EPA440/9-77-001
January 1977
Preventive
Approaches to
Stormwater
Management
-. - - - I Ml NIMIZ E9 buRPACE RUNOFF
COLLECTS RUNOFF FR0M PAVED STREETS iSU?pE g,EL^W
STRUCT U8AL /V\EAb4S
WATERWAYS
WITH OUTFLOW TO
PRAlM
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q? *nl TP 1S 1SS!!ed under Sect1on 3M(e)(2) of Public Law
208 ?hH?Uflr ^r6133!^0 SUpP°rt implementation of sections 208
208 (b)(2)(A),(B), and (C) of the Act. Section 304Ce)(2) provides:
The Administrator, after consultation with appropriate
Federal and State agencies and other interested persons
shall issue to appropriate Federal agencies, the States,
water pollution control agencies, and agencies designated
under section 208 of this Act, within one year after the
effective date of this subsection (and from time to time
thereafter) information including (1) guidelines for
identifying and evaluating the nature and extent of non-
F,nHnt thU$Ce? °f PoUutants, and (2) processes, procedures,
and methods to control pollution resulting from -
"(A) agricultural and silvicultural activities, including
r""°ff from fields and crop and forest lands;
(B) mining activities, including runoff and siltation
from new, currently operating, and abandoned surface and
underground mines;
*u(Ci al11.c9nstruct1°n activity, including runoff from
the facilities resulting from such construction;
(D) the disposal of pollutants in wells or in sub-
surface excavations;
"(E) salt water intrusion resulting from reductions of
fresh water flow from any cause, including extraction of
ground water, Irrigation, obstruction, and diversion; and
II-; changes in the movement, flow or circulation of
any navigable waters or ground waters, including changes
caused by the construction of dams, levees, channels
causeways, or flow diversion facilities.
Sections 208(b)(2)(A), (B), and (C) provide:
"(b)(l) Not later than one year after the date of any
designation of any organization under subsection (a) of
this section such organization shall have in operating a
continuing areawide waste treatment management planning
process consistent with section 201 of this Act. Plans
prepared in accordance with this process shall contain
alternatives for waste treatment management, and be appli-
cable to all wastes generated within the area involved.
The initial plan prepared in accordance with such process
snail be certified by the Governor and submitted to the
Administrator not later than two years after the planning
process is in operation.
"(2) Any plan prepared under such process shall include,
but^not be limited to-
"(A) the identification of treatment works necessary to
meet the anticipated municipal and industrial waste treatment
needs of the area over a twenty-year period, annually updated
(including an analysis of alternative waste treatment
systems), including any requirements for the acquisition
of land for treatment purposes; the necessary waste water
collection and urban storm water runoff systems; and
a program to provide the necessary financial arrangements
L i development of such treatment works;
(B) the establishment of construction priorities for
such treatment works and time schedules for the initiation
and completion of all treatment works;
' ii/h? estab11snment of a regulatory program to-
(i) implement the waste treatment management
requirements of section 201 (c),
"(ii) regulate the location, modification, and
construction of any facilities within such area
which may result in any discharge in such area, and
(m) assure that any industrial or commercial
wastes discharged into any treatment works in such
area meet applicable pretreatment requirements; ..."
If^f-H™0?™011^ M? °,f Sen?ral 1ssued to support implementation
of section 208 of Public Law 92-500 concerning the control of water
pollution from urban runoff and other associated nonpoint sources of
pollution. Other reports include: "Areawide Assessment Procedures
naLUal^VOlUT V"d "' EPA 60«/9-76-014, July 1976 and "Proceedings -
Hn! PB260889?er Management Semi"ars", WPD 03-76-04, January 1976,
This document was prepared for use by local agency administrators,
and others who may be involved in programs to abate pollution from
urban runoff Jh concept of source control (BMP) has been discussed
}n » R PaSMS th1S rep°rt I1st5many techniques that would be included
in a Best Management Practice. The problems associated with imple-
menting these practices, legal, financial, and institutional are
also discussed.
The objective of this study was to provide a basic understanding to
1"3 °" "^ BMP 1S ^ th°S6 tecnn1a.ues which would
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON,; D.C. 20460
MAR 3 B77
SUBJECT: "Preventive Approaches, Jo Stormwater Management"
f l I£$?%^' Ar^OTrector
FROM: Vv Edmund Notzon, Acfnng u^rector
X Uatav Plannina Division i
TO:
\Water Planning Division
v x \
\11 Regional. WaterHlivision Directors
All Regional. 208 Coordinators
Technical Guidance Memorandum: TECH 30
Purpose
^
urban stormwater pollution.
Guidance
The enclosed
...
describes .Wment techniques that should t» ^
arrangements with a case study.
Enclosure
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EPA 440/9-77-001
PREVENTIVE APPROACHES TO
i
STORMWATER ]VtANAGEMENT
Contract No.j 68-01-1945
January j!977
Project Officer
Dennis N. Athayde
Water Planning Division
Office of Water Planning & Standards
Washington,! D. C., 20460
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ACKNOWLEDGEMENT
The efforts described in this report were performed for the Nonpoint
Source Branch of the Water Planning Division of EPA under Contract
No. 68-01-1945. The work was performed under the direction of
Mr. John Willson of Abt Associates Inc. Abt personnel contributing
to this project were: !
Dr. Malcolm Fitzpatrick
Dr. Michael Koplan
Mr. Edward I. Selig
Dr. Richard Howe
Mr. Nicholas White
Chapters 1, 2
Chapter 3
Chapter 4
Chapter 5
Chapter 5
and Mr. Andrew Waldo of EPA who was responsible for Chapter 6.
A project Review Panel was established to review and advise during
conduct of the program. Panel members are listed below:
Dennis Athayde
Robert Bastian
Francis J. Condon
Albert Herndon
Earl Jones, Jr.
David Reynolds
USEPA
Washington, D. C. 20460
U. S. Army Corps of Engineers
Washington, D. C.
USEPA
Washington, D. C.
USEPA
Atlanta, Georgia
Federal Housing Administration
Washington, D. C.
Triangle J Council of Government
Raleigh, N. C.
The project officer wishes to acknowledge the invaluable assistance of
Mr. Andrew Ellicott, Mr. George Fleming, Dr. Joseph Yance, and
Mr." William P. Somers for their fin^l reviews.
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Environmental Proecton Agency
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TABLE OF CONTENTS
Page
1.0 INTRODUCTION |
1.1 Urban Runoff as a Source of Wat4r Pollution
1.2 Best Management Practices for Urban Runoff
Sources of Water Pollution j
1.3 Objectives and Organization of jtne Manual
2.0 HYDROLOGY AND URBANIZATION j
2.1 Natural Determinants of Runoff i
2.2 The Runoff Impacts of Urbanization
2.3 Runoff impacts and Water Qualify Problems
2.4 Protection of Environmentally Sensitive Lands
3.0 TECHNICAL APPROACHES !
3.1 Measures to Reduce Runoff Pollution Due to Surface and
Subsurface Pollutants I
3.1.1 Street Litter j
3.1.2 Highway Deicing i
3.1.3 Fertilizers and Pesticides
3.1.4 Land Disposal of Wastesj
3.1.5 Infiltration/Inflow .
3.2 Measures to Reduce Runoff and jEncrea.se
Infiltration !
i
3.2.1 Delay of Runoff On-Site|
3.2.2 Increased Infiltration pn-Site
3.3 Erosion and Sedimentation Control Measures
3.3.1 Vegetative Measures ,
332 Diversion Measures and 'Slope Drains
3".3]3 Mechanical Slope Stabilization Techniques
3.3.4 Stream Bank Stabilization Measures
3.3.5 Design and Stabilization of Surface
Drainageways j . .
3.3.6 Other Erosion and Sedimentation Control
Measures |
4.0 REGULATORY APPROACHES j
4.1 The Legal Framework and the Scope of
Legal Authority ,
1
2
3
5
8
8
16
21
25
33
37
39
43
46
47
49
51
52
60
68
74
80
84
87
93
97
105
107
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TABLE OF CONTENTS
(Cont'd)
4.2
Specific Regulatory Approaches and Techniques
4.2.1 Acquisitions of Land for Open Space
and Other Non- Intensive Uses
4.2.2 TMe Phased Capital Investment and
Development Guidance
ce
4.2.4 Environmental Impact Assessments
I'l'l ^Vlr°mental Perfor™e Standards
4.2.6 Erosion and Sedimentation Controls
4.2.7 Controls Over Land Disposal of Wastes
4.2.8 control of inplace or Accumulated Sources
4.3 Legal Issues
4.3.1 Securing Compliance Through Monitoring,
°f
5.0
5.1
5.2
5.3
6.0 INSTITUTIONAL ARRANGEMENTS
6.1
6.2
6.3
4.3.3 Eliminating Windfalls and Wipeouts
FINANCIAL CONSIDERATIONS
Financing the Planning Process
Financing the Management Process
Approaches: Five
112
112
115
117
120
123
128
132
134
135
135
139
142
150
154
155
156
170
A Brief History: Leon County, Florida
SELECTED BIBLIOGRAPHY
176
188
192
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1.0
INTRODUCTION
This manual is designed to help lobal planners, administrators,
and elected officials meet their responsibilities regarding management of
urban stormwat^ runoff under the 1972 amendments to the Federal Water
Pollution Control Act (PL 92-500). The UJS. Environmental Protection
Agency believes that stormwater runoff is | a problem of increasing seventy
which must be dealt with in -urban and developing areas alike. *he approach
suggested in this manual is to minimize the adverse water quality impacts
of runoff through a system of source consols. Source controls .tress the
reduction and prevention of funoff pollution before it ever reaches a
collection system or receiving waters. S?urce control is the central
tenet of the various management methods recommended in the manual-so-called
Best Management Practices or BMPs. These: BMPs are intended to help Section
208 areawide and other water quality planners adequately address the
stormwater management problems prevalent Jin their particular locality.
The manual is intended to serve as a companion volume to a separate
EPA study of techniques for data collection, analysis and evaluation of
alternative approaches to urban stor»at*r management. That volume presents
a simplified approach to an initial evasion of the overall s to rmwate,
situation in a specific urban area, and of the costs and impacts of a
variety of alternative solutions. In contrast, this manual is designed to
introduce the nature of the stormwater problem to concerned off.ca.als
and suggest preventive approaches, including a discussion of the legal,
:£JL. aid institutional issues whic^ must be addressed .if these prevents
approaches are to be implemented. | »
Because the stor-ater pollution proW.rn.has only recently received
systematic attention and, further, because source control technology
are still under investigation, much w=4 «— «- * >•_*»- am
ho»ev.r, promises to be a workable. effective, and relative!* inexpensive
means of pollution abatement, according to available evidence.
specifically delegates responsibility f6r refinement- and implementation
of Best Management Practices to design.Ud areawide agencies and the states.
.he Preventive approaches suggested in ^is manual are intended to help s ate
and local officials begin this task. l|t remains to them to adapt and tarlor
^approaches to suit their o™ specific regents for local implementation.
i
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the past
separate storn
pollution i. the result of preoipitatlon
on „ toan area pl(;ks
ana
! galvanlc corroslon
part10mates, ana chMlioals allied for f.rtiliz.tlo», control of ice
rodents, insects, and weeds.
of „ ^ r1™"6 CMSS °f ^ poiiuti°n may be t~*
of nan, and ,flve sources My be readily identifled. ue
effect of Cavity, du5t ana other p»ticulate .atter falls on «J urban
™«t or is rash,a from tte alr ^ ralnfall.
ull e "^ £"m " irea> ^ ^^ ^^ ™°-tS "«- »^ln the
urban envlrol»ent. second, the residual ^uct, of auto^ilea, trucks,
metals'
fro, «... carelessness litters the streets and is a Mjor souroe
™ of sediment. filthf and finaXl,, nie^l industr.a!. co^erlx IT
do^st^c ho=K-ups to stom severs contrite a nu*er of specific Pollutants,
e.g., used motor oil. uctu^,
Polluted runoff contains substantial amounts of organic material
-organic solids, and coliform bacteria, other pollutant, include nutrients
pestzcxdes, and heavy metals. Clearly, these pollutants degrade the
receding water quality, ^is degradation often results in decreased '
dissolved oxygen level and high turbidity. Coliform bacteria indicates
the presence of pathogenic bacteria which are pollutants. Moreover, nutrients
« the form of nitrogen and phosphorus contribute to increased eutrophication
rates, although runoff contains pesticides and heavy metals , their impact
on aquatic environment is yet largely unknown, though recent evidence sug-
gests that the presence of heavy metals decrease., the diversity of aquatic
-DlOtcl •
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The direct effects of runoff u]?on water quality are manifold.
or poorly regulated runoff acelerates the erosion of land
"D*l_3.ritS T?lllS i^iWJ.AVAJ-1--1-*-'" — — i
standards, regardless of the degree of treatment afforded dry weather
WaSte WTday!°glven the realities of industrialization, urbanization, and
population increase, it is evident that |environmentalcontrol is a cr^cal
factor. Wise use and control of water esources is necessary X ^e
water resources are to be protected, the problem of the urban
must be dealf,with. As a small part of|that larger problem,
runoff represents a significant source
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The preventive concept best applies to.developing urban areas, for
these are areas where man's encroachment is more subject to control and
draxnage is essentially natural. These areas offer the greatest flexibility
of approach in preventing pollution. What is required is to manage th*
expected development in such a way as to maintain a runoff regime as close
to natural levels as possible. It is in these new areas where proper
management practices can help prevent long-term problems, and hence, the -•
reason for this- manual's concentration upon managing the runoff problems
associated with the urbanizing process.
Many of the BMP's are based on the concept of flow attenuation.
Plow attenuation, in a hydrologic sense, means to increase the time of
concentration and decrease the magnitude of the peak runoff. Less erosion
results because reduced runoff velocity reduces the erosive force. ; .
Also, with this approach, large volumes of water are not allowed to rapidly
accumulate at constrictions but flow at reduced rates over a longer period of
time, thus diminishing the possibilities of localized flooding
*he improvement in water quality results from reduced pollutant loadings
being conveyed to the receiving stream.
Best Management Practices are an integrated approach incorporating
both source and collection system controls. Source management deals
with pollutants where they accumulate, before they are washed into the
receiving waters. Collection system management begins .with the ground surface
and ends with the sewer outfall. As a planner looks to his own particular
area to implement a program for stormwater management, a number of different
management practices or techniques may suggest themselves. The object of
Best Management Practices is to choose from among the combinations of
technical alternatives designed to address the specific problems of the
local area those which for legal, financial, or institutional reasons could
most reasonably be implemented. Those combinations would be the Best
Management Practices for that area.
According to EPA policy, Section .208 of the Federal Water Pollution
Control Act Amendments of 1972 is intended to be the planning mechanism for the
development of Best Management Practices to control urban stormwater runoff
pollutxon. By definition, stormwater runoff discharges may ±e either point
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« - , .or combinations of the t». (40 « 124.
U303 - 11307,) in the regulation promulgated by the Environmental
Agency, separate storm sewers located In an urban area and primarily operated
for tne Purpose of collecting and conveying stouter runoff come under, the
Hational Pollutant Discharge Elimination System as point sources. It ,s
provided, however, that the EPA Administrator or the appropriate
segional Administrator may designate as i significant contributor of pollu-
tion any discharge of pollutants into navigable waters fro. a stor^ater.
runoff conveyance, even though it is not; located in an urban area, ,n th.s
event, such a conveyance would come «nae|r the regulation. At thls stage,
the proposed regulations authorize discharges from separate •*«•-»
subject to: (1) any future regulations which EPA might issue, and (2) the
right of the permitting authority to require individual storm sewered
dischargers to apply for conventional KPDES permits.
Objectives and organisation bf the Manual
1.3
.anual is intended to helpjlocal officials answer the following
general questions:
What
(1) HOW does the process of urian Development alter the natural
hydrologic cycle and cause, stormwater runoff pollution.
ic physical control measures are available under a
appProLh to stormwater management, and how are
they implemented? '•
lega? issues, if any does their use raxse?
(4) What financing needs do preventive approaches entail, and how
best can these be met? !
"
between and among levels of government best be achieved.
^though these questions are raised in| the manual, detailed answers in terms
of technigue efficiencies, cost requirements , and effectiveness evaluates
are beyond the scope of this volume, kf one word describes the nature of
the stormwater runoff problem, that wo|rd is "variability." Each co-.un.ty
: 5
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loo, to the problems indlgenous to ±ta p>rtlottur ^^ ^
Best ^agement Practices which apply. For ^ ^^ ^
suggest important relationships and introduced, range of issues
be considered for stouter Managemsnt, but ±t oannot pra ^
o deal "ith the speciflc water quali
to the particular sto»,ter „„„>„ situation.
of «,. BMP concept ^ ^ ^ ^ ^ ^ &
been
i.
so ttat tb. reader
or
2 provides
refer to just
brief overview' of the hydropic cycle, the
vew o te hydropic cycle, the
aeter^ant, of an area.a runoff characteristics , the ,ater ,uality activities
lid, *«*«•'**- P«-»ted by certain envirome;»t,lly sensitive
«.-«• ^f^^ PrSSentS' " "°'5Ular faShi0n' a"»^-- of a series of
l ! °al °°ntr01 "eaSU1:eS "hi* CM te ^^ * P^at. developers
local goTOnts to prevent runoff pollution, as appropriate, i,le!
^on .echanis^s are described and successful local e^l.s provided
Chapter 4 discusses the available rectory approaches for preventive
stouter ^ana^ent, their relationship to the !egal structure of Lai
government ^ers, ana lega! issues surroun^ their use. igain,
examples of their application ,re supplied.
* " «— -1 issues, Una con-
—•*• -*-»-•» \*t?o f • ditto. C
D M . ^ C°VerS fUnd±ng needS' av^lable funding sources, arid the
problems xnvolved in putting needs and sources together.
ChafiterjL focuses on the critical institutional problem
implementation of preventive approaches t-h^ *
Jtr£rJ~^^«.t*JLi.CJo • TUlrtTL OT* CJja/^nvT vt«v -*- **-
. * / *-*i&u ui secujTing the
intergovernmental coordination. ;
* seperate bibliography-is. provided at the bade of this voiume.
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The various chapters do not necessarily have tb^be read in order.
Each is meant to stand alone, although ah effort has:been made to interrelate
them at a number of key points. The initial chapter on Hydrology and
Urbanization (Chapter 2) is intended primarily for nontechnical readers and
thus may be skipped entirely by those persons who already -have an adequate
understanding of the relationship.betweeh urban development and water qualxty.
REFERENCES
l of the Water
Control
Vol.
, No
June 1975, pp. 1352-1369. j
EPA Contract No. , with Hydroscienqe , Inc. ..Walnut Creek,
California (in progress). j •
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2.0 HYDROLOGY
AND URBANIZATION
the
the
of urban hytology
discussions of prsventive approaches to
oribes
with
of
°rban aeveiopnent
in rmo« cha»cteristios ,« then
, then
to
to the neea to protect certain environmentally sensitive laCjs
intensive aevelop»ent because of potentially serious .at« quality (an
natural system) impacts of runoff.
2'1 Natural Determinants of Runoff
The Hydrologic Cycle
The hydrologic cycle refers to the.cycle which takes water from the
ocean or land surfaces by evaporation, transports it by winds across large
dxstances during which condensation occurs, and deposits the water on the
earth's surfaces in the form of precipitation (rain, snow, etc.). Once
•there, ^ water gravitates downward ^^ ^ ^^ ^
discharged xnto the ocean or being returned to the atmosphere by evaporation
and translation. The hydrologic cycle is shown schematically in ,igur,
2.1. Especially important to remember is that the individual processes
wxthxn thxs cycle do not occur sequentially, but concurrently, being sup-
plied wxth energy from the sun and gravitational forces
PRECIPITATION
CONDENSATION
TRANSPIRATION EVAPORATION
SURFACE FLOW
SUBSURFACE FLOW
8
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For ease of presentation, the impacts of both natural and man-made
forces on this cycle can be discussed at the level of the individual watery
shed. A watershed is an area bounded by higher elevations, draining ulti-
mately to a single low point at which one
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Figure 2.2
Example of Watershed, Shewing
Natural Contours and Initial Development
| WATERSHED
"^ BOUNDARY
10
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INCHES
OF
EFFECTIVE
RAINFALL
Op
Q (ft3/sec)
DURATION
INTENSITY
Figure 2.4 Example of Hydrograph Showing
Surface and Subsurface Stream
Flow for a Given Rainfall
tp (seconds)
INCHES
OF
EFFECTIVE
RAINFALL
Qpj
Op
Q
.DURATION
Figure 2.5 Example of Hydrograph Showing
Increased Peak Flow from a Rain-
fall of Increased Intensity
INCHES
OF
EFFECTIVE
RAINFALL
QPD
Op
DURATION
Figure 2.6 Example of Hydrograph Showing
Increased Flow from a Rainfall
of Same Quantity (as Figure 2.5)
but of Longer Duration ;
12
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watershed has its own unique! hydrograph relating total and
runoff to time for a given rainfall. Thi's is reflected in its unit hydro-
graph, that hydrograph resulting from onej inch of direct runoff from a storm
oT^ecified duration.
1 Construction of a unit hydrograph for a particular
watershed permits one to develop probable! hydrographs for many different
types of storms and their resulting runoffs. However, any change in the
natural factors which affect runoff willchange the hydrograph for that water-
shed.
Variables Associated with the Natural Environment
The amount and rate at which wat^r gravitates from the point it hits
the earth to another point is determined; not only by the duration and inten-
sity of the rainfall but also by the characteristics of the surface across
which it has to flow. These factors can! be grouped into those affecting in-
filtration and those affecting velocity.! Together these factors determine the
rate of flow (velocity) and the percentage of rainfall which infiltrates into
the ground, and thereby does not become Jan immediate part of the runoff.
Infiltration will depend upon the porosity of the surface and the
length of time the water is able to stanjd on that surface and seep into the
soil. infiltration is facilitated by trie presence of bogs, swampland,
marshes, and surface depressions which have poor drainage. The rate at which
water permeates into the soil is' determined by the soil type itself, unless
soil density changes. For example, "packing down" of the soil. or the paving
of the surface decreases infiltration, j Subsurface flow, in terms of the
hydrograph, is significant due to the extended time it takes for this quantity
of water to flow out of the watershed. | A decrease in subsurface flow will
result in a larger quantity of runoff if a shorter period of time.
Velocity is the distance the flow tra.vels in a certain time period.
It is usually measured in feet per secohd (fpe). Velocity is reflected in
the hydrograph in both the vertical and| horizontal axes. The vertical axis
is the quantity of water (Q) , measured |in cubic feet per second (cf s) , that
traverses a given point in the watershed at a certain time. The quantity of
flow (Q) by the point of measurement is' equal to the result of the cross-
sectional area (A) through which that flow occurs times the rate of flow or
velocity (V) : Q = AV. The horizontal jaxis of the hydrograph is time (t) .
As such, it measures the time it takes j for water to gravitate through
1 13
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the watershed. Therefore, any changes in the factors that affect the time it
takes to pass through the watershed affect both the quantity of flow and the
velocity.
•The factors which affect velocity for a given flow can be grouped
under the following headings:
• the extent of the surface over which the flow has to occur
• the slope down which the flow occurs
• the roughness of*the surface over which the flow occurs.
The effect of the extent of the surface area on runoff flow will vary with
the type of flow. In shallow "overland" flow the runoff occurs in a very thin
flow over a large surface, whether it be pavement or forestland. m shallow
overland flow the ratio of the cross-sectional area of runoff to the surface
which it "wets" during the runoff is very small.3 The containment of flow, as
by "channel" flow or "storm sewer" flow, effectively reduces the surface area
wetted by the flow to those surfaces which contain that flow. The largest ratio
of cross-section of flow to surface affected by that flow occurs when a nearly
full pipe is reached. The larger the ratio, the higher the velocity of flow.4
Figure 2.7: Ratio of Cross-Sectional Are
Wetted, by Type of Flow
Overland Flow:
lowest ratio
Channel Flow:
high ratio
Sewer; Flow:
higher, ratio
The effect of slope on runoff flow is such that, for any type of flow, the
velocity of the runoff increases with an increase in slope. For flow con-
fined to channel flow or sewer flow, the velocity varies directly as 'the
square root of the slope. ;
The effect of the roughness of the surface on runoff is inversely pro-
portional to the measure of the extent of the roughness; a decrease in the rough-
ness will increase the velocity. For shallow overland flow, the interrelation-
ship between slope and surface roughness (as represented by forms of vegeta-
tion) and the resulting effect on velocity is shown in Figure 2.8, a graphical
14
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Figure 2.8: Average Velocities for Estimating
" Travel Time if or Shallot ©vearlafid Flow
1 I 2
VEUCITV W FEET PER SECfli®
10
20
I
'15
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.'representation. For example, for a given 2% of slope, the runoff velocity
(fps) increases from .3 (for forest with heavy ground litter and meadow) to
.66 (for fallow or minimum tillage cultivation) to 2.75 (for paved area).
For contained flows, such as channels and sewers, a coefficient of
roughness has been derived for various surfaces.6 This means that th.
confinement of a stream to a smooth metal pipe (having a coefficient of
0.010), from a previously very weedy and sluggish natural channel (having a
coefficient of 0.112) may have effectively increased the velocity by
ten times in the case of this example.
. A summary of the factors which affect the runoff characteristics of
a watershed is shown in the following figure, Figure 2.9. Channeli2ation,
which is usually thought of as a man-made process associated with
urbanization, is also a natural factor Effecting infiltration and,
surface runoff. Channelization often occurs in large streams during flood
stages, as a result of the velocity and quantity of flood waters; it can
readily be seen in relatively flat terrain where the ox-bow bends of former
rivers have been left behind. During flooding the torrent of the flow cuts
across these bows, thereby straightening out the streams and permitting a
larger volume of water to flow over a shorter distance. After the flood
recedes, usually a new meander or bow is formed due to the natural forces
2.2
The Runoff Impacts of Urbanization
The urbanization process often results in physical alteration of
the environment. Many of these changes result in immediate benefits,
including increased densities and the use of the property under a
wide range of environmental conditions, including intense and prolonged
precipitation. However, such development brings about changes in those
factors which determine an area's runoff characteristics and thereby
affects the hydrologic cycle. Inappropriate or unregulated development can
also lead to secondary effects on other parts of the environment. For
example, a decrease in infiltration because of extensive surface paving
can result in lowering of the water table, thereby killing trees which carry
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Figure 2.9: Factors Which Affect Runoff Characteristics
Physical Factors
Soil Porosity
Drainage
Infiltration
Channelization
Slope
Surface Roughness
Velocity
Impact of Factor on RUnoff Characteristics
Infiltration is affected py actions which change the imperviousness
of the soil; such actions include soil composition and surface pave-
ment, thereby reducing infiltration
Infiltration is assisted by drainage which retains runoff, thereby
providing additional time for the water to infiltrate. Bogs, swamps
and other surface areas| provide temporary retention areas, thereby
providing increased infiltration times and a reduction in the peak
flows of small runoffs.j
Both velocity and quantity of runoff determine amount of water
which can be infiltrated; a reduction in either of these factors
increases the potential'amount of water which will infiltrate into the
ground ]
The velocity of water being drained from the area is a function of
the distance over which it has to travel, the surface bed, and the size
of the channel: by creating a channel which shortens the distance
and reduces the surface roughness, one facilitates an increased
velocity. The quantity of runoff is increased by an increase in the
effective cross-sectional-area of the channel.
i
I
The velocity of the runoff is directly related to the slope of the
watercourse, as demonstrated in the Manning equation (velocity is
a function of the square root of the slope). Any increase in the
slope will therefore increase the velocity of the runoff from the area.
The velocity of waterjrunning off an area is inversely proportional
to the coefficient of roughness associated with the surface
The quantity of water which can run off from an area is a function
of the velocity of the!runoff (and therefore of all those factors
which affect velocity) and the cross-sectional area through which
the runoff can occur.; •
17
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out the transpiration;of vapor to the atmosphere. The destruction:
of these trees permits the sun to heat the pavement, thereby increasing
the ambient heat and making the local environment a "heat island." !
Preventive approaches seek to minimize changes in the natural hydrograph of
an area and reduce or eliminate such secondary environmental effects.
The usual result of the urbanization of an area, whether it be a
large-scale development in a short period of time or an equally large devel-
opment over several years, is a change.in all the factors which affect runoff;
» a decrease in soil porosity through compaction \
• an elimination of surface areas which retain precipitation
• an increase in impermeable surfaces '
• a construction of channels and storm sewers to carry off
the excess surface water
• an increase in site slopes due to terracing
• a decrease in vegetation (trees, grasses, shrubs, etc.)r
thereby decreasing transpiration and interception
• an increase in the smoothness of surfaces.
Often one change can have an effect on several of the factors which affect
infiltration and the characteristics of the runoff. For example, the
paving of a surface reduces permeability of the surface, reduces vegetation,
and reduces infiltration, thereby increasing the quantity of runoff and the
velocity of that runoff, while reducing the amount of water which'will in-
filtrate into the ground for downstream flow augmentation.
The impact of the urbanization process in terms of the hydrograph ia
shown in Figure 2.10, which for ease of understanding is divided into three
parts. However, in the natural process, these impacts occur together, for -
they are interrelated. It can be seen that the immediate quantity of the
runoff is greater and that it occurs earlier, with the increase in runoff
velocity, it takes less time for the water to concentrate and, .therefore, a
greater amount of runoff occurs earlier. This increased concentration of
runoff is augmented by that quantity which is no longer able to permeate
into the soil.
IS
-------
i
Figure 2. 10: Impact of Urbanization as Reflected!in Changes of Hydrograph
INCREASED PEAK FLOW
ORIGINAL
'HYDROGRAPH
Figure 2.10a. Impact: Increased Peak Flow
DECREASE? TIME BEFORE PEAKING
1 Figure 2.10b. Impact: Decreased Time Before Peaking
Figure 2.10c Impact: Increased Peak Runoff
INCHES OF
RAINFALL
QUANTITY
OF
FLOW
-------
The impact of the urbanization process on runoff may be seen using
the typical home as an example. Prior to the purchase of the houselot for
the home, assume the land use was a hay field (or a part of the forest, or
an orchard). As such, it has a vegetative cover with a root system that
provides a comparatively high rate of infiltration to the soil beneath To
construct this home, a series of events has to occur which can be expected
to change not only the immediate site of the house, but also the area surround-
ing the site. The preparation of the site can include the removal of large
trees, if any, which will interfere with the new home or equipment brought in
to prepare the site; terracing of the site if the slope is sufficient to limit
usefulness of household activities; and provision of a road or driveway as well
as other utilities to the site. Therefore, preparation of the site1 entails
surface and subsurface disruption of the vegetation and of the soil, resulting
*n the removal, exposure and compaction of the soil material. Such\ site pre-
paration decreases the permeability of the soil. ;'
The construction of the home on the site provides a roof which is im-
permeable. The rainfall runoff from this roof is carried away in gutters and
drains which, in effect, is channelization of runoff. The driveway '
-------
hydrologic cycle from the elimination of 4e septic systems, which return
water-however polluted—to the ground, arid the export of wastewater via sewer
pipes to a downstream treatment plan can lie significant. Such action reduces
groundwater flow and therefore the natural low-flow augmentation. If the
development entails both a sewer system and a water supply system which im-
ports water from outside the watershed, tlken the above impact is transferred
to the watershed from which the water is feeing withdrawn.
These examples illustrate that the impact of- the urbanization process
on infiltration is not limited to the immediate site, but extends to all
those areas which help provide services tb that site. A solution often pro-
posed to ameliorate the effects of the urbanization process is to decrease
the densities at which the population lives. This is done by encouraging
the population to "spread" out, thereby decreasing the concentration of those
factors which affect the environment. However, in many cases this results in
a decrease of the immediate concentration! of the impacts but an increase in
the overall impact and a significant deterioration to the environment, in addi-
tional areas. The solutions which this manual addresses are those which recog-
nize that there can be urban areas of varying densities, and that the impact
which the urbanization process has on runbff from these areas will depend on
wise use of preventive measures which havje to be planned before, and initiated
during, the development of the area. i
2.3 Runoff Impacts and Water Quality problems
The preceding sections have illustrated how urban development can
lead to reduced infiltration, due to increased amounts of impervious surfaces,
and increased runoff both in terms increased volume and higher velocity. These
changes in an area's natural hydrologic Balance can in turn lead to serious
impacts on water quality. The two major,water quality problems affected
are
e erosion and sedimentation ;
« surface and subsurface pollution
These problems are briefly discussed injthe paragraphs which follow.
211
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Erosion and Sedimentation
The construction phase of urban development can result in significant
alteration of the landscape, the extent of the changes usually depending upon
the size of the development. A construction cost commonly incurred is large-
scale removal of vegetative cover in order that construction can proceed
smoothly and efficiently. The impact, in terms of the hydrograph, is in- ,
creased runoff from the area resulting both from increased quantity and velo-
city of flow. Both of these factors lead to significant removal of soil
through the erosion process. The actual amount worked away from the site
will also depend upon the extent of surface area exposed to the runoff and
the characteristics of the soil.
In the United States it has been estimated that man-made activities
remove nearly four billion tons annually from the land. Three billion tons
of this sediment are deposited in flood plains, river channels, lakes and
reservoirs, and the remainder is carried to the oceans.8 The sediment
washed from areas undergoing development involving new construction is from
five to five hundred times as great as that from undeveloped rural areas.
The consequences of erosion are loss of productive topsoil and the
deposition of the soil, including its organic constituents in streams,
marshes, lakes, and the various water bodies. The resulting impact on
these water bodies is a smothering of streambed organisms and plants,
destruction of their storage capacity for water supply and flood control,
and an increase in the rate of eutrophication of lakes, swamps and other
water bodies.
Sedimentation not only interferes with the functioning of: the natural
ecosystem, but also with the uses which mankind usually expects tb make of
these water bodies. Sedimentation of streams and rivers with a heavy organic
load decreases their aeration capacity and the ability of the water to assi-
milate future waste loads imposed by. discharges from wastewater treatment
facilities. Furthermore, deposition of the sediment in reservoirs reduces
the capacity of the reservoir for its intended use, whether it be water supply,
power generation, or flood storage.- In due time these dams will retain only
silt and the original problem (water supply, power, and flood control) will
22
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still have to be solved. Sedimentation also interferes with the use of water
bodies for recreational purposes. The destruction of'bottom or bed life and
the inflow of organic matter can result in a decrease of oxygen, thereby
killing fish. Furthermore, the transport; of sediment in streams and lakes
reduces the aesthetic appeal of these watjers, whether it be due to the dirty
water-or the resulting muck on the bottom.
Studies of river channels have shiown that the natural forces inherent
in periodic flows naturally construct and maintain a channel with the capa-
city to carry a volume smaller than the average flood; this means that on the
average such rivers will overflow their blanks every 1.5 to 2 years. However,
with runoffs of increasing volumes and velocity, the resulting impact in the
short-term is flooding but in the long term is an increase in the channel's
cross-sectional area through erosion of its banks. This, in turn, means
additional deposits of sedimentation downstream.
i •.--..•
Surface and Subsurface Pollution|
The constituents of pollutants wlUch are deposited on the surface of
urban environments vary widely, ranging from common organic material to
highly toxic metals. Some pollutants are; intentionally placed on the surface,
only to be carried away by the runoff, e.|g. road salt, insecticides, herbi-
cides. Others are the unintentional residue of man's activities, such as
lead from automobile exhausts and oil dripping from trucks and cars. Such
pollutants appear to vary according to the land use and intensity of land
use.
For a given frequency of rainfall, increasing urbanization leads to
greater removal of these surface pollutants due to the increased quantity and
velocity of the resulting runoff. This Becomes important when one realizes
that the most significant pollution occurs when there is just sufficient runoff
to carry the pollutants from their place!of deposition to the receiving
waters; this runoff provides the least dilution in the streams. For the same
frequency of rainfall occurrences, this means that the urbanization process
will result more often in .greater scouring or washing of the pollutants into
!-• , .;'-<" . « ' •- ° " ' ' '-
the streams. '
23
i
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Leaching refers to the removal of soluble materials by percolating
water. If these soluble materials are pollutants, this removal is .harmful.
Subsurface leachage occurs as an intended action in the draining of a septic
tank. However, if a leaching field is blocked or otherwise fails, proper
leaching does not occur and subsurface water containing pollutants often
works its ;way to the surface. There it can be picked up by runoff and carried
to nearby bodies of water, resulting in degradation of water quality. :
Leaching often occurs at landfills, as rainfall percolates down through
the site where wastes have been disposed. If water percolating through this
waste picks up soluble materials, or,harmful viruses and bacteria, and later
becomes part of that groundwater .which augments streamflow, these'pollutants
may also be carried into the stream. Proper landfill location and operation
will serve to minimize leaching problems.
This completes the brief description of how urban development can
lead to runoff-related water quality problems. The conceptual framework
which it has presented (see Figure 2.11 below) will be used to organize the !
discussion of technical solutions provided in Chapter 3. More generally,
it should help the nontechnical reader to understand the basis for the sub-
sequent discussions of implementation approaches and strategy development.
Figure 2.11: Conceptual Framework for Preventive Approaches to Urban Stormwater
Runoff
Urban
Development
Decreased Infiltration
and Increased Runoff
Erosion and
Sedimentation
Surface and
Subsurface
Pollution
Water
Quality
Problems
24
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2.4
I
Protection of Environmentally Sensitive Lands
This section takes up the planning context for protecting certain
environmentally sensitive lands, those jhich play an important role either
in protecting or, if improperly developed-,'in degrading ground and surface
water quality. , The basic planning considerations are the same, regardless
of whether the regulatory approach used! is to acquire the lands (or develop-
ment rights) themsleves or to restrict Development to specified non-intensive
uses. |
The five land types discussed are:
• Streams and creekbeds i
• Aquifers, and th.eir recharge areas
* Wetlands j
• Woodlands j
• Steep slopes j
Many of the natural processes associated with these land types make signi-
ficant contributions to water quality, j The direct costs to the public of
failing to protect them can be high, arjd are associated with the need to
provide storm sewers, higher levels ofjwater and wastewater treatment, and
9 !
new sources of water supply. !
i
2.4.1 Valuable Natural Processes !
i
Streams and Creekbeds. Streams- and creeks play two important roles
within the hydrologic cycle. First, they provide major drainage systems
carrying runoff and sediment from higher elevations to low-lying land and
water bodies. Second, they contribute| water to aquifers during the wet
season and recieve groundwater through; springs or seepage during the dry
periods. Development in these areas, by removing vegetation and introducing
impervious surfaces, increases erosionj and sedimentation which in turn
increases stream turbidity and reduces: available oxygen in the water. The
increased runoff introduces urban pollptants in the form of petroleum pro-
ducts, fertilizers, road salts, etc. Removal of shading vegetation can
increase thermal pollution of the strejams. Development also can adversely
affect overall hydrologic balance within the watershed. Streambed siltation
25.
i
-'V
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obstructs natural flows from surface to groundwater; stream flow becomes
irregular, with lower base flows 'and higher peak.flows, raising'the level
of flooding. •
Aquifers. Groundwater is carried by aquifers, formations composed .
of consolidated (limestone, basalt) and unconsolidated (sand, gravels) rock.
This underground water supply is fed by seepage from streams and lakes
as well as by precipitation^which percolates directly to the acquifer. Not
only is groundwater an important source of water for human consumption, but it
also helps regulate surface"flow by absorbing water during wet periods and
releasing it during dry periods, It also acts as a natural filter since
percolation of water through the soil and other formations can remove cer-
tain impurities. . . r
Inappropriate or unregulated development on or near aquiferk can
unfavorably, affect this water resource in a number of important ways. By
covering recharge areas with relatively impervious surfaces and effectively
sealing them to percolation, development decreases recharge of the ground-
water supply and increases funoff. Development that pumps.water in Excess
of aquifer recharge rates will cause the groundwater reservoir to fall,,
not only reducing the available supply but causing land surfaces to sink.
Where fresh groundwater is located near saline groundwater, overpumping can
also decrease the natural flow from fresh to saline, resulting in saline
pollution of the freshwater reservoir. Again, land use activities can allow
harmful substances to enter the aquifer, e.g. location of septic tonics-, or
cesspools at or below the water table; subterranean disposal of wastes;
agricultural activities involving concentrations of fertilizers or animal
wastes; poorly constructed chemical or petroleum storage tanks; etc.'
Wetlands. The term wetlands encompasses a variety of ecological
areas that are generally classified by their vegetation, water type (fresh,
saline), and predominant water depth. They include fresh or,saline meadows,
marshes, swamps, bogs, bays, and open water, These areas perform, a number of
vitally important natural functions. They affect water quality by filtering
out silt and other pollutants, slowing down runoff, and changing in-
organic nutrients into acceptable nutrient material. Wetlands also serve
to stabilize water quantity by absorbing excess flows during flood periods
and retaining it during droughtsf Wetlands'are particularly important for
26
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the maintenance of fish and wildlife habitat; they provide critical breeding,
nesting, and feeding grounds for birds, jfish and' other aquatic animals, and
contribute to the food chains of upland [plants and animals. Finally, in
addition to supporting general ecosystem| health, wetlands also have import-
ant value as recreation, education, and iaesthetic resources.
Development or alteration of wetlands can create serious water
quality and related environmental problems. Upland development can lead to
nutrient and sediment inflows that exceejd the natural capacity of the wet-
lands to act as a "filter"; it can no linger efficiently transform nutrients
into harmless inorganic matter and remove suspended sedment. The nutrients
stimulate eutrophication and the increased turbidity resulting from the sedi-
ment reinforces this depletion of available oxygen in the stream, degrading
water quality and creating fishkills. Wetlands may function as recharge
areas for groundwater, groundwater discharge areas, or catch basins for
overland flow. Development that increases upland runoff or affects ground-
water levels can upset the intricate cycling of water between wetlands,
groundwater, and surface water, impeding the wetlands ability to counteract
• •'-..-••• • i •
floods and droughts. j
Woodlands. Woodlands help protect soil resources by moderating the
impact of storms and wind, thus reducing erosion and sedimentation. Also
important for water quality, forest vegetation slows runoff, allowing pollu-
tants to be filtered out before water reaches groundwater reservoirs. Clearly,
woodlands represent valuable resources jto the community for a host of other
reasons. Aside from the economic value of the timber, they present oppor-
tunities for recreation activity and aesthetic enjoyment. They provide a
diverse environment for a variety of plants and animals and thus constitute
a significant resource for wildlife conservation. Woodlands also moderate
the local climate, since the forest microclimate (shade, transpiration)
stabilizes air temperature, and serve ]x> buffer urban noise.
Unregulated development of woodland areas can lead to increased rates
of runoff and erosion, resulting in increased problems of flooding and silta-
tion. increased pollutants reach groundwater reservoirs because of reduced
natural capacity for removal. The forest ecosystem is particularly sensi-
tive to chemical pollutants, such as the deicing salts used on highways.
Destruction of woodlands may also remove attractive recreation sites:
|27
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Steep Slopes. Hillsides are geological features which, in combina-
tion with vegetation, soils, and precipitation, affect the natural balance
of the hydrologic system. Hillsides move naturally as the result Iof gradual
weathering and erosion. However, development that removes vegetation
sharply increases soil and slope instability by increasing the amount' of
water in the soil. Construction that alters the natural formation' of rocks,
sons, and other components^of a slope will make it more susceptible to slides
and slumps. Development that, removes vegetation or otherwise alters natural
drainage patterns will increase runoff and erosion, steep slopes and soils
that are relatively less permeable (e.g., "days) are particularly sensitive
to this problem. Radical changes in hillsides due to erosion will" in turn
have impact on surface water quality, groundwater quality and quantity, and
stream flow. Use of improper construction techniques can leave the land-
scape permently scarred. The aesthetic damage is compounded where'site
planning and design ignore the natural contours of the terrain and
obliterate the hillside itself, slopes have positive value to people as
f-hey provide distinctive relief to the landscape and interesting settings
for human activities.
2.4.2 Needed Planning Coordination
Clearly, the various natural functions performed by these types of
environmentally sensitive areas extend beyond merely maintaining or pro-
tecting water quality. Protecting sensitive lands for water quality purposes
would appear to further a number of related community goals:
w protection of adequate groundwater supplies
» reduction of flood damage
«» conservation of urban open space !
« preservation of unique wildlife habitat
» enhancement of recreational opportunity
Restricting private development of such lands may also have negative
consequences for other, equally valid, community goals such as
• adequate supply of local housing
• new business activity and jobs
• lower property tax rates
• higher property values
because of foregone economic development opportunities.
28
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..-• Thus, 208,planners interested in jprotecting sensitive areas from
development for water quality purposes vjill be forced to consider the
implications of their approach for a whole range of related planning
considerations.. 208 planners will havejto coordinate their planning efforts
with a number of other regional and local agencies, chief among these being
the area responsible for master planning and economic development. Existing
plans and zoning ordinances may call fo| more intensive.. uses than will be
consistent with meeting water quality standards. Also, 208 planners will
have to coordinate their efforts with other agencies developing functional
plans for water supply, flood protectioy, coastal zone management, open
'space, and outdoor recreation. The objective will be to identify inconsistencies
and reconcile conflicts that may exist jonong these various single-purpose
separately conceived plans. An existing water and sewer plan may call for
running a sewer through an area propose^, for water quality reasons,
as a passive recreation area. Equally possible, existing transportation
plans may not provide for automobile access to the same proposed recreation
area. Regional solid waste planners at! the same time may be considering
location of a sanitary landfill within [this same area.
2.4.3 Planning Support Activities !
What these various connections between 208 and other community
planning activities point to is the neeld to take into account the close
relationship that exists between water jquality concerns and land use
decision-making. . j -
There has been a growing recognition in the planning literature of
the need to condition land use allocations on land suitability, that is, the
capability of the land to accommodate ^he proposed use while maintaining
the continued functioning of vital ecojogical processes'.10 This has beeft part
of a larger movement toward grounding comprehensive planning in a firm
base of natural resources data on an area's major environmental features.
Numerous methodologies now exist for identifying, interpreting, and mapping
data on environmentally sensitive area^ so that planners can make preliminary
determinations of their suitability toja wide range of potential urban uses.
These methodologies vary greatly in tejcms of data inputs, level of detail,
2?
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extent of machine processing, etc., but they share a common planning objec-
tive. Kach seeks to guide or otherwise restrict development on sensitive
lands so as to assure continued performance of valued natural functions
contributing to maintenance of environmental quality. 1
Some methodologies limit themselves to analysis of a single factor,
such as soil conditions. other approaches, though still earth science-
oriented, take into account a number of geologic conditions such:as slope
stability, flooding, erosion and sedimentation, bearing material]problems,
etc. Still other planning approaches combine earth science with related
natural resource and even visual-perceptual data in determining suitability
of land for development. Some of these rely on map overlays and point
rating systems for integrating multiple environmental variables,14others
make use of computer graphics and related predictive models.15 No systematic
comparison has yet been done of the tradeoffs that exist among these various
approaches in terms of the needed resources, i.e., time, money, technology,
and specialized expertise. However, all of them do make maximum use of data
available from published sources. The major data sources typically called
upon are the U.S. Geological Survey, The Soil Conservation Source of the
U.S. Department of Agriculture, the Army Corps of Engineers, State divisions
of mines and geology, and regional water districts. .
The environmental concerns of such land suitability studies are
clearly wider than just protecting water quality, and they typically will
not be generated as part of a 208 planning exercise. However, when these
studies are available locally, they provide an invaluable resource to the
208 planner in identifying and mapping the water quality-related sensitive
lands discussed above. Together with findings on the potential extent and
magnitude of the non-point source pollution problem in the area, and projected
future land use patterns given expected economic and population growth, they
supply the needed planning base for implementing a program of sensitive
areas protection and regulation.
30
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REFERENCES
1.
2.
Linsley, Ray K., and Franzini, Joseph B., Water-Resources Engineering
2nd ed., McGraw-Hill, New York, 1964. . .
The following terms are commonly used to note various periods of time:
a) "travel time" is the time for the flow to'traverse from one
point to another and can be estimated by dividing the average
velocity by the distance traveled.
b)
c)
6.
7.
j
"time of concentration" is the Sum of the travel times from the
farthest point in the watershed:to the point of measurement.
in terms of the hydrograph, it is the time from the end of excessive
rainfall to the point of inflection on the falling limb of the
hydrograph. I . .
I • .
"lag time" is the time from the'center of the mass of excessive
rainfall to the peak runoff. Firom a range of storms and watersheds
it has been shown that the lag time is equal to six-tenths of the
time of concentration, for average natural conditions and for
approximately uniform distribution of runoff over the watershed.
A limited number of studies indicates that this relationship holds for
urbanized watersheds also. |
In hydrologic terms the ratio is.knbwn as the "hydraulic radius" and
is the ratio between the cross sectional area divided by the wetted
perimeter. j
Channel and storm sewer flow velocities can be estimated by the use of
Manning's equation, in which velocity is a function of the cross-
sectional area divided by the wetted perimeter, all raised to the two-
thirds power:
V = f
tcross-sectional area I
wetted perimeterJ
See following footnote for Manning jequation
5. The complete Manning equation is:
• R2//3 • S1//2, where V is the
velocity of flow, R~is~the hydraulic radius, S is the slope, and n is
the coefficient based on the roughness of the surface over which the
flow occurs. '
Linsley, Ray K., and Franzini, Joseph B., Water-Resources Engineering,
2nd ed., McGraw-Hill, New York, 19^4.
i
Bhutani, Joginder; Holberger, Richird; Spewak, Peter; Jacobsen, Willise,
and Truett, J. Bruce, Impact of Hydrologic Modifications on Water Quality,
U S Environmental Protection Agency, Report EPA-600/2-75-007, April 1975.
i
31
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8.
9.
10.
11.
12.
13.
14.
15.
1972
and Environment.
Belinont
et al" A_ConEarative_Study_ofJResource Anaiysic.
•
32
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3.0
•TECHNICAL APPROACHES
this chapter discusses a numbeij of technical approaches which .
may be employed to reduce water pollution due to urban stormwater runoff.
Since all of these approaches are applied before the runoff reaches the
storm sewer system, they may be termed ; "preventive approaches." -These
individual techniques form the basis for a system ,of Best Management
Practices. The concept of Best Management Practices seeks to control the
twin results of urbanization: increased runoff and increased pollution. The
technical approaches described here ar4 grouped into three categories,
according to the specific runoff problem addressed:
' ' • i
• Measures to reduce runoff pollution due to surface and
subsurface pollutants;
« Measures to reduce runoff and increase infiltration; and
• Erosion and sedimentation cpntrol measures.
In order to place the purpose pf these management practices into
perspective, it is useful to reiteratej some notions about the nature of
the problem and its constituents. Table 3-1 compares total quantities of
raw municipal waste and urban runoff, Deluding base flow, in pounds per
acre of drainage basin size per year. These figures are taken from a
study done at Durham, North Carolina ahd are meant only to serve as an
example of the problem. Urban runoff |contains much greater loads of
suspended solids and heavy metals thari raw municipal waste.
Table 3-2 gives the total annual yield of pollutants,from municipal
and urban runoff sources in pounds per! acre during 1972 based on actual
removal rates for the Durham Third Fork Sewage Treatment Plant. On a yearly
basis, the average ultimate BOD reduction is 46 percent, COD—48 percent,
i . . • •
and suspended solids—4 percent. :
It is important to note here that even if Durham provided 100%
removal of organic and suspended solidjs from raw municipal waste on an annual
basis, the total reduction of pollutanjts discharged would only be 52% of
the COD, 59% of the ultimate BOD, and J5% of the total suspended solids.
Although urban runoff varies widely in! its severity, it can be a significant
source of water pollution in some areajs and,, where this is true, some means
must be devised to control it, over arid above the control of municipal point
sources. The means of control presented here are Best Management Practices.
j
I
i
331.
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Table 3-1
o
BASIS
Pollutant
COD
BOD Ultimate
Suspended Solids
Kjeldahl Nitrogen as
"N"
Nitrate "N"
Total Phosphorus as
"P"
Chromium
Copper
Lead
Nickel
inc
MDNICIPAL WASTE AND URBAN RUNOFF
POUNDS PER ACRE PER YEAR POLLUTANT
AN
Saw Urban Runoff
Municipal
Waste
Ibs/ac
"~* • •• •
~ -
1,027
685
335
7.2
11
.10
.20
<.8
<.16
1.5
**"-• •.
+
I Base Flow
_ ..%* J Ibs/ac | %*"
53%
59
5
73
6
11
21
12
43
T
938
470
6,690
6.1
4.7
1.6
1.6
2.9
1.2
2.0
48%
41
95
27
94
89
79
88
57
Total
Annual
Yield
(Ibs/acre)
-• • •—,,
1,965
1,155
7,025
*% of total annual yield
Table 3-2
, YIELD °F POLLUTANTS FROM MUNICIPAL AND
URBAN RUNOFF WASTES IN POUNDS/ACRE DURING 1972
Parameter
COD
Ultimate BOD
Suspended Solids
Municipal Waste
(Ibs/ae)
Raw
1,027
685
335
• Percent
Removal
91*
91
85
(Ibs/ac)
Effluent
-' •
92
61
50
(Ibs/ac)
Urban
Runoff
938
470
6,690
1
(Ibs/ac)
Total
Release
• - . I,...
1,030
531
6,740
Overall
; Removal
Efficiency
— •
— " -- -
48%
46%
• 4%
*Assumed
34
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The object of Best Management Practices is to prevent and reduce
urban runoff pollution. As such, it is a system of source control. -The
first group of Best Management Practices are those measures intended to
reduce runoff pollution due to surface anjl subsurface pollutants, attempting
to hold and check that material which reaches the impervious surfaces of the
urban environment. Such controls are typically chemical application restric-
tions, litter control, and other public w|>rks activities such as street sweeping
and catch basin cleaning. The second grotq?, measures to reduce runoff and
increase' infiltration, seeks to correct tjhe problem engendered by urbanization
through such techniques as porous pavement and dutch drains. The third set,
erosion and sedimentation control measures, have been largely developed through
the work of the Soil Conservation Services.
These preventive approaches generally can be applied at one of two
points in the development process. A number of the solutions refer to
construction practices, which should be ^plied by the developer when earth
disturbing activities occur. Some erosicjn and sedimentation control measures,
as well as measures to reduce runoff and|increase infiltration, may be
considered as requirements of development after construction is completed.
implementation of these two types of measures (construction practices, post-
construction requirements) is typically fhe responsibility .of the developer,
while municipalities will generally be.- responsible for off-site controls on sur-
face and subsurface pollutants. Of courLe, in the-case of construction of publ.c
facilities, the municipality or other public agency itself may act as the
developer and thus face the same obligations as the private developer.
It should be realized that the! urban environment is merely the
collector of what we put into it; the impervious surfaces provide-the
means of transport . for this material and1 rainfall acts to flush those
surfaces. Again, the concept of Best Management Practices seeks to prevent
and reduce this pollution from reaching the receiving water. In so doing,
the goal is to protect the beneficial uses intended for those waters. No
one technique alone described here can correct the changes brought about by
urbanization. Combinations of these maAagement practices which are designed
to control recognized sources are required. If such is done, a system of
Best Management Practices can be broughj: about to control urban runoff
pollution effectively and yet relative^ inexpensively.
35!
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Implementation of all these technical approaches can generally be
achieved through use of some combination of zoning ordinances, subdivision
regulations, building codes, health codes, erosion and sediment control
ordinances, and other specialized regulations. Public officials, however,
should look to voluntary compliance through public awareness programs before
seeking to enforce stormwater runoff programs through regulatory instruments.
Regulatory aspects of urban stormwater management are discussed in greater
detail in Chapter 4. The costs of installing and maintaining the
construction and post-construction control measures are borne by the
developer and passed on to the eventual occupants of the development. Surface
and subsurface pollutants controls are typically paid for out of public funds.
Financing needs, methods, and sources for a number of control measures are
discussed separately in Chapter 5.
36
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3.1
MEASURES TO REDUCE RUNOFF POLLUTION DUE TO SURFACE AND SUBSURFACE
POLLUTANTS
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3.1
sources:
I
Measures to Reduce Runoff Pollution Due to Surface and
Subsurface Pollutants
Pollution of stormwater runoff! comes largely from four major
i
i
• dust fall j
• contact with municipal and industrial wastes in
combined sewers; i
• litter, debris, and chemicals (including pesticides and fertilizers
washed off vegetation) on parking lots, streets and alleys? and
1 .' ' 2
e silt resulting from soil erpsion.
A number of measures designed to reduce jrunoff pollution due to surface and
subsurface pollutants are discussed in this section. Five subsections are
presented, dealing with the following problems: street litter, highway
deicing, fertilizers and pesticides, land disposal of wastes, and infiltration/
inflow.
The first subsection discusses the problem of runoff pollution due
to street litter, considering such measures as street cleaning and catch
basin cleaning. The second subsection considers the application and storage
of deicing salts, and presents alternatives to the use of salt on highways.
The application and storage of fertilizers and pesticides are examined in
the third subsection, also considering the possibility of licensing persons
handling and applying such chemicals. "Che fourth subsection discusses the
design, location, and operation of septic tank systems and sanitary landfills.
The final subsection considers the problem of infiltration/inflow into sewer
systems and examines such remedies as '.the inspection and removal of illegal
drain connections. !
The measures presented in this section vary in a number of important
ways from those to be presented later, jIn most cases these measures involve
operational solutions (nonstructural solutions) not involving the
construction of a facility. The measures presented in this section are
generally applied after development has! been completed, and are designed to
reduce the impact of various pollutants! remaining after structural methods
have been installed. j
Implementation of these measu'res is often the responsibility of
the locality rather than the developer since,, in many cases, the pollutants
have been deposited on public streets Jfter having been carried off from the
37
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development.. *hey also involve control of off-site pollutants, that i,
pollutants generated elsewhere. Several other measures are clearly
the responsibility of the locality, because they deal with residuals
from public activities such as highway deicing, fertilizer and pesticide
use on public lands, and operation of sanitary landfills, ^e infiltration/
inflow problem occurs at the interface between development and the public
sewer system, while the design and operation of septic tank systems is
usually the responsibility of the developer.
38
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3.1.1 Street Litter
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3.1.1 Street Litter j
This subsection addresses the problem of urban storrnwater contamina-
tion by street litter. A variety of materials may reach the street surface,
including: animal wastes, garbage, grit, oil, road salt, cinders, residual
particulates resulting from auto tire and lj>rake use, and other materials.
measures presented in this subsection ire designed to remove these
materials before they reach the sewer system or other redeiving waters
(lake, creek, stream, etc.). Two major solution approaches are presented:
street cleaning and catch basin cleaning. , A number of other nonstructural
measures will also be discussed which may Deduce the effort required for
these two approaches. i
Although the accumulation of a certain amount of street surface
contaminants is inevitable, much of the lijtter that reaches the street
surface may be eliminated, or at least effectively controlled, at its
source. A direct approach to reducing the! runoff pollution potential can
best be accomplished through active public education and through effective
and enforceable regulations and ordinances; relating to street cleanliness.
The local government can do its part by providing an adequate number of
litter containers, which should be kept presentable and emptied frequently.
Strict cleanliness practices should be followed by city waste collection
forces and other city departments which generate litter. Well-publicized
cleanup campaigns can also provide motivation for the public to clean up
the premises and dispose of accumulated trash.
Ordinances may be established describing improper littering
practices and prescribing penalties for violation. In addition to general
anti-litter ordinances, specific regulations may be directed to the following
typical sources of litter in the urban environment: garbage and refuse
collection, open trucks, public litter receptacles, refuse dumping,
building construction and demolition, street construction, sidewalk
sweeping, vacant lots, parking lots and garages, drive-in restaurants,
trailer courts and campgrounds, sports stadiums, auditoriums and exhibition
halls, theatres, food handling establishments , pet control, distribution
of handbills, posting of notices and political posters, street vending,
garden refuse, scavengers, weed control, jdead animals , produce markets,
and direct discharges into storm sewers.
39
i
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The effectiveness of local ordinances will depend on enforcement,
which will depend in turn on effective interdepartmental cooperation. For
example, the police department can enforce ordinances pertaining to
littering from moving vehicles, illegal dumping of refuse, the storage of
construction materials on sidewalks and streets, etc. -The fire department
can enforce regulations pertaining to storage of refuse which might create
a fire hazard. The health department can regulate the handling and
storage of refuse by food-handling establishments. Enforcement by these
agencies should include both inspections and summonses.3
. Street Cleaning; Improved street cleaning practices, including
increased frequency of street cleaning and increased removal efficiency of
street cleaning methods, may serve to reduce runoff pollutant loadings
and to reduce first flush effects in sewers. Motorized street sweepers
are designed to loosen dirt and debris from street surfaces, transport it
onto a moving conveyor, and deposit it temporarily in a storage hopper.,
The major types of street sweepers include the broom-type sweeper, the
vacuum-type sweeper, and a third type of sweeper which uses a regenerative
air system to "blast" dirt and debris from the road surface into a hopper.4
Mechanical street sweeping is ineffective for fine solids/ which
account for only 5.9% of total solids, but 25% of oxygen demand. The
following removal efficiencies have been estimated: total solids, 25%;
BOD, 45%; COD, 30%; nitrates, 45%; phosphates, 20%; heavy metals, 50%; and
total pesticides, 45%. Sweeping efficiency, however, varies with the
area, rainfall, frequency of passes, frequency of cleaning, and the skill
of the operator.
The accumulation of street surface contaminants may be minimized
by increasing the frequency of street sweeping operations. Commercial
areas are generally swept more often than other land use areas. The
effectiveness may also be improved by sweeping an area more than once.
Repeated passes over the same area can effectively reduce the amount of
pollutants remaining. Since there are only a finite number of available
vehicles, however, an increased utilization of street sweeping may require
additional resources to be outlayed by the responsible agency.6
Street sweeper costs vary widely, depending upon the individual
model. The following capital costs are representative of that range:
3-wHeel., $21,000-25,000; 4-wheel, $32,000-35,000; and vacuum, $35,000-40,000.
40
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A rough estimate of capital costs required for a given street sweeping
program would be on the order of $10 to $15/curb mile cleaned per year,
for the sweepers alone (ENR 2000). Operation and maintenance costs will
vary more widely due to local conditions such as labor markets and the
condition of the streets swept. Vacuum sweepers, in particular, may have
multiple uses. -Porous, paving,.for example, requires sweeping by vacuum to
prevent clogging of the pores which allow water to seep through. Moreover,
a wandering hose attachment .to the vacuum permits cleaning of catch basins
7 i
to a certain degree.. , J . .
.A major problem in most of the,larger cities is parked or abandoned
cars. Parked cars make it impossible| for street cleaning equipment to clean
all of the street. Part of this problem may be solved by parking regulations
which prohibit parking during specifijj hours. Some cities overcome this
problem by sweeping during rush hoursj when parking regulations and tow-away
zones are enforced. In residential afeas, these parking restrictions may
apply only once or twice a week, while in commercial areas they may apply
every day. The problem of abandoned 'cars is much more difficult to
control, particularly in very large c|ities.. Abandoned cars not only
interfere with street cleaning operations, but are,a source of litter.
Abandoned cars should be removed from the streets as soon as possible,
either by.city forces or by a private contractor hired by the city. .The
sale or auction.of, operative vehicle^ (and possibly the sale of parts)
from a city-owned and operated junk yard could help defray the cost
,8 j
of removal. . .. . , . ,
Street cleaning will only be ieffective when no-parking regulations
can,be enforced. When this is not feasible, other approaches must be
considered, such as catch basin cleaning.
'Catch Basin Cleaning; Catch:basins became standard before paved
streets came into common use and were installed partly to prevent sewers
becoming clogged with gravel, partly|as an odor seal. When regularly
cleaned, catch basins are found to be... effective 'in removing-fine solids.
However, few are cleaned regularly enough (in many cities, once yearly at
most; in some cities, once every four years) and may-become a serious
. ' . 9 i • '
source of organic sludge. | •_.;••
-------
Catch basins can be cleaned regularly in areas which are not ser-
viced by street sweeping equipment, depending on the remaining capacity
of the catch basins. The cost of various methods of catch basin cleaning
are on the order of $3 to §4 per catch basin.10 Catch basins remove ap-
proximtely 56% of total solids and about 40% of BOD.
42
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3.1.2 Highway Deicing
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3.1.2 Highway Deicing j
Deicing salts and their additiv4s may cause serious water pollution
problems and deterioration of roadside vegetation. If salt is used to deice
highways, the problem can be reduced through careful application and storage,
but not entirely eliminated. Deicing salts are used in nearly every state
in the snow belt. Heavier applications|are often used on steep slopes;
therefore, the problem may be worse in Ailly areas. Aquifer recharge
areas are particularly susceptible to gtoundwater pollution from deicing
salts, due to the rapid movement of chloride ions in the soil. These
measures generally apply to public agencies, except where private develop-
ments include large paved areas. ,
The use of deicing salts results ::from the demand for bare pavements
during periods of snow. This policy is! based on safety considerations. For
example, stopping distances are 478" onjicy pavement, 183' on sanded pave-
ment, and 66' on saltad'pavement (bare,jbut wet). However, use of deicing
salt also causes serious corrosion to automobiles and highway structures, may
damage the pavement (especially uncuredj concrete), and may cause
deterioration of roadside soils. Additives to deicing salts may also be
pollution hazards (e.g., cyanide from the breakdown of an anticaking agent).
Measures to be considered include: greater use of sand in place of
salt in less critical icing areas; greater use of mechanical snow removal
techniques; careful metering of salt wh'ere used; careful storage of salt;
and the minimization of damage to vegetation due to jmnoff of deicing
salt by the use of salt tolerant speciejs for plantings.
At present there are no economical alternatives for sodium chloride
and calffiium chloride mixes for deicingjhighways. The use of abrasives alone
is not sufficiently effective for public acceptance, and costly programs
would be required to empty sediment traps, clean curbs, etc. Salt use,
however, may be reduced without sacrificing safety: no salt application on
straight, flat sections; better training of operators on salt-spreading
equipment; and improved records of salf use.13 In addition, new types of
salt spreaders and snowplows may be considered, as well as improved cab
monitoring devices that will control salt application more accurately.
A number of other possibilities were examined in an EPA-sponsored
study: external in-slab thermal melting, stationary/mobile melters,
substitute deicing compounds, aompressed air types of snowplows, adhesion-
12
43
i
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reducing pavement materials, solar energy-storing pavement substances,
electromagnetic ideshatterers, improved drainage (enhancing runoff,
accident reduction, and snow melt control/treatment)', salt retrieval/treat-
ment, and improved tire/vehicle design.14
An alternative to salt is the use; of abrasives such as sand and
cinders. However, abrasives do not" fit"into the "bare pavement" policy
which now prevails, and they can become stormwater pollutants. Although
abrasives generally contribute.only small amounts of dissolved,, solids to
runoff, they can contribute significant portipns'of the suspended solids.
Large quantities of sand and cinders can clog, storm and combined sewers.
Most cities remove a large portion of the abrasives during street cleaning,'
but the added cost of collecting large amounts of sand.and cinders must be "
included in the cost of their use. In addition^ abrasives are more! .7
expensive (by weight) than sodium chloride, with salts,, however, many of .""'
the costs (such as those.for.corrosion damage^degradation.of water^
supplies, and damage to roadside vegetation) are.indirect and .often
ignored. Hence, in some instances, a more complete economic comparison
might favor abrasives over salt.15
Salt storage sites should be chosen not only for their accessibility,
but also because they are well drained, not on an aquifer recharge area,
and not subject to overland runoff from upslope areas. Storage areas should
be covered for protection. During loading, the area of the storage heap
uncovered at any one time should be minimized and, following loading, the
loading pad should be thoroughly swept. Cleaning of spreading equipment
should be carried out on the loading pad where brine will discharge into a
holding vault. Better designed salt-handling equipment for loading
spreaders to eliminate scatter and waste should be developed.
Roadside planting may be affected by the salt concentration in
the soil or by spray: salt-tolerant species of trees and grass should be
used for all new plantings. Tree plantings should avoid areas where:salts
tend to accumulate (hollows, etc.). Existing sensitive species should be
protected by diverting contaminated runoff away from their root systems.
Shese recommendations apply principally to plantings within 30- of the
pavement.
A major consideration for highway maintenance is the fact that use
of abrasives in deicing mixtures mixtures will necessitate clean-up •
44
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operations following thaw, especially jsediment traps (about $3 each). Also,
buildup of salt concentrations in highway soils will be reduced if mowings
are harvested (suggested for recharge Ureas), and "dead ponds" will require
annual clean-out if they arenfound to jbe feasible.'
Some courts have stated clearJly that once an authority has started
to maintain a road in a certain condition, it must continue to do so or
run the risk of liability suits. ThejMinnesota legislature has approved
restrictions on the use of deicing chemicals in order to: (a) minimize
the harmful or corrosive effects-of salt or other chemicals upon vehicles,
roadways, and vegetation; (b) reduce the pollution of waters; and (c) reduce
the driving hazards resulting from chemicals on windshields. Road
authorities, including cities, villages, and boroughs, responsible for the
maintenance of the highways, are limited to using deicing salts or other
chemicals only upon hills,. and only if, in the opinion of the road
authorities, removal of snow by plowing or sanding or by natural elements
.-! 17 -
cannot be accomplished within a reasonable time.
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3.1.3 Fertilizers and Pesticides
-------
3.1.3 Fertilizers and Pesticides
A number of measures may be employed to prevent pollution of runoff
due to chemical use on municipal land (parks, recreation areas, golf
courses, urban open spaces, etc.) as well as on agricultural land in
urbanizing areas. The indiscriminate use of chemicals for the control of
unwanted pest infestations and the improvement of soil and plant nutrient
conditions should be reduced. The limited use of these chemicals should
be consistent with their intended purpose, and careful attention should be
paid to their storage and distribution.
A professional licensing system for handlers and users of pesticides
and fertilizers may be practical. Such licenses would be awarded only to
those who demonstrated competence in the handling of such materials, and
could be revoked for failure to comply with applicable regulations designed
to prevent the introduction of such materials into ground or surface waters.
Alternatives to the use of fertilizers and pesticides should also be
examined.
46
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3.1.4 Land Disposal of Wastes
-------
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3.1.4 Land Disposal of Wastes | •
•This subsection discusses the design, location, and operation of
septic tank systems and sanitary landfills to minimize the problem of
polluted runoff due to land disposal of jwastes. These facilities should be
designed to take into account population density, type of development, and
the natural characteristics of the site.j Surface runoff can introduce
septic tank seepage into receiving waters when a combination of high usage and
heavy rainfall are present. Overconcentration of septic tanks within a
given area can overtax the assimilative jability of the subsoil strata. Septic
tanks serve their purpose best when population densities are low.
The soil condition surrounding 4 septic tank plays a vital role in
its operation. If this strata contains]clay-related soils, then a semi-
I-
permeable condition exists which will allow very little, if any, absorption.
Capillary action may then cause seepagejto rise to the surface, where it
can be picked up by surface water runoff. Clay^related soils also contribute
to lateral movement, rather than downward movement, of septic tank seepage.
This seepage will tend to seek its own level and will move along the path of
least resistance until other soil types affect it. At this point it can
18
be either further absorbed or move closer to the surface.
Septic tank systems should be used only in low density developments
and only where soils are well-drained, jPeriodic maintenance is required
to provide reliable operation. Septic i:anks should be pumped out at
approximately 2-year intervals to remove solids that have built up. It is
important riot to overload the system to, ensure a long life span for the
field disposal system. Water from roofj drains or foundation drains should
19
not enter the system.
Many states have adopted detailed regulations to govern the
operation of sanitary landfills, in ordjsr to prevent pollution of ground
or surface water from leachate or overflow at the disposal site..'., Regula-
tions of the State of Hawaii prohibit the establishment or operation of
any solid waste disposal facility withojut a permit from the State Director
of Health. Permit applications must be accompanied by detailed plans and
specifications for the facility and by Ian operations plan report. Per-
mittees are required by these regulations to compact and cover all solid
waste accumulated after each day's operation with earth or other approved
material so as to safeguard the environmental quality of the surrounding
47
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area, They are also required to have monitoring equipment in place to
detect any pollution or contamination that might result from operation of the
facility; to maintain a minimum vertical separation of five feet
between the deposited waste and the anticipated high groundwater table; to
have adequate provisions for minimizing the flow of off-site drainage over
the landfill; and to deposit solid wastes in such a manner as "toiprevent
waste materials, leachate, or eroded soil particles from entering :the
waters of the State without receiving the best practicable treatment or
control."20
Regulations of this type might also establish limits on the widths
of the working space, require all lifts to be graded so as to facilitate
drainage, and require the operator to meet periodic self-monitoring,
recording, and reporting requirements. Lagooning of sewage, sludge, or
seepage could be prohibited, as well as acceptance of infectious or other-
wise hazardous wastes. Sanitary codes may specify the requirements for
design, location, and operation of septic tank systems. \
48
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3.1.5 Infiltration/Inflow
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-------
3.1.5 Infiltration/inflow !
Serious problems result from excessive infiltration into sewers from
groundwater sources, as well as from high inflow rates from sources other
than those which the sewers were intended to serve. Infiltration is the
volume of groundwater entering sewers and building sewer connections from
the soil through defective joints, broken, cracked or eroded pipe, improper
connections, and manhole walls. Inflo* is that volume of water discharged
into sewer lines from such sources as roof leaders, cellar and yard drains,
foundation drains, commercial and industrial "clean water" discharges,
drains from springs and swampy areas, Depressed manhole covers and cross
connections. i
Inflow sources generally represent a. deliberate connection of a
drain line to a sewerage system. Thesfe connections may be authorized and
permitted, or they may be illicit connections made for the convenience of
property owners without consideration pf their effects on public sewer
systems. The intrusion of these waterjs takes up flow capacity in the
sewers, and, especially in the relatively small capacity sanitary sewers,
they may cause flooding of street and jroad areas, thus constituting a health
hazard. In this case the sanitary seyers actually function as combined
sewers, and the resulting flooding becjomes a form of combined sewer
21 !
overflow. j
The measures presented in thisj subsection concentrate on the
reduction of inflow to the sewer system. Correction of inflow conditions
is dependent on regulatory action on t|he part of city officials, rather
than public construction practices. If elimination of existing inflows
is deemed necessary because of advers^ effects of these flows on sewer
systems, pumping stations, treatment plants, or combined sewer regulator-
oveUflow installations, new or more restrictive sewer-use regulations may
have to be invoked. j
The effects of inflows into sewers can be greatly reduced by a
number of methods. Many authorities advocate the discharge of roof water
into street gutter areas or onto on-l6t areas in the hope that it will
percolate into the soil. Discharging] roof or areaway drainage onto the
land or into street gutters reduces the immediate impact on the sewer system
by allowing reduction of the volume and attenuation of the flow. The use
of pervious drainage swales and surface storage basins within urban areas al-
lows the stormwater to percolate intoj the ground (see Section 3.2.2).
4J9
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The removal of connections of roof drains to sanitary or combined
sewers is a method commonly used to reduce the hydraulic loading on
sewers and sewage treatment plants. A successful program of removal of roof
drain connections can provide an effective and economical means of reducing
local flooding and pollution problems if satisfactory means are employed on-
site to handling resulting roof drainage.23 Direct connection of roof
drains to sewers allows large volumes of rainwater to reach the sewer
system in a short period of time, if roof downspouts were permitted to
discharge on ground surfaces instead of intp sewers, there would>be opportunity
for infiltration, detention in small puddles, and subsequent evaporation of
the stormwater, and that portion of the drainage which reached sewer inlets
would be reduced. These various measures can reduce sewer flows appreciably.24
Inspection and removal of illegal drain connections costs approxi-
mately $3 per building inspected and about $4 per downspout removed.
Considerable savings at the sewage treatment plant may be realized due to re- :
duced inflow. The removal of downspouts from a sanitary sewer system will
provide favorable results in the form of reduced complaints, reduced
operational costs, and improved operation of the treatment works, while
similar results may not be as apparent on a combined system, nevertheless
such a campaign can be most effective26 Sanitary ordinances may prohibit
the connection of roof drains to sanitary sewers, but, if they are not
enforced, the inflow problem may remain.
Excessive infiltration is a serious problem in the design, construc-
tion, operation, and maintenance of sewer systems. Neither combined sewers
nor separate sanitary sewers are designed to accept large quantities of
such infiltration flows. The problem of infiltration involves two basic
areas of concern: (1) prevention in new sewers by adequate design,
construction, inspection, and testing practices; and (2) the elimination or
cure of existing infiltration in old sewers by proper survey, investigation,
and corrective measures. Control of infiltration in new sewer systems
involves engineering decisions and specifications of the methods and
materials of sewer construction, pipe, joints, and laying procedures and
techniques. Correction of existing sewer infiltration can be accomplished by
three basic approaches: replacing the defective component, sealing the
existing openings, and building within the existing component.27
50
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3.2
MEASURES TO REDUCE RUNOFF 'AND INCREASE INFILTRATION
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3.2
Measures to Reduce Runoff and Increase Infiltration
The urbanization process involves! an increase in the total area
covered by impermeable surfaces, leading |to two related problems: increased
runoff and decreased infiltration. The technical approaches presented in
this section are divided into two subsections: delay of runoff on-site and
increased infiltration on-site. The majcjr objective of these measures is the
maintenance of runoff volumes and peaks jrom areas undergoing urban develop-
ment at or near those from areas under "riatural" (rough grassland) condi-
tions. Additionally, measures to'increase infiltration may also serve to
maintain sufficient infiltration to shallow ground water to ensure no
retardation in the dry weather flow of streams and to maintain recharge
of major aquifers at a level equivalent fo those under natural conditions.
Reduction of runoff, volumes' and jbeaks will lead to reduced frequency
of flooding and lower flood peaks, alongjwith reduced risk of erosion and
sedimentation. Increasing; infiltration £o maintain dry weather flow in
streams will reduce the impact of various pollutants on the stream quality,
since sufficient dilution flow would be available. Finally, maintenance
of aquifer recharge will ensure an adequate water supply.
The technical approaches to be presented are generally permanent
measures which must be installed by the Developer and must remain in
place after::the development is completed!. A number of the measures,
however, may be applied as modifications to existing developments, in order
to reduce water pollution problems. |
51
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3.2.1 Delay of Runoff On-Site
-------
3.2.1 Delay of Runoff On-Site
Delay of runoff,.,or ion-site detention, may be accomplished by a
number of approaches: ., i
• storage in permanent ponds having provision for variable depth,
• temporary ponding on paved areas, and
• temporary ponding on roofs of buildings
On-site detention of stormwater runoff can be an effective, economical method
or urban stormwater management. Besides controlling local flooding and
water pollution, on-site detention may also provide aesthetic benefits,
recreational opportunities, reduced erosion and sedimentation hazard,
and augmentation of local water supplies (in some cases). On-site detention
of runoff appears most desirable in flood-prone or erosion-prone areas,
and the economics seem favorable for both new developments and .existing
urbanized areas. On-site detention will prevent overflow of combined sewers,
may permit smaller storm sewers to be used, and may reduce flow rates in
sewers to levels at which treatment would be feasible.28 However, a number
of problems must be considered before implementation of such measures is
practical.
•The legal basis to require property owners and land developers to
provide and operate stormwater detention facilities must be examined. Some
of the types of legislation used by local jurisdictions to control storm-
water runoff from new land developments and urban renewal projects include:
subdivision regulations, zoning ordinances, building codes, plumbing and
sewer ordinances, water pollution control ordinances, flood control
ordinances, and drainage fee assessment ordinances (some of which- provide
for reducing the assessment if stormwater detention facilities are
installed). Water pollution laws in Maryland recognize silt as a water
pollutant, and detention ponding is used to control sedimentation from
erosion of land developments, particularly during the construction period.
State flood control laws, such as in Virginia, .have been interpreted broadly
to allow for the inclusion of the requirement for detention ponds to
control flooding. Most local building codes do not require detention storage,
although some public agencies (e.g., the Denver Urban Renewal Agency) do
require that rooftop storage be incorporated into the design of buildings.29
Jurisdictions that mention rooftop storage in building codes specify various
52
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standards of construction, including Jh* maximum water depth on roof,
roof slope, size of roof drainage leaders, and the number of leaders for a
given roof area. At least one national organization, the Building
Officials and Code Administrators, International, has developed standards
for detention storage of rainfall on roofs.
Additional legal considerations or complications may include the
following: legal responsibility for ^naintenance of detention storage
facilities, whether rooftop, parking jlot, surface pond, or other facility;
legal responsibility for damages resulting from operation or physical
failure of stormwater detention facilities; legal responsibility for
damages.caused by excessive flows of jstormwater when released from facilities
located on public or private lands; liegal responsibility for providing safety
facilities to minimize the hazards oi on-site detention facilities,
especially-as an attraction to children; and the legal right to use or
consumption of the stored stormwater< thereby disturbing normal flows of
water into areas downstream from detention facilities.
Potential political problemsjinclude that of modifying existing
laws, building codes, zoning ordinances, subdivision regulations, etc.,
to include requirements for on-site Detention of stormwater runoff that
are practical and effective for solving water pollution and drainage problems,
and are also acceptable to politicians and officials of the various public
agencies involved. Related administrative problems may involve enforcement
of the 'laws and regulations as established.31 Enforcement of local laws
pertaining to land development 'usually includes inspection, approval of
construction, and provision for fines or other penalties. For example,
under the subdivision regulations of a community, the initial plat may not
be approved unless stormwater detention fabilities are provided for in the
plans submitted. Under the community's sewer' permit ordinances, connections
to the sewers might not be permitted; until adequate detention of runoff is
provided. If either law is violated, penalties can usually be assessed.
•Ehis, of course, is an effective mea|ns. of obtaining compliance.
Another factor which must be considered is the problem of securing
public acceptance of on-site detention as the best, or most-practical,
method of handling runoff in their community. A public education program
might be beneficial to explain the alternatives and the reasons for
choosing on-site detention.33 Belated acceptance problems may also be
|
i
53
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associated with, the design and construction of storage facilities, •'
including: the accurate determination of runoff rates (existing iand
future), the availability of space for construction of facilities, the
capacity of downstream facilities to handle outflows, the need to build
facilities to be aesthetically pleasing and compatible with the local
environment, and the reluctance of builders, architects, and building
owners to store water puposefully on roofs of buildings.34
Financial problems may arise concerning allocation of the costs
of the facility and obtaining financial aid for defraying both the
initial and on-going costs. Land developers are often required to bear
the entire cost of construction of detention facilities in the same fashion
that they must pay for sewer construction, in existing land developments,
the costs are not usually borne directly by the property owners in the
area served by the facility.35
OSie biggest problem of implementing effective stormwater detention
programs is in obtaining cooperation from neighboring local jurisdictions.
Since major floods in a community are often the result of excess runoff-
flows from nearby upstream communities, flood-prone areas must depend upon
upstream communities to implement proarams of flood control which may
provide little direct benefit to these neighboring communities.36 A ntunbe*
of the above problems may apply in the implementation of erosion and
sedimentation control measures, as discussed in the next section.
Use of detention storage may reduce the size of the storm sewers '
required. Regular maintenance must be provided on rooftops to clear any
clogging materials. In totally developed areas, rooftop storage may be
the only feasible solution; land for open-space detention ponds and basins
may not be available and the use of deep tunnels or underground tanks may
be impractical, either because of initial cost, cost of operation, .geological
conditions, or the rules and regulations of the public agencies involved.37
It seems that the economics of on-site stormwater detention may be quite
appealing, if the detention facility can serve multiple-purpose uses, such
as recreation, the economic potentials become even more attractive because
a portion of the cost of the facility is allocated to other uses.
Surface Basins and Ponds. Usually detention basins and ponds
constructed on ground surfaces are relatively large, having the appearance
of a small pond or lake. The design of such facilities will vary
54
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'depending,.upon, the land costs, space Availability, physical and aesthetic
characteristics of the area, topography, clinjatefc ;andapther.local factors.
Whether or not the detention facility, is to serve multipurpose uses,.
such as, recreation, is,a factor that ijiay also dictate,size, shape, depth,
and landscaping treatment. For example, a detention, pond designed to
serve as,a recreational pond for bpating and .fishing would require different
design criteria than a pond which is j» serve Iphe single. function of
stormwater.detention. Generally speaking, the availability of large open
areas will permit a: design having gentle side.slopes and extensive land-
scaping, while sites.'where land is limited might dictate deep ponding areas,
pumped discharge, and steep side slopps that require fencing and other
security measures to.minimize safety hazards to children.
The major design characteristics are thevolume of .storage needed
and the maximum permitted release ratje. Storage volume needed is given by the
maximum difference, at any time, between cumulative total inflow volume and
cumulative outflow volume measured fijom the beginning,of inflow. The maximum
permitted release^rate can be calculated by determining the maximum dis-.
charge capacities of downstream sewer,, systems or receiving streams, and
taking into account,administrative restrictions.that may be imposed by local
j 38
authorities to regulate the discharge .rate. .
A detention basin is the mosfeffective, technique for reducing the
peak flow at a point immediately downstream of the impoundment, and
should be used where frequent floodihg of the area immediately downstream
is intolerable. Detention ponds can!be used to delay runoff on sites
where seepage at the source is infeakble; A detention pond requires some
sort of,collection system to feed it[ Developers may.find that the cost
of the collection system makes the. provision of .."at source" detention more
economical. However, where "at source" methods,are expensive or ,
infeasible,:detention ponds may be used. They are especially suited to
cluster development where ponds can j>e incorporated into open-space systems.
A detention pond can be designed to,-catch a .large proportion of
suspended ;solids of more than 10 microns in .diameter. A pond with a.
large freeboard for detention.may halve some recreational and aesthetic ,
benefits if the runoff is not carrying too much sediment. However, a
detention pond for maximum runoff cdntrol will'have very little recreational
or aesthetic value. Detention ponds that empty out entirely can have an..
unsightly nature that can be a detriment in urban developments. Detention
-------
ponds hold runoff and release it at a slower rate, which normally results
in a flattening.of the hydrograph. As a result, detention basins and ponds
*ay allow a significant reduction in the size of required storm sewers.
An example of a jurisdiction which has incorporated detention, devices
into its regulatory framework is New Castle County, Delaware.. Section 440
of the New Castle County Ground-Water Drainage Code states that "in order to
minimize downstream flow increases, developers may be required to provide
on-site stormwater storage capacity in the form of delayed runoff designs.
Such improvements shall be required when downstream improvements are phy-
sically or economically impractical, or when increased runoff is dispropor-
tionate to the rest of the area.39 '
Young et al. report the following estimated capital costs for
detention tanks of various sizes, along with the removal efficiencies of
biochemical oxygen demand (BOD) and suspended solids:40
Cost and Performance
of Detention Tanks
Detention Tank
Volume
Gal Ions/acre
2500
7500
15000
25000
Source: Young, G.K. , et
Nonpoint Source Pollution
Capital Cost
$/acre
§ $1400
4300
8600
14400
al. Model to Design
Suspended
BOD Solids .
% Removal % Removal
. .18%
79
•30.
39
37%
58
65
67
Stormwater Detention Tanks for
Abatement. April 1975. (Unpublished)
56
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Parking Lot Storage. Temporary sjtorage of stormwater on parking
lots is another means employed to reduce Runoff rates and sewer loadings.
The use of paved plazas in and around commercial buildings and office
buildings to detain stormwater, is similar, to the use of parking lots.
However, there are differences, betwen thejse two approaches with regard to
tributary drainage areas, grading requirements,, and the maximum depth of .
water that can be ponded before causing inconvenience to the public.
Unlike ponding on rooftops ther4 is no limit, from a structural
standpoint, to the depth of water that cefn be stored. Another advantage is
that the surface does not need to be dead-level as is true in the case of roof-
top storage. Because of the ease of inspection and access,, the maintenance
and operation of parking lot storage facilities is a low cost item and easy
to perform with mechanical street cleaning equipment. The likelihood of ex-
tensive use of porous pavement in some geographic areas, as discussed later in
Section 3.2.2, may mean that detained wa^er can seep into the ground instead
of being discharged into the sewer syste^n. This can be an important corollary
advantage in watershort areas. .
Problems with the use of parking lots for stormwater detention may be
reduced to acceptable inconveniences by jpcpper planning and design. Detention
of stormwater on parking lots would not jbe favored by parking lot users
because of the inconvenience that ponding imposes and its interference wxth
vehicle access and movements. Steep slopes may be required to provide
sufficient storage in a small area, resulting in water depths that might
cause problems for people when walking |to their vehicles. The
steepness of the lot might be displeasing to some people, and such a lot
might cause difficulty in walking for elderly and handicapped persons. The
steep slopes could also cause problems {,f vehicle entry or exit because of
reduced traction at times when ice forms on the paved areas.
There are two general forms of! stormwater detention on parking lot
surfaces. One form involves the storage of runoff in depressions constructed
at drain locations. The stored water is drained into the sewer system slowly,
using restrictions such as orifice plates in the drain. Proper design
would restrict ponding to areas which Jill cause the least inconvenience to
users of the lot. For example, the pacing lot of a shopping center would
have the ponding areas located in the {east-used portions of the lot, allowing
57
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customers to walk,to their vehicles in areas of no ponding except when the
entire lot is fiiled with vehicles. Drainage of ponded water should be '
fairly rapid, as compared to rooftop storage, to prevent, customer • - ' ;
inconvenience. In most cases, the water would pond to a depth not>o >•
exceed 12" and the ponding area would most likely be drained'within 30
minutes or less after the rainfall. .
Another type of stormwater detention on parking lots consists of
using the paved areas of the lot to channel the runoff to grassed a,eas '
or gravel-filled seepage pits, ^ flow then infiltrates into the ground
Soil -conditions and the effects of siltation in reducing infiltration '
must be considered.
Rooftop Storage. : Horizontal -rooftops are used in some areas for
stormwater detention. Rooftops can provide storage which will not ,
inconvenience pedestrians or motorists. Since such a facility is no1-
usually visible from the ground, a rooftop detention facility is not unsightly
and is not a safety hazard for children. However, potential problems of '
leakage, such as possible structural overloading, maintenance•for removal of
debris and ice, and the possibility, that heavy rainfalls will overflow the
top of the roof if.drains, become blocked, must be considered. Serious
damage to the building and its contents could-result if the facility were
improperly designed or maintained.42 Retarding runoff on flat roofs will •
result in greatly increased loads, in turn resulting in increased cost
of construction, m some cases the savings from reduced storm drainage
costs may make up this difference. Unfortunately, where retardation is
most needed (large acreage single-story buildings) clear spans are also
needed, so^ small increased load on -the roof can result in large cost
increases.
A flat roof may be used as a retarding pond by delaying the flow of
runoff to the downpipe. One approach employs a perforated strainer with
limited capacity on the downpipe inlet. Provision must be made for an
emergency overflow before water spills over the top of the roof parapet
Runoff must also overflow before the .maximum permissible load on the roof
xs reached. Another approach uses gravel detention barriers across a
flat roof. . ,
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On sloping, roofs it is possible to construct runoff checks--which
effectively increase the time of concentration. However, as; soon as the
"findams" are full, the rate of runoff will be constant, provided that the
storm continues at the same intensity. TJiis technique may be useful to
reduce ^runoff peaks of very short, very .ijitense storms which may put an
excess load on a storm drainage system. However, installation of these
barriers, may increase leaks and the retention of larger amounts of snow
A A I
may result in excessive loads.
44
limizi
Potential problems may be minimized by proper design, especially
if storage; is designed into the original plans and not provided later as an
afterthought. Maintenance is a bit more Difficult and will require
periodic attention, especially/in the autumn during and ..-..after the leaf-
falling season. However, all horizontaljroofs in urban areas need>such main-
tenance and the added effort to maintainja roof designed to detain rain
water should, not be,unreasonable. In many cases the roofs will be sufficiently
high or .the buildings will be located iniareas where maintenance would
not be a problem because debris would not/accumulate enough to cause a
blockage.of the roofscuppers, gutters/ or rain leaders.
,. ,osie possibility of. overflows is present with any roof structure,
although it is more likely when stormwatfer is stored on the roof. One • "
alternative usually required by building! codes •• is the use of overflow drains
and scuppers,in,the parapet wall. Proper maintenance and periodic inspection
I . ' 45 . .... ,..-.. • • •
will reduce the possibility and hazards pf overflows.
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3.2.2 Increased Infiltration On-Site j
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3-2-2 Increased Infiltration on site ; '
This subsection deals with a number of measures designed to
increase infiltration on site. The purpose of these techniques is
threefold:
(1) To maintain runoff volumes and peaks from areas undergoing
urban development at or near natural conditions.
(2) To maintain sufficient infiltration to shallow ground water
in order to insure no retardation in the dry weather flow of streams.
(3) To maintain recharge of major aquifers at a level equivalent
to those under natural conditions.
It should be stressed that increased infiltration of severely
polluted stormwater runoff may cause ground water contamination. Therefore,
the measures described here apply more to those areas still undergoing urban
development rather than those areas where dense urban development already
exists. The former group of areas represents a type of land use still in
the process of formation and it is here that stormwater .runoff pollution can
be successfully contained through careful planning. At this stage, the
volume and rate of runoff are increasing due to the encroachment of
urbanization; yet the runoff itself is not so severely polluted. For this
reason, the runoff may be used to recharge ground water in water short areas
through the methods intended to increase infiltration which are described in
this subsection. Where dense urban development is evident, as in the latter
group of land uses, increased infiltration may cause ground water contamina-
tion. Here, where the flexibility of approach is limited, more corrective
measures may be called upon, such as street sweeping and catch basin
cleaning described in the previous section.
Several approaches are described: Dutch drains, porous paving—.,.
asphalt, precast concrete lattice blocks and bricks, seepage basin or
recharge basin (single use), recharge basin (multiuse), seepage pits or
dry wells, and other methods. As mentioned above, these approaches involve
permanent measures, that is, measures which must be installed by ; the
developer during the development process and which must remain in place
after the development has been completed. However, a number of the measures
might also be applied after development has been completed.
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Dutch Drains. Dutch drains are gravel-filled ditches with an
optional drainage pipe in the base. The purpose of Dutch drains is to
reduce the volume of storm runoff and to reduce flood peaks by increasing
ground infiltration. Dutch drains intercept sheet runoff prior to concentra-
tion as compared to infiltration ditches. This measure may be applied on
any type of site where .the permeability of the soil is sufficient or where
seasonably high water tables are not anticipated. These'drains may either
accommodate the maximum flow for a 24-hour flood and thus avoid the need
I , .
for a storm-drain system, or they may be designed to take less runoff, in
which case they will only act as retarding devices as :;far as reduction of
flood peaks is concerned. | . . ; ; r
Dutch, drains enjoy the following advantages: they, reduce the total volume
.of runoff and can reduce peaking effects of local floods; enhance ground-
water supply; improve quality of vegetLtion on site, by increasing available
water,in the ground; and result in a reduction in the size of storm drains
required downslope of. the facility. ^owever, unless "at., source" seepage
facilities are either designed for lar|ge storms or incorporate some method
of controlled runoff release, they may, not effectively reduce flood peaks when
one storm follows another so closely that all facilities are full. ,The
drains,, if possible, should be designed to overflow before their;capacity is
reached during intensive storms. Dut^h drains are subject to clogging.
in addition, Dutch drains do not eliminate the need for a storm drainage.
.system downslope to take the overflow! from exceptional
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during intensive storms. Similarly, if the surface of Dutch drains has a
longitudinal fall allowing runoff during excessively heavy rain, peaks will
be lower. Dutch drains on well-drained soils may reduce the size of ne.eded
storm drainage facilities, resulting in a cost savings.46
Porous Paving—Asphalt. Porous pavement consists of a base course of
crushed gravel with a surface course of porous asphalt concrete.47 While still
an experimental measure with limited application, porous pavement must be
considered in this manual; Porous pavement, is being studied as a means to:
absorb1 rainfall where it falls, preventing runoff and combined sewer
overflows and eliminating the need for treatment plants to handle stormwater;
hold back stormwater surges; allow the water to percolate into the ground at
its own rate, and/or store it for use; conserve water and land; avoid puddles
in flat areas and provide adequate drainage without crowns and sloping;
prevent accidents due to standing water; minimize damage to the environment;
present a satisfying appearance; and provide a possible means of disposing of
solid wastes by reuse of these materials for construction purposes.:
Use of porous pavement will be practical only if it can meet the
following criteria: it must be able to carry loads without damage, :be able
to survive freeze-thaw cycles and other weathering, be easy to repair and hard
to damage; and be capable of absorbing all or most of the rainfall with pro-
vision for cleaning the pavement, should the pores become clogged. Porous
pavement is competitive in cost with normal pavement when the cost of drainage
facilities to service normal pavement is included. However, for parking lots
and playgrounds, the cost of porous pavement is more than the cost of alterna-
tive pavement. Depending on the situation, though, porous pavement may create
additional benefits: no standing water, reduced load in combined sewers, and
restoration of water supply. Porous pavement is thus an atractive alternative
in areas where the natural soil is free-draining. In all cases, the subbase
design must take into account the moisture conditions that must be accommodated.
A roadway or parking lot could provide considerable water storage
without interfering with normal usage and additional storage could be obtained
cheaply by adding more base material. This water can then be allowed to drain
naturally into the soil, depending on the soil permeability; or, if collected,
it can be used elsewhere or routed into the sewer system. In any case, careful
consideration must be given to the bearing capacity of the subbase to assure
proper roadway support. -Finally, groundwater movement may be restored to
62
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! 48
natural conditions, helping to replenish supplies. Of course, other
local factors must also be considered:| geographic and temperature, surface
and subsurface soil conditions, and the possibility of groundwater
48 • !
.contamination. I
Porous pavement reduces the total volume of runoff from paved areas
and can reduce the peaking effect of lockl floods and enhance the groundwater
supply, savings may be realized by redubing the need for storm sewers and curbs;
pedestrians may also benefit since there! would be no puddles. However, it has
not been clearly established that the filtering effect of the subbase results
in a significant improvment in the quality of runoff if polluted. Under certain
circumstances the surface may become clogged, and its permeability would be
reduced. Inadequate maintenance, rain o|n a frozen surface, and certain condi-
tions during snowmelt may all result in jrunoff. Higher construction costs
would be involved where curbs are necessary, and maintence costs may be high.
The sizing of storm sewer systems is determined by ordinance in most munici-
palities. Porous paving is a relative!^ new development, and few jurisdictions
permit its use. Where it can be used, however, regulations may not permit any
reduction in the size of storm drains, r
Precast Lattice Blocks and Bricks. There are a variety of precast
paving slabs which provide a hard surface and yet are porous to varying, degrees.
This measure can be applied only where ihe soil is sufficently porous to allow
rapid drainage. Perforated slabs on a honeycomb base may be used to cover
Dutch drains between areas of impermeable paving (making a lattice of
permeable paving throughout a parking aicea) . Brick strips incorporating tree
pits may be usted in a similar fashion.
The objective of this measure is to infiltrate precipitation "at source"
prior to concentration. These materials have a number of important advantages,
such as that grass, can substantially ccjver the site; they are flexible and
and can withstand a certain amount of njovement; and when used as strips between
asphalt, sections can be lifted to plarjt trees or place street signs, or even
maintain utility lines underground. However, most of these materials are not
as useful as porous asphalt paving, because they are expensive and difficult
to lay, are not as permeable as asphalt, and in most cases do not give as
good a walking surface. Therefore, they tend to be used in situations
where porous asphalt pavement is not suitable, such as very formal "hard"
631
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areas, unstable areas subject to subsidence or heave, and areas where a
grass-covered surface is desired. ;
Lattice concrete blocks may be used for parking areas where an "informal"
grass surface is required but which must be sufficiently hard-wearing to with-
stand regular use. They may also be used for lining grass swales to provide
erosion and sedimentation protection, and for grass ramps. Modular pavers ..'
are perforated bricks or bricks with lugs to control spacing, and may be.used
in areas where more wear is ecpected than for lattice blocks. Interstices and
perforations should generally be kept free of vegetation. This paving type is
used in more formal areas than lattice blocks for paving around trees, for
dividing strips between impermeable paved surfaces, etc. This type is generally
not a comfortable walking surface.
Precast concrete perforated paver may be laid over, precast concrete
lattice block, for use in formal areas, especially where warping of large
impermeable surfaces would be unsightly. This type may also be used as a strip
cover for French drains between areas of impermeable surface. Concrete blocks
may be lifted and the web and sand filter cleaned out if the .percolation
rate falls. Other porous paving types include a metal honeycomb covered by
a butyl rubber mat, and bricks with two perforations through which metal rods.
are passed and the bricks, separated by spacers.51
Seepage Basin or Recharge Basins (single use). The purpose of a
seepage basin is to allow a large percentage of the annual rainfall to recharge a
valuable aquifer. Runoff is collected in various storm drainage systems ,
prior to being discharged into the basin. This measure is used principally
on aquifer recharge areas but may also be used on any site where the water
table is always over 48" below the ground surface. Recharge basins are ;
extensively used in urban areas of Long Island to recharge ground water.
Provided the soil is reasonably porous, a recharge basin can recharge large
quantities of water in a short time without the use of much land.
Because basins are deeper than seepage areas they operate under a
greater head and, therefore, are capable of recharging a greater volume of
water per unit area in a given time. Seepage basins, then/require less land
area than seepage areas. The seepage basin is generally regarded as a
single-use facility, managed intensively for recharge. The basin must be
fenced and regularly maintained and is often very ugly. Seepage basins
need constant maintenance to ensure 'that porosity is not reduced. Where this' does
64 •
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, it may be necessary to bore seepage holes or pits in the base.- Unless
fenced, seepage basins may be a safety hazard where more than 30" deep.
The sizing of the basin depends on the objectives to be served. If it
is to recharge as much water as possiblej, it should be sized to take the maximum
24-hour rainfall from all Pav6d areas. Almost certainly though, this is not
economical; instead, it will likely be dejsirable to recharge most of the annual
precipitation (except for the very large jstorms), which may be accomplished with
a much smaller basin.
Recharge basins are mandatory on Long Island, where geologic conditions
are favorable for aquifer recharge and where municipal supplies depend heavily
52 • l
on a sustained groundwater yield, j
Recharge Basins (multiuse). Wherever soils are relatively permeable
and groundwater is not too close to the basin floor, recharge basins may be
an effective means for aquifer recharge.! They are often used primarily for
disposal of storm drainage, with recharge
as a secondary benefit. This measure
may be used effectively only where the aquifer outcrops at the surface (i.e. at
aquifer recharge areas) or in areas wherfe the aquifer is so shallow that
the basin extends to the aquifer (or in ?ome cases, where strata overlying
• the aquifer are very permeable and allow percolation of water to the aquifer).
When a recharge basin has benefits in disposing of stormwater as
well as 'recharging the aquifer, it may bfe an economically attractive method
of conserving groundwater resources. .Ofjten a recharge basin can be con-
structed as a borrow pit as part of a ma[jor construction project, e.g. a
highway. This measure does not take advantage of the filtering effect of
the soil, as in the case with recharge b^ irrigation; therefore, there is
a risk of pollution where recharge water! is of variable quality, such as
with runoff. Basins are extremely susceptible to clogging unless recharge
water is fairly free of sediment and the basin is maintained frequently. 5S
Seepage Pits or Dry Wells. Seepage pits collect runoff and store it
until it percolates into the soil, but, unlike Dutch drains, they do
not conduct water along their length when filled. Seepage pits may be used
on all sites where the permeability of the soil is sufficient and where seasonably
high water tables are not anticipated, jSeepage pits may be designed to
accommodate a maximum design frequency ?4-hour storm, or they may be designed
at least to allow infiltration of runoff at predevelopment levels. In this
case a supplementary system of storm drains will be necessary to accommodate
i
overflows. ;
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If properly designed, seepage pits may reduce local flooding, enhance
groundwater supply, and in some cases they may eliminate the need 'for storm
drains or reduce the size of the required storm drains. A seepage pit will,
provided the soil permeability is sufficient, accomplish the aim of increasing ''.
infiltration. However, unless very large/ it may not result in a reduction
of flood peaks. Seepage pits are more liable than Dutch drains to clogging by
sediment, as runoff,has more chance to collect solids before reaching the: pit.
Unless the seepage pit is designed to take the total amount of anticipated run-
off for a design storm, some provision must be made for overflow.' .In order ;
to have the maximum benefit in reducing flood peaks the pit should, in'fact,
overflow during intense storms before its capacity is reached. The maximum-
size of a pit should be sufficient to maintain infiltration at predevelopment
levels, such pits are usually filled with gravel or rubble, and sometimes
may be cased. , .-..-. ^. .... : ; , , . >
The Board of Supervisors of the Montgomery County (Maryland):Soil
Conservation District, who are involved in carrying but the county's sediment
control program, adopted a policy in April 1971 to "encourage and assist in
Planning for the retention on and in the soil of the greatest possible percentage
of annual precipitation including the use of ... infiltration devices (pervious
surfaces DU parking areas, dry wells, leaching pits, etc.)." 54
Other Methods
Seepage beds dispose of runoff by infiltration into the soil via a
system of drains set in ditches of gravel. These systems only reduce volume and '
speed of runoff and requires an overflow system. By increasing the time of con-
centration they may also reduce flood1 peaks slightly. This system ,may be used
on all sites except those with periodically high water tables or where soil
drainage is poor. This system may be used where the percolation rate does not
allow the use of seepage pits.
Seepage beds provide distribution of water over a larger area than may
be achieved with a seepage pit, resulting in less hazard of clogging. They may
be placed under areas of paving if the bearing capacity of the pavement
is not affected. Seepage beds allow groundwater recharge and are safer than
infiltration basins. However, no filtering takes place by the topsoil although
there will be some improvement of water quality as infiltration takes place.
Should beds or ditches eventually become clogged with sediments, replacement of
the entire system is necessary; therefore, maintenance of sediment traps must be
frequent and, consequently, is very expensive.55
66 ' :
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Multi-purpose seepage areas may be employed to allow a percentage
of annual precipitation to seep into the: ground, to store excessive runoff,
and.to provide for multi-purpose use of puch a facility through careful
design for recreational use, parking, or! open space. This measure may
be applied in all areas except those wit^i periodically high water tables
or where soil drainage is poor. Such facilities are useful in areas where
open space is not needed for use at all [times and when the alternative
use is not necessary during a storm and jfor a period after. There will be
a problem, for instance, in using overflbw parking areas when there is a
possibility of cars being left on the lojt during a storm.
The recharge facility is designed for multi-use. Where a grass sur-r
face is used, there may be a significant improvement in the quality of
recharged water due to the filtering effect. Because of the requirement
for multi-use, though, the facility must: have a higher rate of recharge and
be shallower than single-use basins. l4 is often difficult to maintain
porosity of multi-use areas, except when those are paved surfaces (porous
56 !
asphalt). - - -
67 i
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3.3
EROSION AND SEDIMENTATION CONTROL MEASURES
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3-3 Erosion and Sedimentation Control Measures
Five major principles of erosion and sedimentation control may
be identified:
• Keep disturbed area small;
• Stabilize and protect disturbed areas as soon as possible;
• Keep stormwater runoff velocities low;
• Protect disturbed areas from stormwater runoff; and
• Retain sediment within the site area, and by doing so,
control other pollutants, such as heavy metals. ;
The development should be made to fit the site with a minimum of clearing
and grading. Existing cover should be retained and protected whenever
possible. Critical areas, such as highly erodible soils, steep slopes,
stream banks, and drainageways, should be identified and protected. When
earth change and removal of vegetation are necessary, keep the area and i
duration of exposure to a minimum. The development should be phased so that
only areas which are actively being developed are exposed. All other areas
should have a good crover of vegetation or mulch.
Disturbed areas may be stabilized by mechanical (or structural)
methods and vegetative methods, or by combinations of these approaches.
The removal of existing vegetative cover and the resulting increase in
impermeable surface area during development will increase both ,the volume
and velocity of runoff. These increases must be considered when providing
for erosion control.(measures to increase infiltration and reduce runoff
have been presented in Section 3.2). Slope changes should be designed to
keep slope length and gradient to a minimum. Short slopes, low gradients, and
the preservation of vegetative cover can keep runoff velocities low, minimiz-
ing erosion hazards.
Measures can be utilized to prevent water from entering and
running over disturbed areas. Sediment can be retained by either filtering
runoff as it flows, or by detaining sediment-laden runoff for a period of
time so that the soil particles settle out. The best way to control sedi-
ment, though, is to prevent erosion. Erosion control measures serve to:
• Divert runoff from exposed soils and other vulnerable areas;
• Safely convey runoff, either in surface or enclosed drainage
systems by:
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!
— controlling runoff velocity
— insuring that all surface jchannels and outlet points
are adequately drained; !
• Stabilize exposed surface areas; arid
• Control the volume arid velocity of runoff discharge
from the development area. <
These measures can be either vegetativejor .mechanical. Vegetative measures
include the planting of grasses and other vegetation to stabilize inadequately
protected soil surfaces. Mechanical measures include control techniques which
involve the building of structures (forjexample, check dams, sediment basins,
diversions) or the operation of equipment to achieve compaction or surface
roughening. Vegetative and mechanical Measures may be either temporary or
permanent. I
Sedimentation control serve's toi:
• Detain runoff for a period oJE time, to allow soil particles
which are in suspension to settle put;
• Filter runoff as it flows; ahd
• Intercept runoff containing jsediment before it leaves the
development site. !
Sedimentation control measures, like erjosion control measures, may be
!
either vegetative or mechanical, j
Vegetative and mechanical erosion and sedimentation control
measures may be classified either as temporary or permanent, depending on
whether or not they will remain in use jafter development. Annual grasses,
mulches, and netting, for example, are .temporary control measures, although
they may remain in place after development has been completed. The planting
of perennial grasses, sod, shrubs, and \trees are permanent vegetative
control measures. Temporary measures generally serve for one year or
less. Permanent vegetative stabilization will be required on all developments
Where the development is a long-term proejct, permanent measures
i
installed in the first phase of development Mil serve the entire term of
development. On large projects, wherejsignificant increases in runoff
volume and velocity are inevitable, permanent structural measures for
controlling the release of runoffs to off-site arid downstream areas will
69 :
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be necessary; Where even limited amounts of erosion and/or sedimentation
would do significant damage, measures to trap sediment and control runoff
will be necessary. Temporary measures are used in the construction process.
In some cases, tenporarytimeasures may be planned into a development in such
a way that they become permanent as the completion of the various phases of
the development occurs. For example, sediment basins can be converted to
permanent ponds which become valuable site amenities. Figure 3.1 illustrates
a number of temporary erosion and sedimentation control measures, while
Figure 3.2 indicates that a number of temporary measures may become part of
the permanent development.
The following subsections cover six types of erosion and sedimenta-
tion control measures:
• Vegetative measures; , . -
• Diversion measures and slope drains; .•':'•']
• Mechanical slope stabilization techniques;
• Stream bank stabilization techniques;
• Design and stabilization of surface drainagewaysy and
• Other erosion and sedimentation control measures. ' '
Figure 3.3 summarizes these various control measures and indicates their
applicability to seven typical problem areas associated with erosion and
sedimentation. 7
The control of erosion and sedimentation is,"by and large, the
product of long years of research done by the Soil Conservation Service..
Before a comprehensive program is embarked upon, it is suggested that the
local official contact the SCS agent in his area.
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icte wp *1wm wta» rwwff
M XiiteMi
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Figure 3.1; Temporary Control Measures
Used Purina Construction
Source: Beckett Jackson Raeder Inc., op, cit., p. 18,
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Figure 3.3 Control Measurjes and Problem Areas
VEGETATIVE
MEASURES
DIVERSION
MEASURES AND
SLOPE DRAINS
MECHANICAL
SLOPE
STABILIZATION
STREAM BANK
STABILIZATION
SURFACE
DRAINAGEWAYS
OTHER
MEASURES
•
» INDICATES APPLICABILITY OF A
SPECIFIC CONTROL MEASURE TO
ONE OR MORE OF THE SEVEN
PROBLEM AREAS.
Control Measure
Mulches
Sodding
nterceptor berm .
Diversion ditch
Bio-technical protect on of stream banks
Filter inlet
i
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Streams and
waterways
O
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* * Surface
drainageways
q
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• • • • * Borrow and
stockpile areas
"• 1
* * * Adjacent
properties
9
Source: Beckett Jackson Raeder Inc., pp. cit.. Figure 2
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73
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3.'3.1 Vegetative Measures
-------
3.3.1 Vegetative Measures
Potential erosion is minimized by providing a protective
vegetative cover, since this vegetation shields the soil from the impact
of falling rain, slows the velocity of the runoff, maintains the soil's
capacity to absorb water, and holds soil particles in place. By limiting
and staging the removal of existing vegetation, and by decreasing the
area and duration of exposure, soil erosion and sedimentation can be
significantly reduced. Special consideration should be given to the
maintenance of existing vegetative cover on areas of high erosion potential,
such as erodible soils, steep slopes, drainageways, and stream banks.58
This subsection describes a number of temporary and permanent
vegetative measures to reduce erosion and sedimentation, both during the
construction phase and after development has been completed. The
following vegetative measures are considered: minimization of stripped
areas, grubbing omitted, conservation of topsoil, temporary seeding and/or
mulching, seeding, mulching, seeding with mulch and/or matting, hydroseeding,
sodding, and bio-technical protection of very steep slopes,, From a
water quality aspect, reducing the contribution of sediment to runoff
leads to a reduction in suspended solids concentration and other materials
which adhere.
Minimization of Stripped Areas. The developer may reduce the area
stripped of vegetation at any one time by careful time-phasing of the
development. The economies of scale in earthmoving costs and the
mobilization costs of large earthmoving machines, however, often dictate
that all earthmoving is done at one time. When large areas must be left
bare for up to 12 months and final grading cannot be carried out,
stripped areas should be mulched and/or seeded.59
Grubbing Omitted. Grubbing is the process of removing roots,
stumps, and low-growing vegetation. If this process is omitted, besides
yielding a cost saving, new sprouts are provided, the existing root mat
system is retained, wind fall is reduced at the forest edge, and
equipment entrance is discouraged.
Conservation of Topsoil. On all sites except those -in wetlands
and along creeks and streams, topsoil should be stripped to a depth of 9"
from all areas which are to be disturbed and which are not to be covered
by buildings or pavements. Topsoil must be stockpiled and respread
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to ensure a rapid vegetation growth following restoration. Unless
carefully located, though, storage banks of topsoil may obstruct site
operations and result in double handling These mounds may sometimes be
used as baffles to reduce noise, dust, fete., reaching neighboring properties,
thus minimizing complaints. If they are to be in position for more than
six months, seed with a temporary seed piix. A shallow trench around these
mounds made with a bulldozer blade will*prevent soil eroded from mounds
from washing onto adjacent property or |Lnto- drainage channels. Topsoil
may also be stockpiled above borrow areias to act as a diversion.
The conservation of topsoil is! in the developer's interest as it-
results in more rapid and health grass jgrowth, which not only prevents
erosion, but also improves the appearanjce of the development. In some
European countries the conservation of Itopsoil is mandatory. Where
such measures are mandatory in this country, however, they are often
I . 61
ineffective due to failure to inspect installation.
Temporary Mulching and Seeding of Stripped Areas. All areas which
will remain open for more than six months on steeply sloping or highly
erodible sites should be mulched and/o* seeded. On other sites, only
those areas larger than one acre must be mulched and/or seeded. (Note:
the protective vegetative cover should;be replaced immediately, however, in
certain critical areas. Any disturbedjarea along a creek or stream should
be sodded, while disturbed areas in wetlands should be reinstated with
local plant material.) This is a relatively inexpensive form of erosion
control offering rapid protection to open areas, but should be used only
when final grading and seeding is not possible. Vegetation will not only
prevent erosion, but will also trap sediment in runoff from other parts of
the site. As temporary cover crop is feown on subsoil in most cases,
growth is often poor unless heavy applications of fertilizer and lime are^
made while seeding. Once seeded, area^ cannot be used for heavy traffic.
Seeding. Standard seeding techniques provide an inexpensive and
very effective measure for preventing erosion and sedimentation. Seed is
drilled or broadcast either mechanically or by hand. A cultipacker or
similar tool is used after seeding to jmake toe seedbed firm and to provide
seed covering. The proper timing of seeding, mulching, and watering is
important for areas seeded in this man'ner. As soon as slopes are brought up
to final grade, permanent vegetative stabilization measures should be
I
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initiated. The selection of the appropriate plant materials for permanent
stabilization should be based on a consideration of the" following factors:
soil and climate conditions; duration, quantity, and velocity of "runoff;
time required to establish cover; maintenance requirements; and site use.
Grass is the least expensive and most effective material for permanent
protection of eroding soils. Grass can be successfully established if
certain basic requirements are met: ; proper seeding mixture is selected
for the site; seeding dates are observed; area to be seeded is covered
with topsoil; proper seedbed preparation and planting methods are
used; adequate fertilizer is provided; and protection from wind and water
erosion is provided during establishment.63
Mulches. Mulch is used after permanent seeding as well as
before seeding to protect exposed areas for short periods. Mulches
protect the soil from the impact of falling rain, slow the velocity of
runoff, and increase the capacity of. the soil to absorb water. Mulches
hold seeds in place, preserve soil moisture, and insulate germinating
seeds from heat and cold. Many types of mulch are available: straw,
woodchips, wood fiber mulch, chemical mulch or soil stabilizer,
excelsior mats, and other materials are used. Most mulches can be anchored.
Asphalt emulsions, can be used, as well as netting made of jute, fiberglass,
or plastic. Another alternative is to disc the mulch just enough to
anchor it into the earth.64 •
Mulched areas should be checked periodically, especially following
severe storms, when damaged areas of mulch or tie-down material should be
• o5 ' ' i
repaired. in some counties chemical stabilizers are considered a mulch,
specified in the county erosion control handbook.66 Seeded area protection
by netting or matting is often considered as a substitute for mulching.
An example is the erosion-siltation control handbook produced by Fairfax
County, Virginia, which is legally supported by county code amendments.67
Seeding with mulch and/or matting. Mulch and/or matting facilitates
the establishment of vegetative cover and is effective for drainageways
with low velocity. As mentioned above, mulches protect the soil from the
impact of falling rain, slow runoff velocity, increase the capacity of the
soil to absorb water, hold seeds in place, preserve soil moisture, and
insulate germinating seeds from .temperature extremes. Areas may be
76
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stabilized with seed alone, mulch alone,jor both seed and mulch, depending
upon site conditions and projected use of the area.
Hvdroseeding. In hydroseeding,|a mixture of seed, fertilizer,
and water is sprayed on the slope. A mulch and a mulch tacking agent •
I 08
may also be applied. T^his method is effective on large areas.. Areas
inaccessible to agricultural machinery m^y be easily seeded, but specialized
equipment is required. If hydroseeded, accelerated germination during dry
^ e I . • 69
conditions may require irrigation later po sustain growth.
Sodding. Sod strips are laid on the slope arid in this way instant
cover is provided. Sod should be placed; on a prepared bed and pegged on
steep slopes. Watering is important. OJtiis method of stabilization is
effective and is often used on steep slopes, where seed may be difficult
to establish. Sod is easy to place and ^iay be repaired .if damaged. Sod
can be placed at any time of the year provided that soil moisture is
adequate and the ground is not frozen. JGood quality sod free from weed
species may be difficult to obtain. If jlaid in unfavorable season, by
midsummer irrigation may be required. tfhis also applies^ very droughty
sandy soils. Sod is heavy and handling Icosts are high.
Bio-technical Protection of Very Steep Slopes. Alternative
measures may be applied to -very steep scopes, cut and fill banks, and
unstable soil conditions that cannot bejstabilized through seeded vegetation.
Vegetation reduces sheet erosion on slopes and impedes sediment at the toe
of slope. Where soils are unstable and liable to slip due to wet
condition, utilization of soil moisture
by vegetation can reduce the
problem. Shrubs and^trees shelter slopes against the'impact of rainstorms
and the humus formed by decaying leaves| further helps to impede runoff.
Mechanical measures help to stabilize sjail long enough to allow vegetation
to become established. Sod walls or regaining banks may be used to
stabilize terraces. Sod is piled, tiltjlng slightly, toward the slope and
should be backfilled with soil and compacted as soon as they are built up.
Timber frame stabilization involves construction of timber frames oh'slopes,
filled with topsoil, and covered with straw; covering'the straw with netting;
and planting ground cover plants througjh the straw into the topsoil. Woven
willow whips may be used to form live ijarriers for immediate erosion
control. Berm planting and brush layers may also be employed. These
techniques are considerably more expensive than conventional slope
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stabilization techniques. Adopted standards for erosion and sediment
control by the state of Maryland include a listing of plants for
critical area stabilization and ground covers, vines, shrubs, and trees.
Standards also give reference to applicable resource areas, site
conditions required, light preference, height, spread, spacing, time to
form cover, size limitations, etc.72
The following table lists effectiveness of various types of
ground cover on erosion loss at construction sites.73
Kinds of Ground Cover
Soil Loss Reduction Related to
Bare Surfaces
(Percent ..Effectiveness)
*Seedlings
Permanent grasses
Ryegrass (perennial)
Ryegrass (annual)
Small grain
Millet s sudangrass
Field bromegrass
Grass sod
Hay (2 tons/acre)
Small grain straw (2 tons/acre)
Corn residues (4 tons/acre)
Wood chips (6 tons/acre)
**Wood cellulose fiber (1.75 tons/acre)
**Fiberglass (1000 Ibs/acre)
**Asphalt emulsion (125 gal/acre)
99%
95
90
95
95
97
99
98
98
98
94
90
95
98
*Based on full established stand
**Experimental - not fully established
Source; County of Fairfax, Virginia. Erosion-Siltation Control Handbook.
•August 1972.
Minimizing erosion on site and limiting the amount of sediment being
carried by runoff may benefit the developer by eliminating the need for
regrading due to erosion and reducing the probability of damage claims by
downstream landowners. Once established, vegetative cover will also
greatly improve the aesthetic appearance of the development. Vegetative
erosion and sedimentation control measures may be classified as either
78
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temporary or permanent depending on whether or not they will remain in i
use after development. Annual grasses!, mulches, and netting, for example,
are temporary control measures although they may remain in place after
development has been completed. The planting of perennial grasses, sod,
shrubs, and trees are permanent vegetative control measures. Temporary
measures generally serve for one year.jor less. Permanent vegetative
stabilization will be required on all ;developments.
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I , .
i
3.3.2 Diversion Measures and Slope Drains
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3.3.2
Diversion Measures and Slope Drains
Erosion and sedimentation resulting from runoff over slopes exposed
durxng development may be reduced by using diversions to intercept runoff
and divert it from the slope face. Such diversions may consist of a berm,
a ditch, or a combination of a berm and ditch, and may be bare channels, '
vegetatively stabilized channels, or channels lined with a hard surface
material. The following factors should be considered in design of diversion
measures: the amount of runoff to be diverted, the velocity of runoff in
the diversion, and the erodibility of the soils on the slope to be protected
and in the diversion itself.
Diversions concentrate the volume of surface runoff and, as a
result, also increase its erosive force, it is important to plan in advance
for the disposal of runoff collected in diversions. Runoff must be
released onto a stabilized area to reduce its erosive potential, m some
cases this can be simply achieved by gradually reducing the gradient of
the diversion channel. Diversions may also be used at intervals along th,=>
slope face to reduce slope length and may be used to collect runoff from
a construction site and divert it to a sediment retention trap or pond.75
Where the runoff cannot be satisfactorily disposed of by conveying
it laterally it can be drained over the face of the slope itself, employing
a slope drain, either on the surface of the slope or below the surface. At
the slope drain outlet energy dissipators are frequently required in order-
to reduce erosion problems by slowing the velocity of the runoff.76
*his subsection presents a number of temporary and permanent
measures to reduce erosion and sedimentation, including the following:
diversion berm, interceptor berm, diversion ditch, berm and ditch, and slope
drains. Temporary measures must remain in place until the slope has been
permanently stabilized, but several of these measures may be incorporated
in the permanent drainage system.
Diversion Berm. Diversion berms, or diversion dikes, are small
ridges of soil constructed at the top of cut or fill slopes to divert
overland flow from small areas away from newly constructed, unstabilized, or
unprotected slopes, shey are normally used as temporary or interim
measures, but may sometimes be appropriate as permanent installations.77
Diversion berms collect and direct runoff to prepared drainageways and may
be placed as part of normal construction operations.78
80
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I
Erosion reducing structures, such as diversion berms, interceptor
berms, and sodded ditches, are normally employed at a rate of 165 feet
per acre, reducing potential erosion by about 50%. High rate usage.^of
these measures (over 165 feet per acre) may reduce erosion by 60%.
As the costs of diversion berms may range from $1 to $5 per linear foot,
the cost per acre will vary from $165 to |$825 per acre for diversion berms,
80 I
at a rate of 165 linear feet per acre. j
Interceptor Berm. An interceptojr berm, or interceptor dike, is a
temporary ridge of compacted soil constructed across a graded right-of-way,
reducing erosion by intercepting runoff 4nd diverting it to temporary
outlets where it can be disposed of with!minimum erosion. Interceptor
berms are usually used across graded rights-of-way that are not subject to
vehicular traffic. Design details and costs of interceptor berms are
1 • i &^-
approximately the same as those of diversion berms.
Diversion Ditch. A diversion ditch collects and diverts runoff to
reduce erosion potential and may be incorporated into the permanent
drainage system.82 The design of temporary drainage channels is basically
similar to the design of permanent channels and must consider such aspects
as capacity, cross section, and design velocity. As mentioned above,
diversion ditches may be bare channels, jregetatively stabilized channels,
or channels lined with a hard surface material.83 The cost of sodded
84
diversion ditches is approximately $825/|acre.
Berm and Ditch. A temporary diversion may be formed by
constructing-a channel and a ridge, usually across sloping land, to convey
runoff laterally at a reduced velocity to a safe discharge point. Such
a diversion measure may also be used at 'intervals across the slope face
, 86 !
to reduce effective slope length. j
Diversions and slope drains may ;be employed to divert runoff away
from critical areas during construction^ in order to minimize the erosion
that would result from runoff crossing highly susceptible areas. A system
of temporary channels prevents siltatio| in partially completed storm drain
age systems. An efficient temporary drainage system minimizes the delays
caused by severe storms during the construction period and minimizes the
amount of regrading, etc,, necessitated;by erosion during the construction
81
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period. Some of the above techniques are temporary in nature and the
removal of these measures will entail some costs, as well as additional
disturbance and possible minor damage to permanent facilities. ; Diversions
may also increase seepage which may cause soil instability.
Temporary diversions and slope drains are especially needed in road
construction projects. Standard specifications of the Delaware Department
of Highways and Transportation (January 1, 1974) specify that "slope drains
may be constructed of pipe, fiber mats, rubble, Portland cement concrete,
bituminous concrete, plastic sheets, or other material acceptable to the
engineer that will adequately control erosion." The Washington County,
Maryland, Erosion and Sediment Ordinance (1971) requires provisions for
temporary measures and a timing schedule. The adopted standards and speci-
fications for soil erosion and sediment control in urbanizing areas of the
State of Maryland include detailed specifications for diversion,dikes and
interceptor dikes.
Figure 3.4 illustrates a number of diversion measures.
82
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83
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3.3.3 Mechanical Slope Stabilization Techniques
-------
3.3.3 Mechanical Slope Stabilization Techniques
Mechanical slope stabilization techniques involve building structures
(benches or terraces, retaining wall) or operating equipment to achieve
compaction or surface roughening. Selective grading and shaping may be
considered to minimize erosion. Seepage control may be required on cut
slopes. Such measures will reduce erosion and sedimentation resulting from
runoff flow over slopes.
Selective Grading and Shaping. One way to stabilize slopes is to
reduce their gradient. The selection of the appropriate grade for cut and
fill slopes should be based on a number of factors: the stability of the
soil; its drainage characteristics, and its.credibility. The type of
vegetative cover and the type of maintenance will determine the degree of
88
slope allowable.
Roughened Surface (Cultivation). During the construction period,
areas may be bare for periods too short to make use of temporary mulches
or cover crops. In these cases, careful cultivation can greatly reduce
the volume of sediment generated on these areas.89 If slope surfaces are
left rough, this can help to reduce velocity and increase infiltration
rates. Rough slopes also hold water, seed, and mulch better than smooth
T 90
slopes. .
Careful attention to cultivation technique will pay the develope..:
since it is one of the cheapest and simplest methods of erosion control.
This technique may be readily incorporated into a development and is
generally used by field supervisors on an as-needed basis. No great
additional construction costs are incurred, since the measure' makes use
of existing equipment and personnel, nor are there maintenance costs involved
Ql
in this interim measure., .
Compaction. On fill slopes compaction may be a major factor in
erosion control. In addition to other compaction controls required by the
nature of the project, the minimum criterion recommended for successful
erosion control on fill slopes is to compact the uppermost one foot of fill
to at least 85% of the maximum unit weight (based on the modified AASHO
compaction test). This is usually accomplished by runnirfg heavy equipment
92
over the fill. Formal testing might not be required.
hold the soil in place, making exposed areas less vulnerable to erosion
Compaction helps
93
84
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Benches or Terraces. Benches orj terraces may be employed to reduce
the? slope length in critical areas. This measure may accomplish two objectives:
to modify the form of a steep slope to njinimize the erosion potential of runoff
originating on the slope; and to control, runoff .from elsewhere so that it can
pass down the slope in a protected chanrjel or be diverted so that it bypasses
steep slopes. Benches check the flow of runoff and collect sediment. Runoff
may be diverted along the bench to increase the distance,of overland flow.
Benches also provide access for maintenance and hydroseeding. Serrated slopes
lower the velocity of runoff, increase ihe distance of overland flow and reduce
the hydraulic gradient, along with holding moisture and minimizing sediment.
Benches and serrated slopes may!significantly increase cut and fill
costs and cause sloughing where excessive water infiltrates unstable soils.
Slope length and the need for benches or terraces is a particular concern in
highway construction. Standard specifications of the Delaware Department of
Highways and Transportation handle the problem this way: "The engineer will
limit the area of excavation, borrow, ajid enbankment operations in progress
commensurate with the contractor's capability and progress in keeping the
finish grading, mulching, seeding, and |>ther; such permanent pollution control
measures current in accordance with the| accepted schedule. Should seasonal
limitations make such coordination unrealistic, temporary erosion control
measures shall be taken immediately to jthe extent feasible and justified."94
Retaining Wall. Retaining walls should be used to reduce extreme
slope gradients. For example, if the final grade of a slope is too steep to
permit the establishment and maintenance of vegetation, retaining walls can
be used to reduce the slope's gradientj. Retaining walls can also be,used
to allow for the retention of existing imature vegetation. The cost of
building retaining walls is often justified because of the maintenance
costs that are saved on, areas that would be,difficult or impossible to
stabilize otherwise. 95
Seepage Control. .On cut slopes ground water seepage can cause
erosion problems. Seepage causes piping and soil slippage. Water seepage,
coming out of the face of the slope should be intercepted by a properly
designed drainage system. A diversion permits percolation of surface
runoff, contributing to underground seepage. Such seepage may be reduced
85
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by providing a sand trench under a diversion at the top of a slope and
a sand layer under the surface of the slope, along with a perforated tile
or interceptor drain at the toe of the slope. 96
Again, reducing erosion on slopes will benefit the developer by
eliminating the need for re-grading. Reducing the slope length may also
facilitate the establishment and maintenance of vegetative cover.
86
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3.3.4 Stream Bank Stabilization Measures
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3.3.4 Stream Bank Stabilization Measures
Stream bank erosion is a natural phenomenon but can become a
problem when it is accelerated due to increased runoff, and where it can
no longer be tolerated due to urban riparian uses. The erosive and trans-
i
porting power of a stream increases with :increasing velocity, turbulence,
depth of flow, and gradient, while the ability of a stream to erode its
banks varies inversely with the amount of sediment it already is carrying,
including both bedload and suspended material. The following events may
result in problems of stream bank instability: realignment of the channel,
an increase in runoff volume, sedimentation of the streambed, and constriction
i
of the channel, j
Often as part of urban development stream channels are realigned
and, almost invariably, shortened. Thisiautomatically results in a steeper
stream gradient which increases the flowjvelocity and erosive capacity.
The stream will compensate for this increase in energy by trying to meander ,
cutting laterally, or eroding its bed, j
Urban development of a drainageibasin will greatly increase the
volume of water which a stream must handle. Not only will the extent of
the floodplain be larger, but the stream'will overflow its bankful stage
more often. It is at or near the bankful stage that most damage is done
to stream banks. Thus the increase in runoff will worsen stream bank
erosion, although the duration of flow at bankful stage may be shorter due
i . -
to more rapid runoff from urbanized areas.
Stream channels may become partially clogged with sediment which
often originates from upstream development activities. This reduces the
capacity of the channel and the stream tries to compensate for the loss by
eroding laterally. A bridge, culvert, landfill, fallen tree, etc., may
cause local channel constriction leading! to erosion. In the case of a bridge
where the stream may be constricted laterally by abutments, the velocity may
be increased resulting in scouring of the streambed beneath the bridge
(which could cause failure of the abutments). Lining of the channel bed
under the bridges is common practice, but this may increase velocity and
constrict the channel vertically. This inay result in a plunge pool where
i
the lining ends and scouring above the constriction, If scouring of the
streambed is limited, scouring of the bahks often occurs where revetments end.
I
87
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A culvert effectively constricts a channel, both vertically and laterally,
and so protection from scouring at both ends, is vital,
The more stable a stream, generally the greater its potential for
fishing, wildlife, and, recreation. However, stabilization of small sections
of stream channel can result in serious erosion problems upstream arid down-
stream. Stream bank stabilization is generally:expensive and should be
limited to critical areas. Ideally, the stream should be allowed as much
freedom as possible to modify its channel and achieve new stability but
should be watched so that prompt action may be taken where and where it is
appropriate. ' •••.,-..•
The center line of a stream is> frequently a. property boundary.
Therefore, a shifting channel may lead to legal disputes. The need for.
channel protection often arises from development activity upstream. A
riparian owner adversely aff ected •: should seek legal advice on whether or not
he can claim compensation for damages. The action of lining of realigning
a stream channel may cause more severe instability of the stream channel for
downstream and sometimes upstream riparian owners, The possibility of
causing damage to neighboring riparian owners should, therefore, be care-
fully considered before undertaking stream improvements.97
The maintenance of existing vegetation on•stream banks is a
fundamental principle of erosion and sedimentation control. Stream bank
vegetation serves to stabilize the soil, slow runoff and dissipate its
erosive energy, and to filter sediment from runoff.98 Appropriate vegetative
stabilization measures were discussed in Section 3.3.1. This subsection
describes a number of structural measures to prevent erosion of
stream banks: falls, deflectors and jetties, revetments, biotechnical
methods, check dams, and weirs.
Falls. A fall is usually installed to dissipate excessive energy
in a stream or channel where the steepness of the gradient is causing high
velocity flow.- This often results from straightening a stream's course.
Falls in perennial streams should be designed by a qualified engineer;
they may be constructed of dumped rock, gabions, or concrete. In all
cases the structure must be protected adequately, as the tendency will be
for a plunge pool to develop at this point which could undermine the
structure. The'dam need not be impermeable. Where loose rock is used it
88
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I ?',
must be of sufficient size to withstand stjreamflow and, consequently,. it
is usually grouted or used in gabions to fprm a massive structure. Falls
may reduce the need for channel lining and create areas of still water
.1 , ', 99
which often increase the stream's recreational value.
.. Deflectors and Jetties. Where vegetation will not provide
sufficient protection banks may be protected with revetments and deflectors,
as well as other mechanical measures. Deflectors and jetties are used to
deflect streamflow away from an eroding bank or to prevent meandering of a
stream, thus encouraging the stream to increase its channel capacity by
scouring its bed rather than by lateral cutting.
Deflectors and jetties cause areas of comparatively still
water where sediment loads are precipitated, increasing the stream's
recreational value. "The buildup of sediment against the bank allows it to be
stabilized without planting. However, deflectors will considerably
restrict the channel capacity and should be used only where the stream's
natural tendency to compensate for this by scouring either the bed or the
10(D
opposite bank.will not cause a problem. j
Revetments. Revetments, which cover the stream banks, are
commonly used where sharp bends or constructions in the stream channel
(such as culverts, bridges, or grade control structures) occur.
Choice of a revetment type will depend on a survey of streamflow
characteristics, soil type, etc., but oftjm the USGS can provide data for
discharge and velocity characteristics for streams of similar size for
more accurate revetment and lining designl
Biotechnical Methods. A combination of vegetative and mechanical
means may be employed to provide protection of critical sections of stream bank.
These approaches should be used in streams with high flow velocity where the
flow/soil conditions exceed the stabilizing effect of purely vegetative channel
protection. Mechanical materials provide! for interim and immediate stablization
until vegetation takes over. Once established, vegetation can outlast
mechanical structures requiring little maintenance while regenerating
itself; their use also entails aesthetic benefits and increased wildlife
propagation. These measures do involve sjlightly higher initial cost than
purely vegetative measures, and may also. Require professional assistance.
While the methods described are effective!, a complete knowledge of soils,
hydrology, and other physical data is required to design measures that will
adequately solve the problem and stand upj to the test of time.
89 :
I _.
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Reed berms consist of a combination of reeds and riprap, and may
be employed to break wave action and reduce erosion of banks by currents.
Willow jetties can be constructed at the water level to stabilize a
cutback by deflecting the current and encouraging deposition of sediment.
Willow gabions may be used when a hard-edged effect is desired to deflect
the eroding flow of water. Piling revetment with wire facings is
especially suited for the stabilization of cutbanks with deep water. In the
lower riparian zone (open floodway) bank stabilization should be concentrated
on critical areas only, willow branch matt revetment may also be employed
to stabilize stream banks. . , . .
A recommendation to change the New Castle County (Delaware) ;
Drainage Code includes the following set of recommendations regarding
stream bank stabilization: "Where the flow/soil conditions exceed the
stabilizing ability of vegetation, then as a second option a combination of
vegetative and mechanical means of stabilization (biotechnical methods of
stream bank stabilization) will be explored,, and as a third and least
desirable option, a straight mechanical method will.be explored."102 Costs
vary according to the local availability of labor. However, there are
practically no maintenance costs for the vegetation once it'is established
as it holds the banks naturally, as compared to concrete improvements that
constantly need repairs.103 ;
Checkdams. Check dams are small structures constructed in
gullies or other small watercourse and may be made of concrete masonry,
rock, rock and earth, straw bales, sandbags, wire fence, or other materials.
Erosion is reduced or prevented by reducing runoff velocities, promoting
deposition of sediment, and stabilization of channel grades.104 Check
dams may be used to prevent gully erosion (usually during the construction
period) either in temporary channels or in permanent channels which are
unvegetated and, -therefore, temporarily unable to handle design flows.
In some cases, if carefully located and designed, these checks can remain
as permanent installations with very minor regrading, etc. They may be
left either as spillways, in which case accumulated sediment would be
graded and seeded, or as checkdams to precipitate further., sediment coming
90
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off that site, in which case a clean-out irould be required. Because of
their temporary nature, many of these measures are visually poor and it is
essential to remove them before dwelling units are let or sold. Removal
of these measures may constitute a significant cost and temporary
i n 105
checkdams are suitable for a limited drainage area only.
Wejr. A weir is a, .small dam setj in a stream to raise the water
level of divert its flow. A weir may be employed to control sedimentation
in large streams. Weirs cause minimal tuirbidity, reduce channel grade
and dissipate the energy of the flowing w,ater.
Bank stabilization was defined ajs follows in the Baltimore City
Erosion and Sediment Control Manual, Ordipance 1013: '"The control of
bank erosion in main stream channels can jbe accomplished in various ways.
Methods commonly used include sod, concrete, riprap, rock cribs, groins,
jetties, fencing, piling, gabions, etc. "The purpose of bank control
measures is to install a barrier that wil|l withstand the erosive forces,
exerted by flowing water or create a bank roughness that will reduce the
erosive power by dissipating the energy of the water as it moves along the
bank line."107 The New Castle County (Delaware) Surface and Ground-Water
Drainage Code (Ordinance No. 69-71) requires on-site stabilization-of water-
courses affected by runoff increases andjalso requires of each person or
corporation making surface changes to "pay his proportionate share of the
total cost of off-site improvements to the common natural watercourse
except those required to existing state roads, based on a fully developed
,,1°8 !
drainage area." ,
Figure 3.5 illustrates several stream bank stabilization measures.
91
_
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Figure 3.5: Control Measures Are Often Used in Combinat
92
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3.3.5
Design and Stabilization of Surface Drainageways
-------
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I
3.3.5 Design and Stabilization of Surface Drainageways
Surface runoff and runoff intercepted by erosion control
measures such as diversions must be collected by drainageways and let
out in stabilized areas, storm sewers, ojr sediment basins. The design of
these drainageways insures that runoff ijs transported without risk of
erosion or flooding. Unless: surface drainageways are adequately designed,
constructed, and maintained, fhey can bejcome a major source of sediment
pollution. i
Development should be planned tjo maintain and utilize the
naturally stabilized drainageways that qxist on a site. Increases in
runoff volume and velocity because of changes in soil and surface conditions
during and after construction must be anticipated. Where the capacity of
the natural site drainage channels is exceeded, additional capacity,
stabilizing vegetation, and/or structural measures may be needed.
Allowable design velocities vary with soil conditions, the
character of the channel lining (eitherjbare, vegetative, or structural),
and anticipated runoff volume. Formulas and techniques for determining
the runoff flows, channel cross sections, slopes, stabilizing covers,
and design velocity may be obtained froik Soil Conservation Service offices.
This subsection presents a number of measures involved in the design
and stabilization of surface drainageways: bare channels, grassed
waterways, lined channels, grade control structures, sediment traps, and
sediment basins. Some of these measures may be temporary only, while
others may become part of the permanent1, drainage system.
Sediment Trap. The first essejtnial step in preventing sediment
from entering streams and waterways is to control erosion on construction
sites. A second necessary step in sediment control is to trap sediment
that is transported by runoff before it! reaches streams and waterways
or leaves the construction site. To trap sediment, the runoff must be
detained for a sufficient period of tiirie to allow the suspended soil
particles to settle out. The amount of; sediment which is deposited will
depend on the speed at which runoff fldws through the sediment trap, the
length of time that runoff is detained/ and the size and weight of the
. illO '
soil particles which are in suspension.;
93
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Sandbags, straw bale barriers, and excavated sediment traps,
placed at regular intervals within a drainage channel, are temporary
sediment control measures which are easy and economical to construct.
Sandbag barrier sediment traps are constructed of bags filled with
sand or crushed rock and stacked in an interlocking manner which is
designed to trap sediment and reduce the flow velocity, straw bale barrier
sediment traps are constructed of bales of hay or straw stacked or staked
in place. Tying the bales to stakes with wire provides additional stability.
Sandbag and straw bale barriers may also be used at storm drain
inlets and along property lines, preventing sediment from entering;a
partially completed storm sewer system, and reducing sediment deposition
on neighboring properties.
Sediment Basin, streams may also be protected from increased
sediment loads by trapping runoff in sediment basins before it is released
into stream channels. In addition to trapping sediment, these basins are
designed to release runoff at non-erosive rates. Such sediment basins may
be constructed by excavating a pit or by construction of an impoundment.
Sediment basins often consist of an earthen dam, mechanical spillway
(including a perforated riser pipe) and an emergency spillway. The
construction of sediment basins should be completed before clearing and
grading begin. They are generally located at or near the low point of the
sites. Points of discharge from sediment basins must be stabilized.
Permanent sediment basins may become part of the final development in the
form of ponds or small lakes, which can be quite attractive after the
development is completed.112
Construction of a sediment basin will benefit the developer by
avoiding a number of problems: downstream riparian properties will not be
damaged by sediment deposits originating from the development; sediment
deposits downstream will not reduce the capacity of the stream channel;
sediments will not cause the clogging of downstream impoundments and other
facilities; and sediments will not reduce the light reaching the
streambed, which might in turn reduce available oxygen. it should be
noted, however, that only particles larger than 10 microns will be settled
out by gravity. The efficiency of the basin in settling smaller particles
is much less than that for larger particles, such as sand on silt. There-
fore, much of the clay particles will probably not settle in the basin.
94
111
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Bare Channels. The least expensive form of drainageway, bare
channels, should be used with caution and| only in areas where the channel
gradient is low. Bare channels should not be used in soils which have
moderate to high erosion potential. i
Grassed Waterways. Runoff can b;e handled by grass channels for
velocities up to 8 fps., if correctly graced and stabilized. A grassed water-
way is a much more stable form of drainageway than a bare channel and
should be used where a bare channel woul4 be eroded. The grass tends to
slow the runoff and filter out sediment, i On steep slopes the use of
grass channels will be constrained by the difficulty of keeping within the
limits of hydraulic gradient prescribed;\in the case of highly erodible
soils a lower design velocity must be usjd. Natural channels may often be
improved by regrading and grassing. j
Grassed waterways are less expensive than those lined with concrete
or stabilized by "bio-technical" methods'and are much more visually acceptable
than those lined with concrete. The vegUated waterway also encourages
infiltration, further reducing the runofjf problem. Careful design and
maintenance of grassed waterways is required if gully erosion is to be
avoided. The capacity of the drainagewa^ must allow for construction of
additional impermeable areas in the area| served by the channel.
Lined Channels. Structural linings are necessary in drainageways
where vegetation cannot be established because flow is of long duration
in the channel, runoff velocities are h^gh, erodible soils exist, or slopes
are very steep. The most'commonly used ichannel linings are concrete,
asphalt paving, or riprap. Information ion how to design and construct
lined channels may be obtained from thejSoil Conservation Service. In
general, vegetative stabilization and'tlfe use of permeable channel linings,
such as non-grouted riprap, are preferred to the use of impermeable linings
like concrete.115 Concrete lined channels are visually unattractive and do
not permit infiltration of runoff. !
Grade Control Structures. Grajle control structures may be employed
to reduce the velocity of runoff in drainageways. These measures may be
either temporary or permanent, and include drop spillways, pipe drops, and
pipe spillways. A drop spillway slows jthe.velocity of;the runoff, reducing
its erosive power. A pipe drop removes! sediment and turbidity, and may
be designed to handle large volumes of |flow, A pipe spillway removes
95 i.
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sediment and turbidity, and may be incorporated as part of the permanent
drainage system. Grade control structures counteract gully erosion in
waterways by reducing the gradient of the channel. They should be used when
physical conditions are too severe for the satisfactory establishment of
vegetation cover, being clearly preferable over an impermeable lining. To
prevent undercutting at the toe, all structures should extend several feet
or more below the existing ground surface, ihe selected design capacity
should be for a storm of a greater frequency than the one used for the
drainage channel because of the damage that could be done to the'structure
if it were to overtop.117 Grade control structures concentrate the volume
of water flow and increase its velocity at the structure, and, therefore,
banks around grade control structures often require additional stabilization
measures.
96
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3.3.6 Other Erosion and Sedimentation Cpntrol Measures
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3.3.6 Other Erosion and SedimentationI Control Measures^
This subsection describes a number of erosion and sedimentation
control measures which may be employed ti protect enclosed drainage systems,
large flat surface areas, and adjacent properties. The following measures
are considered: filter inlet, aggregate cover, curb and gutter, windbreak,
I
filter berm, and traffic. I .
Filter Inlet. The capacity of the storm sewer system itself can
be severely impaired by sediment deposit within the system. Sediment should
be prevented from entering the enclosed |storm sewer by the use of small,
temporary sediment traps and filters at jsystem inlets. Filters made of
crushed rock, sod, or straw bales can be placed at inlets where sediment
traps cannot be constructed. It is essential to regularly check and clean
out these sediment traps and filters to Unsure that they function properly.
A sod filter is inexpensive and easy to I construct and provides immediate
protection. A straw bale filter can be | located as necessary to collect^
sediment and may be used in conjunction!with a snow fence for the site.
Aggregate Cover. Areas being prepared for paving should be
protected by the use of aggregate coverj Aggregate cover stabilizes the
soil surface while allowing the movement of construction equipment on the
right-of-way. The aggregate cover may also be used as part of the permanent
1 121
base in the construction of paved areas,.
Curb and Gutter. Concentrated; runoff leaving paved areas is highly
erosive. After construction is complete, the paved roadway itself can
serve as a drainageway with curbs and gutters conducting runoff to enclosed
drainage system inlets. Where it is not economically feasible to install
curbs and gutters, paved surfaces shoul|d be designed so that runoff will
travel the shortest possible distance across the paved areas. This will
prevent large accumulations of runoff from leaving paved areas at high
112 i
velocities in any one area. ;
Windbreak. A windbreak, such las a snow fence, may be employed
to minimize wind erosion on large flat jsurface areas. Neighboring properties
, 123 I
may also be protected. . j ......
Filter Berm. A filter berm is a temporary ridge of gravel or
crushed rock constructed across a graded right-of-way to retain runoff
while at the same time allowing construction traffic to proceed along the
97
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right-of-way. They are used primarily across graded rights-of-way that
are subject to vehicular traffic, tut are also applicable for use in
drainage ditches prior to roadway paving and establishment of permanent
ground cover. Filter berms intercept and divert runoff to stabilized
areas or Prepared drainageways, and serve to slow runoff and collect
sediment.
Traffic Control on Construction p^0 Being in constant US(3/
construction roads may be a particular source of pollution, .where feasible
alternative routes should be made for construction traffic: one for use
in dry conditions, the other for use in wet conditions employing a number
of control measures, where possible, the construction road should be
routed along the same line as permanent roads so that the permanent roadbed
may be used for construction traffic. Efficient construction road
stabilization not only reduces on-site erosion, but'can significantly speed
on-sxte work, avoid instances of immobilized machinery and delivery vehicles
and generally improve working conditions under adverse weather. Mud on vehicle
tores is significantly reduced, avoiding a hazard by depositing mud on the
public roadway by dump trucks, delivery vehicles, etc. inlets and oth.r
partially completed storm drainage structures are protected during con-
struction. However, measures on temporary roads must be cheap not only to
install but also to demolish if they interfere with the eventual surface
treatment of the area. therefore, in addition to such measures as aggregate
cover, filter inlets, filter berms, etc., it may be desirable to dmploy
alternative routes for construction traffic. Each route can be rested
alternatively and critical areas stabilized, in some cases it may be
desirable to have a good weather route and a wet weather route.126
98
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REFERENCES
Tnf,,rli, Progress Report on tbp Analysis of Best
1. Colston, Newton V., Jr. Characterization and Treatment of Urban
Land Runoff. EPA 670/2-74-096, December 1974, p. 89.
2 Poertner, Herbert G. Practices in I Detention of Urban Stormwater
Runoff. Prepared for the Office of Water Resources Research, U.S.
Beilrtment of the Interior. OWRR Project No. C-3380, OWRR Contract No.
14-31-0001-3722, 1974, p. 2. j
3 Amy, Gary, et al. Water Quality Management Planning for Urban Runoff.
Prepared for the U.S. Environmenta[L Protection Agency. Report No.
EPA 440/9-75-004, 1974, pp. IV-2 - IV-5.
4. Ibid., p. IV-6.
5. Waldo, Andrew. An xn^erxm ±-j.^.i..=oo ^^~ -.... 7nv.-*4-\ •
Management Practices. U.S. Environmental Protection Agency. (Draft)
November 1975. . - j
6. Amy et al., op_. cit., pp. IV-6 - IV-7.
7. Waldo, op. cit. j
8. Amy et al., op cit., p. IV-5. j
9. Tourbier, Joachim, and WestmacottJ Richard.' Water Resources Protection
Measures in Land Development - A Handbook. Prepared for the U.S.
Department of the interior, Offic^ of Water Resources Research.
April ':
10 American Public Works Association' M^^ Pollution Aspects of Urban
Prepared for the Federal;Wa^ir Pollution Control Admxnxstratxon.
Contract
11.
12.
13.
14
15.
16.
17.
Contract No. WP-20-15, 1969.
Waldo, op cit. •
„ i
Tourbier and Westmacott, op. cit.|, p. 149.
Mammel, F.A. '"We Are Using Salt-Smarter." American City. LXXXVII(l):
54-56, 1972. ]
Field, R., et al. Water Pollution and Associated Effects from Street
Salting. EPA-R2-73-257. Edison jWater Quality Research Laboratory.
U.S. Environmental Protection Agency. May 1973.
, John A., and William G. Smith. Urban Stormwater Management and
An Assessment. Prepared for the U.S. Environmental
- — .""" —«-»«. tf\ *-t A r\ A r\ "I Q*7>1 T-\ IxQ
^nooov: n s.
Protection Agency. Report No. EPA-670/2-74-040, 1974, p. 139 .
!
Tourbier and We'stmacott, op. cit\, pp. X49-150
Ibid., p. 150. I
99
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18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
Department of Community Development and Henningson,
Durham, Richardson, and Hart, Inc. Stormwater Management Plan for
Rosa.C°™ties- Prepared for the West Florida ~
.-
Planning Council, Pensacola, Florida. May 1974.
Tourbier and Westmacott, op_. cit. , pp. 153-154.
Hawaii Environmental Laws and Regulations, Volume II, Chapter 46.
Lager and Smith, op. cit., p. 152.
Ibid. , pp. 152-153.
Poertner, op. cit. , p. 6. •'-..
Ibid . , p. 132.
Waldo, op. cit.
Poertner, op. cit., p. 140. ; :
Lager and Smith, op. cit., p. 153.
Poertner, pp. cit . , pp. 4-6.
p Authoritv- ' Redevelopment Plan: Skyline Urban
Project, Denver, Colorado. February 1969. ~~~ — —^i_
Poertner, pp_. cit., pp. 11-16. ;
Ibid., p. 28. ;
Ibid., p. 12.
Ibid., p. 29.
Ibid., p. 5. ;
Ibid., p. 5. \
Ibid., pp. 5-6. :
Ibid., p. 26.
Ibid., p. 46. ;
Tourbier and Westmacott, op. cit., pp. 66-69.
Young, G.K., et al. Model to Design Stormwater Detenf-^n Tanks for
Nonpoint Source Pollution Abatement. April 1975. ~ ~
100
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41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
Pdertner, op. cit., pp. 41-43.
Ibid., p. 35.
Tourbier and Westmacott, op. cit., p. 44.
Ibid., pp. 44-45. i . . , :
Poertner, op. cat., p. 35. i
— —— i
Tourbier and Westmacott, op. cit., pp. 46-47.
Heaney, James P., at al. nrfaan Stormwater Management
Making! U.S. Environmental Protection Agency. ^oDect No
"(11023 GSC), Program Element No. 1BBB034. May 1975, p. 141.
Poertner, op. cit., pp. 151-153. |
Heaney et al., op. cit., p. 141. j
Tourbier and Westmacott, op. cit., jpp. 48-49. ,
Ibid., pp. 50-51. |
i
Ibid., pp. 54-55. ]
Ibid., pp. 56-57. '
Ibid., pp. 58-59.
Ibid., pp. 62-63. j
Ibid., pp. 64-65. |
Beckett Jackson Raeder, Inc. Michigan Soil Erosion and Sedi^ntation
Control Guidebook. Prepared for the Michigan Department of Natural
Resources, Bureau of Water Management, February 1975.
Ibid., p..10. |
Tourbier and Westmacott, op. cit. ,| p. 81
i
Beckett Jackson Raeder Inc., op. git., p. 99.
Tourbier and Westmacott, op. cit. ,1 pp. 81 82.
i -
Ibid., pp. 83-84. j
Beckett Jackson Raeder Inc., pp.. cit., pp. 25-26.
101
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64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
r
Control, Construction
Costs of E
f,r thr -_
— — — __ * ^ -"-^.fcu-ci-i j_i_u. tne u.b. E
Protection Agency. July 1973, pp. 53-57, EPA-430/9-73-016
Ibid., p. 102. •
Ibid., p. 104.
Ibid./ p. 106.
Beckett Jackson Raeder Inc., op_. cit., p. 25,
Tourbier and Westmacott, pp. cit., p. 103.
Beckett Jackson Raeder Inc., op.: cit., p. 25.
Tourbier & Westmacott, pp_. cit., p. 99.
Ibid., pp. 107-108. '
Erosion-Siltation C
Beckett Jackson Raeder Inc., op. cit., p. 17.
Ibid., pp. 20-21. .
Ibid., p. 22. .
Engineering-Science-,'Inc., op_. cit., p. _30.
Beckett Jackson Raeder Inc., op. cit.
Engineering-Science, Inc., pp. cit., p. loo.
Dow Chemical Company. An Economic Analysis of
Control Methods for Watersheds Undergoing
and Sediment
81.
82.
83.
84.
85.
86.
.. .,r
Engineering-Science, Inc., op. cit., pp. 41-42.
Beckett Jackson 'Raeder Inc., op_. '.cit.
Ibid. , p. 20.
Dow Chemical Company, op cit.
Tourbier and Westmacott, o£. cit./ p. 89.
Beckett Jackson Raeder Inc. , c£. cit. ...... / .'...-.•.
102
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87. Tourbier and:Westmacott, op. cit., PP. 89-90.
--,'•;-. . -,' -- ' .. I ... "•-• _..-"•
88. Beckett Jackson Raeder Inc., op_. c±£., p. 23.
89. Tourbier and Westmacott, op. cit., p. 85.
90. Beckett Jackson Raeder Inc., op_. ci£., p. 24.
91 Tourbier and Westmacott, op_. cit., )?p. 85-86.
«.
Prepared for the U.S. Environmental Protection Agency, EPA-R2-72-015.
August 1972, p. 27. . | .-.'.•> •-.
93.
94
95
96.
97.
98.
99.
100.
101.
102.
103.
104.
105.
106.
107.
108.
109.
110.
Beckett Jackson Raeder Inc., op_.
Tourbier and Westmacott, op_. cit.,jpp. 95-96.
Beckett Jackson Raeder Inc., ££. c^t., p. 23.
...-' • " ! • - -.-'-.-•
Ibid., p. 27. j
Tourbier and Westmacott, pp_. cit.,| PP. 123-124.
Beckett Jackson Raeder Inc., op. c£t., p. 28.
Tourbier and Westmacott, op. cit. ,j pp. 123-124.
j- ...••-... - - „ _
Ibid., pp. 129-130. i
Beckett Jackson Raeder Inc., op_. cit., p. 29.
Tourbier and Westmacott, op. cit.* p. 128.
Ibid. , P. 128.; , . ; . ''..,........•-.•..
Engineering-Science, Inc., op_. cit.. , p. 23.
Tourbier and Westmacott, op_. cit., p. 91 •
Beckett Jackson Raeder Inc., op. cit.
Department of Public Works, City bf Baltimore. Baltimore City Erosion
and Sediment Control Manual, May ;1971.
Tourbier and Westmacott, op_. cit.i, p. 132.
! -.---'
Beckett Jackson Raeder Inc., op_. jcit., p. 34*
Hittman Associates, Inc. _^_
on Construction Sites, 19?3, p. 2.
of Sed^ent Generated
103:
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Ill*
112.
113.
114.
115.
116.
117.
118.
119.
120.
121.
122.
123.
124.
125.
126.
Ibid., pp. 7-8.
Beckett Jackson Raeder Inc., op. cit., pp. 32-33,
Ibid., p. 35.
Tourbier and Westmacott,, op_. cit., p. 109.
Beckett Jackson Raeder Inc., bp_. cit., p. 35.
Ibid., p. 35. ,
Tourbier and Westmacott, pjp. cit., pp. 115-116.
Beckett Jackson Raeder Inc., op_. pit., p. 30.
Ibid., p. 37.
Ibid.
Ibid., p. 40.
Ibid., p. 40.
Ibid.
Engineering-Science/.Inc., op. cit., p. 33.
Beckett Jackson Raeder Inc., o£, cit., p. 40.
Tourbier and Westmacott, o£. cit., pp. 87-88.
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4.0" REGULATORY APPROACHES I ' ....... ...-,.•
The technical approaches discussed in Chapter 3 above can be imple-
mented through the" regulatory, fiscal, and proprietary powers of state and local
government. Despite the now dominant' role j>f the federal government in
regulating point sources, the control of nphpoint sources—especially
stormwater runoff and leachate from septic j:anks and landfills-remains
almost entirely a state and local responsibility. This distinction is clearly
recognized in Section 208 of the Federal Wajter Pollution Control Act Amend-
ments of 1972, under which areawide strategies, including regulatory programs ,
are to be developed for controlling all sources of water pollution. Section
208 contemplates, moreover, a planning approach that proceeds from the bottom
up, with important initiatives to be taken jby local governments, both- -separately
and in cooperation with one another. This (approach recognizes that preventive
strategies for managing nonpoint sources a^e inseparable from land use controls,
which have traditionally been exercised for the most part by local governments.
The aim of the present chapter is jxs indicate ways in which' state and
local governments can exercise their power^ for the purpose of regulating
nonpoint sources, especially stormwater runoff. - Eight specif ic regulatory
approaches are discussed:
techniques, not all purely "regulatory.' (4.2.1)
s r
whatever wasteflows it generates. (4.2.2)
of protecting water quality, (4.2.3)
incident to development. (:4-.2.4)
10..5,
I
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(5) Requiring that development proceed along lines and in ways that
preserve natural processes associated with the hydrological
cycle. (4.2.5)
(6) Conditioning development permission upon compliance with
technical standards for controlling runoff, erosion, and
sedimentation. (4.2.6)
(7) Controls over land disposal of wastes for the purpose of
protecting water quality, including controls over solid waste
disposal and use of septic tanks. (4.2.7)
(8) Regulatory and administrative controls over inplace or
accumulated sources. (4.2.8)
Since a great deal has already been written in this field, the
reader will be referred at various points to selected portions of the literature,
Our concern here cannot be to exhaust the subject, but only to survey, with
the aid of examples of actual practices from around the country, the range of
regulatory approaches that are open to state and local governments. Before
adopting any of them, it is strongly recommended that the decision-maker refer
to the relevant bibliography and consult legal counsel on the particular laws
of his state as construed by its courts. The variations in legal authorities
among the fifty states are numerous; the reader is therefore cautioned not to
assume that a solution adopted by one locality can be readily transferred to
any other. On the other hand, the range of possible regulatory approaches is
fmite, and one or more of those described below may be found suitable, with
appropriate modifications, to the needs of many localities.
Several other caveats should be stated at the outset concerning the
use of the materials that follow.
Regulatory power is rarely exercised for the exclusive purpose of
protecting water quality from nonpoint sources of pollution. Additional pur-
poses are almost always present, in the pursuit of multi-faceted environmental,
economic, and social objectives. TOiis is true even with respect to regulations
that are specifically addressed to thei control of runoff, erosion, and
sedimentation. In addition to-preserving water quality, such regulations
may aim to avoid flood damage, preserve land and ecosystems, protect esthetic
and other amenities, recharge groundwater supplies, and channel development
along suitable lines. In choosing among strategies for nonpoint source
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I
control, then, the decision-maker will inevitably find himself taking into
account a host of considerations that include but go well beyond water quality.
He may try to work from a singular point of view, but piecemeal regulation
without overall planning can perpetuate oj aggravate conflict among different
social objectives. It is therefore recommended that nonpoint source controls
be integrated to the maximum possible extent with comprehensive planning for
land use and development in all affected Areas. (Refer to Chapter 2.)
For convenience, each of the regulatory approaches is presented
under a separate heading. It should be emphasized, however, that these
approaches are not mutually exclusive; eajdi has its own distinguishing features,
but they also overlap one another. In fact, the best results are likely to be
achieved by some combination of two or mope approaches. For example, the
districting of sensitive areas (such as wptlancls or hillsides) on which develop-
ment is to be restricted could be combinek,with a capital improvement program
that positively channels development intoj more suitable areas. Ordinances
prescribing control of erosion and sedimentation can operate in buffer zones
surrounding conservation districts, and purchases of conservation easement or
systems of transferable development rights can alleviate inequities caused by
restrictions on development. Natural performance standards with respect to
particular types or gradients of soils cjn facilitate preparation of environ-
mental impact statements whenever these jre prescribed as conditions for
securing approval for development. Such|examples could be multiplied indefi-
nitely; the decision-maker must considerjwhat combination of control strategies
best suits the needs of his locality. , .
Preceeding the discussion of the!specific regulatory approaches will
be a brief description of the sources ofjstate and municipal regulatory
authority over nonpoint sources such as jstormwater runoff. A final section
will raise several issues related to implementation of these approaches.
' j '•'."'-'
4. i The Legal Framework and the Scopis of Legal Authority
The powers reserved to the statejs 'under the Tenth Amendment to the
United States Constitution include the p|owers to tax and spend for the public
welfare and for the maintenance of government itself; to acquire, manage, and
dispose of property for public purposes;, and to regulate private activity in
the.interest of 'the public health safety^ and general welfare. These sovereign
powers of the states, particularly the regulatory ones, are generally known
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as "police powers." They are the ultimate source of authority for all
the regulatory approaches discussed in this chapter. Their exercise is
limited by a number of constitutional restraints, of which the most
important for our purposes are that the governmental power be exercised in the
public interest; that the means of government intervention be reasonably
necessary for the accomplishment of a public purpose; that standards of
procedural due process be observed in the regulation of private activity;
that a state refrain from discriminating unreasonably against any class of
persons in the application of its laws; and that private property not be
taken for public use without just compensation. Within these constitutional
limitations , the states may avail themselves of a broad range of strategies
for environmental protection.
Any or all of the approachesjmentioned previously could be undertaken
entirely at the state level, through enactments of the state legislature and
administration of regulatory, fiscal^or proprietary functions by agencies of
the executive branch to which the legislature,has delegated the necessary
authority. However, the states have delegated a large measure of their
police powers to local governments, either through "home rule" provisions
of state law, or, more commonly, through enabling statutes, state constitutions,
municipal charters adopted in accordance with constitutional or statutory
provisions, and enabling legislation '.are the fundamental sources of local
government authority. It must be borne in mind that local governments have
no inherent authority of their own, but only such powers as are granted to
them by the constitution and statutes of the state in which they are located.
Thus, there may be a threshhold question as to whether a local government has
the authority to legislate in a particular manner to deal with a particular
problem. For example, it may lie within the general police power of a
municipality to regulate the disposal; of waste, but not to impose a tax upon
waste products released to the environment, even though the legislative
goal might be the same in either case. In such an event, the municipality
would have to obtain specific legislative authority to impose a tax.
Home rule provisions, which are designed to carve out a legislative
jurisdiction in which local governments can operate free of state interference,
typically authorize municipalities "to exercise all powers of local self-
government and to adopt and enforce within their limits such local police,
sanitary and other similar regulations, as are not in conflict with general
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laws."2 Such a clause may, for example,jauthorize a municipality to require
of a subdivider that he dedicate land fojr public purposes, even in the
absence of any statutory authority to exfct such a condition. On the other .
hand, municipalities in home rule jurisdictions may not in fact have
greater powers to control pollution thanj in states where home rule is not
recognized. This is true for two reasons. First, state law may "preempt
the field" in matters transcending local! concern. State regulation, in
other words, may be so pervasive or so comprehensive with respect to a
particular activity that no room is left for local governments to adopt
regulations of their own pertaining to t|he same subject matter. It is a
question of legislative intent, commonly: interpreted by the courts, as to
whether state intervention is preemptive; or whether state and local enact-
ments can work concurrently in the samejfield. Where preemption does not
exist, local regulations are commonly sustained if they require controls
as strict as or stricter than state lawJ If conflict is otherwise found to
exist between state and local enactment^, the former will, always prevail.
These determinations are quite independent of the question whether home rule
has been granted municipalities in matters of local concern.
Secondly, state enactments delegating police power to local
governments may be so broad in scope asjto approach constitutional home rule
by legislative means. For example, municipalities may be authorized by
statute to "take all action necessary oj: convenient for the government of
their local affairs," or to "enact all ordinances, regulations, and by-laws
for the well-ordering, managing, and directing of the prudential affairs and
police of their respective towns."3 TlJus, state legislatures may delegate broad
powers to municipalities to provide for! the safety, health, welfare, and
convenience of their respective communities. So even in jurisdictions
without constitutional home rule, municipalities may have extensive
powers to regulate pollutant-generating, activity.
The upshot of this brief discussion of a very complicated topic is
that local governments may have greater powers than they realize, but
should obtain the advice of legal counsel on the extent' to which the absence
of home rule, restricted statutory authorization, state preemption, or judicial
precedent may limit local power, beforfe attempting to extend the reach of
their environmental controls. ]
In most states, enabling legislation authorizes local government to
adopt zoning ordinances, subdivision regulations,, and building and health
codes. These traditional regulatory vehicles can be used to a greater
extent than is generally appreciated for purposes of controlling nonpoint
109
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sources of pollution. Specific authority to regulate waste disposal, land-
tisturbing activities, and stormwater runoff may also be delegated by
enabling laws. The first step of the 208 planner is to determine what can
be done with the laws already on the books.
Zoning enabling acts commonly provide, in part, that local
governments may regulate - ..
the percentage of a lot that may be occupied, the size of
yards courts, and other open spaces, the density of population,
and the_location and use of buildings, structures, and land for
trade, industry, residence or other purposes.... Such regula-
an"?1^ ^ made ... to secure safety ... to promote health
and the general welfare ... to prevent the overcrowding of land,
to avoid undue concentration of population, [and] to facilitate
adequate provision of ... sewerage and other public requirements.
Such regulations shall be made with reasonable consideration .
to the character of the district and its peculiar suitability
for particular uses, and with a view to conserving the value of
buildings and encouraging the most appropriate use of land
throughout such municipality.4
Pursuant to provisions such as these, a municipality may require minimum lot
sizes in areas where the capacity of soils to- absorb septic tank waste is
limited; may designate districts in which land uses are restricted because
of natural features of the land that would affect drainage and seepage;
and may require that the pace and pattern of development be governed by the
time-phased extension of sewerage and other municipal services in
accordance with a capital development program.
In steel Hill Development. Inc. v. Town of Sanbornton.5 a federal
court recently upheld a six-acre minimum lot size ordinance as a
legitimate stop-gap measure, designed in part to prevent water pollution and
other forms of environmental degradation, until such time as the town could
plan some longer range approach for coping with the intense development
pressures it was facing.
Under zoning enabling acts or amendments to them, municipalities may
also be authorized to permit cluster zoning and planned unit development,
which afford flexibility to a developer in designing his site so long as he
meets overall density restrictions and provides certain services or
amenitites. In this manner, development may occur in "clusters or more
environmentally tolerant parts of a site while sensitive areas are retained
as open space. » In Bucks County, Pennsylvania, it has been proposed to
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stipulate through a zoning ordinance-nojb only density requirements but also
permissible ratios of open spaces to impervious surfaces. To; avoid erosion
and consequent water pollution as a resjilt of further development, the city
of Palo Alto, California, recently adopjfced an open space zone in which.one-
i - ' ' 9
family dwellings were the most .intensivje-use that would be permitted. The
zoning ordinance of Harristown, Illinois, contemplates the establishment of
conservation zones, whose purpose is: j . . .
•• • I
to prevent the construction upon or alterations of ...
natural environments which have! natural conditions of soil,
slope, susceptibility to floodiing or erosion, geological
conditions, vegetation,'or interaction between the afore-
said which makes such lands unsuitable for urban development.
Further, this zone is establish'ed to protect areas of the
environment, that, if altered, toould cause health or population
problems, and environmental degradation.
• ' ' ' " " " \ ' ' '•' ' • • 11' - '
In the celebrated case of Golden v. Planning Board of Ramapo the Court
of Appeals of New York held that population growth could be controlled
through restrictions on the sequencingjand timing of development, even though
the relevant zoning law did not expressly authorize such control.
The foregoing examples illustrate the potential reach of the-.zoning
authority in preserving open spaces for retention and infiltration of rain
water, and for guarding against prematiire or unsuitably located development
that could cause nonpoint pollution. It will be necessary to assure in all
cases, however, that land use restrictions do not go so far :as to
constitute a compensable taking of private property.
Under planning enabling acts, 'localities are commonly authorized to
adopt subdivision regulations, to whiclji a developer must conform before
he can obtain approval of his plat. Ih some jurisdictions, courts have held
that local governments may impose conditions requiring a subdivider to
• •_.:•• I. ..-••'."• .•••''•'•••••'•'' j_3 "
dedicate land for public open space betore he can obtain approval. Platting
may be prohibited or severely restricted on critical water-related lands,
such as floodplains, wetlands, shorelands, andsteep slopes, where intensive
development could be expected to jeopardize water quality. Subdivision
approval is also a fitting juncture atjwhich to require submission of
environmental impact statements detailing aspects of the site plan (including
erosion and sedimentation controls) thjat are designed to minimize adverse
effects on the environment, and other jeviderice that the subdivider has arrayed
the components of his plan in harmony jwith the natural features of the site.
ill" -. .'
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Building and sanitary codes typically authorize local governments to
"enact and enforce ordinances regulating the construction ... maintenance,
sanitation ... inspection ... and control of ... buildings, dwellings, and
structures of all types and descriptions, whether used for human habitation
or otherwise " Accordingly, construction codes may require use of
stormwater detention facilities or of permeable materials to increase
infiltration, and sanitary codes may regulate the location and construction
of septic tanks and landfills, in part by reference to the permeability of
the soil and the level of the water table. Moreover, both types of code
can and should impose ongoing responsibilities on owners or operators of
control facilties to maintain them in good repair. For example, the code
may make it the duty of landowners to prevent accumulations of sediment
behind detention devices (as a precaution against sediment runoff) and to
have their septic tanks periodically cleaned out by licensed scavengers.
A good code will also provide for periodic inspection by officials to monitor
compliance. ;
Imaginative exercise of the foregoing traditional sources of
authority can go far toward controlling nonpoint sources of pollution at
the local level. We turn next to taking a closer look at the principal
varieties of control strategies that are in use today in one or another
part of the country.
4*2 Specific Regulatory Approaches and Techniques
4-2-1 Acquisitions of Land for Open Space and Other Non-Intensive Uses
As noted in earlier chapters, particular parcels of land may play a
critically important role in the hydrological cycle by virtue of their
capacity to retain or absorb stormwater, or because incompatible develop-
ments upon them might cause an especially serious problem of runoff, erosion,
and sedimentation. The best and most direct way of securing the protective
functions of such lands is to acquire them for public purposes, including
conservation or recreation, for which extensive grading, stripping, and
paving will not be required.
Grants to defray the cost of purchasing recreational properties
may be available from the Land and Water Conservation Fund administered by
the U.S. Department of Interior's Bureau of Outdoor Recreation, under 16
USC § 4601, and from parallel state programs. Even so, public land acquisi-
tion is likely to be an expensive proposition for a community. There'is
112 ,
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not enough federal and state money to go around for this purpose and the
community will ordinarily have to pay forj some part of the purchase cost.
Conservation easements or restrictions, which can be acquired either
by gift or purchase, are a less costly technique for avoiding environmentally
degrading developments. A New Jersey lavi, for example, authorizes certain
governmental bodies to acquire "interests or rights consisting, in whole or
in part, of restrictions on the use of llnd by others." A Pennsylvania
law enables counties to covenant with landowners for the preservation of
land in farm, forest, water supply, or other open space uses. By such a^
covenant", the land owner commits himself j to maintaining his land as open
space for 10 years and the county promises in turn to assess the property at
a value no greater than it is worth with]the encumbrance of the restrictive
covenant. This device gives the owner sj>me relief from property and estate
taxes as well as a charitable deduction from his income tax. It also
enables him to retain title and to continue living on the land without
intrusions from the public or to use thej land in any manner he wishes so
long as he preserves it consistently witfi the terms of the restriction.
In effect, the owner sells (or donates) |and a local government agency or
charitable corporation buys only certain development rights in the
property, at what^may be a considerable pavings in costs compared to the price
that would have to be paid for purchasing the entire title. Federal and
state assistance, moreover, may be available for such partial acquisitions.
| -J.O - -
The Massachusetts Conservation Restriction Law is an example
worth discussing in some detail. It defines conservation restrictions as
rights appropriate to keeping "land or viater areas predominantly in their
natural, scenic or open condition or in!agricultural, farming or forest use."
Activities that could jeopardize water quality may be expressly forbidden
or limited by such restrictions, including: "(a) construction or placing of
buildings ... or other structures on orjabove the ground, (b) dumping or
placing of soil or other substance or material as landfill, or dumping or
placing of trash, waste or unsightly orjoffensive materials, (c) removal
or destruction of trees, shrubs or othe|c vegetation, (d) excavation,
dredging, or removal of loam, peat, gravel, soil, rock, or other mineral
substance ... (3) surface use except fojr agricultural, farming, forest or
outdoor recreational purposes or purposes permitting the land or water
area to remain predominantly in its natural condition, (f) activities
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detrimental to drainage, flood control, water conservation, erosion control
or soil conservation...." The.restrictions can be tailored to fit the
particular situation. Generally, they provide that all rights not
expressly conveyed are reserved to the grantor, thus allowing a range of
consistent uses. Occasionally, an easement allowing the grantee to enter
on the premises and inspect for violations is conveyed along with the
restriction.
The acquiring party must be either a governmental or a charitable
body whose purposes include conservation. Acquisitions may be by eminent
domain, gift, or contractual agreement, and must be approved by the
appropriate state and local agencies. When a restriction has been recorded
so as to provide public notice that the land is encumbered, it becomes *
enforceable over time from one landowner to another, by means of an
injunction or proceeding in equity if: necessary.19 The landowner may be
released from the restriction upon payment of . such consideration as the
holder may determine, but only after, a public hearing on 'the matter following
upon advance public notice. "The /requirement that a public hearing be held
before any action is taken will safeguard against the use of variance
practices that have proved so dangerous and arbitrary in the administration
f^^ .i_i . ..20
of the zoning power."
Valuing conservation restrictions for tax. purposes may pose some
problems, but these can be surmounted. It is also advisable to provide
for roll-back taxes, conveyance fees, or penalty provisions in the event
that a restriction is discontinued or violated/in order to discourage 'abuse
of this device by land speculators. As for whether the cost of a conserva-
tion restriction in terms of lost property tax revenues will be more than
offset by the benefit of open-space preservation to the community, that is
a question that can only be answered by reference to the community's overall
land-use policies. In this connection, it should be pointed out that develop-
ment of certain lands may saddle a community with higher costs for new
services than it will receive in new tax revenues, and that preservation of
open spaces may well have the effect of increasing the assessable values '
of surrounding tracts.
Perhaps the principal advantage of the conservation restriction is
that it is a non-adversarial technique for preserving open spaces, without
the necessity of having to purchase them outright or to regulate them to
the point where takings might be deemed to have occurred.
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422 Time Phased Capital Investment and Development Guidance
. • • • • j- • •
By guiding the location, sequence,! and timing of new municipal
facilities, including sewerage and drainage, a community can discourage
premature development that might cause ncppoint pollution in the absence
of such facilities and can channel development positively into areas where,
because of favorable topographical conditions, it is least likely to
generate polluted runoff or leachate. Development guidance through the time-
phased provision of municipal services cjm therefore serve indirectly to
prevent sources of nonpoint pollution from arising, while promoting a wide
range of environmental and economic objectives.
A controlled growth plan of this sort in the town of Ramapo, New
York was upheld in the celebrated case oj: Golden v. Planning Board of
Ramapo.22 The Town of Ramapo had amendeja its zoning ordinance to require
special development permits, which wouldjbe granted in each case only if
the land to be developed was located in Jan area served by a minimum level
of certain community facilities. These Ifacilities, including sewerage and
drainage, were to be installed in accordance with a master plan, an
official map, and an 18-year capital improvement program to which the town
had committed itself. Development permits could be granted only on the
basis of a "point system" that reflected! the proximity of the site to such
improvements, but a developer could acquire additional points and
thereby accelerate his eligibility by providing the necessary improvements
himself. Lands whose development potential was deferred under this scheme
could be afforded reductions in property! taxes. The announced purposes of the
program as a whole were to afford relief to the citizenry from the rising
burden of the total tax load and to eliminate unplanned and uncoordinated
growth which outstripped the capacity of availability of supporting
community services such as drainage, ro
-------
Enabling Act to avoid "undue concentration of population" and to "facilitate
adequate provision of public services" included time-phased controls as
"a necessary concomitant to the municipality's .recognized authority to
determine the lines upon which local development shall proceed...."
To the objection that the ordinance was exclusionary, the court
pointed out that the town was committed to expanding its facilities in an
orderly manner and to ensuring "continuous development comensurate with the
town's obligation to provide such facilities. They seek, not to freeze
population at present levels, but to maximize growth by the efficient use
of land...." Finally,, the court held that the ordinance did not amount to
a public taking, since deferrals of development rights under the ordinance
were only temporary and property owners could elect to accelerate the rate
of development by installing at their own expense the necessary public
services to bring their parcels within the required number of development
points. Moreover, even during the period of deferred development rights,
landowners were not deprived of all reasonable uses of their property; they
could, for example, construct single family residences without reference
to the restrictive provisions of -the ordinance. "In sum, where it is
clear that the existing physical and financial resources of the community
are inadequate to furnish the essential services and facilities which a
substantial increase/in population requires, there is a rational basis for
'phased growth' and hence, the challenged ordinance is not violative of the
Federal and State Constitutions."
A somewhat similar approach was upheld by a federal court in Construc-
tion Industry Association of Sonoma County v. City of Petaluma.23 Petaluma
had adopted a 500 per year limit on the number of new dwelling units that
could be constructed in the city, pursuant to an announced policy of
preserving its small-town character and surrounding open space, of keeping
new development within the bounds of available municipal services, and of
providing a permanent green belt around the city. The court held that
the "public welfare" purpose of zoning was sufficiently broad to include
these objectives. The Petaluma plan was therefore deemed "a reasonable and
legitimate exercise of the police power." in so holding, the court observed
that the plan did not freeze local population at present or near-present
levels and did not have the undesirable effect of walling .out any
particular income class or racial minority group. In fact, the plan
116
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contemplated that between 8 and .12 per cent of each year's housing quota
would be allocated fco low or moderate Income housing.
i
These cases teach that a municipality, through careful exercise of
i
its powers to plan for land use and to program for investment, may
regulate the pace and pattern of its own Development in accordance with
environmental objectives. These may include avoidance of water pollution
from nonpoint sources, at least until such time as municipal facilities
are available to collect and treat waterbprne wastes. However, the Ramapo
i
and Petaluma approaches cannot be employe^ unless the municipality is
prepared to establish land-use policies and programs ranging far beyond
control of water quality. Moreover, unless the approach is carefully
conceived, it will run a high risk of being invalidated on constitutional
„ 24 I- '
grounds. !
i
4.2.3 Restrictions on Development Affecting Critical Natural Resources
This approach begins with the recognition that development should
be substantially restricted on certain types of land that play an important
part in protecting or — if improperly developed — in degrading the quality
of ground and surface waters. Included ijn this category are shorelands
surrounding streams and lakes, aquifers and their recharge zones, wetlands,
woodlands, and hillsides. Soils that are{ wet because of high water tables
or that are particularly vulnerable to erbsion might also be included.
A municipality may wish to designate special districts containing
such sensitive natural features as overlays to general zoning districts,
and to subject land use in the overlay districts to supplemental restrictions,
These will be designed, in part, to minimize interference with the natural
capacity of the land to retain, absorb, and purify wet weather flows (storm-
water) or dry weather flows (principally -leachate from septic tanks and
landfills). For example, septic,tanks might be prohibited in wet or
permeable soil districts; minimum percentages of vegetative cover might
have to be preserved on hillsides in order to prevent erosion; and filling
of wetlands might be prohibited or sharply restricted in order to protect
their functions of purifying the effluents they absorb and of recharging
surface waters in times of low flow. FO3J- each special district, a list of
permitted uses, prohibited acts, and procedures for securing approval of
special or conditional uses may be set forth, all geared to protecting
critical natural resources against incompatible development.
117 i
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.Regulations applicable to land-use in special districts may .be of
several kinds. The zoning ordinance of Harristown, Illinois, provides for
conservation zones in which uses are sharply restricted:
"The Conservation Zone is established to prevent the construc-
tion upon or alteration of rural or natural environments which
have natural conditions of soil, slope, susceptibility to flood-
ing or erosion, geological condition, vegetation or an inter-
reaction between the aforesaid, which makes such lands unsuitable
for urban development. Further, this Zone is established to
protect areas of the environment, that, if altered, would cause
health, or pollution problems and environmental deterioration.
The Conservation Zone will also ensure adequate areas for future
conservation and recreation .pursuits."25
With respect to permitted uses, land-use regulations for special
districts (or for any other property) may specify site requirements,
construction techniques, and protective maintenance measures (e.g.,
porous surface cover, no septic tanks close to water tables, periodic
2.fi
removal of accumulated sediments). Alternatively, the regulations may
prescribe natural performance standards, such as rates of runoff or soil
loss through erosion that are no greater than would have occurred if the
land had been permitted to remain in an undeveloped state.27' This approach
could leave the developer free to make whatever use of his land and to install
upon it whatever nonpoint source controls he may wish, so long as the land
in its developed state achieves the; required standards for performance.
Wisconsin law treats shorelands as a special management unit
in order to minimize pollution from;runoff and septic tanks associated
OO i
with shoreland developments. The law authorizes counties
to enact separate zoning ordinances, including protective regulations, for
all incorporated lands within 1,000 feet of a lake and 300 feet of a
29
navigable stream. These ordinances must meet minimum standards for
shoreland protection promulgated by the State Department of Natural Resources.
Accordingly, the Department adopted a set of regulations and a Model
Shoreland Protection Ordinance for the further guidance of the counties.
The Ordinance, which has in fact been widely adopted, specifically
regulates the location and construction of septic tanks and soil absorption
fields; specifies minimum set backs for various facilities; limits tree-
cutting to a 35-foot strip paralleling the shoreline and clear-cutting to
30 per cent of a strip; requires preservation of shrubbery "as far as
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,» arvd, where removed, its replacement with other vegetation
that will be "equally effective in retarding runoff, preventing erosion and
preserving natural beauty;" and prohibits filling, grading,, lagooning,
or dredging that would result in substantial detriment to navigable waters
by reason of erosion, sedimentation, or impairment of aquatic life.
Two restrictive classes of shorelani. zoning districts are established
under the Ordinance. The conservancy distkct is designed primarily to
protect shorelands designated as swamps orjmarshes, which are described as
"seldom suitable for building." Conservation and recreational uses are
practically the only ones permitted in such a district, except that certain
uses (dams, farming, piers, and docks) may•be allowed upon obtaining a
special exception permit. In residential/recreational districts, single-
family dwellings are also permitted, and, t>y means of special exception
permits, commercial and tourist facilitiesj.
The Ordinance also prohibits the subdividing of. shoreland which the
county planning agency deems unsuitable for that purpose "for reason of
flooding, inadequate drainage, soil and rojck formations with severe limita-
tions for development, severe erosion potential, unfavorable topography,
inadequate water supply or sewage disposal capabilities, or any other
feature likely to be harmful to the health1, safety or welfare of future
residents of the proposed subdivision,or qf the community." For subdivisions
not served by public sewers, the ordinance correlates minimum lot areas
with soil, ground water, and slope characteristics.
The Wisconsin, program is a clear example of how the natural resource
functions of critical land and water area^ can be protected by special
zoning for particular uses and by site pl^n requirements designed to
minimize water pollution and other forms of environmental degradation.
It is possible to regulate development in critical areas without
specifying in detail the standards to be met -or the control techniques to
be adopted. For example, the Flood Plainjand Wetlands Protection Ordinance
prepared for townships within the County of Oakland, Michigan, provides •
that conditional use permits to deposit material in or remove it from
designated watercourse or wetland areas mky be issued by the Township Board
upon "such conditions on the manner and ektent of the proposed operation,
use or activity as are necessary to ensurp that the intent of this
ordinance is carried out."3° That intend is quite generally,stated as, in
part, "to provide for,the protection, preservation, proper maintenance and
i
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use of township water courses.and.wetlands in order to minimize disturbance
to them and to prevent damage from erosion, turbidity or siltation,"
as well as "to provide for the protection of the township's potable fresh-
water supplies from the dangers of ... pollution ....» However, in the
absence of express regulatory standards, case-by-case review of land-altering
proposals requires evaluative expertise. If this is not available to the
reviewing agency, it may have difficulty reaching rational decisions and
avoiding abuses of discretion.31
4*2*4 Environmental Impact Assessments
It is possible to exercise control over site design through environ-
mental impact evaluation, even in the absence of comprehensive land use
policies, plans, or programs. By amendment to a-local zoning ordinance or
subdivision regulation, developers can be required to submit environmental .
impact statements on proposed developments (beyond a certain size), as
a condition for getting them approved by the local planning or zoning
board. Even is such a requirement is procedural only, limited to disclosure
of impacts, the exercise of assessing them and of comparing the impacts of
alternative plans often has the effect of sensitizing developers to en-
vironmental values and of inducing them to propose measures for minimizing
environmental harm. Further, an EIS ordinance may provide that develop-
ment of certain kinds will not be permitted unless the proponent can show
that it will not harm natural resources, including water quality. At the
least, EIS provisions can permit case-by-case review of development proposals
and furnish a point of leverage for public reviewing officials to suggest
corrections in the site plan or remedial action to be taken by the developer.
A subdivision regulation of the town of Lincoln, Massachusetts
requires an applicant for subdivisiok plat approval to submit an environ-
mental impact statement "the purpose: of which is to enable the officials of
the Town to determine what methods are used by the applicant to promote
the environmental health of the community and to minimize adverse effects
on the natural resources of the Town."33 in preparing these statements,
applicants are referred by the ordinance to a set of Environmental Quality
Maps adopted by the Town and to the j^oil Survey Map and Manual prepared for
it by the Soil Conservation Service of the U.S. Department of Agriculture.
In reviewing the statement, the Town Board will consider, among other
things, "the degree to which water is recycled back into the ground [and]
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the maintenance and improvement of the fOJOW and, quality of surface waters."
Specifically, the EIS must describe in detail the physical environment
surrounding the development, and.must describe and evaluate the methods to
be used both during construction and on 4.permanent basis to control erosion
and sedimentation. Further topics to be Described in detail include any
areas subject to flooding or ponding, proposed surface drainage systems,
proposed land grading and permanent vegetative cover and methods to be
used to protect existing vegetation, relationship of development to topo-
graphy, any proposed alterations of shorelines or wetlands, estimated
increase of peak- runoff caused by alteref surface conditions, methods to
be used to return water to the soil, subsurface soil and water conditions,
sewage disposal methods, and impact of sjach methods on quality of subsurface
. water. "Where appropriate, the Board may require soil surveys to establish
the suitability of the land for the proposed storm and sanitary drainage
installations." -These regulations clearly impose on the developer the
burden or preparing detailed plans for preventing pollution from nonpoint
i
sources. :
A subdivision ordinance of the To|wnship of Medford, New Jersey requires
preliminary plats to be accompanied by assessments of probable impacts on
municipal services, including water, stcirm sewers, and sewage disposal, and
on local lands, waters, and ecosystems.f Specifically, the environmental
impact statement must explain the impact of the proposed subdivision on
local geology, aquifers, hydrology, wat^r tables, runoff, soils and soxl
loss, soil nutrient retention, vegetation, and other aspects of the local
ecosystem. By reference to an Ecologickl Planning Study done for the town,
including a series of natural resource maps, the developer, is to ascertain
which of the regulations identified in pie study as desirable for protec-
tion of natural resources are applicable the development he proposes. He
must include those regulations in the Eks and describe the actions he will
take or avoid in order to minimize advelrse effects on the local environment.
The regulations35 are designed to enable land and water resources to continue
functioning, by,and large, as they wouid have done in the absence of
development. Their purpose is to mining the loss of valuable resources
such as.aquifers, soils, and vegetatiori, even as development compatible
with those resources is allowed to proceed. But "[w]here there is a question
as to the suitability of ... lots for their intended use due to factors such
as rock formations, flood conditions, rainage or other adverse environmental
-------
impact factor,, the planning Board may after aaecpats investigation withhoia
approval of such lots." ' ;
Such requirements go well .beyond mere disclosure, and they suggest
that environmental impact assessments can be a potent tool for protecting
watsr quality when combined with natural resource inventories. The stronger
the data base provided by a community as guidance for developers, the easier
it wxll be for them to assess and to minimize adverse environmental impacts
through prudent site planning.
Act 250 of the State of Vermont provides that no person may sell any
interest « a subdivision, nor commence construction on a subdivision or
development involving more than 10 acres of land, without a permit from the
State Environmental Board or appropriate District Commission.36(The district
commissioners are also agents of the state, appointed by the Governor )
Before granting such a permit, the board or commission must find that the
subdivision or development will not .result in "undue water or air pollution »
and in making this determination, it is to consider "the nature of soils and
subsoils and their ability to adequately support waste disposal; fand] the
slope of the land and its effect on effluents...... A permit will be
granted lf the applicant can demonstrate that his development "will meot
any applicable health and water resources department regulation reduction
of the quality of ... ground or surface waters flowing through or upon
lands" that include steep slopes, shallow soils, watersheds, public wafer
supplies, or aquifer recharge areas.! Applicants must demonstrate that they
will meet state regulations regarding the disposal of waste; that develop-
:nent on or adjacent to stream banks "will, whenever feasible, maintain the
natural condition of the stream;" and that development along shorelines
"wxll, insofar as possible and reasonable in light of its purpose
retain the shoreline and the waters in their natural condition ... and .
stabilize the bank from erosion, as necessary, with vegetative cover." The
Board or commission must also find that the proposed development "will not
cause unreasonable soil erosion or reduction in the capacity of the land to
hold water so that a dangerous or unhealthy condition may result." Bote
that these provisions (which illustrate the possibility^ administering
BIS requirements at the state level,'largely through district environ-
mental commissions, are rather.general and flexible in thei, application.
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I
Whether or not a proposed development wijll result in "undue" pollution or
"unreasonable" erosion is a judgment le^t largely to the discretion of the
administering agency. While such statuary standards have- the advantage of
allowing the agency to take account of the variant circumstances that dif-
ferent cases present, a statute like Vermont's arguably delegates too
broad a discretionary power , thereby plkcing too great a burden on admxn-
istrators to make principled- even-handed decisions from one case to the
next The risk of arbitarlness should be mitigated,, however, by the status
tory references to the specific regulatory standards that must be met in
Vermont before a development- permit will be issued.
By themselves, environmental impact .statements are no .substitute
for comprehensive land use policies, ^ey assure neither coordination of
environmental and development programs |nor harmonization of the environmental
effects of multiple or cumulative actions over time. "Kather it is hoped
that through ad hoc pro ject-by-projectj review the worst environmental
problems in a single action can be minted."37 Ideally, the disc.pl.ne ^
of the EIS process should be combined With natural resource inventor.es,
in the case of the Medf ord Township ordinance, as well as with overall
development policies and land-use standards. A combination of such
s and controls can be an effective means of assuring that s.te
incorporates measures for presenting pollution from nonpo.nt sources .
4.2.5 Environmental Performance Standards
"The goal of .environmentally oriented land-use regulation . ... is
to maintain or preserve natural processes as land undergoes change for
man's use."38 When such regulations are expressed in terms of the way
Xand actually fuactions - ,for exampl,, to retain or release runoff,
to lose topsoil through erosion - they posit what could be called
natural or environmental performance standards.
,,TO develop- this system of relation
£air s-^^
benefits that are ignored through the ^V^Jo^rosion, and
Specifically, these are P^fJJ?0^1^,^^^ to maintaining
ground water infiltratxon which are closel y droughts,
public water supplies , P-vengng ^a^e^nd maintaining
S/jSls^emselves . The community
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*i t a Specific (Preferably numerical) level at which
d ™ Ti TCeSS Sh°Uld °Perate' and a-ar development of the
land must be done in such a way that the natural process continues
'* ^ 1SVel* ^ C°ntraSt t0 a Deification app o"h,
f re?"lat?-0n d°es not «***« designated construction
or site planning, but allows the developer to choose
processes contSto
This approach is capable of zeroing in, precisely and directly, upon
natural phenomena whose disruption, distortion,, or overloading causes
nonpoint source pollution (as well as other forms of environmental
degradation) . The efficiency of the approach provides considerable freedom
to the developer to use his land as he wishes and to employ whatever control
measures he may choose, so long as his' site plan and his construction and
maintenance procedures meet the prescribed performance standards. Such
standards are usually couched in terms of how the land would perform if
left in a natural state, but it is possible to allow some leeway with respect
to performance characteristics in order to accommodate a degree of develop-
ment. m general, however, development will not meet the prescribed
standards unless it is undertaken in a manner compatible with the natural
environment, and this means that development proposals must reflect a
sound data base and a sophisticated understanding of such disciplines as
soil mechanics, geology, and hydrology as applied to the proposed site.
Application of these and other related disciplines is necessary in order
to measure and to minimize disturbances of natural functions.
The key to this approach is the initial step of constructing an
adequate data base through a multi-faceted study of the geology, topology,
hydrology, and ecosystem continuity of the community's natural resources
The essential data can be displayed in a series of maps and charts to which
planners, developers, and regulators will refer. From those data,
performance standards can be derived to guide the submission and review of
development proposals, perhaps through procedures requiring environmental
impact statements.
This approach need not be confined to particular districts of
critical planning conern, but can be applied across the board to all parts
of the community, including strategically important areas that may border
upon water resources or upon sensitive water-related lands. The necessary
factual and technical bases for employment of performance standards may be
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I
too expensive for some communities to acquire, but considerable assistance
in laying the necessary groundwork can b«* obtained from the U.S. Geological
Survey and from the Soil Conservation Service of the U.S. Department of ^
Agriculture, as well as from the expanding body of literature on the subject.
Pure performance standards, expressed entirely in terms of natural^
functions, are relatively rare. An ordinance of DeKalb County, Georgia,
provides that "[A] combination of storage and controlled release of
stormwater runoff shall be required for Jill development and construction
which will increase the peak rate of.runoff from the site by more than
one cubic foot per second for a ten yearj frequency storm." The ordinance
then sets.performance,standards.for the rate of runoff by.means of the
following formula: •
i
The .peak release rate of stormwatpr from all developments where
retention is required shall: i
i
(1) not exceed the peak .stormwater runoff from the area in its;,
natural undeveloped. state fo|r all intensities up to and
including the one hundred year frequency and all durations of
rainfall; or ;
(2) not be greater than that calculated for a storm of two-year
frequency with a runoff coefficient of .20, .25, and .35 for
land with an average slope elf up to 2%, 2-7%, and over 7%
respectively. ]
The ordinance also sets a performance standard for controlling the volume
of runoff:
"The live retention storage to be provided shall be calculated on
the basis of the hundred year frequency rainfall as published by the
National-Weather Service for theiaffected area. The retention
volume required shall be that necessary to handle the runoff of a
hundred year rainfall for any and all durations from the proposed
development, less that volume discharged during the same duration
at the approved release rate as specified above."42
The ordinance does not tell the developer what kind of retention facilities
to use; in this respect, it is entirely performance-oriented.
More succinctly, the policy of Medford Township, New Jersey is that
"£n].o alternation will be permitted of the amount of surface runoff
presently occurring, both under normal precipitation as well as under
intense storm conditions, as identified! ln the Runoff Management Chart
[e]xcess runoff is to be recharged locally into the ground through fehe use of
recharge ponds or injection wells."43 -The Runoff Management Chart correlates
vegetative cover type, soil type (in terms of both runoff and infiltrative
potential), and relevant land use categories (e.g., 1-acre residential,
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1/4-acre residential, intense urban), with excess runoff in inches produced
during the most intense hour of a 10-year recurrent 24-hour storm, and with
percentage of site area required for withholding that excess in order to
allow its infiltration locally within 3 hours. The three-hour limit
is deemed practicable in terms of the space required for rainwater
retention in suburban development. A separate hydrological map shows
current and permitted runoff for each area of the municipality as well
as outcrops of important aquifers, which are protected by a prohibition
against any increase in the.very low runoff rates prescribed for them.
With these technical aids, a developer can determine how to organize his
site plan and what control mechanisms to adopt, without having to study
the runoff problem from scratch.
The Medford Ordinance also provides that "soil loss [shall be] re-
stricted to three tons per acre per year at all times including all stages
of development." The three-ton limit was evidently recommended by USDA as
capable of being met through feasible interceptive devices (e.g., dams or
terraces) at or near the site. On this point, the ordinance refers the
developer to a Potential Soil Loss Map which shows the potential loss in
terms of tons per acre per year according to three different categories of
soil types, moisture conditions, and steepness and length of slopes. A
chart accompanying the map shows how calculated losses may be modified
according to the type of vegetative cover. For example, if the site
remains covered with grass, actual soil loss will be only 1.3% of the
Potential loss if the land is bare.
Alternatively, a developer might employ the so-called Universal Soil
Loss Equation, which correlates factors for rainfall, length and degree of
slope, erodability of soil, cropping and management techniques, and
conservation practices. By calculating each factor and multiplying, this
equation estimates the sheet erosion that will occur under different
AA
uses of the land.
Another regulation of Medford Township provides that "[application of
nutrients in the form of fertilizer, drainage from septic tanks and effluent
leaking from sewers [shall be]'restricted to types and amounts which can
be absorbed by local vegetation and soils to ensure no^increase in concen-
tration of nutrients beyond present levels at the top of local seasonal
high water table levels. " For meeting this requirement, the developer is
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46
referred to water-table and soil-permejbility maps, as well as to maps of
hydrological soil groups and cover typjs organized according to both
their infiltrative capacity and their runoff potential.
Quantitative performance standards of the sort specified in the DeKalb
and Medford ordinances, however, may b^ difficult to monitor and enforce.
Their principal utility probably lies (it the initial stage where a permitting
agency reviews development proposals, i At that stage, the agency can apply
technical expertise - which this approach assumes it will have at its
disposal — to.determine whether:the developer's proposed site plan,
construction techniques and procedures! for ongoing operation.and maintenance
will result in meeting the prescribed.standards. Once an approved
development is in place, unless sophisticated monitoring and inspection
techniques are available and employed,! compliance with the standards may
have to be inferred from compliance with the plans, techniques, and
procedures on which the development permit was originally conditioned.
Where pure performance standards cannot readily be specified, it is
still possible to prescribe standardsjfor human activity that are closely
related to the natural characteristicj of the site. In general, the
purpose" of such standards is to minimize interference with natural functions,
while allowing development to occur up to some point that is identified,
expressly or by implication, as the natural carrying capacity of the site.
For example, the Medford Township ordinance provides that where the
seasonal high water table is 0-1 feet^ no permanent habitation will be
permitted; where 1-5 feet, septic tank drainage fields are prohibited and
sewers must have leak-proof joints, jcypes and amounts of fertilizer
application are also restricted in arjsas of high water tables. For three
different classes of vegetative or fojcest type, maximum permitted clearings
are established as percentages of thej site area of development, and a
minimum width of undisturbed vegetation is also required. For example, if
the cover is a mature, deciduous lowland or floodplain forest, as shown on
the Vegetation Management Map, and if| the site area of development is 11-25
acres, then the regulation permits 55;% of the area to be cleared. A
2-crown width must be maintained of ijhe dominant mature species present on
site. The Ecological Planning Study ialso includes a set of criteria for
matching suitable land uses to natural profile types and a set of maps
showing what areas are accordingly diemed suitable for forest and ^
agricultural production, recreation,land development of various kinds.
I
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A mixed approach is illustrated by regulations of Mine Hill,
New Jersey with respect to soils overlay. The purpose of these regulations
"is to prevent inappropriate development from taking place in
5£? ^^ C*aracterized bv certai* soil types, siope ^ ^
levels wzthout proper corrective action if possible. Inappropriate
development in these areas increases soil erosion and sedimentation
thereby intensifying flooding by clogging drainage structures
Sedimentation reduces reservoir life and destroys recreational use
or water bodies."48
There follows a listing of soil types keyed to a soil survey map and
showing opposite each type the problems and development limitations to
which it gives rise. Some soil types are listed as "unbuildable," because
of flood plain or excessive gradient, others are described as having
"severe development problems" because of poor drainage, high water table,
erodability, or other natural characteristics. Structures and improvements
of all kinds are prohibited on lands designated as unbuildable, and
areas identified as having severe development problems are to be avoided
"unless corrective action is indicated such as soil erosion and sedimentation
control measures, storm water drainage systems, riprap and retaining walls,
fills, excavations, and other appropriate improvements." Clustering of
development units on larger tracts is encouraged so as to avoid development
on soils that are indicated as unsuitable for this purpose.
The foregoing examples indicate .the possibility of deriving standards
for development from definitions of environmental functions or processes.
In this manner, a community can evolve a set of land-use controls that will
reconcile developmental with environmental objectives and that is likely to
withstand challenge on constitutional grounds.49 it should not be supposed,
however, that development standards can automatically be inferred or
deduced from environmental data; an exercise of judgment, informed by a
community's land-use policy, will always be involved.
^*2*6 Erosion and Sedimentation Controls
Techniques of direct regulation are being applied by a growing
number of communities "to sensitize, development to *he erosion/sedimentation
potential of the site." Ordinances requiring erosion and sedimentation
controls as a necessary condition for development approval may be enacted
under a separate enabling authority or by amendment to the community's
basic zoning or subdivision ordinance. Where a community feels confident
that a particular set of controls should be adopted for all developments
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olass . or for all earthmovJLng activities that can be
identified as having a high erosion potential, it will make sense to
specify the necessary controls in the ordinance itself. Or they may appear
in rules and regulations adopted by the appropriate state agency. Such
regulations can be quite precise, despite [the generality of their
application. For; example, regulations of |the Pennsylvania Department of
Environmental Resources require that:
area
"Diversion terraces shall be constructed up-grade of
to convey runoff around the ... area. For tempo ra *Y
t-h^ channel shall have the capacity! to convey 1.6 cubic feet per
s^ondTefacre of land tributary tb it. For Permanent * .version,
the channel shall have the capacity; to convey 2:" c^ic ^et fo r
each acre of project area tributary to it and shall be provided
w?S a 24-inch freeboard. The basin shall be cleaned when the
s~ rsss ?Lr
rlow of 2.0 cubic feet per second for each acre of project area
tributary to the basin. "51 !
More corrcnonly, state or local regulations do not specify uniform
controls for all development, but provide | instead a set of principles for
evaluating development and concomitant controls on a case-by-case basis,
according to variable site characteristic^ such as type of soils, degree
and length of slope, size and duration of | exposed surf aces . Such principles
may state, for example, that the smallest; practicable area of land shall be
exposed at any one time during development; that natural features shall be
preserved whenever possible; that temporary vegetation or mulching shall be
used to protect critical areas exposed during development and permanent
final vegetation installed as soon as practical in the development process;
and that development in general shall be jfitted to topography and soils in
such a way as to create the least erosion potential. Accordingly,
development proposed for steeper slopes ojr on soils of relatively high
erodibility will be subject to stricter. Standards than equivalent develop-
ment in flat terrain or on more resist^ soil. In this manner, flexibility
in the administration of the ordinance can be assured, taking account of a
wide variety of possible interactions between site characteristics and types
i
of development. |
The ordinance may also refer the Developer to a manual on erosion and
sedimentation control, in which are set ^orth -detailed guidelines or standard
for various types of controls that could be incorporated into site plans,
construction practices and ongoing maintnance procedures. The manual can
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be amended from time to time in light of experience and as new techniques
are developed for controlling runoff and erosion, without having to go
through the formal process of amending the ordinance itself every time a
change is made in the technical guidelines. This approach has the dual
advantage of furnishing detailed technical assistance to the developer
while encouraging technical innovation. Assistance in preparing the manual
can be obtained from the Soil Conservation Service of the United states
Department of Agriculture and from a number of states (including Maryland
and Pennsylvania) which have already developed detailed manuals for tfce use
of their local governments.
Typically, the ordinance provides that no land area may be disturbed
untxl a plan for soil erosion and sedimentation control has been submitted
to and approved by the relevant agency. This could be the planning depart-
ment, the county soil district, the municipal building inspector, city
engineer, planning commission, or even the town council, depending on
"relevant state enabling legislation, the effectiveness and efficient
and the capabilities of the evaluative body."54
Since the effectiveness of this type of regulation depends heavily
upon the judgment of the reviewing body, "it is apparent that additional
evaluative resources are required, such as a competent planning staff with
some training in the soil sciences and soil conservation practices "55
Soil conservation districts, where they exist, can assist in performing the
necessary evaluations. Under some arrangements, "each application for
development is required to have an erosion and sedimentation control plan in
line with the standards established by the district. The district then
evaluates the control plan and, in some cases, serves as the enforcement
agent."
A good example of an erosion and sedimentation control ordinance is
the one adopted by Washington County, Maryland. It provides that "the
surface of land in this County shall:not be 'disturbed or changed for any
non-agricultural purpose whatever ... except in accordance with a plan
for control of erosion and sedimentation approved by the Soil Conservation
District and a grading permit approved by the Building Permit Department :
of Washington County." (m addition to agricultural practices and
structures, the ordinance exempts from its provisions "the construction of
Single-family residences or their accessory buildings on lots of two acres
or more). with each application for a grading permit, the plan,
specifications, and a time schedule must be submitted, accompanied by the
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oertification that all land clearing, construction and
development will be done pursuant to thatjplan. It must be prepared or
approved and signed by a professional engineer, land surveyor, or
architect. The plan and specifications mist show topography and soil types,
vegetative practices, a grading plan, proposed improvements, and provisions
for erosion control both during construction and afterwards together with a
schedule and sequence of operations. Alljgrading plans and specifications
must include provisions "in substantial accordance with" the Design Manual
for Erosion and Sediment Control for Washington County.
If the application conforms to the; foregoing requirements, the Soil
Conservation District must-approve the sa^ie and forward one copy of its
written approval to the County Engineer, jone copy to the Planning .and Zoning
Commission, and two copies to the Buildirjg Permit Department of Washington
County, which then issues the grading permit to the applicant.
The ordinance further provides ttuft the developer and all subsequent
owners of the property "shall maintain all permanent anti-erosion devices,
retaining walls, structures, plantings ai^d other protective devices." To
assure compliance with the ordinance andjthe permits issued under it, the
County Engineer is to inspect the work done under approved plans and ^
permits and to issue certificates of satisfactory completion to permittees.
The approach adopted by DeKalb Cojinty, Georgia, is to specify at some
length in the County Code standards to bf observed with respect to erosion
and sedimentation control, while leaving! most of the details to the
architect or engineer who prepares the cjmtrol plans for submission along
with a development application. For example, the ordinance provides that
" [sedimentation facilities (debris basics, sedimentation traps) and other
control measures such as hay bales, berm|s, interceptor ditches, and terraces
shall be installed in conjunction with ^e initial grading operations and
be maintained throughout the development and construction process to remove
sediment from runoff waters draining land under development." Land which
has been cleared for development must be| protected "by appropriate
vegetation and land covering techniques jsuch as seeding, sodding, [and]
ground cover installation ...." No grading, cutting, or filling is allowed
on any site under development if it wilj result in bringing unprotected
land surfaces into contact with surface|water, "unless erosion control .and
sedimentation control devices can be installed between the grading area
59 |
and water surface " j
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An ordinance can combine specifications for control measures with
some degree of orientation toward natural performance standards. .For
example, it could be required that the erosion and sedimentation control
plan result in runoff and erosion no greater than would occur if the land
had remained in its natural state. To that end, the ordinance could direct
that the developer use, to the maximum'feasible extent, natural control
features such as existing swamps and swales; that he employ cluster
development where practicable in order to reduce the total area of
impervious surface and to preserve open spaces and topographical features
that are critical to surface water management; that he avoid concentrations
of flow, take steps to dissipate runoff velocities, and reestablish
vegetative cover as soon as possible after land disturbance; and that he
adhere strictly to any applicable requirements for designated critical areas
While specifying certain design standards, the ordinance could at the same
time allow innovative control devices; to be employed if their performance
capacities, as shown by engineering analysis, would meet the objectives
of the regulation.
Erosion and sedimentation controls need not and should not be confined
to districts of critical planning concern. Such controls may be needed
throughout a community in orde,r to prevent the migration of sediments from
one location to another. Thus, controls of this sort can usefully supple-
ment other types of land-use regulation.
4'2'7 Controls Over Land Disposal of Wastes
A growing number of states have adopted detailed regulations on the
siting, operation and maintenance of municipal landfills. Such regulations
are designed in large measure to avoid pollution of ground or surface waters
from leachate or overflow at landfill sites.
Regulations of the State of Hawaii51 prohibit establishment or
operation of any solid waste disposal facility without a permit from the
State Director of Health. A permit application must be accompanied by
detailed plans for the facility and by a plan of operations. Permittees
are required by these regulations to compact and cover all solid waste
accumulated after each day's operation with earth or other approved material
so as to safeguard the environmental quality of the surrounding area; to have
monitoring equipment in place to detect any pollution that might result from
the facility; to maintain a minimum vertical separation of five feet
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deported waste and high groundwaW table; to provide for
minimizing the flow of offsite drainage oyer the landfill; and to deposit
solid wastes in such a manner as "to prevent waste materials, leachate :
or eroded soil particles from entering tfaja waters of the State without
receiving the best practicable treatment ^r control."
Landfill regulations might also prohibit acceptance of infectious
or other hazardous wastes; prohibit lagocjning of sewage, sludge or seepage;
establish limits on the width of the wooing face; and require operators^
to meet periodic self-monitoring, recording, and reporting requirements.
Numerous further points of control could [be cited from regulations of one
or another state. Their coverage and defail can be as extensive or as
selective as a state may deem practicable for its own purposes.
Direct regulation of solid waste disposal is a traditional form of
government control that is fairly easy tf> comprehend. The difficulties
it has encountered are rather of « practical nature. In some states, "grand-
father clauses" exempt pre-existing dumpf and landfills from new state
regulatory requirements. This loophole ban only be filled by regulation
at the local level, which is often inadequate., Moreover, regardless of the
division of responsibility between state's and localities, substandard
operation of landfills is commonplace in many parts of the country and
compliance with strict regulatory standards has been difficult to secure.
Many landfills have been located next to water bodies, on wetlands, or
over aquifers, which inevitably become polluted as ever increasing volumes
of solid waste are brought to those sitis for disposal. Closing down a
landfill operation is a feasible remedy!only if alternative disposal sites
or methods are available/and often they are not because of land scarcity,
obstacles to regional!zation, or impracticability of recycling. Regulation,
then, needs to be accompanied by more fbrceful regional planning and a
set of incentives for employing different approaches to the problem of
solid waste pollution. Until then, however, state and local governments
could be doing a better job of monitoring compliance with and enforcing
feasible operating standards for municipal landfills.
Regulation of septic tanks is ariother largely local responsibility
that many communities have not adequately met. An effective regulatory
scheme would prevent pollution of ground or surface waters from failing
septic tanks through a permit system t^at controls their location, density,
I
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construction, and maintenance, state health codes routinely address these
subjects, but may be deficient in ,a number of respects. For example,
rapid percolation may be required in order to avoid nuisance condition or
health hazards from surface contaminants, but if percolation of wastes is
too rapid they may pollute ground waters. Scavengers (those whose business
it XS to clean out septic tanks) ought to be licensed and required to report
their sludge disposal sites and methods to the licensing body, but
effective regulation of scavenging practices is not found in many states
Local boards of health are supposed to regulate septic tanks through local
health ordinances that implement, at a minimum, the standards set forth in
the state code, but pressures for development combined with reluctance
to pay for new or expanded sewer systems often result in permitting
septic tanks on unsuitable soils or in excessive densities. Enforcement of
standards for septic tank maintenance is also practically nonexistent dn
many areas. The problem lies not in learning what can be done, as a
regulatory matter, to prevent pollution from septic systems, but in
mustering the political will and administrative-resources.that are necessary
to bring them under control.
4-2-8 Control of inplace or Accumulated Sources
For residues such as street litter, fertilizers and pesticides,
highway salts, and oil spills onto paved surfaces, the most effective
controls may be upon introduction of these substances into the environment
rather than upon their migration after they have become waterborne.63 Where
threshhold prevention is not practicable, it will still be true, by and
large, that the earlier the point in time at which controls are applied,
the more effective they are likely to be.
A municipality might adopt an ordinance banning outright the applica-
tion of certain fertilizers, pesticides, or road salts, or requiring that their
use be conditioned upon restrictions to be set forth in a use permit. Runoff
of these substances might largely be avoided by restricting the timing,
quantity and methods of application, or by onsite collection and treatment
prior to discharge. Gas stations and parking lots can also be required to
trap runoff in onsite collection basins and to treat the collected flow for
removal of oil, lead, and other offensive substances before discharge to
storm sewers or to receiving waters. At a minimum, such controls might be
prescribed for automobile-attracting facilities located near public water
supplies.
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I
Consider also the advantages of professional licensing systems for
handlers and users of pesticides and othjr toxic materials as well as for
carters of sludges from septic tanks andjother waste treatment processes.
A license would be awarded only to a person who demonstrated competence in
the handling of such materials, and it could be revoked for failure to
comply with applicable regulations designed to prevent their introduction'
i f • , . ." " • - ' ' - '• '
into ground or surface waters ,
It may well be, however, that controls of the foregoing varieties
will be effective only if adopted at thejstate level. In the alternative,
it may be necessary for a group of municipalities to agree upon the adoption
of parallel or identical ordinances in order to make measurable progress in
controlling these pollutants. The same pan be said of all nonpoint sources
whose effects are cumulative rather thanj discrete, or diffuse rather than
confined to particular areas. j
Where road salts are applied by jstate or local highway .departments,
a shift in operating policy may be callejd for, rather than any fresh
enabling or regulatory legislation. Sand may function as well as salt on icy
roads in wintertime, and sand is easier jto pick up or to trap in
sedimentation basins after the winter has passed.
Anti-litter ordinances and coordination of street-cleaning programs
with parking restrictions can be instituted at the municipal level. In
many jurisdictions, the prinicpal obstacle"to cleaner streets, with
resulting improvements in the quality oj: water resources, is not absence
of regulatory authority but lack of wilJL to fund and enforce the necessary
restrictions. . j ' ,
4.3 Legal Issues j ,
This final section addresses two sets of legal issues surrounding
the implementation of a number of the above regulatory approaches: securing
compliance on the part of private developers, and protecting their various
constitutional rights in the process, j
^curing Compliance Through Moriitoring, Maintenance, and Enforcement
4.3.1"
of Controls
The principal weakness of many | regulatory schemes is that they fail
to include adequate provisions for securing compliance on the part of those
to whom they are addressed. This problem arises especially where compliance
is not just a one-shot matter, but consists of continuing activity or
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forbearance over time. Regulations can address the problem by requiring, for
example, that those who undertake land uses or land-disturbing activities
likely to affect water quality must maintain control facilities in good
working order, install monitoring devices, record operating data, and submit
periodic reports to the regulatory agency. Any number of self-monitoring
requirements can be included in a set of administrative regulations, and
the agency can reserve the right to inspect premises for compliance, even
in the absence of a permit system.
However, regulations of general applicability combined with permits to
be^issued on a case-by-case basis are a superior type of control strategy.
This is so for several reasons:
• A permit system has the initial advantage of prohibiting certain
types of land use or land-disturbing activity except upon
compliance with prescribed conditions. The proponent of the
activity has the burden of applying for a permit ^and of
indicating in his application and accompanying plans how he will
meet pollution-control requirements.
• The process of applying for and receiving a permit makes the
applicant fully aware of what is required of him; he cannot
thereafter plead ignorance of the law.
• The issuing authority can write special or particular conditions
into a permit, tailor-made to the applicant's situation.
Regulations alone, by contrast, tend "to be of general applicability
and therefore cannot cover all cases or contingencies.without
growing cumbersome.
• Issuance of a permit can be made conditional upon the posting of a
performance bond by the applicant. Such a bond, executed by a
surety, can be used (for example) to guarantee the faithful execu-
tion of a site plan, undertaking of runoff and erosion control
measures, or compliance with other conditions specified in the
permit. The bond may be deposited with the fiscal officer of the
issuing government. If a default occurs in the performance of any
term or condition of the permit or bond, and if compliance is not
achieved within the time specified in a notice of default, the
issuing government may proceed without delay to use the cash
deposited for completion of the required work. By its terms,, the
bond obligates both the permittee and his surety for payment of
all necessary costs incurred by the government to correct non-
compliance. Moreover, if the cost of the work exceeds the amount
of the bond, the permittee remains obliged to pay the excess.
• For significant violations, a permit can be revoked or the permit-
ting authority may fail to renew it upon expiration. These
possibilities can serve as powerful inducements to compliance.
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Whether by permit or by regulation aj.one, the responsibility to
maintain control facilities in good repair heeds to be clearly spelled out.
ordinarily, the land user has that responsibility, but it may be provided that
the municipality will construct and maintain certain facilities (e.g., a
retention pond) for which the costs will be; passed on to the participating
land users in the form of special benefit assessment.
The regulatory system should provide- for official inspection of
control facilities upon their completion arid prior to giving them final
approval. Unannounced inspections should 41*0 be made from time to txme
thereafter, in order to monitor continuing \ compliance and to check the
veracity of self-monitoring reports submitted by permittees. In particular,
employees of the appropriate government agency should be expressly authorized
to enter upon and inspect subject properties at all reasonable times. Ideally,
they should further be empowered to make emergency repairs to any mal-
functioning facility and to charge the ownfr for the costs if proper
maintenance is his responsibility. _
The Maryland Department of Water Resources has published a Sedxment^
Control inspectors Handbook, which could b^ adopted in all jurisdictions.
The handbook tells the inspector how to prjepare himself for the intellxgent
performance of his task. He should be thoroughly familiar wit* the details
of the governing ordinance, ;with the approved sediment control plans , and
With methods of construction and capabilities of control equipment. Establ.sh-
ment of local training programs for inspectors is recommended by the handbook.
It includes a sample field inspection form and final inspection report.
Compliance should not, however , await inspections.. "Whenever possible,
prior to grading, schedule a meeting with, the field superintendent to
review the sediment control plan, explainj what should be.done, and the
timing involved. Such a preliminary meeting will go a long way towards
establishing necessary understanding and -averting needless confusion.
handbook also contains useful guidelines on what to look for dur.ng an
inspection and whom to contact when violations are discovered. Informal
e—ication and cooperation between injectors and permittees
toward securing compliance without the need for formal enforcement
most cases. ,
The regulations should spell out enforcement procedures
followed in the event of noncompliance .
137
For example, the erosion control
-------
ordinance of Leon County, Florida65 provides that if the County Environmental
Administrator finds a violation of an approved site plan with respect to
clearing and development, a failure to construct or maintain the required
control measures, or a failure to obtain initial approval of development,
he xs authorized to issue written notice to the violator of the nature and
locatxon of the alleged noncompliance and to specify what remedial steps are
necessary, if these are not promptly taken by the violator, the Administrator
may then issue a stop-work order "to cease and desist all or any portion of
the work upon all or any geographical protion of the project which is
contributing to on-site generaged siltation or sedimentation or runoff
except such remedial work as is deemed necessary to bring the project back
«to compliance." Violation of a stop-work order may lead to revocation of
the permit, thereby rendering the land user liable to civil or criminal
penalty. Any person violating the ordinance or a stop-work order
-sued thereunder "shall be punished according to law. Each day such vio-
latxon continues shall constitute a separate offense. Any person may
seek an injunction against any violation of the provisions of this ordinance,
and recover such damages as he may suffer, including but not limited to
the cost of removal of any debris or sedimentation caused by such violation "
*hxs provision incorporates by reference the criminal statutes applicable
to the violation of any county ordinance, and also makes clear that injured
Part.es may seek damages in a tort action. The ordinance of Washington
County, Maryland ^provide, more explicitly that violators "shall upon
conviction be guilty of a misdemeanor, punishable by fine of no greats
than $500 and each day of violation shall be considered a separate offense,"
^ Cxvxl penalties are also possible, in lieu of or in addition to
crxmnal ones. The authority of a municipal government to establish
Penalties for particulr types of violations should be checked out. If the
penalty limits prescribed or allowed under state law are low or if no
Penalties can be assessed ^ violationSf & ^ ^ ^ ^^
be dxffxcult to achieve, in such a case, amendments to state law
providing for significant penalties as well as for injunctive relief through
the courts, can help to show that the state and its political subdivisions
mean business.
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4.3.2 Constitutional Questions
" 4.3.2.1 Takings^ j
As already noted, private property jnay not be taken for public use
without just compensation. The question Whether a taking has occurred
may arise in any case where uses of private property are restricted for
environmental objectives. The law on this! subject is in a state of flux and
it varies considerably from state to state. It is therefore necessary to
refer to the judicial precedents of the federal courts and or your state courts
before deciding where.the line may be dra^n between valid restrictions
imposed in. the exercise of the police pow^r and restrictions that may^be in-
validated as takings, with respect to a .particular piece of property.
A trend can perhaps be observed in!recent case law to the effect that
a landowner is not entitled to convert his property to its most profitable
use by changing its natural characteristics, if the results of such a.change
would be harmful to the public welfare.68, increasingly, the right of the
public to have natural resources preserved in undegraded condition is being
recognized. The courts are beginning to perceive that there are natural
and unnatural uses of particular lands, that land and water resources are
closely interrelated, and that -the public: has an important'stake in preventing
interference with these relations. Thus,| it is said that »[a]n owner of
land has no absolute and unlimited right |to change the essential natural
character of his land so as to use it foil a purpose f or ;which it was ^
unsuited in its natural state and which djnjures the tights x>f others,"
While the securing of benefits not previously enjoyed by the public is
still thought to be a taking, it can perljaps be distinguished from avoidance
of damage to public interests in the environment - a legitimate objective of
the police power. If a regulation can b4 characterized in terms of damage
avoidance, it stands a fair chance of being upheld although it deprives
property owners of profits or even reduces substantially the market values
of their lands. There are limits, however, even to this emerging doctnne;
a taking may still be deemed to have occurred where the restriction
-practically or substantially renders tbk land useless [to the owner] for
all reasonable purposes,"7Q especially ^the land had some commercial value
to begin with apart from the possibility! of converting it artificially to
some new and "unnatural" use. j
139 ! -.' '
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The lessons to be learned from these cases are that the risk of
invalidation by the courts can be minimized if your regulatory scheme (a)
is demonstrably based on avoidance of injury to the public at large from
irresponsible uses of private property; and (b) consistently with that
objective, still leaves the owner free to put his land to one or more
reasonable uses. It will also help if the regulation can be justified in
terms of public health and safety (e.g., protection against flood damage,
punty of water supplies) and not merely of aesthetics or other less
tangible aspects of public welfare.71 Moreover, as indicated in the
Ramapo and Petaluma cases, *se restrictions are more likely to be upheld
if they are of only temporary duration.72 In general, performance or
specification standards, precisely geared to environmental objectives, will
have the best chance of surviving constitutional challenge because they do
not rule out most land uses (even though they may well increase the
costs of development).
4,3.2.2 Substantive Due Process
A regulation may be declared unconstitutional if its provisions are
arbitrary or unreasonable, bearing no substantial relation to the public
health, safety, or general welfare. In other words, regulations must be
based on legitimate governmental purposes and be reasonably calculated
to accomplish them. For example, large-lot zoning may be acceptable if
its purpose truly is to avoid excessive concentrations of septic tanks
on soils of limited absorptive capacity, but not if its underlying purpose
is to halt growth in a town or to exclude lower-income groups.73 Such
measures should therefore be based on objective data which will tend to
justify both the ends and the means. Assuring the constitutional validity
of land-use restrictions and requirements is a major reason for local
governments to incorporate natural resource inventories or ecological
planning studies into their decision-making processes.74
4.3.2.3 Equal Protection
States and their political subdivisions are constitutionally pro-
hibited from denying to any person the equal protection of the laws.
Since environmental regulations frequently restrict some persons to a
greater degree than others, they may run a risk of being invalidated
because of unreasonable, arbitrary, or invidiously discriminatory
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classification for regulatory purposes
"The basic principles of the
equal protection doctrine are well established: any state or municipal
legislative classification must be a rational one, bearing a reasonable
relationship to a proper legislative purpose." Thus, for example,
properties designated as critical wate|r- related lands (riverbanks , wetlands ,
aquifers, steep slopes) could be made jsubject to special use restrictions
without running afoul of this constitutional standard, so long as the
restrictions are essential to sound environmental management in the
public interest. Here, then, is another constitutional reason for gearing
land-use controls to natural resource j inventories or ecological planning
studies. It should be added that a mijnicipality need not regulate all
instances at once in which a problem of a particular type is shown to
'exist. Regulation has to begin somewh'ere, and there is no constitutional
infirmity in a piece-meal approach th^t is free of ulterior discriminatory
! ' '
motives . j
4.3.2.4 Procedural Due Process |
i
As already noted, local governments ordinarily derive their powers
to act from enabling statutes of their state legislatures. Such delegated
powers must be exercised not only for approved purposes but in accordance
with prescribed statutory procedures. | These may require, for example, that
a local agency give advance public notice and opportunity for public hearing
on proposed legislative or regulatory! action; that" it adhere to prescribed
voting procedures; that it afford opportunity for adjudic'atory hearing on
proposed issuance or denial of permits; and that it base certain types of
decision on a judicially reviewable record. Even where state law does not
' require such procedures, it is a good idea to adopt them for the sake of
clarity, fairness and openness in decp.sion~making .
If an agency is to administer |a permit system or to pass upon
proposed development plans, its regulations should clearly indicate who
must apply for approval, what information must be included on the applica-
tion form, within what time- frames it must be submitted and will be acted
upon, and according to what criteria permission will be granted or denied.
It is a fundamental tenet of due procjess that agencies structure the
exercise of their own discretion in Accordance with impartial rules.
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A definite trend can be observed, in judicial case law, toward re-
quiring local governments to honor elementary concepts of due process in '
local decision-making, state Administrative Procedures Acts are ordinarily
applicable only to agencies of state government, but the courts have shown
an increasing willingness to scrutinize local decisions as well by reference
to APA-type standards. :
4'3'3 Eliminating Windfalls and Wipeouts
Government decisions often have the effect of conferring gratuitous
benefits on some people and losses on others. For example, restrictions on
development of water-related lands may substantially reduce their market
value, without going so far as to constitute a compensable taking.
Conversely, the clean-up of a waterway or the location of a new highway
can greatly increase the values of adjacent properties. Thus, public
benefits are secured at private expense, and private benefits at public
expense. The perception of such inequities in the distribution of costs
and benefits can forestall or derail government decisions for want of
political support. Predictably, this type of problem will become more
acute as local governments increasingly restrict land-use for water quality
and other environmental purposes.
To remedy windfalls and wipeouts resulting from government decisions,
a number of schemes have been proposed, some of which may be feasible for
local governments to adopt, in general, they are premised on the idea that
government can recapture a part of the economic benefit it confers on some
property owners and use the proceeds to compensate others to whom it
occasions losses. For example, developers who are favored by zoning
decisions could be required to contribute to a special fund for that purpose.
Alternatively, the government could establish and administer a market in
transferable development rights (TDRs), which works on the principle
that owners of developable land must purchase such rights, as a prerequisite
for development, from those whose land is to be preserved as open space.
"At optimum efficiency, this device, like zoning, requires little
expenditure of public funds for implementation other than administrative
costs, and is thus less costly than the conservation restriction method
The municipality is in effect the middleman. It merely allocates development
rights equitably among parcels of land." 76
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I
it is not enough to think only of jregulating sources of pollution.
Governments must also consider how to remedy the unintended but inequitable
consequences of regulatory control. The Isame holds true of public
investment decisions and other component^ of programs to promote .environmental
quality. , , -.•'.]_ ... •
. r,
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1.
REFERENCES
They are discussed in Section 4.3.2 below, and are mentioned at a
°lntS ** < of ^
2. Ohio Constitution, ART. XVIII, Sec. 3,
3. such a statute in Rhode Island was cited in the case of Wood v
Peckham, 80 R.I. 479, 98A. 2d 669 (1953). ^!22^ "
4' zf'i f^f!*!^ of Commerce, Standard State Zoning i^n^
5. 469 F. 2d 956 (1st Circ. 1972)
6. The court observed, hoever, that a desire to avoid further growth
would not be a legitimate basis for-restrictive zoning. othe°
indicate, moreover, that large-lot zoning may be invalidated if i^
?ri!n!l°™!!! fr.°m I^king any Practi<^l use of their land or" if
deemed undesirable on
7.
- - Reichert' IlLa^ Use Guidance System
529557 7^lronmental Quality," 15 Natural Resources Journal
8. Ibid.
9.
10. Ibid., p. 346
11. 30 N.Y. 2d 359, 334 N.Y.S. 2d 138 (1972).
12. See the discussion below, Section 4.3.2.1
13. See Daniel R. Mandelker, Managing Our Urban Environment—ra.
and Problems 878-904 (Bobbs-Merrill: 1966) . " ~~~^
14. See the discussion below, Section 4.2.4
15. Ky. Rev. Stat. § 83.330 (1962)
16. N.J. Stat. Ann. 15:8A-30(d) (Supp. 1973)
o , Text
f Xt
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17.
18.
19.
Bucks County Planning Commission, "Elan for Implementation df
Provisions of Act 515 of 1965" (Doylestown: Bucks County Planning
Commission, February 3, 1971). j
M.G.L. Ann. Ch. 184, § § 31-33 (Supp. 1974). The description in
the text of the Massachusetts law is taken from Russell R. Sicard,
"Pursuing Open Space Preservation: 'the Massachusetts Conservation
Restriction," IV Knvironmental Affairs 481-514 (Summer 1975). Mr.
Sicard's article discusses various legal ramifications of the device
in some detail. |
i • • • •
One important effect of this statute is to supercede ancient common
law limitations on the extent to which the alienability and use of
land can be restricted over time. j
20. Sicard, Ibid., p. 492 j
i
21. See Sicard, Ibid., p. 497 •
22. 30 N.Y. 2d 359, 334 N.Tf.S, 2d 138 CJL972).
I
I . " - •..-•'
23. 522 F. 2d 897 (9th Cir. 1975) j .
24 An extensive literature has developed upon the Ramapo and Petaluma
cases. See e.g.,' Robert W. Burchell and David. Listokin, Future Land
Use 59-140 (The Center for Urban Pojlicy Research at Rutgers - The
State University of New Jersey, 197,5); David Falk and Herbert M.
Franklin, "Local Growth Management (Policy: A Legal Primer," (The
Potomac Institute, Washington, D.C.I, 1975); II Management and Control
of Growth (The Urban Land Institute, Washington, D.C., 1975).
25. Harristown, Illinois, Zoning Ordinance, Section 3.1, 1972. It should
be emphasized, however, that if a land owner in a conservation zone
is deprived thereby o£ all practical use of his property, the zone
may be deemed invalid as taking ofithat property forpublic purposes
without compensation. See the discussion below,' Section 4.3.2.1.
26. See the discussion below. Section 4.2.7, 4.2.8.
27 See the discussion of natural performance standards below, Section
"425 A natural resource inventory and a reliable environmental
data base are virtual prerequisites for the effective use of this
technique, whatever the nature of the special district may be and
whatever the form-.in'which concomitant land-use regulations may
be specified. j
28. Wis. Stat. 59.971, 144.26 (1966-67j> .
29 The description of the Wisconsin program in the text, including quo-
tations from applicable laws or regulations, is taken from Fred
Bosselman and David Callies, The Quiet- Revolution in Land^Use Control
235-55 (U.S. Council on Environmental Quality, December 15, 1971).
The principles of this program could be adapted to incorporated urban
or suburban municipalities, with appropriate adjustments in coverage
and detail. •
145
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30, Reproduced in Performance .Controls for Sensitive Lands
33.
34.
35.
36.
37.
39.
40.
41.
42.
A Practical
31* See the discussion below. Section 4.2.4.
43.
no f fSSmentS at the local level may, but generally
not, have to include considerations of alternative sites
comparative cost/benefit analyses, and other planning elements found
in EISs prepared under the National Environmental Policy Act (NEPA)
or comparable state laws. The options and resources available to
Sem n^T Pf ^°rdinarilY Wil1 n0t bS «*«*i«t' to warrant making
them prepare full-scale NEPA-type statements,
Subdivision Regulations of the Town of Lincoln, § § 3.2.3.1'- 3 ^.3. 3
Township of Medford, Ordinance 1974-11, §2
They are discussed in detail below. Section 4.2.5
10 V.S.A. Chap. 151, § § 6001-6091.
Robert H. Twiss, "Commentary —Nine Approaches to Environmental
Planning" in Future Land Use. Op. cit . , 20, supra, p. 239.
SE" Isr'v SSe footnote 30 above- This excellent study, prepared
for EPA by the American Society of Planning Officials, should be
read from cover to cover by all 208 planners. It provides a number
of examples used in the text of the present report! as well as a
useful framework for evaluating alternative types of regulatory
control. •*
Ibid., p. 445. .-
See, e.g., the bibliographical references listed in Ibid, at 472-
73 and at the conclusions of the various chapters of Se~same report.
in
°n pp- 459-6°
se DeKalb ordinance as the basis
setting rate and volume standards is questionable. Retention
of so large a storm may require substantial over-capacity in the
control facilities and could conflict with sound principles of
flood management. Experts in this field should be consulted before
deciding upon the formulae to be employed.
Narendra Juneja, "Performance Requirements for the Maintenance of
Social Values Represented by the Natural Environment of Medford
andnSsfa N'n" ;P' ^ ^^ ** Ecol^ical ^search in Planning
and Design, Department of Landscape Architecture and Regional Plan-
ning, University of Pennsylvania at Philadelphia.
146
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44.
45.
46.
47.
The Universal Soil Loss Equation is discussed in some detail in
Performance Controls for Sensitive ILands, pp 462-468.
I
Ibid., at 27. i
Our observations in this paragraph!are admittedly speculative;
limitations on time and resources prevented us from ascertaining
how these ordinances are actually forking in practice. DeKalb
and Medford should be directly consulted by any community contem-
plating similar approaches.- j •
I '
For further discussion of the performance standards approach as _
advanced by Ian McHarg, see Rice okell, "Carrying.Capacity Analysis,
Useful but Limited," Tit Management and Control of Growth 22-28.
"McHarg and his associates have determined what specific tracts
of land have to offer, what their llimitations are, and where de-
velopment might best fit in." Ibid., 24.i
48.
51.
52.
:int!e
The Mine Hill ordinance is; •reprinted in Performance Controls for
Sensitive Lands, pp. 417-419. !
49. See the discussion below, Section |4.3.2.
50. Performance Controls for Sensitive^ Lands, p. 60.
Title 25, §102.23 of the Rules and Regulations of the Pennsylvania
Department of Environmental Resources.
E.g., the'ordinances of Camden, JJJ., described in Performance Con-
trols for Sensitive Lands, pp 62-63.
53 For a selective list of publications on standards for erosion and
sediment control, .see Performance! Controls for Sensitive Lands,
pp. 67-69. ; i '. ' •- - -
54. Ibid., pp. 60-61. j , .'
55. Ibid., p. 63. ! •
•56. Ibid., p. 65. ' J " ' ;
57 This ordinance is summarized in The Maryland Sediment Control Pro-
* aram-Assemblv of Reference Items' 75-80 (U.S. Dep't of Agriculture,
Soil Conservation Service: Colle|ge Park, Md. 1971).
58. The' subjects of maintenance, monitoring and enforcement are further
discussed below, Section 4.3.1. ']"••'
147
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°* ^ ^ examples of erosion and sedimentation control ordinances
see the Model Municipal Land Disturbance Ordinance, prepared b X
New Jersey State Soil Conservation Committee and reprinSS in Per-
formance Controls for 3°"^*--—- -r ^_ „.. •I-<=iJ-LX"lte« in ijer-
cUKi.Sed.nentat3.on Control Manual
Environmental Resources, January 1, 1974; the assemSlJ X Terence
items entitled, "The Maryland Sediment Control Program," 1971
U.S. Department of Agriculture, Soil Conservation Service, College
Park MD; and a publication of Leon County, Florida, J^rJ 1975
" EnV±r0nmental Criteria for Erosion and S^dmenSion
60. The foregoing approach is embodied in a model ordinance prepared by
the South Branch Watershed Association of Clinton, N.J.
61. Hawaii Environmental Laws and Regulations, Volume II, chapter 46
"
^!'r ?", f 1S°n C' Dunnin9' "Pests< Poisons, and the Living Law
The Control of Pesticides in California's Imperial Valley » 2
Ecology Law Quarterly 633-693 (Fall 1972), for a detaileJ analysis
also bfaSed T ^^ **"»" ^ general *~*>**?
sources. Preventive regulation of other nonpoint
Control Workshop,
Ordinance No..73-10, as amended by Ordinance Nos. 73-57
66. Cited above in footnote 57.
67. Ordinarily, the courts will not invalidate such a restriction in all
68. E.g., Just v. Marinette County. 201 N.W. 2d 761 (Sup. Ct. Wis 1972)-
Sibson v. State, 5 ELR 20300 (Sup. Ct. N.H. 1975).
69. Just v. Marinette County, see footnote 68.
70- IMSL- On this point, see also Morris County Land Co v
Troy Hills Township 40 N.J. 539 (1963), 193 A. 2d. 232."
71. E.g.,
(Mass.
. 284 N.E. 2d. 891'
Julv 9
July 9,
. .. .
reader is also referred to the extensive liter-
Ct- -f Sd B°SSelman' Da^ Allies SJoS Sntaf
°n Bnvironmental Quality; Washington, '
xs an excellent starting point.
148
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72. See the discussion above,.Section 4.2,2, and Steel Hill Development
Inc. v. Town of Sanbornton> 469 F. J2d 956 (1st Cir. 1972).
73. See the discussion of the Ramapo arid Petaluma cases above. Section
'4.2.2. j .
74. See the discussion above, Section 4.2.3.
75. Ronald M. Hershkowitz, "Local Environmental Protection: Problems
and Limitations," Environmental Affairs (Vol. II, No. 4: Spring
1973), pp. 783, 793. J
|
76. Sicard, Op_. Cit., n. 14, supra, 504. There is an extensive lit-
erature on the subject of TDRs, e.g*, Jerome G. Rose, "A Proposal
for the Separation and Marketability of Development Rights as a
Technique to Preserve Open Sapce,"| 2 Real Estate Law Journal 635
(1974). I
149
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S-|° FINANCIAL CONSIDERATIONS
Carrying out preventive approaches to urban stormwater management
requires adequate funding. The purposes of this chapter are: to identify
specific funding needs and alternative sources; and to help local planners
evaluate these financing options.
Two types of activities require funding regardless of the particular
preventive approach taken:
• Continuous Planning
• Implementation and Enforcement
and thus will be discussed separately in sections 5.1 and 5.2 The remainder
of the chapter (5.3.1-5..3.5) concentrates on five examples of typical storm-
water pollution problems, in each case discussing funding needs, sources,
and options for several alternative'solutions. The five example problems
discussed are:
• Pollution of groundwater supply due to development in an
aquifer recharge area;; '
• Existing and projected development in an urban drainage area,
leading to increased runoff containing increased contaminants;
• Projected development in a relatively undeveloped area causing
increased runoff and increased contaminants in receiving waters;
• Development adjacent to a stream, causing stream bank erosion
as well as introducing sediment and contaminants into the water;
• Development in and near wetlands.
In order to evaluate alternative funding options, explicit criteria
are called for. Four criteria commonly used to evaluate government revenue
measures are: :(1) revenue adequacy; (2) social equity; (3) economic efficiency?
and (4) administrative simplicity. As with^levies for other public activities,
funding approaches for urban stormwater management should be designed to
meet these tests.
Revenue Adequacy; The basic objective of any levy is to obtain
sufficient revenue to meet costs of providing service. Hence, the funding
system should be designed to reflect the financial implications of inflation,
technological advances, system improvements, additional loads, and shifts in
preferences. It seems reasonable to .expect that costs of services, such .
as stormwater management, will generally tend to increase over time; thus,
a funding system should be able to cope with these changes in revenue re-
quirements with a minimum of restructuring.
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Social Equity; The question of what constitutes a fair tax or
_ i
charge system is not a matter of technical economics but of personal
preference and philosophy. Nevertheless, sbme principles have been
delineated that offer a framework for analysis. The benefit principle and
the principle of ability to pay are the most common bases for discussions
1 i '
of equity. |
Justification for service charges [Ls generally based upon the
i
"benefits received" principle which states that charges should be related
i
to the benefits received from government by! an individual or firm. People pay
for goods and services received in the private economy, the argument runs, so
why not in the public sector as well? If aj charge system violates the
benefits principle, then public services bejcome a form of subsidy for their
users, since the services are obtained at tjhe expense of other people.
Although equity is a basic underlying idea jfor application of the benefit
principle, this form of levying charges also provides a substitute for the
market test. If people who will benefit from expenditures are unwilling to
pay for them, presumably they are not worth1 their cost and should not be
• O .-'•=•• | . ,
undertaken. j ,
Implementation of the benefit principle is difficult because of the
problem involved in quantifying the benefitjs of service and identifying all
the beneficiaries. Three methods for deriving benefits have been suggested.
One approach is to estimate a demand curvejfor the service and compute its
value. Another approach is to estimate th4 cost of the best alternative method.
A third approach is to interpret the benefits received principle as a cost
occasioned method where those using the service are charged an amount equal
to the,cost of providing service to them, j
Each: of these approaches presentsiproblems in implementation. To
I
estimate a demand curve requires that the service be marketed through the
price mechanism. To do this presents two problems. First, there is usually
a single seller of this service. Second, public health and other factors
make the purchase of a uniform level of service compulsory. To estimate the
cost of,the best alternative,method requires that a reasonable alternative
be available. It is not clear that such an alternative could be chosen and
if it were the difficulties in estimating its costs would be formidable.
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Because of the problems surrounding methods for estimating benefits
received directly, the cost occasioned approach has had to suffice for imple-
menting equity in sewerage service charges. This interpretation of the
benefits principle assigns a charge to users equal to the cost of providing
them with the service. ; .
Economic Efficiency: Governments frequently use taxes and user
charges as tools to achieve economic objectives. The charge procedure
employed may affect economic efficiency through its influence on business
decisions regarding location, production process, and output level. These
decisions certainly carry implications for the efficiency of the economic
system.
From a theoretical standpoint, the goal of economic efficiency is
served when the price of each good and service produced equals the marginal
social cost incurred in producing and marketing it. (i.e., the social value
foregone when the resources are diverted from alternative economic activi-
ties) . For this reason, service charges would be equated at the margin to
the social cost of collecting, transmitting, and/or treating the stormwater
runoff. if the charge is not equal to the marginal social cost, then eco-
nomic efficiency will be reduced. For example, if the charge is greater
than the marginal social cost, firms requiring a large quantity of service
will be placed at a competitive disadvantage due to rising costs. Unless
they can reduce other production costs or raise product prices, their
profits will decline. If they choose to increase product prices, the distor-
tion created by the charge is shifted forward to the consumer. If the firm
elects to reduce production costs, the distortion is shifted backwards to the
factors of production. For example, a reduction in production costs may be
accomplished by lower wages paid to labor. The extent of these shifts
depends on the elasticities involved.
On the other hand, if the charge is lower than the marginal social
cost, the production costs faced by a firm will be artificially low and
profits artificially high. In this instance, the burden of managing the storm-
water runoff problems generated by the firm is shifted to society, in the
event that revenues resulting from charges levied as d.utlined above prove
inadequate to cover the user's share of costs, additional levies that are
independent of the marginal cost,for service may be addressed to the user.3
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Administrative Simplicity; A funding procedure should be easy to
understand and enforce, be acceptable to users, and involve reasonable compliance
costs. The basis for the levy should be Usily understandable by all who are
subject to it. Payment should be able to] be verified and the charges not im-
possible to collect. The funding system jshould be consistent with generally
accepted "rules" of fair play, and the charge for service should compare
favorably with the customer's perception bf the value of services received.
Finally, compliance costs should be low. j Prom the viewpoint of the management
agency, this means that the charge system! should be inexpensive to administer
(i.e., IQW computation costs, no expensive inspection). From the customer's
perspective this means convenience of payment.
These criteria will be applied t|o the funding alternatives discussed
in the five sample problems. . They can a3Jso usefully be applied by local
officials considering their own funding options for meeting a much wider range
of stormwater management problems. However, several additional constraints on
their use should be noted. '• '
In describing financing methods jfor various approaches, reference is
frequently made to landowners within the jdrainage area or area benefited by the
adopted approach. In many instances, thepe "areas" will not coincide with
existing political subdivisions. Thus, intergovernmental cooperation agree-
ments, either voluntary or mandated, will have to be utilized. As an alter-
native, special purpose political subdivisions such as drainage districts or
soil conservation districts may provide 4he institutional framework for finan-
cing. The needed institutional arrangements may require enabling legislation.
In approaches which utilize the! "police" power of the government
to control land use, there is the problejn that the constraint on use is so
restrictive that a "taking" occurs. If JLt is deemed a "taking" either the
constraint may not be enforced or the lajid owner must be compensated. The
first possibility defeats the purpose ofj the approach altogether, while the
latter possibility requires expenditure |of. public funds. Thus, the use of
these constraints must be undertaken witjh great care. Aside from the legal
problem, a sense of fairness may require compensation to the land owner who
is severely constrained to benefit or protect the public.
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5-1 Financing the Planning Process
Funding a continuing planning process for urban stormwater runoff
involves two distinct phases. Phase 1 is the initial planning effort that
includes data collection, analysis, preparation of basic maps, and the
variety of other activities that go into developing management strategies.
Phase 2 is the continuing planning effort necessary to keep, management
strategies current in terms of development patterns in the region and
emerging management approaches. Phase 2 is frequently the more difficult
problem to cope with from the standpoint of funding. Transportation planning
which was heavily financed by the federal government in the early 1960's
for the'initial planning phase did not receive much support as a continuing
process. Section 208 Areawide Waste Treatment Management planning is in-
tended to be a continuous planning process, with annual updating of the
approved areawide plan; but in the absence of continued federal support it
will be necessary for localities to pick-up the added planning costs and this
may prove to be a serious sticking point.
There are three basic approaches open to local government for
funding a sfcasrawater management planning process;
• Prepare stormwater plans as an integral part of the larger
208 areawide water quality management plan;
• Prepare stormwater plans in conjunction with other on-going
city or county planning efforts; or
• Prepare stormwater plans as a separate, distinct city or
county planning activity.
Funds will be needed initially for the range of activities involved
in the development of urban runoff management strategies. These activities
include review of existing information, data collection, delineation of
physical methods, analysis of alternative physical methods, identification
of implementation measures and institutional arrangements, and formulation
and evaluation of alternative runoff management strategies. After the initial
planning effort has been completed, funds will.be needed for publication of
the draft plan, informal public discussions, formal public hearings requiring
legal notice and record, and revision and final preparation*of an urban
runoff management strategy. Following adoption of a management strategy,
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funds will be needed for implementation ?nd enforcement (See section 6.2)
and for the periodic review and revision of the approved plan. This periodic
review and revision, when appropriate, ijs the essence of a continuing planning
process. ,• . \'
Sources of funds for an initial! planning effort will usually come
either from federal and/or state grants,; or from general funds. For example, '
urban runoff management planning would cjlearly be an appropriate activity
for 208 Areawide Water Quality Planning Agencies funded under PL 92-500;
another source of grant monies might be jthe HUD 701 Program. The local
general fund is always a potential sourcje of monies for planning, provided
that responsible local officials can be persuaded to appropriate the funds.
Other sources of funds, such as special Assessments and full-cost recovery
user charges are theoretically available, but as a practical matter they are
not available to finance initial planning. However, the continuing planning
process might be funded in this manner.I
5.2
Financing the Management Process
Funding the implementation and j enforcement of urban stormwater run-
off strategies is also a multifaceted problem. Implementation activities
may be undertaken by either the public 6r the private sector. Enforcement
activities are usually carried out by pjoblic entities. Implementation
activities include: monitoring quantit^ and quality of runoff; administering
a permit procedure; holding public hearings; and installing and operating faci-
lities for retaining, .retarding, and/or! treating runoff before discharge to
receiving waters and similar activitiesj. Enforcement activities include: sur-
veillance of construction sites; inspections required to obtain operating permits;
preparation and presentation of materials for enforcement actions,* and
similar activities. !
There are five basic approaches available for funding implementation
and enforcement activities related to ijrban stormwater management:
1. General Fund revenues j
2. Permit and Licensing Fees |
3. User Charges • j
4.. pines and Penalties j
5. Grants j '
i
155-
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Rather than discuss these alternative funding approaches in the abstract,
the rest of this chapter is devoted to consideration of their utility in
meeting a series of specific local stormwater problems. The choice among
alternatives, in each instance, will be evaluated in terms of revenue
adequacy, social equity, economic efficiency, and administrative simplicity.
5*3 Financing Specific Preventive Approaches; Five Examples
The following examples have been selected to illustrate methods of
financing various preventive approaches designed to overcome already
identified stormwater problems. The examples illustrate a variety of financing
methods, and as can readily be observed, these financing methods can be
applied to a number of problems. The methods can be used singly or in
combination with other methods to provide the needed financing.
Some approaches require substantial outlay of public (government)
money while other approaches•avoid the necessity of expending public funds.
For example, a permit program shifts the cost directly to those who seek
permits. Thus, financing specific approaches may be viewed as (1) identifying
sources of funds to defray public expenditure or (2) identifying approaches
which reduce or avoid the use of public funds and thrust the burden of
costs, if any, on the private sectbr. In some instances neither the public
sector nor private sector which is subject to the regulative impact of the
selected approach may experience a reduction in value of its property, or a
capital loss.
5'3-l Development in an Aquifer Recharge Area
Problem; .she quantity and quality of a water supply dependent
upon an aquifer is endangered due to increased development in the aquifer
recharge area. ;
Approaches;
1. Designate aquifer recharge areas as a critical environmental
area^ 'Public acquisition of title to the recharge area to maintain
it in its natural state.
2, A public system to recycle stormwater from developed portions
of the recharge area to the-still undeveloped areas.
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Needs for Financing; j
1. Approach 1. Cost of purchasing the land comprising the recharge
area. . • j
2. Approach 2. Cost .of land "acquisition, if required, plus costs
of constructing, maintaining, and operating the recycle system.
Sources of Financing; \
i
1. Approach 1. The publicly owrjed water supplier could issue
revenue bonds (long-term borrowing) to be retired from revenues
of water users who are dependent jupon the aquifer for their water
supply. This could be an element; in the charge system for water
j
users. |
i • • . • •
2. Approach 2. j .
a. Issuance of revenue bond$ as set forth in approach 1.
b. To the extent that owners 'in the developed portion are benefited
by the stormwater drainage system, such owners could be assessed
on a benefit basis to provides funds to retire bonds issued to
provide capital. j
c. The costs of maintanancei and operation of the recycle system
could be financed by "user charges" on the benefited property
owners in the drainage area '(i.e., charges based on amount of
runoff as computed by lot .si'fee, soil permeability, and existing
improvements, such, as driveways and roofs), or more broadly
through charges t© all water; users.
i
Evaluation; !
These methods of financing can b;e manipulated to provide adequate
funds since charges to users can be adjusted to assure the needed amount.
It is fair in that those benefited—users of the water and those benefited
by the storm sewer system—bear the costs;. It is, however, somewhat rigid
since it is capital intensive, and once tjhe costs are incurred they must
be repaid. The methods should be within jthe legal authority of local
governments or water districts since 'this* is not an unusual method of raising
capital. It does require constant administration, but the administrative
agency is most likely already in existence, and it could make the collection
process part of that already established!' While water bills would increase,
the assurance of a water supply should enhance public acceptability.
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5.3.2
Polluted
Existing and projected development in a drainage
causing, and threatens to cause, increased stormwater
increased levels of contaminants.
Approaches;
area is
runoff
containing
1. Site planning which requires each major developer
drainage area to provide for delaying runoff
in the
nants.
and removing contami-
2. Publicly owned and operated runoff retention and treatment
facilities such as settling ponds adequate to handle
flush" during rainstorms and the water from periodic
parking lot cleaning.
3. Comprehensive maintenance program, including litter pickup
street cleaning, catch basin cleaning, parking lot cleaning
Needs for Financing:
1. Approach 1. The primary costs to the public
approach are planning and management (monitoring and enforced)
The major costs will be borne by the private sector in providing
the facilities to delay runoff and to remove contaminants
2. Approach 2. The principal costs in this approach are borne
the public and include: (a) land acquisition for retention and
settling ponds, (b) construction of stormwater collection
(0 construction of retention and settling ponds
to handle the "first
street and
etc.
sector in this
by
systems,
and maintenance of the entire system
3. Approach 3. The
(including
principal costs will
and (d) operation
treatment, if necessary)
and include: (a) acquisition and maintenance
equipment, and (b) labor and supplies.
Sources of Financing;
Approach 1. The public monies needed for planning
: are relatively small. As noted previously these
from general revenues, assessments on benefited
borne by the public
of street cleaning
ment are
and manage-
may be paid
license or permit fees
land owners, or
or a
combination thereof. The private
sector, which must bear the most significant share
can recover this by increasing the price of their land and/or
of the costs.
improvements
on the land when the land is sold.
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2. Approach 2a. Long-term borrowing in the form of bond
issues is the most likely source tb supply funds for capital expen-
ditures such as land acquisition and costs of construction. Typically,
the context within which these typjes of needed capital investments
arises is multi-jurisdictional in [nature! These bonds could be
repaid from assessments on benefited landowners—i.e., those within
the drainage area sewered by the facilities. The assessment would
be based on, or in proportion to, j" (1) amount of runoff from each
parcel of land, or (2) area of lajnd which is developed.
Approach 2b. The costs of maintenance and operation of the
system could be financed by user dharge on owners in area served.
This user charge should be based on volume of runoff and contaminants,
if any, in the runoff which need treatment. Volume can be calculated
on size of lot and soil permeability. Contaminant-based charges
can be based on use of land—parking lots, heavily fertilized
i , •
areas, outdoor storage areas, etc.'
3. Approach 3. The costs ofjequipment, if substantial, may be
financed by long-term borrowing iiji the form of bond issues. More
I
likely, however, this cost plus operational costs will come from
the general fund.
Evaluation:
In the case of the first approach which places the heaviest costs
directly on the private sector, those creating the problem— developers and
those purchasing from developers — bear the i cost. This approach may, however,
not provide the economies of scale that may be gained with, larger,
publicly owned facilities (such economies of scale do not exist! in all cases).
It may, however, result in cooperation amoijig private developers and in more
innovative approaches to the problem since j the private sector would be attemp-
i
ting to minimize costs. Costs to the public sector are greatly minimized.
In the second approach, in which the public sector incurs jtiie-- ini-
tial expense, the placing of the ultimate burden on those creating the problem
is fair. From the public sector point of view this method should provide
an adequate source of revenue. To a certain extent, the adequacy is depen-
dent upon the basis on which benefit assesjsments are calculated. As an ex-
ample, if based on area and permitted intensity of development of each parcel,
the owner pays on the basis of the benefit,1 whether developed or not. If based
on calculated runoff the cost of constructing the facilities based on projected
development will be incurred, but development may not occur.
159
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Both should be easy to administer and there should be no,need for new legis-
lation. By spreading the costs among those benefited, it should be poli-
tically feasible and socially acceptable.
The third approach (comprehensive maintenance) in which the public
generally bears the cost is a fair one, and also one which promises adequate
revenue possibilities. It also may serve multiple objectives, including
public health, aesthetics, reduced unemployment. Finally it is attractive
because these maintenance activities are traditional functions of muni-
cipal government, and can readily be redirected to water quality goals.
s-3-3 Polluted Runoff in Undeveloped Area
Problem: Projected development in a relatively undeveloped area
will increase surface runoff and increase contaminants in receiving waters.
Approaches;
E
As a first step, determine and establish acceptable quantities
of runoff. This in turn can be used to control the composition of the
runoff indirectly,'through local ordinances incorporating performance
standards. Other means available to control development include:
1. Limit overall development and/or paved and roof surfaces in
the area. As part of this approach, allocate development
riglits to each parcel based on size of the parcel. These should
be recorded as part of the land records. This could result in
a form of land use control for each parcel not based oh density,
but based on paved and roof surfaces.
2. Allow a market in the development rights, e.g., "trans-
ferable development rights" (TDK's) with public agencies over-
seeing the transfers and maintaining records of them.
3.. Require maintenance of open or undeveloped areas, or
require planned unit developments.
4. Acquire development rights so that the public may directly
control and prevent their use.
5. Encourage "open space," forest/or agricultural preserves
by substantially reduced real estate taxes and/or by credits
against other state taxes for land maintained in accordance
with preservation objectives.
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I
Needs for Financing; I
1. Approaches 1, 2, and 3—Public Sector.
In all three of these approaches, th4 primary need for public
sector funds is in planning:and management. Funding needs may
be considerable, since establishing the "acceptable" runoff is
technologically complex. The monitoring and enforcement aspects
of management may be more expensive j:han usual if the governmental
entity becomes involved in administering the market for TDR's.
2. Approach 4—Public Sector: Fundk will be needed to purchase
the TDK's. |
3. Approach 5—Public Sector. While funds are not needed for out-
of-pocket payments, there is a loss jbo the public sector in the
form of reduced tax income. Although difficult to measure, this
lost tax income should be partially joffset by a reduced need for
public funds to meet water quality standards in the receiving waters.
4. Approaches 1, 2, and 3—Private Sector
The private sector may experience increased development costs
although "cluster developments" usually result in lower development
costs per dwelling unit for roads aijid utilities. As in the case
of restrictions on development the private sector bears the loss of
profits -that could have been gained j through more -_«£l^nsive development
5. Approach 4—-Private Sector. Th
-------
If the public sector becomes involved in administering the
transfer of TDK's, a transfer fee could be charged for such admin-
istrative service.
2. Approach 4-Public Sector. Funds to purchase TDK's could come
from a bond issue to be repaid from assessments on all properties
in the drainage area. '.
3. Approach 5-Public Sector. The reduced tax income would have
to be offset by tax income from other sources such as an increase
in taxation on the developed property in the drainage area.
4. Approaches 1, 2, and 3--Private Sector. As in the case of '
other restrictions and constraints on development, there is an
economic loss of possible profits resulting from more intensive
development. These can be recovered to the extent that the market
will bear increased costs 'for the land.
5. Approaches 4 and 5-Private Sector. NO need for private funds
except to the extent that taxes on other property owners would have
to be increased to provide funds or offset lost income tax revenues.
Evaluation;
Since the need for public sector funds is small, revenue adequacy
would not appear to be a problem. The use of planning already conducted or
being conducted pursuant to the Federal Water Pollution Control Act would be
economical and would enhance coordination. The fee .charged for facilita-.-
ting and administering the transfer,of TDK's would offset the costs.
By allocating TDK's to each parcel, landowners could transfer
these so as to facilitate development but within the overall constraint of
allowable runoff. This provides flexibility and the opportunity for
economical development while maintaining open spaces. This also provides
a mechanism for government to acquire TDK's thus lessening the burden on
those private owners whose land is restricted. This would avoid a possible
"taking" issue. Such an approach may, however, require new legislation,
and it must be coordinated with other land use control objectives-traffic
schools, providing industrial zones, etc. The tax incentive in the "preserve-
approach may require new legislation in order to avoid legal problems such
as a requirement that all property be taxed on a uniform basis. To the
extent that all of these approaches are somewhat novel-not conceptual^
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itv application—there will be an increased administrative burden. Until
the approach is implemented and experience gained in its application, it
will take more time and staff to administer as compared to more familiar
approaches . I
5.3.4 Development Adjacent to a Stream |
Problem; In an area adjacent to] a stream existing development
will cause (1) stream bank erosion, and j (2) sedimentation and pollution
from surface runoff into the. stream, j
Approaches; i
1. Designate the areas adjacent! to the stream as a "critical
environmental area," and acquire! conservation easements (i.e. limiting
development or maintaining area iin its natural state) 'from property
owners along the stream by purchase or by requiring dedication of
easement as a prerequisite to development.
2. Site planning by land use cdntrols which restrict development
along the stream. This could bej coordinated with flood plain land
i .
use regulations. |
3. On-site construction activity controls which require maintenance
of vegetative cover and construction methods that prevent erosion
and runoff. • ; .
4. "User charge" or "contributor charge" based on the Universal
Soil Loss Equation--!. e. a charge levied on property owners in
the watershed based on their contribution to the sedimentation
problem. The elements of the sfil loss equation include soil type, slope,
ground cover, etc. J
Needs for Financing; i
1. Approach 1. Acquiring conservation easements directly means
outlay of public funds. Alternatively, the locality could require
dedication of conservation easejments by owners and developers
before allowing development in jthe area, resulting in no costs to
the public sector. I
2. Approach 2. The principal j costs to the public sector in this
approach are planning and management (monitoring and enforcement) .
Costs to the private sector ari not "6ut-of -pocket" costs but
rather lost oppdrtuni
-------
in this
3. Approach 3. The primary costs to the public sector
approach are planning and management (monitoring and enforcement)
(1) planting and/or maintenance
(2) any increase in construction
Costs to the private sector are
of required vegetative cover, arid
costs necessitated by compliance;with required construction methods
Plus maintenance costs if any. if the private sector fails to
perform its maintenance requirements, the public
its enforcement function must step in and perform
sector as part of
Approach 4. The costs to the public sector
are for
determining
and collecting the charge. Costs to the private sector, are, of
course, the "user" or "contributor" charge.
Sources of Financing:
1. Approach 1. Alternative 1. The costs of conservation ease-
ments should be substantially less than acquiring the fee (entire)
title to the land adjacent to the stream.
determined by the difference in the value
after imposition of the easement. Funds could
This cost is usually
of the land before and
come from general
revenues or from assessments on all lands within the drainage
All such lands tend to benefit since the conservation easement
may allow them to make more intensive use of
the vegetative cover of the land
surface drainage into the stream. Alternative
area.
public sector is negligible since dedication
their lands in that
in its natural state would retard
_2.- The cost to the
made as a
of the easement is
sector
is
prerequisite to development. . The cost to the private
recovered by increasing the sale price of the developed
lands. A problem could arise if the landowner does
sufficient land to develop after dedicating the conservation
not own
easement
2.
are
Approach 2: The public moniesjneeded for planning
comparatively small. These may be paid from
and
management
general revenues
or assessments on benefited landowners-i.e. those within the drain-
age area. The private sector, while not bearing any out-of-pocket
expenses, suffers the loss of opportunities to develop. This may be
recouped by an increase in sale price
which is contrary to the public good--
waters in the stream.
may
on the balance of the land
i.e.
causes harm to the public
164
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3. Approach 3. The public monies needed are only for planning and
management (monitoring and enforcement). The costs to the private
sector are recovered in increased costs to purchasers of the developed
lands. TO the extent that the public sector must step in and perform
maintenance, such costs can be Assessed directly against the bene-
tited parcel~i.e., the parcel Jon which the maintenance is performed.
4. Approach 4. Public monies jare needed only for determining and
collecting the charges. The cljarges can be collected along with
other property taxes which minimizes the administrative burden.
The private sector will pass the costs along in the same manner as
other property taxes or assessments.
Evaluation: !
To the extent that public fundL are used, the public generally
benefits by cleaner waters in the streaiu Thus, use of general revenues is
fair since the public generally is benefited by the imposition -of the con-
servation easement on a few property owners. To the extent that the private
sector bears the costs, these can be passed on to purchasers of the developed
portions of the land. A definite problem arises, however, if the servant
landowner—i.e., the owner whose property is subjected to the conservation
easement-does not own sufficient land j for development outside the area
subject to the easement. In considering Approach 2, there is the same
impact on the private sector, as in,the|case of the dedication of the
conservation easement. In the case of|Approach 3, the increased costs
are passed on to purchasers of the lanf In the case of costs to be borne
by the private sector, these "financing methods" appear fair in that those
causing the problem bear the cost. i
There is little or no problemj as to adequacy of funds from the
public sector if the funds are appropriated when the governmental entity
decides to use the conservation easement approach. In the case of the
private sector, the additional costs mjay be passed along if the market
conditions allow. If not, then development will be curtailed.
The exacting of a conservation easement and the imposition of
land use controls under the "police" powers of the government always run
the risk of being held a "taking" as discussed previously.
165
_
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5.3.5
Wetland Development
.Problem; Wetlands, which provide breeding grounds for
are
life and water fowl,
and in adjacent areas. Dredge and fill operations in the
runoff of fertilizers and pesticides from nearby developed
principal threats.
Approaches;
aquatic
endangered by development in the wetlands themselves
wetlands and
areas are the
1. Designation of wetlands as a "critical environmental
Alternative 1 would be to limit development in wetlands ]
restricting dredge and fill operations, in conjunction
and regulations applicable to navigable waters
Harbors Act of 1899). Alternative Ib would*be public acquisition
of conservation easements to limit development in the wetlands
or keep them in their natural state.
area,
with laws
(e.g. Rivers and
Regulate use of pesticides and fertilizers
in the drainage
area that affects the wetlands. Such regulations include limiting
types of fertilizers and pesticides used and licensing applicators
to assure control of methods of application.
Needs for Financing;
1. Approach la. The principa-1 costs to the public sector in this
approach are planning and management (monitoring and enforcement).
The costs to the private sector are not out-of-pocket, but are the
loss of speculative profits based on development of the wetlands.
2. Approach Ib. The cost to the public sector
acquiring conservation easements in the wetlands
sector bears no cost since owners are compensated for any "loss
in value by imposition of the conservation easement.
3. Approach 2. As compared with the customary planning and
agement costs, the costs of monitoring and enforcement may be
considerably higher. This results from the necessity, to license
and constantly monitor the distribution and application of ferti-
lizers and pesticides.
is that of
area. The private
man-
166
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Sources of Financing;
.1. Approach la. Federal planning grants under such laws as the
Coastal Zone Management Act jre a possible source of planning funds.
Other sources include the general fund and, perhaps, financing on
an intergovernmental cooperation basis. From the private sector's
point of view loss of speculative profits may be offset by increased
or enhanced value of adjacen^ lands. The wetlands could also be
used in computing density retirements for non-wetlands areas.
'•' Thus, more intense development may take place in the non-wetlands
area to help offset the loss! of speculative profits.
2. Approach Ib. The costs !of conservation easements should not be
large since the wetlands are| not ready for development without
extensive and expensive dredjge and fill operations. Thus, the
difference in the fair market value of the wetlands in its natural
state and the wetlands burdened with the conservation easement is
small. Such costs could come from general revenues of the political
subdivisions having jurisdiction of the wetlands. A wetlands pro-
tection district might be formed with'authority to accept and/or
raise funds to acquire such conservation easements. To the extent
that commercial enterprisesI or even sports groups, benefit from
the maintenance of the breeding grounds, license or permit fees
could be assessed to provid<2 funds.
3. Approach 2. The additional costs of monitoring and enforcing
the regulatory program coulji be offset by license,and permit fees
imposed on distributors andj applicators of fertilizers and pesti-
cides. To the extent that ^he public sector uses such fertilizerss
and pesticides—e.g. highwajy department, parks and public recrea-
tion, public health, etc.--monitoring and enforcement should be
less expensive since such government agencies could "police"
themselves. j . .
'•'"• •'["'•'"' '
Evaluation; | •
To the extent that development in wetlands is quite expensive,
the value of the wetlands in its natural state is low compared with non-
wetlands development areas and restricting its use does not place a great
i
k.67
-------
burden on the private OMers. Bnen conservation events are acquired by
use of public funds, fairness is assured to.,11 concemed-both to the public
and Private sectors. tte source of funds fro, general revenues is, no^ver,
sublet to appropriations and runs tMs.ris* of uncertainty. «. llc«»sing
of distributors and applicators May reguire enabling legislation or at least
promulgation of regulations by environmental or coastal Zone
agencies.
168
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I
CEg
REFERENC
' '' !
These two principles of public finance! have been stated by Musgrave.
See Richard A. Musgrave, The Theory of! Public Finance (New York:
McGraw-Hill Co., 1959). j
• - ,l''''' "- "
In practice, the ability to pay a levy! is usually defined in terms _
of income. This principal is not generally considered in an analyses
of sewerage service charges because thjese charges are rarely, if ever,
related to an individual's ability tojpay them.
i
As a measure of value this test is rather crude because total revenues
are compared with total costs and no Analyses are made at the margin.
I
Connection fees and minimum charges bdth meet this criterion. Total
costs would be equal to either marginal cost of service plus a
connection fee or a minimum charge computed by dividing total costs by
population served.
169!
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6'° INSTITUTIONAL ARRANGEMENTS
The success of stormwater management depends upon its implementation
Master plans can be created, technical solutions proposed, and legal ob-
stacles surmounted, but eventually officials responsible for the control of
stormwater runoff must address the crucial question: what institutional
arrangements will be required to carry out an effective stormwater manage-
ment program?
Previous chapters have dealt with the,elements of a stormwater
Program and these elements fall within a suggested approach-a preventive
one. The preventive approach of best management practices requires the
sxmultaneous and coordinated application of control measures. Its simpler
alternative, end-6f-pipe treatment is too expensive, calling for astrono-
mxcal expenditures, if stormwater programs are thus constrained by the
technical measures available, they are equally limited by the complexity
of the governmental system which is responsible for the implementation of
Programs. Because radical political reorganization around the watershed
will most probably not occur, local government must look to informal
mechanisms and existing institutions. How existing governing bodies can
best be adapted to the implementation of stormwater runoff control, is,
then, the subject of this chapter.
6-1 Existing Patterns of Control for Stormwater Management
The control of stormwater is vested in several layers of government
and, on addition, is related to oth.r goals. Depending on the jurisdiction,
the State may assume a more important role than other governmental units
such as counties, municipalities, or special purpose districts. The func-
tion of stormwater control also encompasses other objectives: erosion con-
trol, flood control, transportation planning, and solid waste management,
for ^stance. Again, the spectrum of concommitant goals creates the necessity
of coordination across functions with .responsible agencies which may, in
turn, have local, regional, or statewide authority.
Stormwater pollution respects no political boundary. As a result
the institutional coordination required for storm water control directly '
involves many different levels of government.
170
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State Agencies ]
In each of the fifty States, at leasij one statewide agency has the
primary responsibility for water quality control within the State. These
agencies will be deeply enmeshed in stormwater runoff problems, for as the
LuLiluiuiiLiil .1 rml-rrti-n »T""T M^^ "™"-^ Strategy Paper indicates;
"Control strategies will be developed by designated Areawide planning
agencies and by States. For both, section 2J>8 provides the principal auth-
ority for addressing nonpoint sources."1 Foj: this reason, State water pol-
lution control authorities will continue to have a direct hand in the imple-
i
mentation of stormwater management programs.I
Within a number of States,2 however,|. the responsibility for water
pollution control has been retained by the skate public health agency; such
an arrangement is probably not conducive tojvigorous and comprehensive
stormwater control efforts, if only because jthese health agencies will be
occupied with many other quite different concerns. The "mission" orien-
tation of public health agencies may dampenjefforts to, analyze stormwater
problems where no direct and incontrovertible threat to human life is
present, such as the presence of pathogens, j ••;..<•.
State involvement in stormwater control also occurs because agencies
of nearly forty percent of the States3 may carry out flood control projects
by building levees, dams and so on. The authority to prevent the construc-
tion of flood control works is another source of State influence. In
several States, the plans of all flood control projects must be approved
by a designated State agency, thus allowing] an effective veto over the
actions of local agencies in this area. j
Soil and erosion control, a goal cl|bsely related to stormwater
control, has come under the influence of Statewide direction in many^areas,
especially through statutes which create sojil conservation districts .
Most of these soil conservation district statutes grew out of the Dust Bowl
disasters of the 1930's. Recently, they helve often been amended to reflect
current concerns over the water pollution Caused by sediment transport.
The use of the veto power against local efforts which do not conform to
a unified soil erosion and sedimentation control program is a common mech-
anism for statewide direction. For exampl^, Michigan provides for local
control; yet "an ordinance which is not approved by the commission as con-
171
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forming to the minimal retirements of
no force or effect."
of man *" 0bJe°tiVeS °£ «<— - control thus come under the authority
of many easting state agencies. ; For ^^ beaaase transportation J_
duals so directly affect the loading intensity of streets J because
last
laws. State
reSponSlBle for highwiy plamiing Md
en f
the need for solid waste disposal.
trol » Sor™,ater o
trol. The plethora of related agen=y involvement causes problem. Tor
oo»-
on a
sta
statement
was to include * 618 acre i.pounrtnent
proposal to create . 3500 acre recreation facility
wh.ch .hauen.ed the water ^ality impacts
r 1 *
ertedthe state to many overlooked detrimental effects
vesting authority for runoff control
„ was not . state agenoy
of the proposal.
al-
-«. *us,
area.
Should not be seen necessarily as a desirable
government plays a decisive role in this
Cities and Counties
fare is o? TtT"
fare „ one of the most important purposes
of the impound-
at the State level
and automatic choice Local
«-
health and wel-
be e*erclsed. The power vested in municipal authorities
dra
drai ±s not
for which the police power
to oonsLct
can
-
that may be exercised to supply needed facilities
rconstruct and maintain a draina.
at any time. This
system is conferred by charter
runoff «or™,ter
thT^r-f tracea *° ^ history:°£ io°ai e°ntoi £°r '-»'-»• *
the past, lt was thought that the overriding purpose of a stormwater
drainage system should be fast removal and efficient disposal. The manage
«= of these systems was seen as an engineering problem divorced LT
other urban systems and activities. ;In addition, sewer design by the
172
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national Method considered neither the timiig of the flow nor the quality
thought wjis. given to designs employing
environmental damage .caused b}
of
water control as a local problem with an engineering solutxon.
Nevertheless, the authority to construct and maintain sewer systems
remains critical to the future of stormwate|r management. Because urban
growth7 -tends to follow along the patterns jof sewer construction, thxa
power-if directed through careful planning--can accomplish much toward
the retardation of runoff velocities. Muci therefore Spends upon the wxse
use of local police powers.
L,nd use control is another area traditional within the purvtew
of local government, zoning, being an exercise of the police power which
resides in the several states, is , form o^ land use control usually dele-
gated to local governments through enabling legislature. This means of
regulation provides a cornerstone to the preventive approach, and ,s more
fully dealt with in other chapters of this manual, as it affects a related
goal, that of transportation planning. th«j zoning retirements of the many
local Planning boards o» do much toward ,he reduction of pollutant loadings
rr.r^p-rrr; =.-
„„.„„„«.,.„ —.....t't""
lations made to lessen traffic congestion! as well as through
requirements. I • .
Therefore, in the pattern of institutional arrangements for storm-
water control, local governments play a fundamental role. Planning boards
shape the programs which seek to achieve ^any of the objectives related to
stormwater runoff management. Departments of public works determine the
success of the technical solutions suggested in the preventive approach-
street sweeping, sewer flushing, and catch basin cleaning to name a few.
Counties share with cities many features and, of course, have regu-
latory powers which are supplemental to Ihose of the State. In many
instances counties creat, pollution control offices which play a part xn ^
runoff control. The Metropolitan Dade County Pollution Control ordnance
which creates such an office is an example of the exertion of a county a
173
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in runoff management. Although not specifically enacted for that pur-
pose the ordinance, for instance, prohibits the disoh,™ f
t-xic U.LOOlioLiyQ OIT ^^clSt^*^! "I irfr^
5tOjtl'lll SSV7S3T SVS"f"(^TT1<2 "R'v^ve^ "
aY &-LSO be exercised IDV courrf-i #ac» -»«
A*»4 -3^y_ j ^ i_T_ • ^v**.i* u-a-co Clo
,. n olicy and Land Development Standards or-
dxnance of Dekalb County Georgia.9
Special Districts
Special districts are the most diverse and least understood,.group ,
I rr*~iTT£i-*-v\m^^«.a.m, •__ . i __ _ . *•
l
: rst as sep"ate corporate enes and which h-
and ad^strative independence fro, general purpose local govern-
ments. Many perform functions related to stormwater control. Their pre-
valence is illustrated by the following table.
Figure 6.1
Multiple Function
Source: Census of Government
As Figure 6.1. indicates, the prevalence of special districts varies
— :
re-
174
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hand does not. Overall, the,primary reason^ for their creation are: (1)
fiscal self-sufficiency, (2). emphasis on technical specialization, (3) efficiency,
(4) geographic flexibility.10 Special purpose districts have only those .powers
that are expressly granted to them or are necessary to carry out the conferred
•powers. Their creation will generally be invalid only where requirements in
.11 i ''.'•"''
enabling legislation are lacking. ]
in their relation to stormwater management special districts have few
. powers in the area- of pollution control, buf in such areas as drainage and
flood control they are,by far the-most important governmentalbody. In addition,
soil conservation districts are a dominant [nethod for erosion control; the crea-
tion of-such districts is authorized in forty-Six states. Such districts are
empowered to develop comprehensive plans whjere earth disturbance occurs.'
Special purpose districts do not ofjfer a general solution to the
fundamental dilemma at hand. An instance o|f an acute jurisdictional morass
existed in one county which included withirj its borders one county-wide drain
board, one county-wide park board, three separate water management districts,
two soil conservation districts and most oi one irrigation .district. To make ;-
matters even worse, that irrigation district extended into two other counties
so that coordination, between the several districts would require contact with
two drain boards, three park boards, four fater management districts, and four
soil conservation districts. This/chaos if not atypical. One survey indicated
that there were 143 counties across the nation which contained over 25 special,.
districts within their'boundaries. |
.As an intergovernmental solution, [special districts have several fail-
ings. First, there is commonly a duplication of roles to be fulfilled by
different districts. Second, there does not often exist a mechanism for state-
wide supervision that would ensure adequate coordination of the districts'
plural and separate efforts to meet their .overlapping responsibilities.
the variations possible in jurisdictional |boundaries make cooperation even
more difficult. . ; . ...... ,. '• ! •
The Intergovernmental Tangle Facing Stromwater Control
in light of these existing patterns of control, one implication is clear:
the control of stormwater .programs is fragmented between levels of government
and across functional responsibilities. State agencies., local departments,
175
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and special districts confront each other with different interests yet pos-
ssess coordinate powers. One director of a western Urban Drainage and
Flood Control District indicated how difficult it was to embark upon a pro-
gram of water quality monitoring, owing to the functional distinctions be-
tween flood control and water quality control. Even though the district
was the appropriate institution to conduct such a survey, the impediment
lay an the difficulty of a single purpose agency to control a multi-faceted
problem. The preventive approach to stormwater management must confront
and successfully deal with this reality of fragmented responsibility.
Because the preventive approach involves regulatory as well as phy-
sical controls, the tendency toward institutional conflicts remains ever-
present. Where conflict does not openly arise, responsible agencies may
well work at cross-purposes. Public works departments may not perform
maintenance operations (street sweeping, catch basin cleaning and the like)
xn coordination with the programs of transportation planning bodies or
other related agencies.
Essentially, the institutional problems remain intergovernmental
ones given the balkanized arrangements of functions in our system of
government. An areawide approach to the problem such as that envisioned
by Section 208 of the Federal Water Pollution Control Act Amendments of
1972 attempts to ameliorate the dilemma, but the problem persists. other
measures, such as A-95 review, seek to avoid duplication of efforts where
federally funded programs are involved, yet conflict continues.
6'2 Coward Better Institutional Arrangements for Stormwater M.^^
Bertrand de Jouvenel stated the problem succinctly at the 1967
Water for Peace Conference, "All our institutions are aimed at regulating
relations between men practically none at regulating the relations be-
tween men and Nature."12 Although this state of affairs has improved con-
siderably with the passage of the Federal Water Pollution Control Act Amend-
ments of 1972 and the strengthening of state water quality agencies, the
dxffzculty remains in bending institutions to a purpose they are unaccus-
tomed to serve and in directing separate efforts toward common ends '
176
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If the nature of our institutions Represents a problem, it is only
part of the dilemma; the nature of the preventive approach also leads to .
complexity in the number and type of institutions involved in a control
program. The preventive approach to stormWater pollution is, by and. large,
an indirect one. The more direct approach| would be to capture the sewer
discharge through interceptors and then to| treat the effluent at a plant
designed for this purpose. Although direct, this approach would be very
costly. More importantly, it addresses iiself to the results, not the cau-
ses of the pollution. When the causes of pollution become the focus,
then the control of runoff becomes one amjng a number of goals of a control
program. The sources of runoff pollution)are also sources of other prob-
lems, and control techniques useful for pollution abatement are also use-
ful for other functions. For example, th|i debris-laden curb is a source
of pollution as well as a blight on the cleanliness of the city. Clogged
drainage ways resulting from sediment cazjried away from construction
sites also increase the potential for flojoding problems. Trees serve to
hold sediment in place in addition to offering pleasing landscapes for the
community. Detention facilities may be designed to ameliorate flooding
as well as to allow a sizeable reductionjof pollution through the settling
out of particulate matter. j ;
While this increased degree of complexity can be a disadvantage,
it can also lead to certain important benefits: (1) it is more equitable
to shift the burden of control onto thosfe areas and individuals which
cause the problem; and (2) it is more acceptable to the electorate that
tax dollars should be spent on programs ^hich contain several legitimate
goals instead of attempting to justify expenditures upon the grounds of
stormwater control alone. Thus, even with the added institutional com-
plexity, a comprehensive approach to tluj causes of stormwater pollution
may make sense on grounds of both equity and practicality. .
At least four major factors should be considered when selecting
among alternative approaches to stormwater pollution control. The allo-
cation of responsiblities and authority|for stormwater management among
agencies ought to take into account:
. the nature of the particular stormwater problem;
« the nature of the controls employed and the
coordination needed to carryj them out;
177
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"fintenance requirements of the program
which ensure the effectiveness of thi consols,
the implementation needs of a control program. .
.en faotors hi9h"9hts a aifferant aspect °* the
arrangements necessary to carry out a stormwater control program. First
the nature of the problem itself enables the planning agency to identify'
those governments and agencies .which hold Jurisdiction over particular
sources or pollution. Second, the type of cooperation desire, from these
response agencies depends in large part upon what controls appear
proving, since many of these controls necessitate different forms of coor-
dination. ^rd. whatever the control program selected, its continued
^ ^*— - -e physical technics employed,
Planning or permitting system, must be coordinated with inspection
enforcement agencies, rinally, an overriding concern is to consider
the means reared to impZement the program to Ma,e it.^to^J^^,
aceeptable not only to the agencies which will 4o the regulating, but also
those interests being regulated-and the public-at-large.
me aature of the Partin,n..- stormwater p^.t.,-.'
area in^ "^ °" *"" ^^^ "^^ ^^ ta ' >««— local
«. influences the institutional arrangements appropriate for its control.
»at such an influence is critical to the planning agency's efforts may
be demonstrated from three perspectives,
-------
Chicago Metropolitan Area suffered from thfLs predicament, as a committee
report of the Metropolitan Sanitary District indicates:
The region-wide or basin-wide, floo'ding problems,
within the Chicago Metropolitan Ar^ea result from
a number of causes, for example, unrestricted flow
from upstream areas outside of thej jurisdiction
of the Metropolitan Sanitary District...The
solution to these basin-wide and region-wide
flooding problems cannot be accomplished through
the sewer permit ordinance, but must be performed
by the responsible governmental bodies.
It is not the intent of the Sub-Committee that
numerous small puddles and ponds be constructed
throughout the Metropolitan Area.j Such scattered
ponds may create nuisance and posspiJble health
hazard and fail to provide flood protection if
not adequately maintained. Rather, the purpose
of the recommended amendment to the Sewer Permit
Ordinance is to encourage the development of well
maintained landscaped lakes to act jointly as
detention reservoirs and recreation facilities or
aesthetic focal points in new viljLage parks, either
in incorporated or unincorporated! areas...
The Sub-Committee believes that the Federal, State,
County, Metropolitan Sanitary District and other
local agencies, should work together to provide
overall planning, scheduling and jfunding for the
large drainage basin projects.13 j
As a matter of equity, the reverse shoulcj also hold true: that a locality
should not ignore the problem if it is inj the fortunate position of being
able to pass its problems downstream. j
Although the drainage characteristics of an area are an important
basis for identifying and ,invblving; the Appropriate agencies of govern-
ment in an effective control program, thejy are still only one consideration.
Another is the characteristic of the runoff pollution's constituents.
Figure 6.2 indicates how the various conjtitutents of stormwater pollu-
tion (during one event) vary with respect to distance. From a glance,
it can be seen that most pollutants are iarried far and endanger the
receiving waters beyond local boundaries[ For this reason, intergovern-
mental coordination will be required in ijaany cases. Figure 6.3 describes
how stormwater constituents vary in their persistance over time. Heavy
metals, for example, are regional in scoj?e and long-lived. In contrast,
bacteria and viruses from a. storm may not extend beyond local waters,
179
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Figure 6.2
Stormwater Constituents and Their Effective Distance
MILES
LOCAL
REGION-
BASIN
180
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Figure 6.13
Stormwater Constituents and Their Persistence.
4
BACTERIA AND VIRUS
METALS-- PERSISTENT
MhiAL ORGANICS
HOUR
WEEK
i
4-6, 1975 j
:
_
-------
nor over a week's time. Some constitutents and their sources may tran-
scend the abilities of any one community to implement control. A common
example would be the lead compounds resulting from car emissions No
one could reasonably expect to achieve abatement of these compounds in
runoff through local prohibition,- the severity and extent of this problem
has reared federal regulation, and for reasons other than runoff control
Other constituents, such as the; nutrients which cause eutrophication, may
also require the action of superior authority, whether by the state
or federal government. :
in these cases where the runoff problem is clearly beyond the power
of the affected localities to control, the appropriate course of .action
may be to petition the state government. An example is the Recommended
Resolution for Regulation of storm Drainage which Affects Separate Sewered
and Unsewered Areas adopted by the Metropolitan District of Greater
Chicago :
bS ifc resolved,.that the President
of the Metropolitan Sanitary District of Greater
Chicago hereby petitions the Governor of the
State of Illinois to direct the appropriate
department of the State. of Illinois to:
(1) Establish a flood control program for the
State of Illinois based on the principle of
retaining storm water runoff at or near its
source, and
(2) Regulate and control storm flow which pass
from one county to another within the State of
Illinois by establishing maximum flows at the
county lines... 14
It should not be concluded that runoff pollution is always beyond the scope
of local government to influence and reduce and that local government
lies helpless until superior authority acts. On the contrary, the indi-
vidual community will be the iinch-pin of any successful program of
abatement when areawide cooperation comes. about.
In addition to those natural features which affect the specific
runoff problem, there are man-induced considerations-e.g. , patterns of
growth, the design of the sewer system, the traffic patterns of an area-
which determine the total loadings of stormwater runoff in large measure
*hese elements of the problem, however, have always remained within the
purview of .local land use controls. Cities and counties through their
182
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I
police powers greatly influence pollutant loadings in stormwater runoff
(See the discussion in Chapter 5) .
rhe Nc
3f the Controls Employed and thel Coordination Needed
to Carry Them Out
institutions having different authorities and functions are likely
to become part of any areawide stormwater management plan. Once the
cooperation of - these organizations is gaine|d, the type of coordination
desired from them depends on the nature of jthe solutions which appear
promising. i
How does the nature of the controljprogram affect the type of
coordination necessary? Differing degrees of cooperation may be called
for. To provide an example, let us assumejthat two communities adjoin and
that a transportation network covers the locales evenly. Furthermore, the
assumption might be made that the loading ff the street runoff degrades
the quality of the receiving water. In thks case, if it is determined
that an area containing multiple jurisdictions would benefit from street
sweeping, then the type of coordination-needed may be an inter-local con-
tractual agreement which would share the capital investment in sweeping
equipment and the maintenance costs for itjs operation. In this example,
the nature of the problem dictates a concerted effort from two commu-
nities and the solution-street sweeping-jrequires the close and continued
cooperation of the communities' public worjks departments. The coordina-
tion would involve scheduling of sweeper rjoutes to achieve the maximum
pollutant reduction, for if each department acted independently the effec-
tiveness of the combined program could be jdrastically reduced and the addi-
tional expenditures wasted. '
If an area experiencing rapid urbjn growth staddles jurisdictions
and sediment constitutes a major difficulty, then the appropriate measure
may instead be the simultaneous adoption by ordinance of performance
standards for developers. To do so couli involve the independent imple-
mentation by several jurisdictions of similar ordinances enacted with
common objectives. Once these objectivesj are agreed upon by the affected
governments, the operation of the program could proceed quite independently
in each jurisdiction. This result was achieved in several counties
surrounding Atlanta, Georgia. Dekalb CouLty passed such an ordinance
183
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establishing performance standards for runoff from development, and as
a result the bordering counties of Clayton and Cwinett have since adopted
similar reflations, These counties evidence co^on problems, since two
Of the si* major drainage basins in Clayton County. Georgia, originate in
rulton and Detalb counties the passage of similar ordinances functioned as
a form of cooperative agreement to control a com«,n problem. The counties
however, have Jurisdiction onlr ever unincorporated areas, mcorporated '
areas fall within the purview of municipal Public Worfcs departments.
To achieve systematic control over sediment delivered to the area's rivers
has retired that cities rely on regulations concerning the grading of
land in this manner, ordinances enacted by the counties and the cities
in the Metropolitan Atlanta Area have, by and large, been successful in
controlling stromwater pollution from sediment. This coordinated program
evolved informally aore by example than design. a Aether path may 1
found if the objectives desired from coordination are clearly stated at
the outset, before independent programs are launched.
Runoff pollution problems are rarely staple, and even if one type
of pollution predominates, such as erosion and sediment runoff, many agen-
cies may become involved. ». state's highway department may be a contri-
butor to runoff pouution through initial construction activities and sub-
sequent highway runoff, in addition to private developers. From another
perspective, no one stormwater management technique can be applied without
regard for its unavoidable interdependence with other techniques. For
.nstance a comprehensive catch basin cleaning program cannot be designed
Without due consideration for the schedule of street sweeping activities,
because the sweeper reduces the load avails for entry into the catch
basln. »here street sweeping is frequent, catch basin cleaning may be an
infrequent need. Therefore when organisational responsibly for the two
techniques Is split between different agencies cr departments, coordinated
Planning is necessary to ensure the maximum efficiency of an overall control
progra,,. This coordination should not end with the initial formulation of
Plans, but continue on a frequent basis as the program in implemented
Once the nature of the problem and its sources have been assessed,
the cooperation of those governments holding Jurisdiction over elements
Of the problem must be gained. In some cases close cooperation may be re-
ared, but this is not always so since looser and more informal mechanisms
184
-------
may suffice. Part and parcel of this cooperation must be the identification
and involvement of all those agencies whifh will be required to achieve
the goals established for the control program. When methods of abatement
are adopted for reasons including but expending beyond water quality,
coordination may become an extremely intricate process involving many
different organizations and interests
ram Which Ensure
IrementsoftheJPr
The Maintenance Re
the Effectiveness of the Controls
It is not sufficient that planning activities cease with the ini-
tiation of a preferred stormwater management program. Adequate means to
ensure the continuation of the controls fust be provided, otherwise the
controls may become ineffective or even ^acerbate runoff pollution.
The need to maintain the control's provided for stormwater runoff
may create additional coordination problems. For example, while the auth-
ority to require on-site detention of ruUff may be granted by statute
to one entity, such as a soil conservation district, the statute may not
vest enforcement or maintenance in the sjame agency. Similarly, the appro-
val of development plans may rest with i special purpose district, whereas
inspection of sites for noncompliance mly remain with a department of the
county government. Another typical arrangement is that maintenance may be
left to the property owner. A description of Fairfax County's (Virginia)
experience is instructive for the typesjof problems that can arise:
County personnel feel that the iaajor problem with
their erosion and sediment control program is the
inspection. Most of the inspection is done
"after the fact" when little ca^ be done._ In
addition, utility inspectors are used as inspec-
tors for erosion and sediment Control and usually
lack the experience necessary for effective
inspection within this area. Tfwice a year the
County Development Department does give an
erosion and sediment control refresher course
to its inspectors in an effort!to correct this
situation and provide interaction between the
Plan Review Section and the Infection Department.
Where possible the planning agency shoild develop means to ensure that the
authority to inspect is clearly provided and that this responsibility
be carried out by qualified personnel.1; The allocation of responsibility
for stormwater runoff management shoul)* include consideration of the
• i.
' 185! ' .
-------
inspection function as part of any existing or proposed runoff ordinance.
The risk of inadequate inspection is that runoff control measure
will not be carried out or that they will be inoperative or ineffective
during the construction period. A related aspect of the inspection
problem is the involvement of the design engineer which can supplement local'
government inspection while not replacing it. In some cases, the consulting
engineer hired to design the system does just that, he designs the drainage
system and never sees the project again. Another engineer, usually employed
by the developer, signs the as-built drawings. Especially in the control
of erosion and sedimentation, when the construction phase is very important,
some sort of continued inspection by the design consultant might be needed.
The necessary maintenance of the physical devices which become part
of the runoff control program is closely allied with the inspection sys-
tem, m some areas of the country, maintenance bonding is required of the
developer. The ultimate success of any system of controls will depend on
inspection and maintenance, but to achieve this success the planning agency
must solicit the interest and awareness of the developer and of the
public-at-large. !
Implementation Needs of the Program
Many well conceived plans are currently collecting dust on agency
shelves, in the planning process the nature of the runoff problem may be
accurately conceptualized, coordination plans 'developed; maintenance require-
ments passed into law, and still the plan may not be implemented in the ab-
sence of a concerted effort to educate those who will beat the brunt of
regulation, as well as the public at large. The principal obstacle to
implementation stems from an indifferent attitude toward precious environ-
mental resources and ignorance of the significant threats posed by runoff
pollution. This attitude persists and requires much effort to,change .it.
Education may do much to ellicit a willingness to act.
For example, when Dekalb County passed its runoff control ordinance
the contractors and developers reportedly accepted the restrictions as
outlined in the ordinance and very few problems resulted. One reason
for this lack of problems could be that the Drainage Department conducted
a series of workshops in which the drainage ordinance was explained and
where the contractors and developers had the opportunity to ask questions
186
-------
•-.-•• I
concerning the application of the ordinancte.
Another approach is to create "bluk ribbon" committees, such as
was done by the Metropolitan Sanitary District in Chicago. This committee
was composed of representatives from the Sanitary District, consulting
firms, contractors, developers, public worjks personnel, and interested
citizens. A wide range of disciplines and backgrounds can then contrxbute
to the development of policy and this can jadd measureably to the success
of a program. I
Yet another way of attacking the problem of public participation
is to develop public service announcement! for broadcast by local television
stations. The Huron River Watershed Counkl in Michigan achieved great
success with this method. The StormwaterI Runoff Program within the Water
Planning Division of EPA is currently developing a slide show for use by
areawide 208 agencies in explaining the pjroblem of runoff pollution and
• . .i
what can be done to abate it. |
Summary
; The Preventive Approach |
Because the preventive approach requires coordination at many
stitutional difficulties are
levels, it will cause conflict. These in
clearly a drawback to the approach, but ^hat other alternatives are
there? Available evidence suggests thatistormwater runoff will eventually.
dominate as a major source of water pollution. The reason is sd^ply that
as point source control meets the requirements of P.L. 92-500, urban run-
off will be' a remaining major problem, jlso,Durban areas do not remaxn
static; they grow, and with this growth jnmoff increases.
A basic proposition advanced hert is that existing institutions can
be molded to fashion effective stormwatejr'management programs. To accom-
plish this objective, however, the dilemma of stormwater management must
be viewed from a certain perspective: controlling the sources of runoff
pollution through their reduction and prevention. This perspective entaxls
a family of abatement measures which arJ both physical and regulatory.
in order to control stormwater runoff pollution these abatement measures
must be applied systematically. To succjeed at this task and to implement
the management program requires an awareness of the institutional con-
straints which are present. These can l|e overcome through a careful con-
sideration of who has jurisdiction over!the sources of the pollution and
187
-------
what is required of these agencies and governments, both initially and
on an on-going basis. Finally, the institutional constraints cannot be
overcome without the awareness and education of those regulated
6.3
A Brief History; Leon County, Florida
In 1973 Leon County, Florida passed three related ordinances:
directed to the protection of trees
one
sion,
sedimentation,
the second for the control of
ero-
and runoff; and the third aimed at the development
a landscape and open space plan. Each of these regulations influences
stormwater runoff and demonstrates how stormwater man ' "
alone as an individual objective. Rather, stormwater
into a spectrum of environmental goals, in addition, the development
these ordinances indicates how stormwater management
of
management cannot stand
management must fit
of
support of many groups
will require the
During the latter part of 1970, the
onset of construction for Inter-
state 10 around the area of Lake Jackson and the construction
Tallahassee Mall caused isolated instances
of the
polluted runoff into the Lake. At this
of concern over the impact of
point, the homeowners surrounding
Lake Jackson organized themselves and demanded the protection
property and Lake Jackson
of
individual
Commission recommended a study of the
this public expression of concern the County
Thzs analysis was undertaken by the City Sanitation Department
Unzversity Department of Oceanography, the Tallahassee and St;
Health, and the State of Florida Department of Transportation
study verified the pollution problem and urged specific sediment
issue by various local and state agencies.
Florida State
and State Departments of
as well as county-wide runoff control
Indeed, the
controls
In
consequence, the Department of Transportation and the developer
set up sediment control structures on the two construction
issue—that of county-wide runoff
sites. The larger
control—remained. Upon recommendation
a joint meeting of the
of the Tallahassee-Leon County Planning Department, _ __
Tallahassee City Commission and the Leon County Commission
decided that the County Commission would
was held. It was
take the responsibility for the
adoption and implementation of the environmental ordinances
county funding was arranged. After a citizens' task force _ ^
the Planning Department, a series of workshops and public hearings
As a result, the Erosion, Sedimentation, and Runoff Ordinance
, but joint city-
task force was appointed by
were held.
was adopted.
188
-------
The
example, the
was in
at
istrumental in the passage
the workshops held prior to
of
each of the following attended
Florida State
and many other groups
What can be
demonstrates
that citizen
and re;
vironmental
of larger en
the public-at-large
Council in Michigan. Through public
Oceanography
the Huron
Moreover,
•epresentatives of
Game Commission;
Architecture
First, it
local leaders
runoff, as part
ipport from
River Watershed
servicL announcements, public meetings
and
,\^^*j~ ^.*~ — — — —•
dissemination of educational materials
from the electorate. In
an inexpensive yet
the Council had a wide response
iationax 1110.1.5=-^-• ujiw
particular, the public service announcement proved
e j_ c~-*- 4-v.a nouncil
Effective method to gain citizen support
for the Council's
activities. Whatever the method chosen,
panied by public awareness.
Second, this example shows how the
stormwater management must be accom-
problem
of runoff cuts across
tsportation
and
the Fresh Water Fish and
Game Commission b'ecame
local
unregulated
Lgencies concerned with planning. Again
i • i_ J « *-.4-
the detrimental effects of
construction extend beyond the activity
_ *r m«*
of the developer to
involve state agencies such as the Depar
Finally, the joint efforts of the
intergovernmental cooperation is possible
i i. _ «Ai-i4- VQC
:ti|ient of Transportation
county and the city prove that
Because the problem
tr,
ranscended
the city limits it was
agreed to vest responsibility
at the county level,
of stormwater runoff was
but
-r an the issue of stormwcn-ei. o.«*
joint funding was arranged. In all, p aesthetics, erosion control
m^ov of related issues—aesthetics,
presented
as one
among a number of relat
noise
reduction, water quality
rec
;reaticlnal benefits, and aquatic life
protection. The experience
of Leon County,
while not a model, proves that
runoff control can be
acc<
jomplished.
189
-------
REFERENCES
1. Water Quality Strategy Paper- A
the Requirements of £e Federal War
U.S. Environmental Protection" °
P°llcy for
gus,
-ota, Oklahoma, Rhode Islemd,
sections
works; Hawaii
state agency given broad powers st± ^ ^ 1OnS 179-1 to 179~4 (1968):
ance to communities, and Lt SnSacts for ?f T' ^^^ technic*l ^ssist-
Constxtution, Article II, Sections 22 7-f?9- °f .C°ntrO1 W°rks; Mississippi
a levxe system; Pennsylvania StaJJtff I \ * authorized to maintain
ageno/may
4.
5.
6.
7-
Outdoor Kecreation, dated
74
Dlr°°t0r °f
n
8. Dade County, Florids, code, chapter 24.
9- Detelb county, Georgia, Code, chapter 6&.
^el_0rdinance, February,
14. Ibid., p. 238
190
-------
15. Ibid.,
208.
16. Beckey Chason,. "An Analysis ^of the Role
of Planning and the Develop-
Rpckev ason,. - . ... -
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lished paper developed at Florida State Universxty, Tallahasee, Flonda,
March 20, 1973.
191
-------
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PP
ssr
Southeastern Wisconsin Regional Planning
Southeastern Wisconsin (Watershec
Controls). Technical Report No. 2, (1966), pp. 41 92.
Commission. Water Law in
Management and Pollution
207
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