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Compost
Use In Wetland FINAL REPORT Report No. CM-96-2 TABLE OF CONTENTS
EXECUTIVE
SUMMARY.............................................................................................................
1.0 SITE
AND PROJECT HISTORY........................................................................................
1.1 SITE HISTORY...............................................................................................................
1.2 GOALS.............................................................................................................................
1.3 COMMUNITY SUPPORT AND INVOLVEMENT....................................................
1.4 STATE GUIDELINES FOR WETLAND RESTORATION........................................
2.0 SITE
DESIGN.......................................................................................................................
2.1 DESIGN GOALS............................................................................................................
3.0 EXPERIMENTAL
DESIGN................................................................................................
3.1 TARGET PARAMETERS.............................................................................................
3.2
COMPOST INCLUSION RATE...................................................................................
3.2.1 Similar
Species Nutrient Uptake...............................................................................
3.2.2 Application
Rates For Fen And Experimental Plots...................................................
4.0 EXPERIMENTAL
RESULTS..............................................................................................
4.1 PLANT GROWTH RESPONSE AND SURVIVAL RATES.......................................
4.2
SOIL ANALYSES...........................................................................................................
4.2.1 Total
and Volatile Solids Content.............................................................................
4.2.2 Particle
Size Analysis...............................................................................................
4.2.3 pH..........................................................................................................................
4.2.4 Conductivity............................................................................................................
4.2.5 Nitrogen
Dynamics..................................................................................................
4.2.6 Phosphorus
and Potassium Levels............................................................................
4.2.7 Copper...................................................................................................................
4.2.8 Other
Analyses Performed.......................................................................................
4.3 SURFACE WATER QUALITY......................................................................................
4.4 WILDLIFE OBSERVATIONS......................................................................................
5.0 GUIDELINE
FOR USE OF COMPOST IN WETLAND RESTORATION.....................
5.1 TYPE OF COMPOST.....................................................................................................
5.2 REQUIRED ANALYSES...............................................................................................
5.3 SUMMARY
WORKSHEET FOR COMPOST APPLICATION................................
6.0 INFORMATION
DISSEMINATION EFFORTS..............................................................
7.0 ACKNOWLEDGMENTS.....................................................................................................
BIBLIOGRAPHY...........................................................................................................................
APPENDICES: (Not included in
this electronic file but available upon request) APPENDIX
A
- GROWTH AND PLANT SURVIVAL RATE SPREADSHEETS......
A-1 APPENDIX
B
- LABORATORY RESULTS...................................................................
A-2 APPENDIX
C
- SITE DRAWINGS.................................................................................
A-3 APPENDIX
D
- WETLAND SPECIES SUITABLE TO WESTERN WASHINGTON
A-4 APPENDIX
E
- WORKSHEET FOR AGRONOMIC LOADING RATE.................... A-5
Table
l Experimental
Plot Design Loading................................................... ....... 8 Table
2 Plant Species and Quantities
for Experimental Plots...............................11 Table
3 Similiar Wetland Species
Nutrient Uptake.............................................14 Table
4 Estimated N Uptake and Weighted
Averages...................................
.....15 Table
5 Cadman Wetland Restoration
Compost Application Rates.....................17 Table
6 Everett Wetland Target Compost
Loading Rates...................................17 Table
7 C:N Ratio and Organic Content
Estimates....................................... .. ..18 Table
8 Micronutrient Analyses.........................................................................32 Table
9 Surface Water Quality Analyses
Results................................................34 Table
10 Example of Analyses
of Existing Soils and Compost........................ .....38 Table
11 Sample Plant List..................................................................................39 Table
12 Agronomic Rates
of Plant Groups.........................................................39 Table
13 Soil Parameter
Comparison...................................................................41 Table
14 Worksheet for
Agronomic Loading Rate of Compost to Wetland..........42 Table
15 Inches of Compost
to be Applied..........................................................43 Table
16 Conference Attendance
and Information Dissemination.........................44
List of Figures
Figure
l Wetland Nitrogen Cycle.......................................................................13 Figure
2 Experimental Plot
Growth Comparison................................................20 Figure
3 Survival Rate
Comparison for Experimental Plots................................21 Figure
4 Total and Volatile
Solids Content........................................................23 Figure
5 Particle Size
Analysis...........................................................................24 Figure
6 Analysis of pH
at 12 Months................................................................25 Figure
7 Conductivity Analysis..........................................................................26 Figure
8 Organic Nitrogen
Analysis...................................................................27 Figure
9 Ammonia Nitrogen
Dynamics..............................................................28 Figure
10 Nitrate Nitrogen
Dynamics..................................................................29 Figure
11 Phosphorous Levels.............................................................................29 Figure
12 Potassium Levels.................................................................................30 Figure
13 Copper Levels in
Experimental Plots....................................................31 Figure
14 Cation Exchange
Capacity...................................................................32 Executive Summary
This project was undertaken
with support from the Recycling Technology Assistance Partnership
(ReTAP), a program of the Clean Washington Center of the Washington
State Department of Community, Trade & Economic Development.
The intent was to determine if the use of compost in wetlands
had benefits which could add value to compost by decreasing the
frequency of failure of restoration efforts.
Commonly, restoration efforts fail for one of the following
reasons:
·
Hydraulic
miscalculations
·
Death
of the target wetland plant species
·
Invasive
species propagation
The last two reasons stated above may very well be
curtailed by the addition of compost.
The addition of a rich strong organic matter with some
essential plant nutrients ( i.e. nitrogen, phosphorus, and potassium)
can promote strong growth of target species and allow them to
compete with the opportunistic invaders which adapt well to adverse
soil conditions. This
report presents the findings of a year long study at a wetland
restoration site which showed excellent results in these areas. The results indicate that if a stable compost
is applied at agronomic rates, the growth and survival rate of
target wetland species can be aided.
The plots which used compost showed approximately 20% more
growth and 10 to 15% higher survival rate than the control plots,
which used no compost. The surrounding surface water quality did not
degrade as a result of the application.
This report outlines the steps necessary to design
compost applications for restoration projects.
A worksheet provides a template for the calculation of
an agronomic rate of nitrogen application from a specific compost
to a specific wetland condition.
The aim of this report is to serve as a tool for the
wetland community to responsibly use compost in restoration projects
and reduce the number of failures associated with the construction
of wetlands. The results of this study indicate that a compost
with a high organic content and a low nitrogen content will serve
this end use best by:
1.
Providing
strong organic substrate to mimic wetland soils
2.
Preventing
overloading of nitrogen and contamination of the surface water
3.
Providing
organic matter for absorption of ammonia
N to prevent transport in surface water. 1.0 Site and Project HistoryIn
early 1994, staff at the City of Everett’s Department of Public
Works , with the help of E&A Environmental Consultants, Inc.
(E&A) and Adolfson Associates, Inc., submitted a technology
validation project proposal to the Clean Washington Center’s Recycling
Technology Assistance Partnership (ReTAP). The proposed project was to determine if the
use of compost in wetlands had benefits which could add value
to compost by decreasing the frequency of failure of restoration
efforts. The City knew that such a project was of keen
interest to the Clean Washington Center (CWC) for its potential
to open the wetland restoration market to compost products and
funded the project. This report documents the findings of the study.
Ultimately, the study will lead to guidelines outlining
the best procedures for using compost to replicate wetland soils. 1.1 Site HISTORYLower Bigelow Creek in the City of Everett, which flows from the Lowell neighborhood into the Snohomish River,< consists of two large riparian wetlands connected by a 550 foot 18-inch culvert. This culvert diverts water around a two acre parcel which was filled in decades ago for the construction of a sawmill. At the outset of the project, the site was barren and all water was routed through the culvert. The fill material was very sandy, and the site was covered with Scot’s Broom, an invasive brush. This plant is generally considered a nuisance and is not native to the area.
Railroad lines run through the property
near the upper wetland. The
wetlands are home to a variety of wildlife including a relatively
large population of beavers.
Beaver activity in and around the 550 foot culvert has
caused constant flooding of the railroad tracks adjacent to the
upper wetland. The railroad
and the City of Everett proposed to alleviate the flooding problem
by “removing” the beavers. However,
a well organized group of neighbors opposed this plan, and as
a result, a great deal of public attention has been focused on
this project.
In response, the City proposed to
expand the upper wetland at Bigelow Creek in order to control
flooding, as mitigation for other impacted wetlands, and in order
to allow the beavers to remain in the wetland area.
The expansion of the upper wetland consisted of replacing
the old culvert with a shorter, (80 foot) fish passable culvert.
The shorter culvert would be easier to maintain and the
expanded wetland would provide better flood attenuation and increased
wildlife habitat. In addition, the City proposed to install perforated
pipes in the series of existing beaver dams in the upper wetlands
to further reduce the flooding.
All would be accomplished using compost as the restoration's
substrate. 1.2 goalsThe goals of the project included
the following:
1.
Promotion of the use of compost in wetland projects,
2.
Promotion of the beneficial re-use of locally-generated “waste”
in local applications
3.
Flood control for the area, and
4.
Generate and evaluate data for determination of success.
One of the compost materials used
was a biosolids and yard debris material from the Everett Wastewater
Treatment Plant pilot composting project (which was also conducted
by E&A). The use of this material constituted a full
cycle recycling effort, since the compost feedstocks were all
generated by the residents of the city of Everett and the product
was returned for beneficial reuse within the City limits.
Although the practice does promote responsibility for one's
own waste, the concept of using biosolids compost to construct
wetlands resulted in some concern in both the regulatory community
and the local neighborhood. First, the neighbors were concerned about the potential contaminant
levels of treated biosolids.
However, the U.S. Environmental Protection Agency maintains
strict guidelines to assure that biosolids compost from wastewater
treatment plants are “high quality” and considered safe.
Everett's material meets all guidelines and is considered
a high quality material. Second,
regulators were concerned about the potential for compost overloading
resulting in nitrate transport to the surface water, and metals
leaching. A surface water monitoring plan proposed as part of the experiment
eased concerns about unmonitored application of the compost. In fact, the results of surface water testing
during the project indicated no adverse effects from the compost
application. After extensive
collaboration with both groups, the project was able to proceed
and demonstrate the concept of full cycle recycling.
Other goals included those associated
with the marketing of compost.
This use of compost could potentially add value to compost
by opening new markets within the area of wetland restoration. If the use of compost increased the success rate of wetland restoration,
it would be viewed as a means of preventing the costly replanting
required when a site failed to promote the appropriate plant community. In addition, the wetland construction project
served to stabilize the water levels in the area. The site handled the flow of 1996’s heavy winter
rains quite well, and the railroad tracks did not flood. This is an indication that the fen area served
its purpose as a flood plain in heavy rain conditions.
In addition, there were research
and demonstration goals which were addressed during the course
of the project. The experimental plots examined the growth
and survival of the target plants as well as the invasive species
growth. The soil from each plot was analyzed for an
array of parameters in an effort to replicate the soils in the
surrounding existing wetland.
These results are presented in Section 5 of this report. 1.3 Community support AND involvementCity staff conducted a series of one-on-one meetings with neighborhood leaders and other interested persons in the neighborhood to informally discuss the project objectives and to gather input for a conceptual design. The concept of using composted products as a wetland soil substitute was introduced during these informal meetings. Collaborating with the neighborhood leaders created a positive problem-solving atmosphere which lead to the creation of a plan addressing the concerns of the City, the railroad, and the neighborhood.
Early and comprehensive involvement
of key members of the local neighborhood resulted in a project
that was not just tolerated but demanded by the neighbors. Everett's community involvement program successfully formed an alliance
with the local neighborhood that was instrumental in negotiating
the regulatory hurdles that had to be cleared.
After the consultant and Dan Thompson attended a community
meeting and briefed the citizens, over 30 letters of endorsement
requesting that the City restore the wetlands using biosolids
compost were sent to the Mayor. The neighborhood civic association voted unanimously
to endorse the use of biosolids to restore wetlands near their
homes, and the majority of the project was planted by volunteer
labor from the local neighborhood.
The overwhelming support of the neighborhood overcame the
initial skepticism of the regulators.
All necessary permits were negotiated in less than four
months. 1.4 state guidelines for wetland restorationThe Washington State Department of Ecology published
a report entitled Restoring
Wetlands in Washington - A Guidebook for Wetland Restoration,
Planning and Implementation. The guidebook is a strong reference for such
projects in the state, and offers suggestions on suitable substrates. The report states that restoration sites with
suitable soil types are often limited.
Organic amendments are recommended in order to boost organic
content of wetland soils. Suggested
materials are processed peat, straw, or hay which can be mixed
with mineral soils to provide preliminary levels of organic matter.
It is also suggested that importing hydric soils can be
a benefit, since roots and microbes will aid in the success of
a restoration project. The guidebook states that these measures are
necessary to promote moisture retention, add organic materials,
and add nutrients and micronutrients.
The use of compost is not specifically outlined, although
compost would add to all of the above stated criteria.
This report will be forwarded to the state DOE and an amendment
recommended.
2.0 Site Design2.1 DESIGN GOALSThe site restoration plan was designed to allow for
flow through the fen area, which served as a flood plain during
heavy flow periods. The
excavation plan also called for the gradual sloping of the experimental
plots down to the water surface, which allowed for the planting
of a wide variety of wetland species throughout the water regime.
These excavation plans are shown in Appendix C.
In addition to the excavation plans, Appendix C contains
the plot plans for the planting design. The fen area is shown, with the prescribed plant arrangements.
The planting schemes for each of the experimental plots
shows that the target species were placed in the same areas of
each plot. An effort was
made to ensure that each of the plots had similar slope, sun,
and water conditions. This
was accomplished for all but plot one, which was flooded after
the original drainage culvert was plugged.
The remainder of the plots all had similar conditions,
and therefore represent identical plots aside from the compost
application rate.
The application rates of the compost were designed
to bracket the agronomic needs of the plant community chosen for
each plot. Two plots were
established for each of three application rates for two types
of compost (greenwaste and biosolids/greenwaste) and a control
(no compost) for a total of 14 plots. One of the three application rates was designed
to closely match the agronomic rate, and the other two were designed
to be higher and lower than the agronomic rate. Table 1 describes the application rates and compost type for each
of the 14 plots.
Table 1: Experimental Plot Design Loading
gw = greenwaste, bio = biosolids 3.0 Experimental Design3.1 TARGET PARAMETERSThree application rates of two different composts were applied in an effort to simulate the existing wetland soil conditions. Analysis of the surrounding wetland soils defined the desired target ranges of the chosen soil parameters to be achieved in the restoration effort. These ranges were met through the introduction of a compost and sand mixture as a substrate in the newly constructed area. Parameters studied included organic content, C:N ratio, pH, conductivity, water holding capacity, soil oxygen levels, cation exchange capacity, and trace nutrients. In addition to the lab analyses, plant populations and dynamics (survival rate and plant height) were recorded to study the effect of compost use on promoting the growth and survival of target species as well as suppressing invasive species. 3.2 COMPOST INCLUSION RATECompost inclusion rates were based on creating optimum
conditions for wetland plant growth while minimizing environmental
impacts. A table was developed
that summarizes literature information on nutrient uptake of wetland
plants. Nitrogen (N) uptake will usually be the limiting
factor for the application of the compost, since over-application
of nitrogen can cause water quality degradation.
The nutrient uptake shown in Table 3 follows the list of
plants (Table 2) which were used in the experimental plots.
The plants were grouped into similar categories (trees, shrubs,
herbs, etc.). Each experimental
plot contained a predetermined number of plants from each grouping. By assigning an average nitrogen uptake for each of the groups of
plants, a weighted average of uptake can be estimated according
to the number of each type of plant in each plot.
This estimate can then be presented in pounds of nitrogen
per acre. Table 2: Plant Species and Quantities for Experimental
Plots
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