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LOW IMP ACT DEVELOPMENT:
BARRlERS TOWARDS SUSTAINABLE STORMWATER MANAGEMENT
PRACTICES IN THE PUGET SOUND REGION
by
Chrissy Bailey
A Thesis: Essay of Distinction
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
June 2003
This Thesis for the Master of Environmental Studies Degree
by
Chrissy Bailey
has been approved for
The Evergreen State College
by
arolyn Dobbs
mber of the Faculty
ABSTRACT
Low Impact Development: Barriers Towards Sustainable
Stormwater Management Practices in the Puget Sound Region
Chrissy Bailey
As a nonpoint source of pollution, stormwater runoff is a serious threat to water
quality and quantity. The trend in stormwater management has been to devise
complex designs to address increases in stormwater created by development.
Conventional management methods have not adequately addressed either
pollution prevention or factors relating to groundwater and surface water impacts.
Low Impact Development is an emerging technology-based approach to
managing urban stormwater. The goals of Low Impact Development, known as
LID, are maintaining or replicating the predevelopment hydrologic regime of a
site and maximizing the use of upland landscape to treat runoff. Through careful
site design, stormwater generated from an area within a watershed is more
effectively and naturally utilized and managed, avoiding the impacts of
development on water resources.
In the Puget Sound region, Low Impact Development has not often been the
chosen tool for stormwater management. Parties involved in the development
process cite different reasons for this occurrence, ranging from a lack of
information and education/training to current economic systems. For the
purposes of this paper, these barriers have been placed into two general
categories, technical and philosophical. Recognition of these barriers in order to
formulate strategies on how to address them will be crucial in making Low
Impact Development a more common and attainable stormwater management
strategy in this area.
Conclusions regarding the origin of the barriers to Low Impact Development have
been made through interviews with development-related professionals and an
analysis of the existing data on the promise of Low Impact Development and its
implementation. As each of these barriers and their bases are recognized,
suggestions and recommendations regarding what are necessary to overcome
them follow.
In general, the technical barriers seem to serve as "red herrings" to avoid asking
the more difficult questions (represented by the philosophical barriers) regarding
society, philosophy, and change.
T ABLE OF CONTENTS
Page
Introduction
Objectives
Problem Statement (Importance of Stormwater Related Issues)
1
3
4
Effects of Stormwater
Effects on Stormwater Runoff on Groundwater
Effects of Stormwater Runoff on Surface Waters
Effects of Stormwater Runoff on Water Quality (Water Pollution)
Laws and Regulations Pertaining to Stormwater
6
6
6
7
8
Conventional versus Sustainable Stormwater Management
Conventional Stormwater Management
Low Impact Development
LID versus Conventional Stormwater Management
Costs and Financial Considerations
13
13
16
20
23
Barriers to the Implementation of Low Impact Development
Technical Barriers
Philosophical Barriers
25
25
27
Case Studies
30
Conclusion
Discussion and Conclusions
Recommendations
Closing Thoughts
43
43
46
54
Works Cited
56
III
LIST OF FIGURES
Basin Map
SEA Streets Section View Before
SEA Street Section View After
SEA Streets Arial Before
SEA Streets Arial After
2
41
41
42
42
LIST OF TABLES
Table 1 "Unit Cost of SubdIvision Development"
Table 2 "Remlik Hill Farm Example: Costs, Land Cover,
and Pollution Associated with Two Plans"
Table 3 "Low Impact Development"
32
33
36
IV
AC~~OWLEDGEMENTS
A very sincere thank you to all of those contributing to this paper in one
way or another. This includes Carolyn Dobbs, Larry Coffman, Derek Booth and
Eric Hielema in particular. A huge thank you is also in order for all of my co
workers at the City of Lacey. Each uf you has succeeded in helping make this
adventure possible. Last but definitely not least, thanks to my family for helping
me believe and for helping me remember to have a sense of humor!
v
Chapter 1
Introduction
Thurston County has been one of the 'astest
g~'owing
counties in ihe state
of Wa~,hington since the 1960' s, consistently exceeding the state' s overall growth
rate. Between 1990 and 2000, 46,000
ne~'
residents have been added to the
county's population (TRPC II-I). The Central Puget Sound region, made up of
King, Pierce, Kitsap and Snohomish counties, is one of the most rapidly growing
and urbanizing regions in the United States. Here, the total population has
increased by 19.2% since 1990 (over 480,000 new residents), with a 48(Yo inr::rease
in incorporated land since 1990 (Alberti 4).
The expansion of cities and increasing urbanization triggers a chang/" :n
land cover. Previously undeveloped or "natural" areas are converted to urbal!
areas, including such features as roads, buildings, and lawns. In the last 15 years,
the large-scale change in land cover detectable from satellite imagery indicates
that in Thurston County, approximately 32,000 acres of land were converted from
intact forest stands, agricultural lands, or large expanses of shrub vegetation to
urban landscapes (TRPC VIII-2).
Watersheds within Thurston County experiencing the greatest percent of
urhanization over the last 15 years are Henderson Inlet with 14% and Black River
with 10%. Rural basins within Thurston County that have experienced rapid
changes in urban land cover in the last 15 years include the Budd/Deschutes
Watershed with a 19% increase, Henderson Inlet with a 25% increase, and the
Nisqually River Watershed with a 27% increase (Figure 1) (TRPC VIII-2).
One significant land cover change resulting from development and
urbanization is an increase in impervious surfaces, which has numerous
<lssociated impacts on water systems such as inhibiting precipitation from
infiltrating the soil, changing local hydrology, and increasing pollution sources. It
is generally believed a watershed's natural hydrology can continue to function
without any significant water quality problems until impervious cover reaches
10% to 20% within the drainage basin (NRDC 2; Ballantine, Clarke and Wilding
54: Aponte Clarke et al 130). As a result of an increase in impervious surfaces and
I
soil compaction, rainfall that had previously infiltrated the soil or been stored on
site becomes stormwater runoff, which must be collected and disposed of to
protect downstream properties from potential flooding increases.
Map1 - Thurston County Watersheds
N
W~E
L....
\
3 1.5 0
3
8 Miles
L..L-l
j
J
L
~6.
-Source: Thurston Regional Planning Council, 2002
The lack of the ability of water to permeate the soil on a developed site
inhibits the area's natural hydrological cycle, resulting in less groundwater
recharge as well as altered surface water flows. Within highly developed urban
areas, the loss of tree canopy and shrubs further degrades the watershed's ability
to remove considerable quantities of precipitation through interception and
evapotranspiration (Ballantine, Clarke and Wilding 54). Predevelopment, natural
surface runoff can range from lO to 30% of total annual precipitation. Alteration
through development can result in increases to over 50% (PGC 3-6).
2
Stormwater runoff from urbanized areas typically poses two major
problems in watershed basins: increased volume and velocity from impervious
surfaces, and the concentration of pollutants in the runoff (NRDC I; Aponte
Clarke et al 129). Impervious surfaces and compacted soils prevent rainfall from
infiltrating the soil, creating sudden rushes of water in receiving streams during a
storm. The increased volume and increased vdocity of runoff can cause
streambed scouring and erosion in the receiving body, further contributing to
water quality and habitat degradation (Ecology, Final Plan 154).
Conventional Siormwater management approaches usually involve very
efficient site drainage through the use of curbs, gutters, and pipes. The intent of a
Best Management Practice (BMP) is to create a drainage system that will prevent
on-lot flooding, promote good drainage and quickly convey runoff, commonly to
a pond (US EPA, Literature Review I). BMPs are defined by the Washington
State Department of Ecology as "Schedules of activities, prohibition of practices,
maintenance procedures, managerial practices, or structural features that prevent
or reduce adverse impacts on waters of Washington State" (Manual 1-2). These
facilities drain excess rainwater from the site providing excellent on-site drainage,
but greatly altering the natural hydrologic regime of a site and providing a higher
pollutant transpOlt capacity (PGC 3-8).
On an undeveloped site, many of these pollutants are removed from water
as it infiltrates through soils and vegetation. When collected in detention
structures, stormwater has generally not undergone the levels of treatment
inherent in natural systems and can be released into receiving waters with
increased and concentrated pollutant quantities.
Objectives
The focus of this paper is primarily on the impacts to water systems
resulting from the effects of development through land cover change and it was
formulated with two main objectives in mind. The first objective was to provide
eVidence of the effectiveness of LID and the second was to identify the barriers to
its implementation, particularly in the Puget Sound region. The first half of thi~
3
paper focuses primarily on the first objective, and indicates the promise of Low
Impact Development. The primary means of addressing the second objective
were an analysis of the existing data regarding Low Impact Development,
including projects that have gone forward, interviews with professionals having
experience with these types of proposals, and an analysis of stormwater
management issues in general.
Importance of Stormwater Related Issues - Problem Statement
Stormwater management is an important issue in Washington State,
especially in the Puget Sound region, which is an extensive area of potential
receiving waters. As a nonpoint source of pollution, stormwater runoff will
continue to be recognized as a serious threat to water quality and quantity.
Therefore, efforts must be made to ensure stormwater management techniques
adequately address not only pollution prevention, but also factors relating to
groundwater and surface water impacts.
Despite significant development regulations, the contribution of
stormwater to the degradation of our water resources has continued. The
following chapter outlines some of the specific impacts of stormwater on water
resources. The trend in stormwater management has been to devise more
complex designs to address increases in stormwater created by development,
while its ultimate goal has always been to mimic the natural hydrology of a site
BMPs most commonly collect and detain runoff and generally involve
discharging it into a receiving body once a certain water level is reached within
the detention structure (Ecology, Manual 1-5). However, shortfalls inherent in
conventional BMPs are beginning to be recognized, which work against their
effectiveness in mimicking the natural hydrology of a site.
One emerging stormwater management tool that can be used to more
adequately accomplish the goals of pollution prevention and natural hydrological
mimicry is Low Impact Development (LID). LID is a practice that some
stormwater professionals believe is not only more effective but also can be
achieved at lower economic costs as well as being more aesthetically attractive
4
than traditional BMPs. These statements will be further explored in the following
chapters.
In general, Low Impact Development is a technology-based best
management practice with the goal of maintaining the predevelopment hydrologic
functions of a site. This is accomplished through minimizing the disturbance of
the site by reducing the use of impervious surfaces and the utilization of natural
features to maintain natural drainage patterns and mitigate pollution (Coffman
158). Through site design, the stormwater generated from an area within a
watershed is more effectively and naturally utilized and managed, helping avoid
the impacts of development on water resources and maximizing the beneficial
uses they provide.
LID has not often been the chosen tool for stormwater management in the
Puget Sound region. The purpose of this research is to understand why, through
an analysis of existing data and literature on LID and communications with
variuus parties involved in the development process. The first ubjective is to
explore and present the potential of LID. The second is to identify the barriers to
its implementation. I hope to gain an understanding of these barriers that can then
be used to make recommendations regarding information or actions that will
required to overcome them. At completion, this paper wiJJ be able to serve as a
source of information regarding the usefulness of LID and provide some specific
examples of where it has been successful and why.
The information included in this paper will also examine the relationship
of LID to conventional stormwater management techniques. Presentation of the
case studies where LID has been used serves to highlight its effectiveness in terms
of cost savings to the developer and avoidance of water quality and quantity
impacts. The conclusions and recommendations provIde guidance on issues that
need to be addressed to overcome the barriers to LID
5
Chapter 2
Effects of Stormwater Runoff on Groundwater
The protection of Washington's groundwater resources is vital in
maintaining instream flo\.\'s and water quality in the state's streams and lakes
during summer months, Groundwater contributes significantly to our surface
water bodies; the estimated base flow contribution for streams is 70% (Ecology,
Final Plan IR), When land is compacted or paved in urban areas, significant
reduction of recharge and of summer streamflow results, Water that flows as
storm runoff is not able to recharge the groundwater to supply baseflow during
dry weather, Low flows are therefore exacerbated, decreasing water yuality
during the summer months (Dunne and Leopold 277),
In addition to groundwater recharge and the maintenance of stream flow,
groundwater is also a source of drinking water, In Washington, groundwater
provides approximately 60% of the drinking water (Ecology, Taking Action 5), If
contaminated by runoff, groundwater has the potential to cause significant health
problems The Washington State Department of Ecology identifies contaminatlOn
of groundwater due to nonpoint sources as apparently the most significant
widespread threat to groundwater quality in Washington (Final Plan 19), This is
of particular concern as the Department of Ecology ex peets an increased demand
on groundwater as the population grows from current levels to an estimated 1 i
mi II ion by the year 2045 (Final Plan 18),
Effects of Stormwater Runoff on Surface Waters
Stormwater affects surface water flows prImarily through increased
vOlumes and velocities (peak rates) of runoff (NRDC 1). In particular, when
compared to natural systems that infiltrate and slowly release runoff, areas of
urban development result in increased peak flows in winter, and reduced base
flows in summer (Ecology, Taking Action 3). In most natural, undeveloped
watersheds, runoff is slowed at every point along the flow path by a hierarchy of
vegetation and soft soils allowing infiltration into the groundwater and then into
streams, and swales, creeks, and streams that meander and are covered with
6
vegetation (Sonnenberg 106). This natural slowing attenuates runoff by allowing
lower reaches of a watershed to flow into streams and dissipate before runoff
from the upper watershed arrives at the lower reaches of the streams.
The variable that describes this process is called the Time of
Concentration, or Tc. The time of concentration is defined as the time it takes
water from the most distant point in a watershed (hydraulically) to reach the
watershed outlet. Tc typically decreases as imperviousness increases (PGC 3-7).
Development can increase velocities along the natural flow path because
of the associated compaction and paving, storm drain piping, minimal infiltration,
vegetation removal, creek bank lining, and straightening of stream channels.
These changes can increase stormwater runoff rates up to three times, aJlowing
the stormwater from the upper watershed to enter the lower stream channel before
the lower reaches have a chance to dissipate (Sonnenberg 106). Such changes to
a natural regime in a comparatively small area often bring significant and even
disastrous effects on the whole river basin downstream of the city
(Niemczynowicz 2).
Effects of Stormwater Runoff on Water Quality (Water Pollution)
When discharged into receiving waters, stormwater is classified as a
nonpoint source of pollution. The Washington State Legislature has defined
non point pollution as: "pollution that enters any water of the state from any
dispersed water-based or land-use activities, including, but not limited to,
atmospheric deposition, surface water runoff from agricultural lands, urban areas,
and forest lands, subsurface or underground sources, and discharges from boats or
other marine vessels" (Ecology, Final Plan 13). The U.S. EPA estimates that more
than 60% of Washington's water pollution problems are a result of non point
sources. Urban areas are the third most significant contributor to nonpoint
pollution, despite their relatively small share (2%) of land coverage in
Washington (Ecology, Taking Action 10). In combination with specific
contaminants, runoff from impervious surfaces delivers nutrients, sediments, fecal
7
contamination, and toxic chemicals to stream systems, affecting stream pH and
rc
temperature (Ecology, Final Plan 15).
al
According to the Department of Ecology, the primary water pollution
tl
problems in Washington are high temperature, pathogens, pH, low dissolved
oxygen, metals, and nutrients (Final Plan 5). Most of these problems are caused
hy nonpoint pollution. Orban areas are one category of six major sources of
1]
non point pollution, contributing through stormwater, on-sIte sewage systems,
I
hazardous materials., and construction and maintenance of roads and bridges
r
(Ecology, Final Plan 5). Stormwater runoff in particular contributes to nitrogen
I
pollution, erosion and sedimentation, pH alterations, pesticide contammation, and
changes in water temperature (Ecology, Final Plan 7; NRDC 2).
In nearly all cases, urban development is the main source of phosphorus,
which ultimately ends up in lakes (Ecology, Final Plan 15). Impacts to estuaries
from upland development include excess nutrients and toxics and increases in
bacteria counts, which result in shellfish harvesting downgrades and closures and
in some extreme cases, complete swimming prohibitions (Ecology, Final Plan
17). Other sources of nonpoint pollution associated with urbanization include
misuse of pesticides and fertilizers, household hazardous wastes, landfills,
underground storage tanks, waste oil, tires, batteries, etc. (Ecology, Final Plan
181).
Temperature in water quality samples has shown a nearly 2% increase in
sample failure rates in the past 20 years. Sample failure rates are the percent of
the total number samples that fail to meet standards or limits set forth for their
particular occurrence (Ecology, Final Plan 22). Fecal contamination is the only
parameter of four: (pH, temperature, fecal contamination, and dissolved Oxygen),
that has shown a decline in sample failure rates, nearly 5% (Ecology, Final Plan
24).
Laws and Regulations Pertaining to Stormwater
Recognizing that stormwater runoff from urban areas poses a threat to
receiving waters, the following is a brief outline of federal, state, and local
8
regulations that have been formulated to address a:,pc(:ts 0;- its (:oniroL and
attempts to confront the problems presented above,
Comprehensive stormwater regulation is required under Section 402(p) of
the Clean Water Act. Since 1992, certain industries, cities with populations over
100,000, and construction sites over 5 acres have been required to develop and
implement stormwater management plans under Phase I of the National Pollutant
Discharge Elimination System (NPDES) stormwater regulations, Originally
planned for October of 1999 but now for March 2003, new United States
Environmental Protection Agency (EPA) rules, outlined in the "Stormwater Phase
II Final Rule", will be implemented requiring municipalities with populations
fewer than 100,000 located in urbanized areas (defined as those with population
densities>I,OOO persons per square mile) to develop stormwater plans_ This
requirement is known as NPDES Phase II.
Various additional regulations exist on the federal level. The planning
prvvisions of Section 6217 of the federal Coastal Zone Act Reauthorization
Amendments (CZARA) require states with coastal areas to develop and
implement comprehensive nonpoint source programs in those areas, The
planning provi sions of Section 319 of the federal Clean Water Act (CWA) also
require states to develop comprehensive nonpoint source control programs.
Section 320 of the CW A created the National Estuary Program, and although not
a requirement for creation of state nonpoint source control programs, the EPA
subsequently adopted the Puget Sound Plan as a Comprehensive Conservation
and Management Plan for the Puget Sound Estuary, which also strives to control
nonpoint sources of pollution. Indirectly, the Endangered Species Act (ESA)
relates to stormwater as it has the potential to affect salmonids and other species
through stream now and habitat alteration.
On a state level, the 1998 Watershed Planning Act enacted by the
Washington State Legislature establishes a framework to identify and rectify
problems with water quality, quantity, and aquatic habitat. The Legislature also
formulated the Salmon Recovery Act. Both of these planning processes identified
non point source pollution as one of the primary causes of impairment of water
9
quality and salmon habitat in Washington State. Revised Code of Washington
(RCW) section 90.48 is Washington's Water Pollution Control Act. RCW 90.48
and the CW A designate the Washington State Department of Ecology (DOE) as
responsible for water quality.
The Puget Sound Water Quality Action Team, now Puget Sound Action
Team (PSAT), is responsible for program planning and overseeing
implementation of the Puget Sound Plan, referenced above. RCW 36.70A the
Growth Management Act (GMA), provides legislative direction to local
governments, requiring them to develop policies and regulations to ensure the
designation and protection of critical areas. The GMA is based on RCW 36.70,
the Washington State Planning Enabling Act.
The Shoreline Management Act, RCW 90.58, declares that the interest of
all of the people shall be paramount in the management of shorelines of statewide
significance. The Department of Ecology, in adopting guidelines for shorelines of
statewide significance, and local governments, in developing master programs for
shorelines of statewide significance, shaJJ give preference to uses in the following
order of preference which: (l) Recognize and protect the statewide interest over
local interest; (2) Preserve the natural character of the shoreline; (3) Result in long
term over short term benefit; (4) Protect the resources and ecology of the
shoreline; (5) Increase public access to publicly owned areas of the shorelines;
and (6) Increase recreational opportunities for the public in the shoreline.
Washington Water Quality assessments are done based on data collected
by the Department of Ecology and other agencies. These assessments determine
if water quality standards are being met, and beneficial uses being protected. The
results are reported semi-annually to the EPA in a "305(b)" report, named after
section 305(b) of the Clean Water Act.
As a result of the regulations above, various programs have been
developed to address surface water, groundwater, and aquatic habitat in
Washington, particularly the Puget Sound region. Listed here are those relating to
stormwater.
10
At a state level, under the Watershed Planning Act (90.82 RCW, bill
number HB25 14), by April 2000 thirty nine of sixty two Water Resource
Inventory Areas (WRIA) had begun the Watershed Planning Process, which
establishes processes to assess the availability of water, develop base instream
flow levels, protect water quality, and restore fish habitat. Under the Salmon
Recovery Act, 75.46 RCW, bill number SB5995, forty-one WRIAs are now
involved in limiting factor analyses. The intent of this act is to address salmonid
habitat restoratiun in a coordinated manner.
Local governments are working to coordinate the Watershed Planning Act
(WPA) and the Salmon Recovery Act (SRA). The data and habitat information
gathered during the SRA process can provide baseline information to a WPA
planning unit for the instream flow and optional habitat plans. Under the
Statewide Strategy to Recover Salmon, required by the SRA above, an "Early
Action Plan" was developed that specified activities related to salmon recovery
that state agencies would undertake. Many of the early actions were nonpoint
source control activities.
Watershed Analysis, adopted into regulation under Washington
Administrative Code (WAC) 222-22, includes a biological and physical
assessment of a watershed, followed by development of "prescriptions" designed
to protect and restore public resources. The Washington State Department of
Natural Resources (DNR) approves these prescriptions after public comment
through the State Environmental Protection Act (SEPA). The Puget Sound Water
Quality Management Plan and Local Watershed Action Plans are promulgated
through the planning processes in WAC 400-12. The purpose of these plans is to
identify, correct, and prevent nonpoint source pollution, and protect beneficial
uses of water. Later plans also deal with habitat restoration and protection.
Coordinated Water Systems Plans serve to integrate water utility development
with land use planning. They include Source Water Protection Plans, Watershed
Control Programs, Wellhead Protection Programs and Conservation Plans. Under
NPDES Phase L development and construction requirements and Best
11
Management Practices are established by the Washington State Department of
Ecology in the September 200 I manual.
(
Regional1y, the Puget Sound Action Team produces the Puget Sound
Water Quality Management Plan under RCW 90.71, the Puget Sound Water
g
Quality Protection Act. The purpose of the Action Team is to coordinate the
d
activities of state and local agencies by establishing a biennial work plan. This
1
work plan delineates actions necessary to protect and restore the biological health
]
and diversity of the Puget Sound, and implement the Water Quality Management
v
Plan to the maximum extent possible.
Counties and cities have adopted various ordinances aimed at protecting
S
water resources. With regards to Low Impact Development, in Thurston County
Ii
the cities of Lacey and Tumwater have each adopted standards relating to zero
effective drainage discharge. These standards can be found in Lacey Municipal
c
Code Title 14.31, and Tumwater Municipal Code 13.22. The city of Olympia has
c
adopted Low Impact Development regulations for the Green Cove Basin, and at
'1
this time the Thurston County planning depaltment does not have specific
regulations pertaining to LID proposals.
12
CHAPTER 3
Conventional Stormwater Management
Conventional stormwater management centers around the use of BMPs,
generally designed to prevent or reduce the impacts of stormwater on the waters
of Washington State (Ecology, Manual 1-4). Storms of various intensities,
recurrence intervals, and resulting volumes of runoff are used to size and design
BMPs. Storms with 2- and 10-year return intervals are commonly used fur
subdivision, industrial, and commercial development design (PGC 3-4). Long
term BMPs are subdivided into those that manage the volume and timing of
stormwater flows, prevent pollution from potential sources, and treat runoff to
remove sediment and other pollutants (Ecology, Manual 1-5).
BMPs that prevent pollution or other adverse affects from occurring are
called source control BMPs. The Washington State Department of Ecology ha:.;
called this type "generally more cost effective" than the others (Manual 1-5).
Treatment-type BMPs include facilities that remove pollutants, and 'facilities
involve the construction of engineered structures. Flow control-type BMPs
typically manage flow rate and frequency and flow duration of stormwater surface
runoff (Ecology, Manual 1-5).
The most commonly used stormwater management practice has been to
manage flows through the use of detention ponds, which are intended to capture
and detain stormwater runoff from developed areas (Booth 4). The on-site
drainage management approach relies on facilities designed to control peak flows
primarily for a given storm size and does not control those storm events smaller
than the design storm (PGC 3-9). The runoff from storms smaller than the design
size bypass the facility and are routed directly to an outlet structure (Ritter pers.
comm. 3/5103). The higher pollutant transp0l1 capacity of on site drainage
systems is a result both of pollutants collecting in a single centralized facility and
of smaller storms bypassing the facility altogether.
The notion of "first flush" can be used to demonstrate a shortcoming of
conventional storm water management systems particularly in relation to
poJ[ution. "First flush" alludes to the fact that pollutant concentrations tend to be
13
much higher at the beginning of a storm, compared to the middle or end of an
event. This is based on the fact pullutants have accumulated on site since the last
storm event. Therefore, a much smaller volume of runoff storage is technically
needed to treat and remove urban pollutants than that provided in a BMP, because
90% of the annual pollutant load is found in the first half inch of runoff. This is
most pronounced for hIghly impervious areas. At greater than 50% impervious
cover, the rate of pollutant load capture drops off sharply. Only 78% of the
annual load is captured at 70% impervious cover, and only 64% is captured at
90% impervious cover (Holland and Schueler 88).
A different type of pollution-related problem with the extensive use of on
site sewer systems is that in some areas, distinction between pluvial drainage and
household sanitary sewer systems hardly exists. For example, in Santa Catarina,
Brazil, 71 % of the municipalities are endowed with household sewers connected
to storm sewers (Pompeo 157). In situations where these systems are combined,
an overflow in the storm sewer system can cause an overflow in the household
sanitary sewer system, resulting in human waste overflows into receiving waters,
known as combined sewer overflow (CSO).
Since pollution control is designed into some source control and treatment
type Best Management Practices, certain BMPs do have the capahility to treat
stormwater runoff at certain levels. However, one limitation of "end of pipe"
(after the fact treatment and flow control-type) BMP installations is that they
often cannot account for the cumulative impacts of individual land uses. These
individual land uses generate relatively few pollutants by themselves, but
collectively can have a significant adverse impact on the water quality of the
receiving water bodies in the region (Kunz 39). Although traditional stormwater
control measures have been documented to remove pollutants effectively in some
situations, the natural hydrology of a site is still affected (US EPA, Literature
Review 1).
It has been documented that nearly all water quantity problems stemming
from development result from one underlying cause' loss of the water retaining
function of the soil in the urban landscape (Booth and Leavitt 314; Booth 3).
14
"Urban soils" tend to be highly compacted, poor in structure, and low in
permeability. Pitt (1993) noted one-third of the disturbed soils he tested had an
infiltration rate of zero or near zero, exhibiting the same runoff response as
concrete or asphalt (Holland and Schueler 235). Typical runoff calculations often
significantly underestimate the amount of rainwater that runs off a site, due to the
fact much of the runoff from a constructed site exists because native soils are
removed and no amendments are replaced on top of the compacted layers (Kunz
40).
The magnitude of hydrologic change (increases in volume, frequency, aid
rate of discharge) is amplified as natural storage is lost on a developed site.
Typical conventional site design results in developments devoid of natural
features that increase travel times and that detain or infiltrate runoff. The amount
of impervious surface is increased, the time of concentration is decreased, runoff
travel times are decreased, and the degree of hydraulic connection is increased
(PGe 1-5). The lack of natural features typically adversely affects the ecosystem,
and trying to control or restore these functions using after the fact management
techniques is difficult, if not impossible (PGe 2-4).
In addition to the hydrologic changes outlined above, efficient on-site
drainage systems result in a significant increase in off-site flooding potential, as
well as high downstream environmental impacts associated with increased peak
flows and their frequency of occurrence, higher storm flow volumes, and
increased delivery of pollutant loads (US EPA, Literature Review 9). Post
development conditions on sites with conventional stormwater BMPs result in
hydrographs exhibiting significant increases in the runoff volume and duration of
runoff from the predevelopment condition (PGe 3-3).
Taken as a whole, there are several drawbacks to attempting to hold all
runoff in a central facility, removed from a developed area. First, construction
and maintenance of stormwater facilities are erratic, often with a divergence
between design targets and actual performance. Second, there are practical limits
to applying drainage regulations to individual small-scale land developments
(Booth and Leavitt 315). Jurisdictions usually set a "threshold of concern" for
15
nearly all development activities, above which all regulations apply, below which
regulations are minimal or absent. For example, King County between 1987 and
1992 stipulated a minimum 0.50 cubic foot per second (cfs) increase in runoff
(which is equal to about 0.5 acres impervious surface) before mitigation was
required. However, permit activity between this time indicated about one-quarter
of the impervious areas added to the County's watershed was in individual
developments below this threshold, and so was constructed without any detention
facilities at all (Booth and Leavitt 315).
Finally, even the largest and best-designed stormwater ponds cannot
transform precipitation during the wet season into base flow during the
subsequently dry season; detention times are simply too brief (Booth and Leavitt
315; Booth 6).
The next section includes a discussion of LID; followed by ways it can
address many of the shortcomings of conventional stormwater management
techniques outlined in this section.
Low Impact Development
Low Impact Development (LID), pioneered by Prince George's County,
Maryland, is a comprehensive, technology-based approach to managing urban
stormwater (PGC 1-3). LID has a goal of maintaining or replicating the
predevelopment hydrologic regime on a site through the use of design techniques,
to create a functionally equivalent hydrologic landscape (US EPA, Literature
Review 1). The LID approach attempts to match predevelopment conditions by
compensating for runoff through the maintenance of infiltration potential and
surface storage, conservation of natural soils, evapotranspiration through the
preservation of vegetation, as well as increased travel times to reduce a rapId
concentration of excess runoff. A second goal of LID is to maximize the use of
upland landscape with its soil/plant/microbe complex to treat runoff (Coffman
165). The combination of these goals is intended to avoid both the water quality
and quantity impacts of development on a watershed.
16
Elements fundamental to understanding LID include impact avoidance
versus minimization in an effol1 to maintain the ecological functions of the
receiving waters and determination of appropriate technological tools. It is
essential that technologies and tools be appropriately integrated into a site to
avoid impacts to terrestrial and aquatic systems. thereby avoiding impacts to or
disturbance of the overall ecological functions of receiving waters. Impact
avoidance is better for maintaining ecological function in its entirety than impact
minimizing techniques (Coffman, pers. comm. 4/25/03).
LID consists of five major components: Site Planning, Hydrologic
Analysis, Integrated Management Practices, Erosion and Sediment Control, and
Public Outreach Programs (PGC 1-6). following is a brief description of thre~ OF
these components and what they involve.
Site Planning: LID site planning requires that hydrological goaJs be
incorporated into the site planning process as soon as possible (PGC 2-1). This
involves defining a development envelope with respect to the site's hydrology and
preserving areas that affect it. The purpose is to find the development envelope
that will have the least impact on the site while maintaining natural hydrologic
features, maximizing undisturbed areas, and preserving environmentally sensitive
areas. This involves evaluating layouts to reduce, minimize, and disconnect direct
connections of the total impervious area at the site (PGC 2-3). Additional benefits
can be derived by designing for water flow from impervious to pervious cover as
'runon', thereby significantly reducing the volume of runoff and possibly of
stormwater pollutants as well (Holland and Schueler 235).
Hydrologic Analysis: The preservation of the predevelopment hydrology is
evaluated by comparison of pre and post development hydrologic conditions
(PGC 3-10). Four hydrological functions should be analyzed when investigating
the effectiveness of LID practices: Runoff curve number (CN), time of
concentration (Tc), retention, and detention (US EPA, Literature Review 9).
Curve number is an empirical rating of the hydrologic performance of a large
number of soils and vegetative covers throughout the United States (Dunne and
Leopold 291). Time of concentration was defined in Chapter Two, and refers to
17
the time it takes for runoff from the farthest reaches of a watershed to reach the
outlet. Retention and detention of rainfall are the key components of increases in
Tc (US EPA, Literature Review 10). Maintaining the predevelopment Tc
involves maintaining the predevelopment flow path length by dispersing and
redirecting flows (generally through open swales and natural drainage patterns),
increasing surface roughness, detaining flows, minimizing disturbance, flattening
grades in impacted areas, disconnecting impervious areas, increasing interception,
increasing or preserving natural depressions and storage, and connecting pervious
and vegetated areas (POC 3-19).
Integrated Management Practices: Specific LID controls are called
Integrated Management Practices (IMPs), which integrate stonnwater control
throughout a site in many small discrete units (micromanagement) at or near the
source of impacts, virtually eliminating the need for a centralized Best
Management Practice (POC 1-3). The goal is to select an appropriate
combination of management techniques that simulate the hydrologic functions of
the predevelopment condition to maintain the existing CN and corresponding
runoff value (Coffman 162). IMPs provide controls to mitigate or restore the
unavoidable disturbances at a site using an at-source control approach, in contrast
to conventionaJJy used end-of-pipe control methods (POC 2-1). These controls
more closely mimic a natural site than conventional management practices in that
they are relatively more evenly distributed throughout a site, as are natural
features on an undeveloped site. In addition, they are likely more cost effective if
the Department of Ecology's assessment regarding the relative cost effectiveness
of source controls is accurate.
Most of these controls are site-specific and are designed to be simplistic
and non-structural. Controls include such practices as bioretention, grass swales,
vegetative roof covers, and penneable pavements. Other LID strategies include
such things as implementation of rain gutter disconnects (redirect rain flow out of
gutters and storm sewers into functional landscape devices), shared driveways,
rain barrels, cisterns, and attention to the design of residential streets (US EPA,
Literature Review 8). Some BMPs, although not the most commonly used, mirror
lR
these IMPs. On sites where LID is implemented, the volume of flow in closed
channels (pipes) should be minimized to the greatest extent possible (PGC 3-21).
The Erosion and Sediment control component of LID, component four,
primarily applies to construction site activities. As th{; focus of this paper is
primarily on the impacts to water systems from the effects of development
through land cover change, this component will not be explored in any detail.
Additionally the fifth component, the Public Outreach component, will not be
explored in detail; however, this should not diminish its importance In general,
public outreach involves encouraging and educating property owners about the
use of effective pollution prevention measures and the maintenance of individual
controls (Coffman 165; Kunz 39). Details on the Public Outreach Program Prince
George's County implemented can be found in Low Impact Development Design
Strategies: An Integrated Design Approach.
Specific technical explanations and evaluatIOns of each of these controls
are beyond the sC(Jpe of this paper; however, both Prince George's County and the
US EPA have published information on these aspects. Costs and financial
considerations of Low Impact Development and conventional stormwater
practices wilJ be discussed in more detail at the end of this chapter.
Overall, Low Impact Development is based on the ideal that the most
effective stormwater strategies enhance natural processes, recognizing eff(Jrts
such as buffer zones and sensitive area protection (Aponte Clarke et a1 132). It
can be thought of as a new philosophical approach to site development, one that
will allow the designer to retain the natural hydrologic functions of a particular
site and focus on the avoidance of impacts to receiving streams rather than their
minimization. LID borrows basic principles from nature, primarily the uniform
distribution of micro-management controls. Site design techniques ensure every
development feature (green space, landscaping, grading, streetscapes, roads, and
parking lots) can be designed to provide some type of beneficial hydrologic
function, such as infiltration or maintenance of the time of concentration
(Coffman 160).
19
Low Impact Development Versus Conventional Stonnwater Management
As outlined in the previous section, one of the main goals of LID is to
preserve the predevelopment hydrologic regime of a site. One of the most
significant differences between conventional stormwater management practices
and LID is that LID controls runoff from the full range of storm events, including
that of storms smaller than the conventional facilities' design storm (PGC 3-1).
While still providing for on-site drainage, it strives to avoid hydrological
alteration and pollutant transport capacity resulting from development, rather than
minimizing them as when traditional management approaches are employed.
Manning's roughness coefficient ("n") represents the boundary resistance
to the f10w and velocity of a water body based on the makeup of its boundary.
For example, a smooth concrete channel would have a lower "n" value than a
natural stream, causing less friction than a natural stream and thereby producing
less drag or resistance to affect the discharge or velocity of the stream (Dunne and
Leopold 593). Using LID techniques to maintain the predevelopment time of
concentration effectively shifts postpeak runoff times to that of predevelopment
conditions and lowers peak. runoff rates. This can be accomplished in a small
watershed because LID controls can maintain or raise the Manning's roughness
coefficient for the initial overland (sheet) f10w at the top of the watershed (PGC 3
20), which can increase flow path length to the most hydraulically distant point in
the drainage area.
LID is centered on the premise that using micro-management to control
both runoff discharge volume and rate is the key to replicating predevelopment
hydrology. Using LID practices also produces runoff frequencies that are much
closer to predevelopment conditions than can be achieved through the application
of conventional BMPs. Hydrograph analysis showed using just LID site planning
techniques (no llVIPs) resulted in a significant reduction in both postdevelopment
peak rate and volume in postdevelopment hydrographs (PGC 3-18). This is an
j llustration
of implementing compensation or restoration of hydrologic functions
as close as possible to the point or source where the impact is generated
20
With reference to particular LID controls, vegetative rooftops have been
used extensively in Germany for more than 25 years. Results show up to a 50%
reduction in annual runoff (volume) in temperate climates (US EPA, Literature
Review 8). A biodetention system (essentiaIJy a filter with native grasses and a
rock berm), disperses concentrated flow to sheet f1ow, in an effort to maintain the
time of concentration, decrease peak runoff volumes and rates, and increase
infiltration to predevelopment levels (Murfee, Scaief and Whelan 47).
In a 2000 review oJ literature regarding Low Impact Development, the US
EPA presented an analysis of fourteen LID practices for effectiveness using the
four components of LID hydrologic analysis (Literature Review 9). As a recap,
these four components are a lower postdevelopment eN (curve number), an
increase in the time of concentration, retention functions, and detention functions.
Of the fourteen practices. eight resulted in lower postdevelopment eN, twelve
increased the time of concentration, seven effectively functioned as retention, and
three as detention. Through these various comparisons, six of the fourteen
practices were classified as "good", meaning they functioned effectively under at
least three of the four hydrologic analysis components. These six practices were
vegetative filter strips, rain barrels, rooftop storage, bioretention, revegetation,
and vegetation preservation (9).
In addition to runoff volumes and velocities, one of the major drawbacks
to conventional stormwater management illustrated in the first section of this
chapter is water quality protection. One example outlined the notion of "first
flush", referring to the relatively high pollutant concentrations found in the firsl
half inch of runoff from a developed site. In terms of pollutant removal measures,
LID provides a higher level of water quality treatment controls due to runoff
volume controls of the first flush as opposed to conventional systems (US EPA,
Literature Review 10). This is because conventional Best Management Practice
facilities are designed to allow runoff from storms smaller than the design storm
[0
bypass the system, which is not the case with LID micro controls. In general,
by increasing the time of concentration and decreasing the flow velocity, LID
practices result in a reduction in pollutant transport capacity and overall pollutant
21
loading (US EPA, Literature Review 10). The Department of Ecology's Final
Washington Nonpoint Source Management Plan recognizes, "Future development
using today's BMPs will continue to exacerbate the situation" (15).
The majority of the available data on LID controls and pollution have
centered on bioretention systems. Generally, the experimental data show a fairly
consistent removal rate for all of the tested bioretention systems for heavy metals
and most nutrients (US EPA, Literature Review 31). In a study conducted in
Ontario, Canada, a loading comparison revealed that the system released
significantly fewer pollutants than conventional systems (US EPA, Literature
Review 32). Additionally, as a result of the increased vegetation used in
bioretention, sediment trapping is increased (Murfee, Scaief and Whelan 47).
a
LID has additional benefits not specifically related to runoff velocities,
volumes, or pollutants. For example, a major technical advantage of LID
(
micromanagement techniques is that one or more of the systems can fail without
t
undermining the overall integrity of the site control strategy (PGC 2-5). Failure
I
of a conventional pond or other single facility would not have the same result. In
addition, LID provides a much greater range of control practices that can be
adapted to specific site conditions. It can provide functions such as volume
control and the maintenance of predevelopment groundwater recharge, thereby
compensating for significant alterations of infiltration capacity while adding
aesthetic value (PGC 2-1).
LID provides many opportunities to retrofit existing highly urbanized
areas with pollution controls, as well as to address environmental issues in newly
developed areas (US EPA, Literature Review 3). In urbanizing watersheds, less
and less land is available for mitigation and implementation of regional
management alternatives (SPAC 4). In existing highly urbanized areas,
permeable pavements and vegetative rooftops are two ways to reduce impervious
surfaces (US EPA, Literature Review 3). In addition, developers can implement
LID in retrofits by disconnecting impervious surfaces from conventional drainage
infrastructure and installing LID integrated management practices to capture and
treat runoff (NRDC 2).
22
As noted previously in this chapter, LID urban landscape or infrastructure
features can be designed to be multi-functional. For example, in a
bior~tentiol1
cell, the tree canopy provides interception and hydrological and habitat functions.
Lhe 6 inch storage depth provides for the detention of runoff, soils, organic litter
and mulch provide pollutant removal and water storage, planting bed soils provide
infiltration, pollutant removal, and groundwater recharge, and evapotranspiration
is provided by plant materials (PGC 2-5).
While providing a more environmentally benign alternative for stormwatf;r
management there are potential constraints to LID that must be acknowledged.
For example, not all sites are suitable for LID. Considerations such as soil
permeability, the depth of the water table, and slope must be considered, in
addition to other factors (US EPA, Literature Review 3). A designer must
carefully consider how best to make use of the hydrologic soil groups and site
topography to help reduce and control runoff (Coffman 160). Further, the use of
LID may not completely replace the need for conventional stormwater controls,
depending on specific site limitations (US EPA, Literature Review i). The use of
LID may necessitate the use of structural BMPs in conjunction with LID
techniques in order to achieve watershed objectives (US EPA, Literature Review
3).
In addition, LID maintenance issues can be more complicated than for
conventional stormwater controls because the LID measures reside on private
property (US EPA, Literature Review i). However, it is also more likely for a
homeowner to monitor and maintain these controls than traditional stormwateI
ponds, because of their location on one's property and the fact that it contributes
to or takes away from the total value of the property (Coffman, pers. comm.
4/25/03).
Costs and Financial Considerations
In general, LID measures are more cost effective and lower in
maintenance than conventional, structural stormwater controls (US EPA,
Literature Review i). This is based on construction and maintenance costs,
23
representing both shor1 and long tenn costs. LID can significantly reduce
development costs through site design by reducing impervious surfaces
(roadways, curbs, and gutters), decreasing the use of storm drain piping and inlet
structures, and eliminating or decreasing the size of large stormwater ponds (PGC
1-3). This is because control or treatment structure costs can increase with
distance from the source (PGC 2-4).
The US EPA's 2000 LID review produced the following general cost
information:
•
The Center for Watershed Protection (1998) reports the cost for traditional
structural conveyance systems ranged from $40 to $50 per running foot. This
is two to three times more expensive than an engineered grass swale (7).
•
Vegetative roof covers are especially effective in older urban areas with
chronic combined sewer overflow (CSO) problems. They also add a variety
of henefits such as extending the life of roofs, reducing energy costs, and
conserving valuable lands that otherwise would be required for stormwater
runoff control (7).
•
The Center for Watershed Protection (1998) reports the cost for pervious
paving may range from $2 to
~4
per block/stone, whereas asphalt costs $0.50
to $1 to cover the same area (7).
Permeable pavements are more expensive to construct than traditional
asphalt pavements; however, costs of these systems may be offset hy the
reduction of traditional curb and gutter systems to convey stormwater (US EPA,
Literature Review ii). LID practices offer an additional benefit in that they can be
integrated into the infrastructure and are more aesthetically pleasing than
traditional structural stormwater conveyance systems (US EPA, Literature
Review 1).
More specific informatIOn and findings related to cost
ar~
presented in the
case studies in Chapter Five.
---
24
Chapter 4
Barriers to the Implementation of Low Impact Development
Low Impact Development has not often been the chosen tool for
stormwater management in the Puget Sound Region. To gain an understanding of
[he barriers and insight on how to overcome them, it was necessary to extend the
area of inquiry outside this region to areas where it has been practiced relatively
more often. Although it definitely is still not a common approach in any region,
there are areas of the country where it has been more widely used and experts to
share their experiences.
The results of interviews and analysis of existing data reveal banlers that
can essentially be broken down into two categories, technical and philosophical.
Although these categories are not mutually exclusive nor are each of the baniers
within them, they represent a general break between the levels of complexity
determined to exist during examination of their aspects.
Technical Barriers
Technical barriers can be thought of as specific issues needing resolution
in order for LID to be an option that development parties wi II use. They are not
as broad as philosophical barriers and concern particular questions with relatively
tangible answers. Technical barriers tend to center around questions of
technology and process. During the analysis and interviews a few barriers of this
sort seemed to surface consistently. Following is a description of the most
common.
On a general level, there has been a slow accumulation and lack of
dissemination of information regarding Low Impact Development (Booth, pers.
comm. 4/16/03). This finding relates to the lack of many different types of
information and can be in the form of specific details or more general and broad
based communication. Technical assistance and uncertainty among stakeholders
as to whether stormwater programs even work were two common themes the
Washington State Stormwater Policy Advisory Committee (SPAC) identified as
high priOrIty and needing further attention (7). Along with this lack of information
25
being circulating is the lack of information regarding successful LID projects,
including such information as effectiveness and financial considerations.
Funding shortages compound the ability of government agencies in
particular to generate and disseminate information. The 1999 local government
infrastructure study conducted hy the Washington State Department of
Community, Trade and Economic Development found significant funding gaps
for stormwater projects. This funding gap was the largest of any of the study's
infrastructure categories, including roads, bridges, domestic water, and sanitary
sewer (SPAC 17).
On a more technical level, there are genuine engineering questions
surrounding LID. Specific issues in this region are soils (Booth, pers. comm.
4/16/03). Soils in this region are spotty, meaning the soil matrix in one location
has been found to be completely different than that in an area less than one-half
mile away (Ritter, pel's. comm. 5/14/2003). In addition, there is a proliferation of
hardpan underlying much of the soils in this region. There is uncertainty
surrounding the construction and effectiveness of certain Integrated Management
Practices with reference to this fact. The public questions how something smaller
(considered "less") will be capable of accomplishing what the existing larger
("more") storm ponds have not necessarily been able to, referring to effective
infiltration (Ritter, pel's. comm. 5/14/2003).
Specifically in terms of maintenance, questions exist surrounding what is
involved, how often what types of maintenance must be done, and what will
happen if the practices are not maintained (Tosomeen, pel's. comm. 3/25/03).
Difficulty also exists in the determination of responsibil1ties for maintenance of
LID practices. The wisdom of conferring maintenance for what are thought to be
complex facilities to lot owners associations or individual lot owners with no
knowledge or understanding of the systems has been questioned (Coffman pel's.
comm.4/25/03).
A specific barrier to LID from the viewpoint of construction associations
has been agencies' use of prescriptive standards in their implementation
ordinances (Booth, pers. comm. 4/1612003; DeForest pers. comm. 5121/03). They
26
feel that with many questions surrounding the success and effectiveness of
various LID technologies, construction standards and requirements are too rigid.
High levels of stormwater mitigation requirements are applied in blanket fashion
(SPAC 13), and
agencie'~
do not typically give full credit for the anticipated
capabilities of these systems as an incentive (Booth and Leavitt 317). llulsmann
(as quoted in Corvin) bclieves this is unacceptable for what developers feel is a
potentially risky and ex pensi ve undertaking (C 1).
Construction challenges were cited as a technological barrier to the
acceptance of LID from an agency perspective (Tosomecn, pers. comm. 3/25/03).
Generally these challenges related to thc specifications for construction or
fabrication of certai n LID elements, such as bioinfiltration swales and pervious
pavements Structures of these types require specific inputs or specific assembly
methods, which if not precisely followed can render them entirely ineffective. An
example is porous pavement, which requires a specific mix of aggregate to
properly function. Agencies responsible for pubhc safety are extremely wary of
the possibility of failures relating to these chaJJenges.
Philosophical BatTiers
Occurring on a broader level than tcchnical barriers, philosophical barriers
involve traditional models and ways of thinking that do not lend themselves to
discernable solutions as simply as technical barriers. Philosophical barriers are
also founded in a larger temporal scale than technical barriers and anything aimed
at overcoming them must address the notion of change and all it encompasses.
One of the most common reasons for the avoidance of LID is its portrayal
as 'something new' (Coffman, pers. comm. 4/25/03). It is true that LID involves
a different thought process and paradigm than conventional stormwater
management, but the premise behind it is certainly not new. The same goals and
ideals behind LID can be found when examining the ways in which a natural.
undeveloped site manages stormwater. Coffman believes this barrier exists
beneath many of the technical barriers, which in effect serve as 'red herrings' to
27
avoid the acceptance that LID is not something new, radical, or worthy of being
'"'e'
afraid of (pers. comm. 4/25/03).
an:
]
m
Another barrier to LID is a result of its confusion in development circles
with the use or success of other 'ecological' or 'environmentally friendly'
development tools (Coffman, pers. comm. 4/25/03). Other approaches, such as
'conservation design' or 'smal1 growth', do not focus primarily on avoiding
watershed impacts but rather on minimizing them. This difference is key to
understanding Low Impact Development, and this is not to say that the other
approaches are without merit. As previously indicated it may be necessary to use
elements of them all to achieve watershed objectives or depending on site
constraints.
LID requires a multidisciplinary approach involving multiple agencies,
professionals, and consultants with different backgrounds and also the public.
This situation is often marred by communication problems. Often the involved
II
parties have different goals, different or even conflicting missions and
o
responsibilities, and individuals have different educational and professional
d
backgrounds. The result is ineffective communication and 'spinning wheels',
which require pointed efforts to overcome (Coffman, pers. comm. 4/25/03).
One of the most significant barriers can be characterized as multi-layered
and can be summarized with the words "regulatory structure". This barrier results
from the conflicting goals, policies, and philosophies of the multiple agencies and
interests involved in the development process (Coffman, pers. comm. 4/25/03).
An illustration can be found in the numerous regulations and programs having to
do with stormwater presented in chapter 2. Because of the unfamiliarity and
uncertainty surrounding LID, agencies and individuals are relatively more
cautious than they would be with more common proposals. Each party has
constituents, which are often the public, whose interest they are charged with
protecting. This barrier is also related to responsibility and assurance (risk
avoidance).
A final broad-scale barrier to LID is that it is contrary to the current
economic model of managing stormwater, referred to throughout this paper as the
78
"end of pipe" approach. When regulations were passed requiring the treatment
and mitigation of stormwater in the 1970's, conventional approaches were
modeled on existing sanitary sewer engineering techniques. Conventional
approaches have come to involve centralized thinking, techniques, and
technologies from which there is little variance. Over time, the companies and
individuals specializing in these management techniques have captured a
comfortable market share (Coffman, pers. comm. 4/25/03).
Although the barriers discussed above do not represent the only
obstructions to the acceptance or use of Low Impact Development, they
encompass the mosi commonly encountered issues in the literature and
correspond to experiences related by professionals with LID experience. Based
on an understanding of the possibilities LID holds for avoiding the impacts of
development on water resources and an understanding of some of the common
barriers to its use, especially in this region, conclusions and recommendations for
overcoming these barriers can be formulated. Chapter six involves more detailed
discussions of some of the barriers presented above.
29
CHAPTERS
Case Studies
The purpose of this chapter is to highlight the results from a number of
projects utilizing Low Impact Development that provide evidence of its
effectiveness. Following are excerpts from reports documenting these results,
mostly centered on the concepts of effectiveness in terms of pre- and post
development hydrological considerations and pollutant removal capacities.
According to Prince George's County (3-1), 'The preservation of the
predevelopment hydrologic regIme of the site can be evaluated through
consideration of the runoff volume, peak runoff rates, storm frequency and size,
and water quality management". The other major focus of these case studies is
cost and financial consideration. An effort has been made to communicate which
LID strategies or controls were implemented in each situation, when available.
The following excerpts of results, which primarily focus on the function
and effectiveness of different LID strategies, are from the US EPA's 2000 Low
Impact Development Literature Review. According to the US EPA these case
studies were the best examples of projects that use LID concepts and both
hydrologic and pollutant removal effectiveness were investigated (11),
Bioretention Facility - Beltway Plaza Mall Parking lot, Greenbelt,
Maryland
•
Removal rates of heavy metals by the bioretention system were 97% for
copper, and more than 95% for lead and zinc. The removal for ammonia was
over 95%, nitrate concentrations were below input levels with a removal of
about 17%, phosphorous removal was observed at approximately 65%, and
Total Kjeldahl Nitrogen (TKN) removal was about 50% (12).
30
Permeable pavements and swales - Florida Aquarium Parking Lot,
Tampa, Florida
•
Four different scenarios were tested: Asphalt paving with no swale, asphalt
paving with a swale, cement paving with a swale, and permeable pavement
with a swale.
•
For rainfaJl events less than 2 em, the basins with swales and permeable
pavements resulted in 80-90% less nmoff than basins without swales, and 60
80% less runoff than basins with the other pavement types and swales. Larger
rainfall amounts show fewer differences in runoff amounts between the
different pavement types. but overaJ] basins with swales have approximately
40% less runoff then the basins without swales.
•
Metal removals for the permeable pavement with swale treatment were copper
at 81 %, iron 92%, lead 85%, manganese 92% and zinc 75%. The removals
for the cement with swale treatment were somewhat lower, with the asphalt
with swale treatment showing the poorest performance of the three treatments
with swales (18).
Vegetative roof covers - Green Rooftop, Philadelphia, Pennsylvania
•
Green roofs are comprised of three components: subsurface drainage, growth
media, and vegetation.
•
During a nine-month period, 44 inches of rainfall was recorded at the pilot
scale test station, with only 15.5 inches of runoff generated. Attenuation was
approximately 40%.
•
Benefits of the project included extended life of the underlying roof materials,
reduction of energy costs by improving the effectiveness of insulation, and
restoration of ecological aesthetic value of open space in densely populated
areas (23).
In addition, the Ontario, Canada, study referenced previously concluded
that no evidence existed to show that nutrient or metal concentrations in soils
31
increased with age in grass swales, as concentrations varied regardless of age.
Also, the study determined no degradation in vegetative quality resulted from
pi:
continuous exposure to stormwater runoff (32).
reI
In addition to effective pollutant removal and hydrologic controls, the use
pn
of LID measures result in cost savings as a result of less impervious surfaces and
other types of infrastructure compared to conventional developments.
Infrastructure (roads, sidewalks, storm sewers, utilities, and street trees, for
c
example) normally constitutes over half the cost of total subdivision development
c
(Holland and Schueler 472). As such, the minimization of infrastructure can
SI
provide considerable savings. In subdivisions, savings occur at the rate of
4
approximately $150 for each linear foot a road is shortened, including pavement,
d
curb and gutter, and storm sewer. Savings of $25 to $50 are found for each liner
s
foot of roadway that is narrowed, and $10 for each linear foot of sidewalk that is
eliminated (Holland and Schueler 473). See Table 1, below.
Commercially, reductions in impervious cover leading to savings include
$1100 for each parking space eliminated in a commercial parking lot. When
future maintenance is considered, lifetime savings in the range of $5000 to
~7000
per space occur (Holland and Schueler 473).
Table 1: The Unit Cost of Subdivision Development
(Source:
S~'1BIA
1987 and others, as published in Schueler 1995 - pg 475)
Subdivision Improvement
Roads, grading
Roads, paving (26' width)
Roads, curb and gutter
Sidewalks (4 feet wide)
Storm Sewer (24 inch)
Clearing (forest)
Driveway aprons
Sediment Control
Stormwater Management
Water/Sewer
Well/Septic
Street Lights
Street Trees
Unit Costs
$22.00 per linear foot
$71.50 per linear foot
$12.50 per linear foot
$10.00 per linear foot
$23.50 per linear foot
$4,000 per acre
$500 per apron
$800 per acre
$300 per acre (variable)
$5,000 per lot (variable)
$5,000 per lot (variahle)
$2.00 per linear foot
$2.50 per linear foot
32
One method of reducing infrastructure is using the LID tool of site
planning. Cluster development has been identified as one design concept that can
reduce the capital cost of subdivision development by 10 to 33%. This is
primarily by reducing the length of infrastructure needed to serve the
development (Holland and Schueler 472). Cluster site design can reduce
impervious cover 10 to 50%, thereby lowering costs for both stormwater
conveyance and treatment. Cost savings resulting from this reduction can be
considerable, as the cost to treat the quality and quantity of stormwater from a
single impervious acre can range from $2000 to $50,000 (Holland and Schueler
472). An example of estimated development costs associated with two different
development scenarios (conventional and cluster) for the Remlik Hill Farm
subdivision in Maryland are presented in Table 2 below.
Table 2: Remlik Hill Farm Example: Costs, Land Cover, and
~
Scenario A
Scenario B
Conventional Plan
Cluster Plan
$79,600
$39,800
20,250 linear feet
9,750 linear feet
$1,012,500
$487,500
1. Engineering Costs
(boundary survey,
topo, road design,
plans,
monumcntation)
2. Road Construction
Costs
3. Sewage and Water
(permit fees and
design only)
Individual septic and
wells
$13,200
$25,200
4. Contingencies
$111,730
$54,050
GRAND TOTAL
$1,229,030
$594,550
33
~
Land Cover and Stormwater Pollution Estimates
Total Site Area = 490.15 acres
Scenario A
Scenario B
Total Developed Land
287.41 acres (58.6%)
69.41 acres (14.2%)
Roads and Driveways
19.72 acres
11.75 acres
Turf
261.09 acres
54.04 acres
Buildings
6.60 acres
3.92 acres
Total Undeveloped Land
202.74 acres
420.64 acres
Forest
117.55 acres
133.01 acres
Wetlands
11.46 acres
11.46 acres
Total Impervious Cover
5.4%
3.7%
Total Nitrogen (lbs. per year)
2,534 lbs./year
1482 Ibs./year
Phosphorus (lbs. per year)
329 Ibs./year
192 Ibs./year
The three foJlowll1g case studies are excerpts from the book Green
Development: Integrating Ecology and Real Estate, published by John Wiley and
Sons in 1998 (Rocky Mountain Institute). From the findings set forth in their
publication, the authors of this book claim "the financial rewards of green
development are now bringing mainstream developers into the fold at an
increasll1g pace".
1. Land development and infrastructure costs for Dewees Island
(Charleston, SC), which used a LID approach, were 60% below average.
Thi~
was because impervious roadway surfaces and conventional landscaping were not
used. Porous sand roads and low maintenance native vegetation for landscaping
were instead utilized. However, it is important to note this island is car-free.,
which may contribute to the ease with which impervious roadways were avoided,
34
2. In Davis, California, developer Michael Corbett saved $800 per lot in
the two hundred forty unit Village Homes subdivision, by using natural swales for
stormwater infiltration in place of a storm sewer system. As a result of a better
looking product, homes here command $10 to $25 more per square foot than
those of surrounding developments, and homes sell more quickly when they come
onto the market.
3. Prairie Crossings near Chicago, Ulinois, is a 667 -acre residential
development. By designing infrastructure to reduce environmental impacts, the
developers saved $1.4 million total, and $4400 per lot. This was accomplished by
designing streets that are eight to twelve feet narrower than normal, minimizing
impervious concrete sidewalks, and using vegetated swales and detention bCl:;inJ
for infiltration rather than conventional storm sewer systems. In the
Davi~
;nd
Chicago examples above, savings were spent to enhance common open space ane'
other project amenities.
Pembroke, a half-acre plot residential subdivision in hederick County,
Maryland was the first Low Impact Development subdivision permitted in this
county, and one of few comprehensive LID subdivisions in the country. The use
of LID practices throughout the development enabled the developers to eliminate
the use of two stormwater management ponds they had envisioned in an earlier
site conception (NRDC 5). This elimination represented a reduction in
infrastructure costs of roughly $200,000. It also permitted them to preserve a 2.)
acre wetland and surrounding area in an undisturbed state, which resulted in
considerable savings for wetland impact mitigation. The use of LID site planning
allowed the preservation of approximately 50% of the site in an undisturbed
wooded condition. Site footprinting allowed developers to gain two additional
lots by using LID design, increasing the overall forty three-acre yield from sixty
eight to seventy lots. This added roughly $100,000 of additional value to the
project (NRDC 6).
Within Pembroke, the developers also converted approximately 3000
linear feet of road from "urban" to "rural" standards, by replacing curbs and
gutters with vegetative swales and reducing the paving width of the road from
35
thirty six to thirty feet. The use of swales saved the developers $60,000 in
infrastructure construction, and the reduced road width lowered paving cots by
17%, while reducing overall imperviousness (NRDC 6).
Another comprehensive Low Impact Development
IS
the one hundred
thirty-acre residential site of Gap Creek, in Sherwood, Arkansas. The developer
originally envisioned a site planned and developed in accordance with
conventional methods. When preliminary engineering and cost estimates revealed
unusually hrgh costs for such an ordinary development, the developer (Terry Paff,
President of Metropolitan Realty and Development in Sherwood), decided to take
a new direction. He abandoned the plan and opted instead for a 'sustainable' site
plan (Tyne 28). Table 3 below presents a comparison of the two different land
plans
~
PROJECTED RESULTS FROM TOTAL DEVELOPMENT
Total Site
Conventional Plan
Sustainable Plan
358
375
Linear Feet Street
21,770
21,125
Linear Feet Collector
7,360
°
Lot Yield
Street
Linear Feet Drainage
10,0C)8
6,733
103
79
$4,620,600
$3,942,100
$12,907
$10,512
Pipe
Drainage Structures:
Inlets/BoxeslHeadwalls
Estimated Total Cost
Estimated Cost Per Lot
36
TABLE 3 CONTINUED
ACTUAL RESULTS FROM PHASE I
Phase I
Conventional Plan
Sustainable Plan
(Engineer's Estimated
(Actual Figures)
Figures)
Lot Yield
63
72
Total Cost
$1,028,544
$828,523
$16,326
$11,507
Total Cost Per Lot
ECONOMIC AND OTHER BENEFITS FROM LOW IMPACT
DEVELOPMENT
Higher Lot Yield
17 additional lots
Higher Lot Value
$3,000 more per lot over competition
Lower Cost Per Lot
$4,800 less cost per lot
Enhanced Marketability
80% of lots were sold in first year
Added Amenities
23.5 acres of green space/parks
Recognition
National, State, and Professional
Groups
Total Economic Benefit
More than $2,200,000 added to profit
Tyne & Associates, North /,ittLe Rock, Arkansas (pg 28)
The numerous benefits of thIS design are documented in the article
"Bridging the Gap: Developers Can See Green - Economic Benefits of
Sustainable Site Design and I,ow Impact Development", written by Ron Tyne, the
37
project consultant. While the entire report documents the project benefits, the
following excerpts reference some specific economic benefits:
The LID design was projected to achieve a per lot savings of nearly
$2400. After completing Phase I, cost savings were almost $4800 per lot. When
completed, the LID plan also added 17 lots. So far, Terry Paff has been able to
sell his lots for $3000 more per lot than larger lots in competing areas. Upon
completion of the total project, Paff expects the added economic benefit resulting
from a 'green approach' will exceed $2 million over the projected profits (30).
With respect to cost savings for control mechanisms, the benefits of LID
are not only for construction, but also for long-term mamtenance and life cycle
cost considerations. The LID design also resulted in a reduction of landscape and
maintenance costs, by emphasizing the use of native trees, natural vegetation, and
low maintenance prairie grasses (30).
In 1999 the City of Olympia installed 1,500 linear feet of five and one half
foot-wide porous pavement sidewalk along North Street. The average bid for
regular concrete was $20/yard 2 , and $25/yard 2 for porous pavement. Estimates
during this time period were lower than the usual $30/yard 2 for concrete and $40
to $45/yard 2 for porous pavement. While using porous pavement increased the
total project cost approximately $10,000 over that estimated using regular
concrete, the total project savings was approximately $100,000 taking into
consideration the cost to obtain land for and construct a stormwater pond
(Tosomeen, pers. comm. 3/25/2003).
While cost savings and water quality and quantity benefits have been
documented in projects utilizing LID, land use plans that retain open space, a
rural landscape, and recreational opportunities also can contribute to the quality of
life of a community or region. A 1992 National Park survey of Chief Executive
Officers ranked quality of life as the third most important factor in locating a new
business. This should be of interest to regions and communities because as
regional economies become even more competitive, a high quality of life ranking
can provide a critical edge in attracting new businesses (Holland and Schueler
470).
38
As previously indicated, local conditions will dictate under what
circumstances Low Impact Development is most likely to be effective. The US
EPA states, "Detailed comparison of pre- and post development conditions and an
analysis of adjacent areas using traditional stormwater controls and LID practices
side by side would provide the best possible assessment of LID effectiveness"
(Literature Review 33). In an attempt to illustrate where this has been done with a
regional representation, an evaluation of the 2
nd
Avenue NW Street Edge
Alternative (SEA) Streets Millennium Project in Seattle is presented below, frorr:
Burges, Horner, and Lim's Hydrologic Monitoring of the Seattle Ultra-Urbar:
Stormwater Management Projects, 2002.
Evaluation of the SEA Streets project (an "ultra-urban" stormwater
management project) was undertaken jointly by the University of Washington
~
Center for Urban Water Resources Management and Seattle Public Utilities
through a memorandum of understanding in the summer of 1999. The project
was deigned to reduce stormwater quantities discharged to Pipers Creek.
The SEA Streets project represents a full street right of way design, on 2
111
nd
111
Ave NW between NW 117 and NW 120 streets. The roadway length of six
hundred sixty feet was reduced from a width of twenty-five feet to fourteen feet.
parking spaces were provided at angles to the street, and sidewalks were added.
The remainder of the sixty-foot right of way was devoted to runoff detention
ponds planted with native vegetation. The original right of way covered
approximately .91 acres, about .38 acres of asphalt and the remainder in
vegetation on the edges. The redesign reduced hard surfaces to approximately .31
acres, with the remainder given to ponds. The catchment area draining to the 2 nd
Ave NW pond system totals approximately 2.3 acres.
Results evaluated are from the period beginning just after the completion
of construction (approximately January 20, 2001) and concluding on April 30,
2002. The evaluation found that with the new street design, there was no dry
season (April 1,2001 through September 30,2001) runoff release, even during a
large August storm. Over the entire study period, 98.2% attenuation was
achieved. The mean average flow volume decrease was 99.5%. Two specific
39
rainfall events (January
(i
and January 9, 2002) yielded only 4.9% and 3.2%
runoff volume of the precipitation volumes falling on the catchment, respectively.
The SEA Streets design thoroughly outstripped the prediction made during
the initial study period that it would reduce total discharge from the pre-existing
street for equivalent conditions by only 42%. A project benefit ratio comparison,
determined using the overall retained volume of runoff per month under each
system, resulted with SEA Streets having a benefit ratio of 3.7 times that of the
original street at this location. The benefit ratio was equal to a factor by which
runoff discharged to Pipers Creek in wet months was reduced. In comparison to a
conventional street designed to the City of Seattle's current standards, SEA
Streets compared with a 4.7 times higher benefit ratio.
Overall, during monitoring the 2
nd
Ave SEA Streets project has prevented
discharge of all dry season flow, and 98% of the wet season runoff. Whereas all
events in the baseline monitoring period created a discharge, only about 10% have
since the project's construction. The SEA Streets design can fully attenuate 2300
ft 3 of runoff, which represents the volume produced by approximately 0.75 inch
of rain on its catchment. For context, the mean storm quantity at Sea-Tac
International Airport is 0.48 inch. Figures 2 and 3 on the following pages,
courtesy of Seattle Public Utilities, are photos of the SEA Streets project.
40
FIGURE 2
SEA STREETS CROSS SECTIONS
BEFORE AND AFTER
41
FIGURE 3
SEA STREETS AERIALS
BEFORE AND AFTER
42
Chapter 6
Discussion and Conclusions
The first sections of this paper address the potential of LID as an
alternative tool for stormwater management in the Puget Sound region. While it
is evident that technical and process-related questions exist, research and data
SUpp0l1 the notion that Low Impact Development holds promise as an effective
technique, in terms of both the cost to implement it and the benefits it projects.
As indicated previously there are questions among stakeholders about the
effectiveness of stormwater management programs. It would make sense when
investing time or money into answering these questions to extend the inquiry to
addres:; Low Impact Development.
One of the barriers to more common use of LID was identified as a lack of
available information. My research has mdicated this is not a lack of available
information on the subject as a whole, but more a lack of a 'regional
clearinghouse' for the information that does exist and a lack of projects in this
region to relate to local conditions. The lack of information is circular in that it
also ties in with a lack of education and training for many engineers, consultants,
developers and planners, who could then help further disseminate information
(Coffman, pers. comm. 4/25/03).
However, efforts are currently underway to address this lack of
information in this region, due primarily to the efforts of the Puget Sound WaLer
Quality Action Team (PSAT). The Action Team has accumulated information
regarding LID practices used in this region and published a manual entitled
Natural Approaches to Stormwater Management: Low Impact Development in
Puget Sound. The Action Team has also developed an assortment of educational
materials on the subject, and educated people at LID conferences and regional
workshops throughout Puget Sound (PSAT 2). This agency is in the process of
establishing itself as a potential clearinghouse for LID information and actively
engaging many communities in discussions regarding LID.
In terms of the more technical questions regarding design and technology,
consulting and engineering firms within the region have begun to use the "lack of
42
43
information" to their benefit. These firms, such as SCA in Lacey and AHBL in
Tacoma, have put forth the effort to educate themselves in LID strategies and
technologies and are creating a market niche for themselves as interest in LID
spreads. As LID catches on and becomes more competitive and people become
more comfortable with it, these firms will be able to capitalize on their expertise
(Coffman, pers comm.4/25/03). Business consultant Michael Porter, of the
Harvard Business School, cautioned in the Harvard Business Review:
We are now in a transi tional phase of industrial history in which
companies are still inexperienced in handling environmental issues
creatively ... The early movers - the co'mpanies that can see the opportunity
first and embrace innovation-based solutions, will reap major competitive
advantages, just as the German and Japanese car makers did [with fuel
efficient cars in the early 1970's] (Browning et al 7).
In addition, governments and establishments in the reglOn, such as the
City of Bellingham, City of Olympia and The Evergreen State College, have
begun to experiment with using LID technologies in their agency projects.
Examples include the City of Olympia's porous pavement sidewalk along North
Street and the Evergreen State College's implementation of recommendations
from its Zero Impact Feasibility Study. These include a garden roof on the new
Seminar 2 building currently under construction and rebuilding portions of its
parking Jot using pervious pavement systems (PSAT 28).
The City of Olympia's porous pavement project on North Street provides
a good working example of a barrier resulting from maintenance issues. Due to
the nature of porous pavement and the ability for the pores to become clogged and
inhibit infiltration, regular maintenance is required. However, as is fairly
common knowledge, Washington State agencies and local municipalities are
facing severe budget constraints at this time. The likelihood of the City installing
any further porous pavement as a part of City projects in the near future will be
limited duc the funding issues regarding requirements for its maintenance
(Tosomeen, pers. comm. 3/25/03).
The same maintenance issues exist in private developments and
maintenance responsibilities are often assigned to lot owners associations, or to a
44
single lot owner if the control is entirely placed within their lot. With association
maintained facilities and the lack of direct single-party responsibility, the
possibility exists that the maintenance will never actually be done, presenting the
same problem as the maintenance of conventional stCJrmwater ponds at the presem
time. However, in the experience of Larry Coffman there are multiple ways to
address the question of maintenance issues within a private development.
First, it has been his experience that individual controls placed on privaLi';
lots are better maintained than community or association maintained facilitie:s
This appears to be the case because the appearance and functiun of the contro:
have a direct effect on the value of the private property. To help educate the
private lot owners and associations, creation and designation of an ecological
committee is required as part of the lut owners' associatiuns when they are
created. Coffman stated that on a large scale, however, he does not feel these
concerns are necessary. This is because in mCJst cases the proper use of site
design techniques can minimize or do away with individual controls and,
therefore, the necessity for their active maintenance (Coffman, pers. comm.
4/25/03).
To illustrate construction challenges, porous pavement can again be used
a~
a good example. The mix designs for these types of systems are aggregate
specific, and testing of the mix is required each time it is done, resulting in higher
engineering costs The concer'1 is that this mix balance can be difficult to
maintain and tricky to specify. Education of the suppliers and lllstallers is
necessary, requiring additional time and money of developers and their
construction teams (Tosomeen, pers. comm. 3/25/03). However, as maintenance
issues are resolved, education increased, and example projects more prolific, a
market niche is likely to open up for those with experience in LID and expertise
in implementing its management practices. Investing in this education now may
prove to be of immense benefit for developers and firms in the future (DeForest
pers. comm. 5/21/03; Coffman, pers. comm. 4/25/03).
As indicated in the previous chapter, the process-related technical barriers
such as those discussed above seem to act as a diversion for avoiding larger
44
45
ljuestions and barriers to LID. The larger questions exist on a broader scale and
are more philosophical in nature. It has been my experience as a professional
involved in the development process that the efforts required to address details
such as these consistently arise during project design and are inherent in the life of
almost any project. Questions such as these, while important to address, are not
the real barriers that are going to stop LID development projects with a dedicated
and prepared group of applicants. Essentially, technical balTiers are not
necessarily specific to LID projects and are not necessarily the barriers that need
to be addressed to facilitate its acceptance and use. The primary balTiers exist in
getting to the point where dedicated and prepared applicants and staff exist. and
are capable of and committed to working with one another towards a common
goal
Recommendations
The first step in making LID more feasible will be a common
understanding of its true definition and a commitment to the goals it strives to
achieve. In essence, LID strives to maintain the predevelopment hydrology of a
site and treat stormwater runoff using the natural features of the site. The key to
understanding this goal is the fact that LID does not involve mitigating or
lessening the impacts of development on a receiving stream, but rather alleviatmg
them all together (Coffman, pers. comm. 4/25/03). Therefore, it is critical to
separate LID from other development techniques with goals of impact
minimization. Confusion or blurring of the lines among these techniques will
serve as a barrier to the implementation of LID because techniques involving
minimization do not command the same level of commitment as avoiding the
impacts of development on receiving waters.
Larry Coffman, creator and pioneer of LID, is adamant about separating
LID and organizations affiliated with its promotion from other strategies like
Conservation Design, the Center for Watershed Protection's Better Site Design,
and the EPA's "smart growth" endorsements (pers. comm. 4/25/03). It is not that
these strategies completely lack merit, but Coffman believes their focus on the
46
minimization of impacts will not require or lead people to recognize the fact that
as we change the terrestrial ecosystem we also alter the aquatic ecosystem, a chain
which he believes
begin~
with soils (pers. comm. 4/25/03). Other strategics often
consist only of relatively easy actions such as the minimization of paved surface:::.
that do noL reyuire a paradigm shift or focus on the consequences of human
actions.
Another issue resulting from the widespread use of conventional
mitigation practices is the question of cumulative impacts. Because conventional
techniques focus only on lessening development impacts, there is still the
potential for influence on receiving waters. There is concern this may
fundamentalJy alter a watershed's hydrological regime and water quality
adversely affecting receiving waters and the integrity of their ecosystems
(Coffman 195). This issue has been recognized as an important one, as the
Stormwater Policy Advisory Committee illustrates in their Report to the
Legislature. They outline an example of a coordination and implementation issue
that stakeholders identified as needing identification and prioritization as, "How
the GMA planning framework or other stormwater management mechanism takes
into account cumulative effects of development" (11).
Coffman questions whether strategies like those listed above even
realistically benefit receiving waters. Objects like paved surfaces possess
characters thaL result in effects on streams, bUL are not themselves the direct
effect. An example can be made using polluted runoff. While paved surfaces
contribute pollutants to the runoff resulting from precipitation, minimization or
removal of only this paved surface under typical development scenarios would
not alleviate polluted runoff. The compaction of soils results in an impervious
like surface that acts almost exactly like a paved surface. On a site with extensive
grading and compaction the lack of pavement will not result in benefits to
receiving waters. It is key that correlation be separated from cause (Coffman,
pers. comm. 4/25/03). In addition, these strategies often are not effective in infill
or retrofit projects. Again consider the polluted runoff scenario and compacted
46
47
soils remaining even after pavement has been removed. It is essential to
remember that streams run through these areas as well.
Related to the necessary paradigm shift for a true understanding of LID,
Coffman points to the way in which many rules and regulations address water
quality as a significant roadblock. Repeated mention of the "beneficial uses" of
waters has been made and can be found in the section of this paper relating to
stormwater laws and programs. However, specifically the EPA has traditionally
interpreted beneficial uses and the Clean Water Act to deal only with water
yuality. The customary interpretation of these laws and regulations has not been
extended to include the ecological integrity or physical or biological aspects of the
receiving waters (pel's. comm. 4/25/03), while the spirit of these laws is intended
to address these functions. When they are considered, the shortfall of many
traditional management techniques and mitigation measures are even more
glaring.
In terms of regulatory structure, much has been written on the critical need
for agencies and groups to work together if success is to be possible.
Washington's Water Quality Management Plan to Control Nonpoint Sources of
Pollution states, "Relationships between agencies, tribes, and key local
counterparts need considerable strengthening if water quality is to improve"
(Ecology 10). Aponte Clarke et al echo a statement to this effect in the "Water in
the Public Realm" conference proceedings. They have identified through over
lOO case studies that there are nine critical elements of effective stormwater
programs, two of which are strong leadership and effective administration (133).
The NRDC has carried this finding one step further, and promotes these nine
critical elements as recommendations for local action in the executive summary of
their Stormwater Strategies publication (5).
Elements like education and familiarity with Low Impact Development
projects and their results will be critical to the success of LID on a regulatory
level. As referenced in the previous section, the Puget Sound Action Team has
been active in taking on this role at a regional level and is striving to educate
stakeholders and broaden the base of available information. However, as
48
information and advocacy continue to gain momentum, the time is approaching
when an agency must step forward and enrich the information movement with
something concrete. This step most likely needs to be a pilot project that caL
provide monitoring data and act as a case study from which to gather results
(Booth, pers. comm. 4/16/03; Ecology, Final Plan 160). The SEA streets project
represents a step in this direction. An agency is also more likely to be successful
at catalyl.ing interest in a LID project because as Doug DeForest states, "Most
builders and developers are not innovators. They do not generally look down the
road, and their operations are focused on building on the land that is [readily
available] now" (personal communication 5/2l/03)
With the funding issues being experienced in the State of WashingLon
011<
undoubtedly in other areas, the question will be which agency should entirely
undertake or enter into a partnership to undertake an LID pilot project Different
individuals and agencies all have different suggestions. In Washington the
Department of Ecology has been given the responsibility for water quality by the
EPA under the Clean Water Act. The Puget Sound Action Team is responsible
for program planning and overseeing implementation of the Puget Souml Plan,
which has been adopted as a Comprehensive Conservation and Management Plan
for the Puget Sound Estuary and strives to control nonpoint sources of pollution.
However, the EPA has stated their analysis of water quality issues in Washington
State indicate nonpoint source control is largely a local land use issue with the
exception of forest practices (Ecology, Final Plan 10).
In the interim report to the Washington State Legislature, the Stormwater
Policy Advisory Committee issued a policy statement maintaining, "Washington
needs to clarify a collaborative stormwater leadership structure", referenced as the
"Coordination Team" (9). They recommend, "an effective convener for such a
structure is the Governor's Office, based on the opportunity for this team to then
examine broad problems and give legitimacy to solutions and players" (9). They
state that vesting leadership in (The Department of) Ecology is an option, as it
would provide "the benefit of close integration with direct stormwater regulatory
authority and strengthening program legitimacy". However, they also state the
48
49
importance of the perspective of the Coordination Team remaining broad, without
particular allegIance to any agency, program, or regulation (9).
The formulation of a Coordination Team under leadership of the
Department of Ecology working to clarify stormwater related issues would be
well vested to extend its area of inquiry to include specific analysis of Low
Impact Development. This is a logical suggestion for the reasons outlined above
regarding DOE's responsibilities for the promulgation of stormwater regulations.
Should this committee be able to represent a broad perspective as the SPAC
advised, local governments, developers, tribes, other offices of the Governor, and
numerous agencies would have the responsibility and opportunity to participate.
I find the issue of collaboration of mUltiple agencies, and particularly local
agencies, of great importance when examining the Department of Ecology's
(DOE) Water Quality Management Plan to Control Nonpoint Sources of
Pollution. In it DOE states, "six groups had a key role in developing this plan"
(313) followed by an outline of the composition of each of those groups. While
making statements throughout the document like, "A locally managed watershed
plan is one of the best approaches to implementing a Nonpoint Source Total
Maximum Daily Load "NPS TMDL (336)", "Enforcement by local
governments ... plays an important role in nonpoint source programs" (339), and
legitimizing statements, such as the EPA's regarding nonpoint source control
being largely a local land use issue, not one single local government
representative is listed as a member of any of these six key groups (313).
In accordance with formulating a coordination group or solidifying a
regulatory structure where stormwater issues can be identified and analyzed,
iJroblem definition is another key barrier to overcome regarding the acceptance of
stormwater regulations and management techniques. This barrier also relates to
the barrier of inaccurate definition recognized by Larry Coffman.
In terms of problem definition, the Stormwater Policy Advisory
Committee acknowledges a perceived lack of demonstrated benefit from
stormwater mitigation and control methods (13), or as identified previously in this
paper, the fact stakeholders questiop whether BMPs and IMPs are or can be truly
50
effective. They explain this perceived lack of demonstrated benefit is
compounded by inadequate problem and goal definition and that "it is difficult to
determine the best solution when the problem and its causes are complex and not
well defined" (13). I would argue this relates to Coffman's definition barrier with
regards to the ability (or lack of) strategies other than LID to force people to
recognize that their actions have an effect on receiving waters.
It will be essential for any Coordination Team to begin with the task lIf
illustrating this fact, adequately and accurately defining "problems', and
puhlicizlOg demonstrable benefits in the suggested solutions. In order to be able
to be to demonstrate benefits, a baseline from which to begin must be established.
As of April 2000, approximately half of Washington State's surface waters and a
vast majority of ground waters had not been monitored and needed baseline data
(Ecology, Final Plan 21). Consistent enforcement measures must also be
formulated to provide a sense of equity and establish accountability (NRDC 4;
Ecology, Taking Action 2 I). As it is recommended this route be taken for all
stormwater management and regulations at this point it seems very logical to
integrate LID into this process, as this would provide much of the data and
contribute to the comfo11level it is believed will be necessary for LID to be more
commonly implemented.
Regional planning processes and management coordination will be
required to add clarity to the process of stormwater management as a whole, and
to simplify the process of negotiating a predictable path through the regulations
(SPAC 8). In turn, if LID can be recognized as fulfilling the potential it has
demonstrated in this region, incentives and benefits must exist for developers and
interested parties to 'get on board'. The opportunities for consultants and
contractors to break into this market have already been discussed. In addition to
the information presented in this paper, developers must be able to depend with
almost absolute certainty on the fact their investment will provide returns. In
addition, permitting and approval processes cannot be so confusing, burdensome,
or unpredictable as to discourage an applicant from being interested in this route.
Additionally, permitting agencies and water quality authorities must he convinced
50
51
there is
110
risk involved in permitting projects such as these, and that the provided
controls will serve to protect the public health, safety, and welfare.
In terms of risk associated with these types of projects, r would
recommend exploration of a tool comparable to "stopgap" insurance. Stopgap
insurance typically functions as a protection to cover costs above and beyond
those estimated for a specific type of project. An example is costs associated with
environmental cleanup or decontamination of brownfields prior to redevelopment.
Stopgap insurance can be purchased in some cases and is being further explored
to cover unexpected costs resulting from pollution or contamination that is far
worse and costlier to address than originally expected and budgeted for. This sort
of insurance mechanism for LID projects could serve to address the fears of
possible failure or performance below an expected level.
On a similar note, the US EPA in conjunction with several states,
IS
currently exploring funding mechanisms and grant and loan programs for
brownfields redevelopment. I would recommend similar programs, primarily to
fund pilot projects by public agencies, be explored for Low Impact Development.
After projects have been constructed, monitoring must be carried out and
the results made widely available to both the public and the development
community (Booth, pers. comm. 4/16/03). At the present stage, I would suggest
monitoring schemes such as those required for wetland mitigation projects. These
typically require a 5-year monitoring plan be implemented at completion of the
project, with specific requirements regarding the content of the plans anJ specific
goals for which results will be gathered.
Generally a developer does not want to be tied to a project after its
completion and will not want to be bound by this requirement. A solution might
be a requirement that the developer bond for this monitoring, allowing the
permitting agency to hire a consultant at the specified time to determine whether
the project was indeed "successful" in meeting its established goals.
Unfortunately, it is also unlikely most developers will agree to be bound by
conditions of this sort, which do not appear to be incentives. In the long run, this
illustrates why it will likely be necessary for state, regional and local agencies to
52
"get the ball rolling" by participating in nilot projects ana gathering perlinenL
informatiun from their results.
Tn terms of ediJcation, as indicated previously, the Puget Sound Action
Team has begun the general education process in this area. Independent
contracturs and consultants are following, recognizing the need to educate
themselves in their respective fields to break into this market. Training for
agencies and the general dissemination of information, results, and success
ston~s
is also beginning to take place. Universities are recognizing the necessity fm
urban water resources and management programs, and the University of Nortil
Carolina, University of Virginia and Boise State have all implemented coEcge
level programs covering LID methods (Coffman, pel's. comm. 4/25/03)
One putential barrier to Low Impact Development that this paper does not
address is the financing of projects of this sort. In order for LID to be a truly
attractive and advantageous option, the securing of loans or credit for their
development must be as straightforward as that for any parallel project. It is
likely this will not be entirely possible until their effectiveness has been
established and successes have been recognized and can be counted on repeatedly.
Beyond these suggestions to facilitate generally better stormwater
management and Low Impact Development in paIticular, a final philosophical
and social issue relating to water protection must be recognized. This issue has
been referenced in numerous sections of this paper with regards to people's
reactions to something "new", our openness to change, and the necessity for
recognition of the fact that our habits and llfeslyles have an impact on water
quality and quantity. The NRDC recognizes, "LID
IS
much more than the
management of stormwater - it is rethinking the way we plan, design, implement
and maintain projects. Comprehensive [LID] programs usually compliment LID
practices with broader issues such as: considering where growth disturbance
should occur, increasing awareness of the cumulative impacts of development,
involving the community and raising watershed awareness ... " (3).
With regards tu questions relating to the preservation of water the
avoidance of the impacts of development on a watershed or receiving waters is
52
S3
unquestionably beneficial. However, the question of the effects of human habits
Clnd lifestyles outside of development must also be addressed if water protection
efforts are to be successful These include such issues as stream buffers, pesticide
and herbicide application, and combined sewer overflows (Booth, pel's. comm.
4/16/03).
Water protection will not be successful if development is the only facet of
human habits and lifestyles we acknowledge and address, and therefore LID
cannot do it alone. The Center for Watershed Protection notes, "While many
advances have been made recently in innovative stormwater practice designs,
their ability to maintain resource quality in the absence of the other watershed
protection tools (e.g. aquatic buffers and non-storm discharge) is limited"
(Holland and Schueler 132).
An example of a human habit that must be acknowledged is our
proliferating population, which has been identified by many as a factor in
environmental problems worldwide, including stormwater. In their article
Stonnwater Management: Shifting the Present Paradigm, Ballantine, Clarke and
Wilding recognize, "It appears as environmental efforts take one stride forward
today to improve the water quality of a watershed, the water quality in the future
will be taking two or more steps backwards with the addition of more people,
more impervious area, and more runoff being managed by poorly maintained
ponds" (55). In Washington in particular, the Department of Ecology maintains,
"Population growth has had a disturbing impact on water availability that in tum
impacts the quality of the water in streams and rivers" (Final Plan 15).
Closing thoughts
Throughout the ten years that Larry Coffman has been involved in the
creation and growth of Low Impact Development, he relates he has consistently
experienced a single initial reaction. This reaction is ridicule. His advice?
WORK THROUGH IT. Larry relates that time and again, this initial reaction is
followed by a process of consideration, in which new information begins to
accumulate and people become more comfortable with a dIfferent style. lIe states
54
that what then follows is a recognition that "it works", which is then followed by
(' gain in its acceptance and its engagement into convention. LID is not a
technique that will be accepted overnight, and the acceptance process is a slov,;
one. Derek Booth relates he believes its common acceptance in this region will
take five to ten years, unless there is a significant shift in the approach of all
involved parties, and we begin to seek the information we say we need rather than
wai tlOg for it to come to us.
Two quotes from Albert Einstein are in hindsight eerily applicable to this
situation and to almost any situation relating current environmental problem::: arc
technology. The first quote reads, "Any intelligent fool can make things bigger
and more complex ... It takes a touch of genius -- and a lot of courage -- to move
in the opposite direction." The second states, "The significant problems we face
can not be solved at the same level of thinking we were at when we created
them." It is evident that the wisdom of these statements has not changed, and
recognition of this fact can be found in Ecology's Stormwater Management
Manual for Western Washington:
The engineered stormwater conveyance, treatment, and detention systems
advocated by this and other storm water manuals can reduce the impacts of
development to water yuality and hydrology. But they cannot replicate the
natural hydrologic functions of the natural watershed that existed before
development, nor can they remove sufficient pollutants to repJicate the
water qua1ity of pre-development conditions. Ecology understands that
despite the application of appropriate practices and technologies identified
in this manual, some degradation of urban and suburban receiving waters
will continue, and some beneficial uses will continue to be lost due to new
development. This is because land development, as practiced today, is
incompatible with the achievement of sustainable ecosystems. Unless
development methods are adopted that cause significantly less disruption
of the hydrologic cycle, the cycle of new development followed by
beneficial use impairments wiU continue. (1-21).
54
55
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