

��CDE = 2.25 %"�

� = 0.06 ; ! "�1��5 �:�88 J: 3�:: 9 85B

! = 0.37 %"

I = 0.03%"/%"

J = 3.0 %"

3KLMCLE�EL = 6.0 %"

3DM6LCE�EL = 6.60 %"

�KLMCLE�EL = 0.5 %"

�DM6LCE�EL = 0.6 %"

�O6CPLQLR6 = 3.41 5%8

�O6CPLQLR6TE�EL = 4.78 5%8

�2DU2KLMCL E�EL = 3.47 5%8

of 52

�2DU2DM6LC E�EL = 5.31 5%8

�O6CPLQLR6 < �2DU2KLMCL E�EL ; �: �� X�" 1 0�> 18�� ;�:: 5��> A "ℎ %:�; �O6CPLQLR6TE�EL < �2DU2DM6LC E�EL ; �: �� X�" 1 0�> 18�� ;�:: 5��> A "ℎ %:�; 2.3 Inlet Pipe

1. �88B4�� %B:: , "B1NB: �" /�/ %:�;; � = �s2�-s1 + VL + VK + V2�

�E�EL = 0.20 %"�; 6 ��5ℎ /�/��

J�8 � �� 0 8�� " 2; - = 5.28 %"�

VL = 0.50

VK = 2.40

V2 = 0.50 %"�m

�E�EL = 49 %"

�2DU2 = 0.32 5%8

�2DU2 > �ZL2vUC�RD6C ; <�/ ;�:: 5��> A "ℎ %:�;

2.4 Pipe Outlet Protection

�� = 8.00 ��5ℎ 8

�D = 5 %"

XD = �� + �D = 5.7 %"

�b� = 8 �� (�:�88 J)

� = 1.5�b� = 12 ��

2.5 Flashboard

1. J1�� − �1 8" � X �1 I�F��: � = �Y�-_�

� = 3.08 %"

�Y = 3

-Y = 0.22 %"

of 52

2. W1�%�5 I�F��: � = w�Z�(2�-)m�

�Z = 0.6

- = 0.67 %"

� = 8 ��5ℎ

� = 0.349 %"

� = 32.2 %"/8�

2.6 Planting

1. 0 8�� " 1

I� = 5576 %"�

1 <:��" = 4 %"�

JB::1B8ℎ = 700 <:��"8

��""��: = 700 <:��"8

1 <:��" = 2 %"

� = 339 %"

<�5� 1 :; � = 170 <:��"8

2. 0 8�� " 2

I� = 5837 %"�

1 <:��" = 4 %"�

JB::1B8ℎ = 730 <:��"8

��""��: = 730 <:��"8

1 <:��" = 2 %"

� = 350 %"

<�5� 1 :; � = 180 <:��"8

of 52

3. 0 8�� " 3

I� = 3807%"�

1 <:��" = 4 %"�

JB::1B8ℎ = 480 <:��"8

��""��: = 480 <:��"8

1 <:��" = 2 %"

� = 288 %"

<�5� 1 :; � = 150 <:��"8

of 52

Appendix 5: Budget

Design Candidate 1

Wetland Dimensions

Area 0.128 ac

5575.68 sq ft

Cut/Fill 115 cu ft

Haul 77 cu ft

Topsoil 2787.84 cu ft

103 cu yd

Item Price Quantity Total

Substrate 50 lb Bentonite (CETCO) $9.49 168 $1,594.32

13 cu yd Topsoil $345.00 8 $2,760.00

Riprap (ton) $50.00 4 $200.00

Subtotal $4,554.32


Plants Bullrush $1.00 700 $700.00

Cattails $1.00 700 $700.00

Pickerelweed $1.00 170 $170.00

Kentucky Tall Fescue

No. 30-20 lb bag $30.00 2 $60.00

Rygrass- 50 lb bag $60.00 1 $60.00

Subtotal $1,690.00

Price/Volume Volume (cu ft) Total

Earthwork Cut/Fil $3.00 115 $345.00

Haul $9.50 77 $731.50

Subtotal $1,076.50


Diversions Corragated Sheets $20.00 14 $280.00

Galvanized Sign posts $26.00 18 $468.00

Subtotal $748.00

of 52


Piping 6" PVC- 10' pipe $35.00 5 $175.00

4" PVC- 10' pipe $13.00 1 $13.00

6" PVC Pipe Tee $30.00 1 $30.00

6" PVC Gate valve $250.00 2 $500.00

6" 45⁰ Elbow $20.00 2 $40.00

6" 90⁰ Elbow $18.00 1 $18.00

6"x6"x4"x4" Wye $90.00 1 $90.00

8" corrugated pipe- 25'

(20ft/roll) $50.00 2 $100.00

Flashboard Riser $1,500.00 1 $1,500.00

Subtotal $2,466.00


Labor Surveying (per hour) $150.00 20 $3,000.00

Site work- 5 man crew

(per hour) $225.00 80 $18,000.00

Site Work- 3 man crew

(per hour) $165.00 80 $13,200.00

Subtotal $34,200.00


Equipment Bachoe $2,500.00 1 $2,500.00

Trencher $1,000.00 1 $1,000.00

Bobcat $1,000.00 1 $1,000.00

Subtotal $4,500.00


Area Protection

Silt fence- 200 ft

(100ft/roll) $25.00 4 $100.00

Straw wattle (25 ft) $25.00 2 $50.00

Wooden Stakes

(50/bundle) $16.00 1 $16.00

Tree Protection Fence-

200 ft (100ft/roll) $36.00 4 $144.00

5ft Steel t-post $4.00 80 $320.00

Subtotal $630.00

Total Costs: $49,864.82

of 52

Design Candidate 2

Wetland Dimensions

Area 0.134 ac

5837.04 sq ft

Cut/Fill 3 cu ft

Haul 655 cu ft


108 cu yd


Substrate

13 cu yd Topsoil $345.00 9 $3,105.00

Rip Rap (ton) $50.00 3 $100.00

Subtotal $3,205.00

Price Quantity Total


Cattails $1.00 730 $730.00



No. 30-20 lb bag $30.00 2 $60.00

Rygrass- 50 lb bag $60.00 1 $60.00

Subtotal $1,760.00



Haul $9.50 655 $6,222.50

Subtotal $6,231.50




Subtotal $788.00

of 52


Piping 6" PVC- 10' pipe $35.00 5 $175.00

4" PVC- 10' pipe $13.00 1 $13.00

6" PVC Pipe Tee $30.00 1 $30.00

6" PVC Gate valve $250.00 2 $500.00

6" 45⁰ Elbow $20.00 2 $40.00

6" 90⁰ Elbow $18.00 1 $18.00

6"x6"x4"x4" Wye $90.00 1 $90.00

8" slotted corrugated

pipe- 200 ft (20ft/roll) $50.00 10 $500.00

Flash board riser $1,500.00 1 $1,500.00

Subtotal $2,866.00




(per hour) $225.00 80 $18,000.00


(per hour $165.00 80 $13,200.00

Subtotal $34,200.00



Trencher $1,000.00 1 $1,000.00

Bobcat $1,000.00 1 $1,000.00

Subtotal $4,500.00


Area Protection

Silt fence- 200 ft

(100ft/roll) $25.00 2 $50.00


200 ft (100ft/roll) $36.00 2 $72.00

5ft Steel t-post $4.00 40 $160.00

Subtotal $282.00


of 52

Design Candidate 3

Wetland Dimensions

Area 0.0874 ac

3807.144 sq ft

Cut/Fill 69 cu ft

Haul 114 cu ft


71 cu yd


Substrate 50 lb Bentonite (CETCO) $9.49 116 $1,100.84

Top Soil $345.00 6 $2,070.00

Riprap (ton) $50.00 4 $200.00

Subtotal $3,170.84



Cattails $1.00 480 $480.00



No. 30-20 lb bag $30.00 2 $60.00

Rygrass- 50 lb bag $60.00 1 $60.00

Subtotal $1,230.00



Haul $9.50 114 $1,083.00

Subtotal $1,290.00




Subtotal $656.00

of 52


Piping 6" PVC- 10' pipe $35.00 9 $315.00

4" PVC- 10' pipe $13.00 1 $13.00

6" PVC Pipe Tee $30.00 1 $30.00

6" PVC Gate valve $250.00 2 $500.00

6" 45⁰ Elbow $20.00 2 $40.00

6" 90⁰ Elbow $18.00 1 $18.00

6"x6"x4"x4" Wye $90.00 1 $90.00

8" corrugated pipe- 25'

(20ft/roll) $50.00 2 $100.00

Flashboard Riser $1,500.00 1 $1,500.00

Subtotal $2,606.00




(per hour) $225.00 80 $18,000.00


(per hour $165.00 80 $13,200.00

Subtotal $34,200.00



Trencher $1,000.00 1 $1,000.00

Bobcat $1,000.00 1 $1,000.00

Subtotal $4,500.00


Area Protection

Silt fence- 200 ft

(100ft/roll) $25.00 4 $100.00

Straw wattle (25 ft) $25.00 2 $50.00

Wooden Stakes

(50/bundle) $16.00 1 $16.00


200 ft (100ft/roll) $36.00 4 $144.00

5ft Steel t-post $4.00 80 $320.00

Subtotal $630.00


of 52

Appendix 6: Derivation

The derivation began with two equations for mass of nitrate:

G = ! ∗ ∆" ∗ �

! = � ∗ �

G = �(") ∗ � ∗ 0Where: M= Mass of nitrate, M R= Removal rate, M* T-1*L-2 ∆t= Change in time, T A= Area, L3 k= Nitrate removal rate constant, L*T-1 C= Nitrate concentration, M*L-3 D= Depth, L

Each equation was differentiated with respect to time:

�G = �� ∗ � ∗ �" GH = �(" + �") ∗ � ∗ 0

Finding the change in mass:

G − GH = � ∗ 0 ∗ [�(") − �(" + �")] Setting

�G = G − G′ Gives:

�� ∗ � ∗ �" = � ∗ 0 ∗ [�(") − �(" + �")] Dividing each side by common terms gives:

− ��0 = �(" + �") − �(")

�"

Taking the limit of each side:

limZ6→� − ��0 = − ��

0

limZ6→��(" + �") − �(")

�" = ��"

Gives: �� = − �

0 �" Integrating both sides:

of 52

} ��

~~�

= − } �0 �"6

�

} ��

~~�

= − } �0 �"6

�

ln � − ln �� = − �0 (" − 0)

ln �� = − �

0 "

Exponentiating both sides: �� ~~� = ��6

�� = ��6

Solving for C: � = �� 6

Efficiency is: $%% = 1 − �(")

��

$%% = 1 − �� 6��

$%% = 1 − ��6

Solving for percent efficiency and substituting time/depth to 1/Hydraulic Loading Rate gives: %$%% = &1 − � ��()*+ ∗ 100

Appendix 7: Gantt Chart

Figure 22. Gantt chart first semester

Figure 23. Gantt chart second semester

Page 51 of 52

wastewater treatment wetland in pilot mountain state park

Documents