oo )
Draft April 26, 1994
STREAM RESTORATION:
THE COSTS OF ENGINEERED
AND Bio- E N GIN EER^D. ALTERNATIVES
'by
DENNIS M. KING, 1 CURTIS C. BOHLEN, 1 MARK L. KRAUS 2
• Research funded by
Environmental Protection Agency, Office of Policy Analysis
• Contact: William Painter
under
EPA Cooperative Agreement No. CR-818277-C1
with
University of Maryland, Center for Environmental and Estuarine Studies
Chesapeake Biological Laboratory, Solomons Island, MD 20688
1- University of Maryland, Center for Environmental and Estuarine
Studies, Chesapeake Biological Laboratory, Solomons, MD 20699
2. Environmental Concern, Inc., St. Michaels, MD 21663
EPA 230-D-96-001
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Draft April 26, 1994
INTRODUCTION
NEW FOCUS ON STREAM QUALITY
Over the last few years, a new approach to water quality issues one
which de-emphasizes simple chemical measures of water 'quality and
emphasizes a more holistic view of water quality, has gained strength
Evidence of this change can be observed in a variety of contexts, including
increasing attention to watershed planning, growing interest in biological
indicators^ water quality, increasing focus on nonpoint sources of pollution
and growing recognition that water quality depends as much on the ecotoW
of watersheds as on the chemistry of surface water. This new approach to
water quality is based on the recognition that "fishable and swimable" surface
waters result from and are maintained by functioning watersheds and relv as
much on intact wetland systems and healthy streams as on the chemical
f-O^ciUcij of Water bodies. ' <
i , , •", . . i ' ' ' ,
. The recognition that water quality and water chemistry are not
synonymous has helped focus attention on the dynamic roles that streams
rivers, and floodplains play in creating, maintaining, and even restoring
healthy surface waters. These systems receive and transport nonpoint
pollution and, if they are healthy, can ameliorate the effects of nonpoint
pollution on receiving water bodies. For this reason, stream restoration— the
act of rebuilding and repairing stream banks, stream beds, and adjacent
natural habitats— has been identified as a potentially cost-effective method of
improving water quality, controlling nonpoint pollution, and creating
healthier watersheds. Research is now underway to evaluate the effectiveness
of stream restoration in improving water quality, increasing the capacity of
watersheds to absorb and process pollution, and improving overall ecosystem
P
Interest in stream restoration is also increasing because the financing of
even large-scale stream restoration projects may soon be possible if
pomt/nonpoint pollution trading systems now' being discussed are
implemented. Under such systems, those responsible for point-source
pollutant emissions may fulfill their legal responsibilities to protect water
quality directly by investing in emission reductions at the point source or
indirectly, by funding projects that reduce nonpoint pollution. Further
reductions in point-source emissions from most industrial and municipal
sites will be very costly. Therefore, if stream restoration can be shown to be a
cost-effective way of achieving water quality goals, it may become an
important and widely used tool for improving water quality and watershed
health.
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Draft April 26, 1994
eCOn°miC
ides a preliminary assessment of stream restoration cose-
in F^Tr^'1^ iaut0rS that affeCt Stream restoration costs. Combined with
mtormation aoout the expected ecological and water quality payoffs from
stream' rStoratidn'ca ^ i?formatio^can ^e used to determine what rok.
lt^Si?'eT? ^"p^np^t TourcetTtlV^
aoout the relative cost-effectiveness of strpam '<• • <-'iij.idi.iuii
also help, those responsible .for guiding strea'm °resto«tLn'efforts Tnd
developing design and construction standards for-stream restoration project
SCOPE OF THE .ANALYSIS "
- The term stream restoration has been used to describe such varied
'reclImSorf orTo^em^1 fl°ws. to .Provide sewa§e treatment, mine
waterfowl habitat or water chemistry. The wide°range oTdSmilaf amities"
capered under the term makes it difficult to analyze* the cost or performance
of stream restoration m any aggregate sense.' This paper presents the results of
an initial screening of costs associated with a small, number of projects tha
are .typical in the sense that they have commonly encountered goals and
consist of^activities or tasks that are often included in stream restoration
projects. The paper also identifies additional data that would be needed for a
fuller understanding of project costs and how they are related to project
success. Where it is useful, the paper compares and contrasts the economic
context under which stream restoration projects are designed and constructed
with those under which wetland restoration projects are undertaken.
For purposes of this paper; the term stream restoration is limited in
meaning to physical activities within the stream's corridor and surrounding
buffer ttiat are undertaken to improve water quality or wildlife habitat. These
activities could include fencing stream buffers to prevent livestock-related
impacts; returning meanders -and uneven channel configurations to
previously channeled streams; planting stream edges .and buffers with
vegetation; building structures such as dams; and using a variety of other
techniques to change the characteristics of stream banks or stream beds It
excludes efforts intended to change offsite sources of stream degradation such
as programs to reduce agricultural or urban stormwater runoff, or efforts to
better manage large scale water control or diversion projects.
Two specialized types of stream restoration are also'excluded from
consideration in this report. The first is stream restoration carried out
specifically to improve stream aesthetics. Such projects rely heavily on the -
planting of trees, shrubs, and herbs that are pleasing to view or use and like
other types of landscaping projects, may not contribute significantly to broader
habitat or water quality objectives. The second exclusion is stream restoration
carried out .in association with mine reclamation. These projects tend to focus
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,' Draft April 26, 1994
primarilv on changing the chemistry of severely polluted'waters draining
from mines and mine tailings. Because these projects deal with exceptional
afer qua i "problems, thev are often qualitatively different from those
designed to deal with more typical stream quality problems. By excluding.
the4 two tvpes of stream restoration projects, we avoided a potential source .
of bias in our cost analysis, and were able to focus on restoration projects wi h
wider water quality and ecosystem health benefits,and with applicability
under a broader range of circumstances.
, ' ' / i
BIO-ENGINEERED VERSUS ENGINEERED APPROACHES
In o-eneral, stream restoration techniques can be broken down into two ,
broad categories: engineered or hard techniques and bio-engineered or sot
techniques Engineered techniques. generally involve building permanent
structures and fnclude such activities as constructing dams and fish ladders
and S rip rap or gabion walls for stream, bank protection. Bio-engineered
L,hnToueDs relv less o§n permanent structures, and include such activities as
plantin- vegetation for erosion control or using coconut fiber matting and
?oCvegetation mats, and bundles of live willow stakes to simultaneous y
reduce Shoreline erosion and establish riparian vegetation. ™ere are
circumstances where one or the other - an engineered or a bio-engineered
aDD^ach-is clearly preferable. In many cases, however, both types of
ues can be us^to accomplish the same basic result as illustrated by a
not Rip-rap" publicity campaign currently being used by an East Coast
t^n to to promote its patented bio-engineering solution to shoreline
erosion problems.
,As the focus of stream restoration shifts from shoreline erosion control
to other water quality and habitat objectives, interest in and use of bio-
Ingineering techniques is increasing at the expense of more traditaonal
enlneered approaches. Where soft bio-engineering approaches are suitable
Sey areToften considered preferable to hard heavily-engineered approaches
for'at least three reasons:
m LOWER UP-FRONT COSTS—Bio-engineered techniques are
generally less expensive than engineered techniques at _the design
and construction phase because they emphasize simplicity, tend to
require inexpensive construction materials and techniques, and
take advantage of the work that natural stream systems can
provide to achieve desired stream condition.
m LOWER OPERATING AND MAINTENANCE COSTS-Bio-
engineered alternatives can more easily be designed to.work with
rather than a'gainst stream hydrological, ecological, and geological
processes. As a result they are more likely than engineered
techniques to produce self-maintaining stream reaches that
. 3
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• "Draft April 26, 1994'
'. maintain desirable characteristics over the long term. This reduces .
' ' the need for expensive maintenance or reconstruction.
(3) -ANCILLARY BENEFITS—Bio-engineered projects -typically
produce a variety' of -incidental environmental benefits, "in.
addition to the specific, narrowly defined engineering goal for
which they are usually designed. Willow stakes planted' for stream
bank erosion reduction/for example, also supply- substantial
riparian vegetation that .provides shade and supplies organic
inputs to streams and thereby enriches the local biota and
contributes to water quality. ,
THE ECONOMICS OF STREAM RESTORATION -
The. stream restoration industry consists of many different-types'of
engineering, research, and landscaping firms and a few specialized restoration
firms that offer to design, construct, maintain, and monitor restored streams.
Firms in this industry are more diverse than those in the better known
wetland restoration industry. Since stream restoration is still a relatively
.young and fragmented industry few industry standards exist and the industry
lacks a general consensus about when and where specific techniques can and'
should be applied. Training programs and handbooks explaining principles
and techniques of stream restoration are still rare, and the practice of stream
restoration is still heavily influenced by the work of a few innovative
individuals, and small specialized restoration firms. Large environmental
consulting and engineering firms who are moving, into this practice are just
beginning to acquire the. expertise needed to supply this growing market and •
in many cases, are still learning from their mistakes. Although information
about what works and what doesn't is still shared openly among most
restoration experts, the market for stream restoration is growing and
competition among larger restoration firms is increasing. As a result, there
will be a growing tendency for firms to view more of what they learn from
their successes and failures as "trade secrets/' Although each' firm .striving to
gain a competitive advantage could promote innovation, the structure and
performance of the industry should be monitored to insure that conditions
do not begin to limit the access of small firms and inhibit innovation.
-o
Unlike wetland restoration, modern stream restoration serves a market
that is not linked specifically with regulatory requirements. The market for
wetland restoration is driven almost exclusively by the demand for permits
under Section 404 of the Clean Water Act. The demand for stream
restoration, on the other hand, is driven by such things as stormwater
management requirements and the desire of organizations and local
, governments to improved stream aesthetics or fish habitat, or achieve local
and regional water quality goals. Since regulatory .forces-are seldom driving
stream restoration projects, they differ substantially from typical wetland
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Draft April 26, 1994
restoration projects in the way they are conceived and carried out. Among the
most significant differences are:
(1) DIFFERENT MOTIVATION—The ' sole motive behind most '
wetland restoration projects is the desire on the part of the project
sponsor to acquire a wetland permit. Thus strong incentives exist
on the part of the project sponsor to minimize project costs and
avoid any liability for failure to meet mitigation requirements.
Th-e choice of specific wetland restoration techniques, therefore, is
often driven by legal and regulatory, not ecological criteria. The
motivation behind most stream restoration projects, on the other
hand, is usually more complex. Since stream restoration projects
are not driven by regulatory requirements, project sponsors decide
what types of stream restoration techniques to apply and how
intensive or extensive the effort will be on the basis of their own
assessment of costs and benefits.
PI LACK OF OBJECTIVES AND PERFORMANCE GOALS—Since
stream restoration is seldom carried out as' mitigation for other
environmental harm, few stream restoration projects need to
achieve specific goals or reach performance targets Since the
stream restoration' industry has yet to develop widely accepted
project design standards, this lack of clear performance criteria-
makes it difficult to determine how the restoration techniques
used in a stream project were chosen or how to evaluate their
results.
(3) LOWER PLANNING AND MONITORING COSTS-Wetland
restoration often requires substantial commitments of time and
money for advanced planning, design, monitoring, and
maintenance. These costs arise in part from regulatory needs, in
particular, requirements for documentation of project planning,
construction, and success or failure. Without specific performance
targets, much of the scrutiny that wetland mitigation projects
undergo would be unnecessary. Thus the design and construction
of stream restoration projects are seldom documented as carefully
as modern wetland restoration projects, and they do not get the
same level of monitoring.
The economic and political context under whichjrtream restoration
projects take place are important in evaluating cost data because they have a
sSdfSant influence on the selection of techniques and approaches (e.g.,
en^neering and bio-engineering) used to accomplish stream restoration
S Until the stream restoration industry matures and develops standard
Approaches for solving common stream restoration problems, no simple
scheme for categorizing stream restoration projects will adequately
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. . • - • Draft April 26, 1994 - . " • • :
summarize.the range of stream types, project goals and constraints found in
the United States. This study makes no effort to develop a • detailed
categorization of stream restoration activities or projects based on expected
results/or cost-effectiveness. Instead, we'.-take the simpler route and, examine.
actual stream restoration costs for'"typical" projects. carried out on streams
with different physical characteristics. Subsequent research will need to focus
on the relative cost-effectiveness of different techniques applied at similar
sites and the, relative cost effectiveness of. the same technique' applied at
different sites. •. , ' .
MET HO DS
STREAM RESTORATION COST ESTIMATION • . . .
- .For purposes of cost analysis a stream restoration project can be
characterized in terms of a number of discrete tasks or 'activities that require
cash outlays for labor, material, equipment, and other inputs. These tasks
involve: (1) designing and planning the project, (2) site management
activities such as trash removal and fence installation, and (3) structural
stream restoration practices that may vary from planting vegetation to
constructing dams and levees. The cost of completing a given project then can
be estimated as the sum of the costs of all of the tasks required to complete the
project. . J . • ...
The procedure for estimating costs for a given stream restoration project,
therefore, involves four simple steps:
• " .Step-1 • Estimate,the cost of completing each pre-construction,
construction, and post-construction task that could be used in
a project. '
Step 2 Characterize the project in terms of the number of each task
required per unit length or area (e.g., per linear foot of
stream). .
StepS Adjust cost per.task estimates to account for economies of
scale and'other site-specific factors.
Step 4 Calculate overall project costs by multiplying the adjusted, ,
cost of completing each task (Results of Step 3) by the number
of each task required (Results of Step 2) and adding them.
6 .
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Draft April 26, 1994
Tasks and Costs Per Task
For our preliminary cost analysis we started with a partial list of stream
restoration techniques .(tasks)' and cost estimates developed by Apogee.
Research Inc. under contract to EPA. This list included a wide variety of
structural and non structural restoration practices, from trash removal to
boulder 'emplacement to construction of "K" Dams, and included an average
cost per unit (e.g., per boulder, per linear foot of planting or fencing) for each
technique on the list. We supplemented this list "of tasks to include some
recently developed bio-engineering techniques (e.g., use of willow or shrub
"mattresses" and fascines — bundles' of live stakes from willow or other
riparian shrubs — to reduce streambank erosion), many of which are now
becoming more widely used. We also worked with practicing restoration
specialists to develop estimates of project design, planning, and management
costs, and we refined and updated some cost estimates on the initial list 'of
tasks on the basis of a limited survey of material and equipment suppliers
and restoration contractors. The final list of stream restoration tasks and
associated per unit costs is presented in Table 1. While it is by no means
comprehensive, it includes the techniques most , typically used in stream
restoration projects.
Overall Project Costs
Fourteen project profiles, including detailed information on design and
management tasks, site management activities, and structural restoration
practices were developed on the basis of discussions with stream restoration
specialists that we subcontracted and collaborating stream restoration
practitioners. Each project profile included information on stream
classification (see below), the techniques used, and the number of techniques
(e.g., check dams and wing deflectors placed), or quantity of techniques (e.g.,
length of streambank fencing or amount of material dredged) that were used.
All profiles were based on actual . stream restoration projects. In some
cases, however, detailed records of project inputs and costs were unavailable,
so the number of tasks and the quantities of inputs required per task (labor,
equipment, materials) and their costs (wages, rents, prices) were estimated
through discussions with collaborating restoration specialists and individuals
familiar with the design and implementation of the project in question. A list
of projects, overall project cost estimates, and project costs per linear foot of
stream reach that resulted from this exercise are presented in Table 2.
STREAM CLASSIFICATION
Existing Stream Classification Systems
The concept of stream ordering and a system for stream classification was
developed by Strahler (1952) and Shreve (1966). Using this system, a small
7
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Draft April 26, 1994 - • ,'
.stream with a limited watershed area,is classified as a first order stream. As a.
stream grows and reaches confluence with other streams, the larger stream
would increase in order. Two first order streams that converge produce a
second order stream, two, second Border streams converge to produce (in.
.Strahler's numbering scheme) a third order stream, and so on. Later/ Pennak
(1978) proposed a classification system based on a "cluster" of physical and
chemical measurements, which was refined further by Rosgen (1985) in a
stream classification system based on a much larger suite of chemical and
physical parameters. '-..•'
None of these popular stream classification systems,' however, are
appropriate for the purposes of this .study of stream restoration costs. The
simple stream order classifications of Strahler (1952) and Shreve (1966) do not
describe the gradient (slope) or volume of a stream sufficiently to allow
stream type groupings for purposes of evaluating restoration opportunities.
Rosgen's (1985) approach suffers from the opposite problem in that it is so
thorough that it requires too many particulars ,to be used in a survey of
relatively small-scale projects. In time, a complex stream classification system
may be developed that will prove useful for aggregating projects according to
restoration opportunities and appropriate techniques and associated costs.
This, will only occur after the stream restoration industry matures to the point
of developing standard approaches and techniques, or after data on a large
enough number, of restoration projects is available , to allow statistical
comparisons. For purposes of 'this study, we developed a simple stream
classification system that groups streams into broad categories within which
generally similar stream restoration techniques are likely to be used.
A Simplified Classification Scheme for Studying Restoration
Costs
Two, of the-major factors determining what methods are appropriate for
a stream restoration project are (1) the .stream's slope or gradient, and (2) the
volume of water the stream conveys. In order to consider how different
restoration techniques can be applied to various stream types, we therefore
developed a simplified stream classification system based on stream gradient
and stream volume. The criteria used to group streams in the classification
system are as follows: .
Low Gradient A stream channel with a gentle slope that under
normal conditions causes low turbulence water
, flow. Example: a backwater river in. the Piedmont
or coastal plain.
High Gradient A stream channel with steep slopes that under
normal-conditions" causes, turbulent water flow.
Example; a mountain stream.
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Draft April 26, 1994.
Low Volume A stream with a small channel that conveys water
from -a limited watershed area. Example: a first
order mountain stream, or a headwater stream.
Medium Volume Usually a stream receiving water from two or more
Low Volume Streams, or a first order stream with a
large watershed. Example: The Susquehanna River
at Oneonta, NY.
Hi^h Volume Usually fourth or fifth order streams (or higher)
with very large watersheds. Example: the
Mississippi River at St. Louis, MO.
Intermittent A stream that, flows only part of the year, ...
Tidal Streams, both freshwater and saltwater, influenced
by tidal action.
Using these criteria we defined six major stream classification:- for
purposes of evaluating the characteristics and costs of restoration:
(1) Low Gradient, Low Volume
(2) Low Gradient, Medium Volume
(3) Low Gradient, High Volume
(4) High Gradient, Low Volume
(5) High Gradient, Medium Volume
(6) High Gradient, High Volume (omitted from the analysis)
In order to focus attention on practical stream restoration alternatives,
the sixth category—high gradient, high volume streams—was eliminated
from further consideration. These involve large volume rivers that must
collect water from large watersheds and then maintain a sufficient vertical
drop before reaching sea level to enable high stream gradients to persist in the
face of prolonged erosion and sediment deposition. These conditions are so
rare (e.g., the Laurentian great lakes and the Niagara escarpment ) and are so
infrequently considered within the context of restoration that they were
eliminated from the analysis. ,
Special Cases
There are certain stream types for which appropriate restoration
approaches and techniques cannot be predicted by stream volume and
gradient alone. Among these are intermittent streams, tidal streams, and
urban streams. For purposes of this initial scoping effort we decided to classify
these projects separately as described below:
Intermittent streams include small seasonal, low volume streams in humid
regions as well as low. and medium volume streams in
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Tidal streams
Urban Streams
Draft April 26, 1994 '. , •. .'
arid climates. Intermittent streams may "be" either low"
or high gradient. Arroyos and other intermittent
streams that convey surface runoff from storm events
in arid ..regions are among the most likely intermittent
streams "to be the focus of restoration interest. These
channels convey large volumes of water for very short
periods of." time., 'High peak flows, complex
relationships with groundwater systems, and the
difficulty of reestablishing vegetation in arid
environments make these streams difficult to restore.
(both freshwater and salt) also have unique restoration
requirements. Bi-directional water flow, regular'
oyerbank flooding, and daily inundation create a
system in which stream restoration must generally be
carried out in the context of broader wetland
restoration efforts. Tidal streams may be of low,
medium, or high volume.-They are, except for over
extremely short distances, low gradient streams, '
in urban environments also require special restoration
treatments. The high imperviousness of urban
watersheds prevents adequate management of peak
flows following storm events. This situation creates
extremely flashy streams which generally require the
use of mechanical and structural restoration
techniques rather than bio-engineered or vegetative
techniques. In addition, 'many urban stream
restorations include the cost of "releasing" streams,
removing them from culverts and pipes and restoring
a more natural stream channel.
RESULTS
COST OF STREAM RESTORATION
Costs per task estimates are presented in Table 1 and overall project costs
and costs per linear foot of stream for the fourteen projects we evaluated-are
presented in Table 2. , ,
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Draft April 26, 1994
Table 1:
Estimated typical costs of component tasks of stream restoration
project, as used in this study to estimate total project costs.
(1)
(2)
(3)
Best Management
Practices (BMPs)
Adding/Movina a Meander
Bank Crib and Cover Loa
Boulder Placement
Brush Bundle
Brush Mattresses/Mats
Channel Block
Channel Constrictor
Debris Removal
Excavation / Fill
Fascines 1
Fence Stream Banks
Barbed Wire Fence
Chain Link Fence
Fiber Schines 2
Gabions
Gabions With Willow
Gravel Bedding .
Live Stakes
Log and bank shelter
Plant Trees or Shrubs
Bare Root Tree
Container Tree
• Shrub
Planting Emergents
P re-Rooted Live Stakes
Project Design
Reed Rolls 3
Rip-rao
Riprao + Willow
Rootwad
Seeding Grasses and Herbs
Grass
Herbs
Single-wingJDef lector
Trash Catcher
Tree or Log Cover
Tree Removal
Wedge. K. or Other Dam
Willow Branches
Unit Cost Per
Unit
See Excavation/Fill
1
10
If
sf
1
1
dav
cy
If
mile
mile
If
l.f.
. If
cy
1
1
tree
tree
shrub
. Plug
1
hours
If
If
If
10
acre
acre
1
1
1
10 sf
1
If
$1,364
• $520 ;
$62
• $30
$454
$1.167
$823
$6
$18
$20,000
$40,000
$7.50
$80.00
$90
$11
$1
$352
$12
$20
$11
$1.40
$2.50
$75
$10.50
$70
$80
$150
$2,500
$3,000
$362
$346
$47
$10
$1,081
$10
Fascines are bundles of live stakes of willow or other hydrophytic shrubs.
Fiber.Schines are bundles of organic fiber placed along shorelines to reduce erosion and
provide a stable rooting medium for plant establishment.
Reed Rolls are fiber schines pre-seeded or pre-rooted with desirable plant species.
11
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Draft April 26, 1994
Table 2: Summary of Stream Restoration Projects Examined.
Project Name
— _____
• Blue Route Expressway
Pratt Hollow Run
Democracy Boulevard
Linville Gorge
Milwaukee River
Ohio River
Upper Mississippi •
Fort'Belvoir
Johnstown
.South Branch Potomac
Chama River
Lick Run
Rio Puerco
Tidal 1
1
State
PA,
.MD,
MD
NC •
IN
Several
Several
VA
PA
WV
NM
VA
NM .
MD
Restoration
Type
Bio-engineered
Bio-engineered
Structural, Mechanical
Bio-engineered
. Bio-engineered
Bio-engineered ..
Mixed >
Mixed
Bio-engineered
Bio-engineered
(Stream Fencing)
Structural
Bio-engineered
Structural
Mixed
'"•""•"— «— •
Stream
Class
— ..— .
. -1
1
1 / •
1 •
2
• 2 ,
3
4-
•4
5
5
A
A
• B
.
Project
Size (l.f.)
'
600
2,640
1,800
• 200
4,752 •
13'2,000
3,696,000
6,336
1,000
158,400
15,840
- . 900
10,560
300
*— — • — t i
Total Cost
'• $36,426
' $30,016
$154,050
$5,550
' $22.000
: $211,929
$83,210,000
$333,303
$32,836
$12,560,
. $729,975
$16,961
$1,719,600
$1-9,872
-"•^^^••^^^•i i
Cost' Per
Linear , Foot
$60.71
$-11.37
$85.58
527. / p
$4.63
$1.61
$22.51
$52.60
$32:84
$0.08
$46.08
$18.85
•$162.84
$66.24
_ Costs per linear foot of stream restored varied tremendously among the
ixteen projects-from well under $1 to over $150 dollars. This range reflects
the-diversity of stream types, goals and definitions of stream rltoraSn
a gressive and passive approaches to stream restoration, and site-specific
aKTa'nd^ f ^^ T^ reSt°ration ****** that L not
cinSctor, fl VI ^ ^^ Way ^ different ^storation specialists or
contractors. Until there is more standardization within the industry'the
^aractenstzcs of restoration project and costs, even at apparently simiJsites
with apparently similar goals, can be expected to be quite variable. •
Preliminary Observations '
While it is impossible from such a small sample of projects to make anv
defimtive statements about differences in project costs among stream
categories, the data suggests certain patterns. ' , 5 ^rea.m
. . • Projects carried out on small streams tend, to be relatively
expensive, (higher cost per linear foot), even though they.'
12
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urarc April 26, 1994 ,- ,
involve altering relatively low volume systems with lower
hydrologic forces to manage. This reflects differences in the
nature of the restoration efforts more than conventional
economies of scale issues.
Project, size, as measured by the length of the stream reach being
restored, tends to be smallest for low volume streams. Until
more disaggregation of data is possible, this will confound efforts
to estimate economies of scale or evaluate the relative cost
effectiveness of small-scale versus large-scale projects.
• The most expensive projects in the database are structural (hard
engineering) projects carried out in a small volume-intermittent
stream and in small volume-low gradient streams,-and mixed
(structural with bio-engineered) restoration of a tidal freshwater
stream.
• By far the least expensive restoration project (approximately
$0.08 per linear foot basis) was a project to restore several miles
of the South Branch of the Potomac River by placing 3,000 linear
feet of strategically located .barbed wire fencing to exclude
livestock from the river banks and allow natural revegetation.
RESTORATION TECHNIQUES AND STREAM GLASS
Certain types of restoration practices (e.g., boulder placements) are more
likely to be used in restoration projects in high gradient streams, while others
(e.g. reed rolls or planting emergent vegetation) are most likely to be used in
low gradient streams. Similarly, some practices (e.g., "K" dams) are difficult to
use in medium or high volume streams, and are easy to apply successfully in
low volume "streams. Table 3 illustrates the relative effectiveness of specific
management practices applied in various stream types. '
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Draft April 26, 1994
Table 3:
Best Management Practices (BMPs) used in Streams^of each category,
/_!_• 7""\£f cm U££-._i.*,_ - ^ . r< i? T-. * f .. - - O >
PreaScticMesn "'&' L°w Gradient Streams 'mgh^radient Durban |
Addina/Movinq a Meander
Bank Crib and Cover Log
Boulder Placement
Brush Bundle
Brush Mattresses/Mats
Channel Block
Channel Constrictor
Debris Removal
Fascines 1
Fence Stream Banks •
Fiber Schines 2 -
Gabions
Gabions with Willow
Live Stakes
Planting Trees or Shrubs
Planting Emeraents
Pre-Rooted Live Stakes
Reed Rolls3
Rip-rap
Riprap .+ Willow
Rootwad
Seeding Grasses & Herbs
Sinqle-winq Deflector
trash-Catcher
Tree or Loq Cover
Wedqe, K, or Other Dam
Willow Branches '
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Volume
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===^==
DISCUSSION
Low VOLUME VERSUS HIGH VOLUME STREAMS
- . Our results show that restoration projects carried out in the smallest
streams, which are generally low volume .streams, are more expensive per
hnear foot than projects carried out in medium and high volume streams
The magnitude of the forces being managed and the volume of water being
affected are both much larger for high volume streams. This, combined with
the fact that it should be easier to achieve restoration goals on small streams
where the erosive and other disruptive forces are smaller, made-these results
somewhat counter-intuitive. Conventional economies of scale certainly
14
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Draft April 26,, 1994
account for some of the difference, but our initial review suggests systemic
differences are as important as scale differences.
As a general rule costs per task can be expected to decline as the number
of tasks used in a project increases—typical economies of scale. However, in
our case studies, a greater number of restoration tasks were used, both hard
and soft, per linear foot of restoration on small streams than on large streams.
This higher number of tasks, contributed to the higher relative costs of small
stream projects more than higher costs per task.' More intensive restoration
efforts on small streams; as reflected by more tasks per linear foot, probably
reflect a stronger desire on the part of sponsors of these projects to achieve
substantial restoration benefits in the shortest amount of time. Sponsors of
larger projects, especially projects on medium and high volume streams, may
be less willing to invest in intensive efforts—higher costs per unit area—and
more willing to wait and let restoration benefits accrue gradually as a result of '
natural forces. This would explain why relatively few techniques were used
per linear foot for relatively large projects and may also explain why more of
the techniques that are used in relatively large'projects were bio-engineered
techniques that are less expensive and yield results gradually as the restored
stream achieves a new biological, hydrodynamic, and geological equilibrium.
The issue of whether large scale projects or projects on medium or high
volume streams are less costly in general or simply tend to be less costly
because they involve less aggressive restoration- efforts requires additional
research. Of course cost is only part of the picture. The cost effectiveness of
small and large scale projects also depends on how successful they are at'
achieving water quality arid habitat goals. Further research into the causes of
cost differences for different project types should be undertaken in
collaboration with research aimed at measuring restoration-induced
improvements in habitat and water quality.values.
ENGINEERED VERSUS BIO-ENGINEERED TECHNIQUES
Comparing costs of "typical" stream restoration projects using
engineered and bio-engineered alternatives is difficult because the field of bio-
engineering is new and has developed almost as a cottage industry with little
careful research and few industry standards. Regional experts and agency
staffs tend to promote the techniques with which they are most familiar/
which may limit opportunities to observe the cost-effectiveness of innovative
methods. Because of the wide variety of soft and hard restoration techniques
that can often be used to achieve similar results and the lack of generally
accepted standards or guidelines, it is difficult to sort through and interpret
the causes of observed cost differences or evaluate whether they are
universal, project-specific, or site-specific.
15
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: ' ' Draft April 26, 1994 ' ..
Comparisons of engineered, and bio-engineered approaches to stream"
restoration based purely on costs may-also be misleading. Bio-engineered
approaches to stream restoration do not have as long a track record as
engineered approaches, Bio-engineering methods tend to take lon-er to-
achieve final results than engineered methods, and thev have beneficial side
effects that engineered approaches do not share. Moreover, project costs often
vary .not only because of what is being done, but also because different
contractors use different practices to achieve similar ends, and have different
f™6 S/rjertlSe ^^rand carrying thenrout Thus the results of this
limited study can offer only a few insights ,on the relative cost-effectiveness of
engineered or bio-engineered restoration approaches, and cannot be* used to
, compare specific techniques within these two general categories.
A few general rules, however,-do, emerge from our analysis. Stream
restoration projects that, rely on engineered (hard) techniques: are generally
more expensive than projects that rely on bio-engineered (soft) techniques
Ihis^may be because engineered techniques require building structures out of.
relatively expensive materials such as timber or concrete, whereas bio-
engineered techniques tend, to use locally available materials and relatively
inexpensive commercially .available natural ;fnaterials such as coconut fiber
mattings and live vegetation. Engineered techniques also emphasize resisting
the erosive and 'Other dynamic forces found in the stream environment
whereas bio-engineered approaches emphasize working with those forces to '
"produce desired results. •-.-•-'
, Bio-engineered techniques, however, cannot be used under all
circumstances or incorporated into all restoration projects, so they should not
be viewed as perfect substitutes for engineered solutions. They often work
poorly or cannot be used at all, for example, in projects that involve high
volume or high,gradient streams, or in stream systems where stormwater
cannot be adequately controlled resulting in "flashy" characteristics (e g
urban streams,, arroyos). In these situations, the volume and velocity of the
water have the potential to wash away the results of many bio-engineered
projects, so,engineered structures, at the present time, are the only option.
Bio-engineermg techniques may also be more prone to project failure in the
event of an unexpected severe storm during or immediately following project
construction than are most hard engineering techniques. Moreover since
many of the bio-engineering techniques, although promising, do not have "
long track records, little is known about their long-term success. In principle,
bio-engineered stream restorations may have extremely long project
lifetimes, since a fully restored stream reach can maintain desirable stream
conditions indefinitely. In practice, however, it is still unknown how well
bio-engineered strearn systems, will" stand up in many urban, suburban, and
even agricultural landscapes where stream hydrodynamics are severely "
altered. • • , ' -' . • . ' ,>J'
16
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Draft April 26, 1994
For all these reasons bio-engineered techniques may not be suitable
when the expected cost of project failure in economic or ecological terms is
relatively high. In some cases, however, the additional risk of failure may be
more than offset by the ancillary habitat and watershed benefits that are
expected if the bioengineered efforts are successful. Attempting a bio-
engineered solution when costs and risks are relatively low and later
implementing an engineered solution if necessary may be a preferred option.
More research into the relative costs and preference of.-.different types of
projects and opportunities to initiate follow-up restoration/in efforts when
projects fail, will help determine when and where this option is possible
As a general rule the larger projects that we studied relied more heavily
on bio-engineered solutions, while the smaller projects relied more on
conventional engineered techniques. This pattern probably reflects not just
pure differences in project scale, but also several other differences between
large and small projects. Small projects are more often located in urban or
suburban areas, where engineering constraints imposed by the flashiness of
streams in developed watersheds make bio-engineering approaches difficult
or impossible. Small projects are also more often carried out to solve specific,,
narrowly defined local problems that have a long history of being addressed
successfully using traditional engineered techniques, and a more limited
record 'of being addressed using bio-engineered solutions. Large projects, in
contrast, are often carried out in • order to achieve more general
environmental benefits that are often broadly and vaguely defined, and are
difficult or impossible to achieve using traditional engineered approaches.
Large projects also rely more heavily on bio-engineered approaches because
they are generally less expensive and help keep the 9verall costs of large
projects under control.
As stream restoration becomes a more frequently used tool of
environmental policy, associated costs and effectiveness will both rise. Recent
studies on wetland restoration projects, however, suggest that regulatory
requirements, unless they are carefully thought out, can drive the costs of a
restoration project up significantly with no corresponding improvement in
project performance (King and Bohlen 1994). Discussions with stream
restoration practitioners suggest that, despite a relative lack of regulatory
involvement in most stream restoration, government involvement does
bring with it additional costs. One stream restorationist, for example,
estimated that planning and design costs could be as high as 30%-50% of
overall project costs when government funds are involved, compared to 5%-
10% of. overall project costs for privately funded projects. We have not been
able to examine this claim in detail, nor adequately explain it, if it is true.
Such differences may reflect more stringent planning and design
requirements, the need to more carefully document project activities and
expenditures, the cost of consultations with government sponsors,
government procurement requirements', or other factors that may-or may not
17
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• •- Draft April 26,. 1994 ' ' ' . ~
affect project results. On the other hand/the higher cost of government'
sponsored projects may reflect requirements that contractors not cut corners,
use proven materials and techniques, guarantee their work, or provide long-
term site monitoring and maintenance; that should result in more successful
stream restoration over the long term: As stream restoration becomes more
closely linked with new or existing government programs^ the project costs
associated with planning, implementing, monitoring, and maintenance are
likely to increase. If the emerging standards for completing these tasks are
designed with care, the payoff from these higher costs should be more
successful projects. If they are not, the higher costs 'could inhibit the use of
stream restoration as a water quality management tool and undermine public
support for such endeavors.
STREAM RESTORATION AND WATER QUALITY
A significant amount of time .and energy is being spent researching the
effects of wetlands on water quality. Much of the information being generated
is directly related to stream restoration using either bio-engineered and
engineered techniques. Simply putting up fencing along stream banks to
prevent livestock from grazing within a narrow stream buffer or entering the
stream can significantly reduce sediment and nutrient loads and improve •
water quality. Adding vegetation to the stream bank and buffer can cool
streams and reduce thermal pollution, as well as provide wildlife habitat and
improve nutrient processing within the stream. Returning meanders to
channeled streams, and building check, dams to provide areas of quiet water
provide, water velocity reduction benefits, which in. turn promote the
settlement of particles out of the water column so they are not transported to
other parts of the watershed. Such alterations' also improve habitat for fish, •
waterfowl, and other wildlife arid generate economic values associated with
the enjoyment ,of these resources.. However, while surface water quality can
be improved through a concerted effort of stream restoration, to be the most
effective, stream buffer and .stream bank restoration should be planned
within the context of an overall strategy for watershed restoration that
includes implementing Best Management'Practices (BMPs) for controlling
urban, suburban, and agricultural runoff, as well as improving conditions in
streams and wetlands.'
,18
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Draft April 26, 1994
REFERENCES ,
APOGEE Research Inc. 1994. Draft Report, Bethesda, MD.
King, D. M., and C. C. Bohlen. 1994. Making Sense of Wetland Restoration
Costs. University of Mary land-Center for Environmental and Estuarine
Studies Technical Report UMCEES-CBL-94-045.
Rosgen, D. L. 1985. A stream classification system. General Technical Report,'
Rocky Mountain Forest and Range Experiment Station, U.S. Forest
Service, Fort Collins/CO, pp. 91-95. . -
Pennak, R. W. 1978. The dilemma of stream classification for the USA,]
including aquatic habitats. USFWS Office of Biological Services,
Washington, DC/pp. 59-66., '
Shreve, R. L. 1966. Statistical Law of Stream Numbers. /. Geol. 74: 17-37.
Strahler, A. N. 1-952. Dynamics Basis of Geomorphology. Geol. Soc. Am. Bull.
63: 923-38.
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