Hinman Swamp Restoration
Schuyler County, NY
Department of Biological and Environmental Engineering
Masters of Engineering Report
By Rachael Brooks
Spring 2015
Table of Contents
I. Executive Summary ................................................................................................................. 2
II. Background ............................................................................................................................ 3
III. Scope of Project ..................................................................................................................... 3
IV. Site Description ...................................................................................................................... 3
V. Analysis of Site Conditions ..................................................................................................... 4
A. Hydrologic Analysis ................................................................................................... 4
B. Hydraulic Analysis ..................................................................................................... 6
C. Alternative Flow Analysis .......................................................................................... 6
VI. Design and Management Plans ............................................................................................ 6
A. Weir Design ................................................................................................................. 6
B. Cattail Removal ........................................................................................................... 9
C. Japanese Knotweed Management ........................................................................... 10
VII. Cost Estimate ...................................................................................................................... 12
Appendix A: Photographs and Drawings ................................................................................ 13
Appendix B: Quotes and Material Specifications ................................................................... 19
Appendix C: Constants and Calculations ................................................................................ 24
References ................................................................................................................................... 34
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I.
Executive Summary
Road construction on County Route 11 in Alpine, NY in 2014 resulted in culverts being
replaced approximately one foot lower than their previous depth. This resulted in the
draining of the Hinman Swamp lake and wetland area. The county realized the error and
partially obstructed their flow. This lowered the capacity of the flow through the culverts
to 114 cubic feet per second (cfs) from 226 cfs. New York State requires culvert capacity
under county roads with low traffic volume to accommodate the peak flow of a 25-year
storm. Data from a nearby watershed with a gauged stream was used to estimate the 25year flow for Hinman Swamp, resulting in a flow rate of 219 cfs. Based on this analysis it
was determined that the obstruction of the culverts was not a sufficient solution and must
be removed.
As an alternative method to maintain the Hinman swamp lake height, a weir was
designed to hold back the water upstream from culvert inlets. The weir is 46.5 wall feet
constructed of steel sheet piles supplied by Shoreline Steel Inc. A schematic of this weir
can be found on page 7 of this report. Installation can be handled by the land owner by
borrowing or renting an excavator with a pile driving hammer, or installation can be
handled by a local contractor that specializes in pile driving. Contact information for
contractors and equipment rental is provided in the reference section.
In addition to the design of a solution for the lake height, a management plan was
requested for the eradication of cattail that established when the hydrologic conditions of
the wetland changed, and for Japanese knotweed which was introduced in the backfill of
the 2004 culvert construction. Cattail should be removed in conjunction with the weir
construction and can be accomplished by cutting the stocks as close to the roots as
possible at the time when the root system has exhausted all of its stored energy, and then
raising the water level and drowning the cattails. Japanese knotweed can be managed by
injection of the herbicide Rodeo into each knotweed stock during peak flower. Details of
these procedures can be found on pages 9 and 10 of this report.
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II.
Background
In 2004, Schuyler County performed road construction along Route 11. When they
replaced two existing culverts with three new culverts designed by Hunt Engineers,
Architects, Surveyors, they installed them lower than the previous ones, resulting in the
partial draining of Hinman Swap along McClure Creek, owned by Charles Reynolds. Upon
discovering the mistake, the county installed a partial blockage system consisting of steel
brackets on either side of each culvert that held wooden 1x4s against the entrance of each
culvert. This system worked until a large storm flooded many areas of the Southern Tier in
2008. A neighbor of Charles Reynolds became upset that his land was flooded and removed
boards from each culvert entrance with a sledgehammer, resulting in the lowering of the
lake height by approximately eight inches. Since this incident in 2008, there have been
court battles involving the New York State Department of Environmental Conservation,
the United States Army Corp of Engineers, Charles Reynolds, Schuyler County, and Hunt
Engineering. The courts ruled that no blame could be placed on the county or Hunt
Engineering because the statute of limitations had elapsed, and declared no further action
be taken until a feasible solution is proposed.
III.
Scope of Project
The purpose of this project is to design a restoration plan for Hinman Swamp. The design
is to include a revised stormwater management system for the Hinman Swamp watershed
that will allow the water height to rise by eight inches. This plan will also include a method
to eliminate cattail that established in the swamp after its hydrologic conditions were
changed, and a management technique to eliminate Japanese knotweed that was introduced
in the backfill used for the 2004 construction.
IV.
Site Description
Hinman Swamp is located in Schuyler County in the Finger Lakes Region of New York
State. This area is a wetland that contains a small lake created by the land owner, Charles
Reynolds. The three culverts that drain the lake and wetland are located on County Route
11 approximately one mile west of Alpine, NY. They are each four feet in diameter and
are obstructed by wooden 1x4s that block the lower two feet of each opening.
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Figure 1. Satellite image of the lake portion of Hinman Swamp
The vegetation in the wetland and lake area is consistent with common wetland vegetation
in this region, although Cattail (genus: Typha), commonly found in wetland areas
throughout the northeast U.S., were not present until after the partial drainage in 2008
occurred. Japanese knotweed (Fallopia japonica), an invasive species known to cause
severe structural damage and ecosystem disruption, has also established on the lakeshore
both upstream and downstream from the culverts. The surrounding watershed is
predominantly agriculture and mixed forest, and includes the hamlet of Alpine, NY and a
few other homes scattered about the landscape.
V. Analysis of Site Conditions
A. Hydrologic Analysis: Peak storm runoff
In accordance with the 2003 edition of the Cornell Local Roads Program Roadway and
Roadside Drainage specifications for a low traffic county road, a 25-year design storm was
used to calculate peak storm runoff. This quantity was calculated using the TR-55 curve
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number method with a triangular hydrograph. Precipitation data for Schuyler County New
York was retrieved from the Northeast Regional Climate Center. The watershed was
delineated in ArcGIS using a DEM with 98ft grid cell resolution and 0.33ft elevation
resolution. The delineation provided a watershed area of 2,360 acres, a longest flow path
of 19,690 feet, and an average watershed slope of 3.6%. United States Department of
Agriculture (USDA) soil type and hydrologic group data was then intersected with United
States Geological Survey (USGS) land use/land cover (LULC) data to determine the curve
number for each created section and an average curve number was determined by
weighting the individual curve numbers by percent area. When options of hydrologic soil
group or soil condition were available, the option resulting in the higher curve number was
chosen. This provided a conservative estimate of the average curve number for the
watershed of 80.08. A peak flow of 822 cubic feet per second (cfs) was determined using
these data and methods.
Mixed Forest
Evergreen Forest
Agriculture
Pasture
Wetland
Residential
Water
Figure 2. Land Use and Soil Type boundaries for Hinman Swamp Watershed.
Keyed colors represent land use. Varying shades of a similar color depict soil type.
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B. Hydraulic Analysis: Current Culvert Capacity
The capacity of the current culverts was evaluated for both their obstructed condition and
unobstructed condition and were found to be 114 cfs and 226 cfs respectively. The method
used for this analysis is demonstrated in David A. Chin’s text, Water-Resources
Engineering, third edition. Due to the dramatic difference between the estimated peak flow
calculation and the capacity of the existing culverts, an investigation of the area’s
precipitation event history was conducted. Upon finding evidence of storm events with
precipitation amounts approaching the 25-year storm precipitation, without reports of
significant flooding, it was determined that the curve number and triangular hydrograph
method could be overestimating the peak flow from this watershed. This is a reasonable
conclusion considering the relatively small size of the catchment, and the unaccounted for
impacts that the large wetland may have in intercepting the runoff.
C. Alternative Flow Analysis
As an alternative method to determine the peak flow rate of the 25-year design storm,
discharge data was acquired for a nearby gauged stream, Fall Creek, located approximately
20 miles northeast in Ithaca, NY. A Log-Pearson Type III frequency analysis was
performed on the maximum annual discharge data and the 25-year discharge was
determined for Fall Creek. This was then scaled to fit Hinman Swamp using the ratio of
the watershed areas. The scaled 25-year discharge for Hinman Swamp was found to be 219
cfs. This shows that the unobstructed culverts have a satisfactory capacity to accommodate
the 25-year storm but are insufficient with the current obstructed configuration.
VI. Design and Management Plan
A. Weir Design
This design is meant to provide an inexpensive structure that can be installed by the
landowner that will raise the water level of the lake within Hinman Swamp by eight inches.
The proposed structure is a weir constructed of five gauge interlocking steel sheet piles
acquired from Shoreline Steel Inc. These piles are 18 inches wide and can be custom cut
to any length in one half foot increments (see figure 3).
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Figure 3. CAD drawing of the side view of the weir facing the road (upstream side of weir)
Figure 4. CAD drawing of the top view of the weir
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The center of the weir will serve as the water height control and will consist of three piles,
giving it a width of 4 1/2 feet. Using stream gauge data from Fall Creek, an average annual
flow was determined for the Fall Creek watershed and was then scaled to the Hinman
Swamp watershed, providing an average annual flow of 5.4 cfs. Given this flow rate, the
central three piles should rise two inches above the existing water level, 43 inches below
the top of the bulkhead. These dimensions will provide the necessary flow restriction to
achieve eight inches of water level rise in the lake.
As shown in figure 3, the central, or inner piles are eight feet long and will need to be
buried 46 inches into the lake bed at the deepest part, which is four feet deep. The middle
piles have a total length of nine feet and should be positioned 35 inches from the top of the
bulkhead, ten inches up from the existing lake height. There are 22 middle piles, 11 for
each side of the inner piles. Due to significant amounts of debris and varying lake depth,
the depth to which the middle piles are buried into the lake bottom will vary as the
construction of the weir progresses closer to the shoreline. This can be circumvented if the
landowner, or person responsible for the installation of the weir, first removes the boards
that are obstructing the culverts and allows the lake to drain. Once the lake height has
lowered, the lake bottom can be cleared of debris and leveled as much as possible to make
construction of the weir easier. The removal of the culvert obstruction is also required for
the execution of other parts of this restoration plan and should be done within the guidelines
of all management techniques.
The outer piles are five feet long and on the right side of the weir when facing the culverts,
two outer piles should be placed 16 inches from the top of the bulkhead, and on the left
side of the weir when facing the culverts, four piles should be positioned 16 inches from
the top of the bulkhead. The majority of the outer piles will be on the shore and the depth
that they are buried will vary as the slope of the shore is quite steep. The reported depth to
the restrictive layer for this area is 80 inches and should not be an issue during installation.
Installation of the sheet piles can be achieved using a pile driving hammer attachment on
an excavator, if the landowner has access to one, or can be handled by a local pile driving
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contractor. Contact information for a contractor can be found in the cost estimate section
of this report.
The capacity of the larger middle weir is 264 cfs, which is greater than the predicted
flowrate for the 25-year storm (219 cfs), and the capacity of the culverts when unobstructed
(226 cfs). This flow rate is sufficient to avoid any additional flood risk that may be
associated with restricting storm flow. The weir is also in compliance with New York State
regulations for maintaining a 25-foot right of way from the center of the road.
B. Cattail Removal
Removal of cattail can be challenging, as they are adapted to many different soil conditions.
They are also very prolific due to their strong rhizome system that allows them to recover
from stress. According the USGS National Wetlands Research Center (NWRC) an
effective way of controlling or eliminating cattail stands is by controlling the water level
of the affected area, cutting the plants down, or excavating their rhizomes. The following
management plan incorporates a combination of these techniques.
The first step in removing the cattails from the property is to lower the current lake height
by removing the boards that are obstructing the culverts at the road. Once the lake height
decreases, the cattail should be cut to the ground where possible and at the water level in
areas that are still submerged. The lower the cattails are cut, the more successful eradication
will be. Therefore using and underwater
mower or trimmer would increase the
probability of success. Cutting the cattails
should be done early to mid-summer when
the pistillate spike of the cattail is light
green and the staminate spike is dark green
(see figure 5). This will ensure that all of
the energy stored in the rhizome will have
been used to generate new growth, but the
Figure 5. Flower segments of a cattail.
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plant will not have had sufficient time to restock the rhizome with carbohydrate energy for
overwintering and for next year’s growth.
Once the cattails have been cut, the weir should be constructed. This will bring the water
level up to its intended height and cover the cut stocks of the cattails. Because the stocks
and leaves were severed from the rhizomes before energy could be sent back into the root
system, the plants will not have enough energy in their rhizomes to send shoots above the
waterline next spring. This will result in the plants drowning, as they will not be able to
syphon oxygen to their root systems through their aerenchyma and will die.
Any cattail that cannot be sufficiently drowned using the above method can be cut at the
same time as the submerged cattail. This will still prevent the re-energizing of the rhizome
but will need to be repeated as attempted growth continues through the fall. This process
can take a few years to successfully weaken the non-submerged plants.
C. Japanese Knotweed Management
Japanese knotweed was introduced to this site in 2004 during the reconstruction of the
culverts on Route 11. This invasive species spreads vigorously via underground rhizomes
and thrives in temperate riparian zones. Removal of Japanese knotweed can be achieved
with limited success by physical removal of the rhizomes or with higher success using
chemical herbicides. Rodeo, an herbicide produced by the Dow Chemical Company, has
been shown to be successful in killing Japanese knotweed, and is the only glyphosate
herbicide approved for use in aquatic and wetland settings. However, this herbicide is nonselective, meaning it will kill any plant it contacts and should be used with care to avoid
leaving an area barren and vulnerable to re-infestation by knotweed or other invasive
species.
Personal correspondence with Todd Bittner of the Cornell Plantations provided the
following method for the irradiation of Japanese knotweed using Rodeo. This method is
currently being used in the Cornell Plantations to manage their infestation. Using a JK1000
injection System from JK Injection Tools a 5mL dose of undiluted Rodeo concentrate is
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injected directly into each stem of the Japanese Knotweed just below the second node from
the ground (see figure 6). This should be
done when the plant is at its peak
flowering stage. This will ensure that
the rhizome has expended all of its
stored energy into the growth of the
plant and will be starting to recharge its
rhizomes with energy produced during
photosynthesis. When drawing energy
from the plant foliage it will also draw
the herbicide into the rhizome and will
Figure 6. Rodeo injection using the JK 1000
injection tool
not have stored energy to combat the
effects of the glyphosate. Injection can be performed on all stems that are one-half inch or
larger. Any smaller stems should be left for one month after injection, then cut just below
the second node and Rodeo should be applied directly to the stem with a small brush.
The above method has been shown to be 98% effective in the Cornell Plantations and is
ideal for preventing unwanted dieback of other species. All specifications are in accordance
with the product label and accepted by New York State.
VII.
Cost Estimate
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The following cost estimate was generated based on information attained by personal
communication with Shoreline Steel’s sales office, information found on the JK Injection
Tools website, and Amazon’s website. The price of istalation will vary significantly based
on what resources the land owner has access to.
Materials Cost Estimate
Steel Sheet Piles
Materials
Shipping *
Knotweed Removal
JK1000 Injection System
Rodeo 2 x 2.5 gal**
Total
$2,211.30
$1,800
$249.98
$201.94
$4,463.22
*This is the maximum shipping cost. Arrangements can be made with Shoreline Steel to
hold the order until another order is being shipped to Upstate NY. This will bring the
shipping price down by at least 50%.
**Comes in 2.5 gal containers, which can treat 1892 stems. It is estimated that the land
owner will need two of these containers.
Contractors to contact for instalation services in Upstate NY:
J & E Pile Driving Inc
6456 E Taft Rd
East Syracuse, NY 13057
315-458-2236
Equiptment rental coumpanies to contact for pile driving equiptment:
Admar Construction Equiptment, Rental, and Sales
449 Commerce Rd.
Vestal, NY 13850
607-798-0333
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Appendix A:
Pictures and Drawings
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Inlet side of old culvert, May 2004
Inlet side of new culverts, September 2014
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Steel brackets and boards used to obstruct culvert entrance. Inlet side, September 2014.
Top vie of boards obstructing culverts. Inlet side, September 2014.
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Western shore of lake just upstream of culverts, where weir is to be constructed. April 2015.
Eastern shore of lake just upstream of culverts, where weir is to be constructed. April 2015
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Area of lake where weir is to be constructed. Inlet side, September 2014.
Weir placement with respect to the culvert bulkhead at the road and the shorelines
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Weir design and component dimensions. Image is facing northwest, toward the road from the upstream side.
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Appendix B:
Quotes and Material
Specifications
19
Specs and contact information for sheet piles to be used for weir construction.
Quote prepared by Tim Kuecken at Shoreline Stee
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21
22
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Appendix C:
Constants and Calculations
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25
26
27
28
29
30
31
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References
Bittner, Todd. Director of Natural Areas, Cornell Plantations. Personal Communication.
16 April, 2015.
Chin, David A. (2013). Water Resource Engineering: Third Edition, Upper Saddle River,
New Jersey: Pearson.
Orr, David P. (2003). Roadway and Roadside Drainage, Cornell Local Roads Program,
Ithaca, Ney York.
Sojda, R. S., & Solberg, K. L. (1993). Waterfowl management handbook. Fish and wildlife
leaflet, 13(13), 13.
http://www.nrmsc.usgs.gov/files/norock/products/wmh_13_4_13.pdf
Data
1:250,000 Scale Land Use Land Cover, Elmira Quadrangle. Provider: U.S. Geological
Survey. http://cugir.mannlib.cornell.edu/ Accessed February, 2015
Fall Creek streamflow data. http://nwis.waterdata.usgs.gov/. Accessed March, 2015.
Fall Creek precipitation data. http://gis.ncdc.noaa.gov/. Accessed March, 2015.
Site measurements. Brooks, Rachael; Saia, Sheila; Truhlar, Allison. Survey conducted
September, 2014
Smith Valley Station, Alpine, NY precipitation data. http://gis.ncdc.noaa.gov/. Accessed
March, 2015.
Soil Survey Staff, Natural Resources Conservation Service, United States Department of
Agriculture. Web Soil Survey. Available online at http://websoilsurvey.nrcs.usda.gov/.
Accessed February, 2015
Websites
http://www.jkinjectiontools.com/
http://www.shorelinesteel.com/
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