United States
Environmental Protection
Agency
Great Lakes
National Program Office
230 South Dearborn Street
Chicago, Illinois 60604
EPA-905/9-91-003
GL-03-91
vvEPA
Sludge Fertilization of
State Forest Land in
Northern Michigan
Printed on Recycled Paper
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FOREWORD
The U.S. Environmental Protection Agency (USEPA) was created because of increasing
public and governmental concern about the dangers of pollution to the health and welfare
of the American people. Noxious air, foul water, and spoiled land are tragic testimony
to the deterioration of our natural environment.
The Great Lakes National Program Office (GLNPO) of the U.S. EPA was established in
Chicago, Illinois to provide specific focus on the water quality concerns of the Great
Lakes. The Section 108(a) Demonstration Grant Program of the Clean Water Act (PL 92-
500) is specific to the Great Lakes drainage basin and thus is administered by the Great
Lakes National Program Office.
Several demonstration projects within the Great Lakes drainage basin have been funded
as a result of Section 108(a). This report describes one such project supported by this
office to carry out our responsibility to improve water quality in the Great Lakes.
We hope the information and data contained herein will help planners and managers of
pollution control agencies to make better decisions in carrying forward their pollution
control responsibilities.
Director
Great Lakes National Program Office
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EPA-905/9-91-003
February 1991
SLUDGE FERTILIZATION OF STATE FOREST LAND
IN NORTHERN MICHIGAN
by
Dale G. Brockway, Ph.D.
Michigan Department of Natural Resources
Lansing, Michigan 48909
Grant Number SOO5551
Project Officer
Stephen Poloncsik
Municipal Facilities Branch
U.S. Environmental Protection Agency
Chicago, Illinois 60604
Great Lakes National Program Office
U.S. Environmental Protection Agency
Chicago, Illinois 60604
Chicago, IL
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NOTICE
This report has been reviewed by the Great Lakes National
Program Office and Water Division of the United States
Environmental Protection Agency in Region V and approved for
publication. Approval does not signify that the contents
necessarily reflect the views and policy of the USEPA, nor
does mention of trade names or commercial products constitute
endorsement for use.
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ABSTRACT
A five-year research-demonstration project to examine the
logistic, economic, environmental and sociological aspects of
municipal wastewater sludge application was conducted on State
Forest land occupied by forest types of major commercial
importance in northern Michigan. The procedures utilized for
site preparation, sludge transportation and sludge application
proved to be cost-effective and made possible uniform distribution
of sludge upon the forest floor. Sludge applications averaging
9 Mg/ha (4 tons/acre) provided nitrogen additions of 531 kg/ha
(473 Ibs/acre) and phosphorus additions of 300 kg/ha (267 Ibs/
acre). Sludge applications resulted in increased levels of
nutrients in forest floor and vegetation. Tree diameter, basal
area and biomass growth increased as much as 78%, 56% and 57%,
respectively. Leaching losses of nitrate-nitrogen and heavy
metals were minor and did not degrade groundwater quality. Sludge
nutrient additions increased the structural complexity of wildlife
habitat and improved the nutritional quality of important wildlife
food plants. Wildlife numbers and browse utilization increased
on sludge fertilized areas. Food chain biomagnification studies
found no significant risk of heavy metal transfer to wildlife or
humans. Public preference among various sludge management
alternatives is a direct result of the perceived level of
protection each affords public health and environmental quality.
While residents do not hold strong opinions concerning forest
land application, it was their second most often preferred
alternative, following incineration. As the public comes to
recognize the environmental hazards and economic limitations
inherent with incineration and the value of sludge as a byproduct
resource, forest land application should receive increasing
attention as a major sludge management alternative. State
regulatory and resource management authorities are committed to
use of this newly developed technology in addressing waste
management and land management issues.
111
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CONTENTS
Abstract ill
Figures vii
Tables viii
Acknowledgement x
Introduction 1
Summary 2
Background 8
Historical Development 8
Current Issue 9
Management Objectives 10
Investigative Approach 12
Early Studies 12
Recent Studies 13
Methods 14
Site Selection. 14
Related Studies 14
Technical Criteria 15
Public Involvement 15
Site Description 17
Aspen Site 17
Oak Site 17
Pine Site 22
Northern Hardwoods Site 22
Site Preparation 23
Experimental Design 23
Sampling and Measurements 23
Access and Treatment 26
Logistics and Economics 27
Sludge Application 33
Sludge Composition .33
Sludge Loading and Distribution 35
Laboratory Food Chain Studies 37
Environmental Study Results 38
Forest Vegetation 38
Tree Foliar Nutrition 39
Short Term Tree Growth 41
Long Term Tree Growth 41
Tree Mortality 46
Understory Vegetation 46
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Forest Floor and Soil 48
Forest Floor Weight 48
Chemical Composition 49
Element Retention 49
Water Quality 52
Monitoring 52
Nitrate Leaching 54
Leaching of Other Elements 57
Wildlife 59
Habitat 59
Populations 60
Food Chain Assessments 60
Sociological Study Results 64
Public Opinions and Concerns 64
Public Education Materials 66
Significance to Agency Programs 72
Existing Land Application Program 72
Development of Technical Guidance 73
Impact Upon Environmental Programs 81
Impact Upon Resource Programs 82
Information Dissemination 83
Future Direction 83
References 84
Project Publications 89
Principal Investigators 91
Research Assistants 92
VI
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FIGURES
Number Page
1 Sludge fertilization sites in northern Michigan 18
2 Sludge application on aspen site 28
3 Sludge application on oak site.. 28
4 Sludge application on pine site 29
5 Sludge application on northern hardwoods site 29
6 Diameter growth responses of trees at the aspen site 42
7 Basal area growth responses of trees at the aspen site...43
8 Biomass growth responses of trees at the aspen site 44
9 Hypothetical mean annual increment (MAI) curve for oak
showing growth resulting at (A) high, (B) low and
(C) moderate rates of nutrient retention 47
10 Relation of sludge application rate to nitrate leaching..53
11 The sludge nitrogen cycle 55
12 Soil water pattern for nitrate 56
13 Concentrations of calcium, magnesium, potassium and
sodium in soil water 58
14 Public attitudes toward forest land application of
sludge 65
15 Public priority of concerns about sludge management
practices 67
16 Public preference for sludge management alternatives 68
17 Developing a planning process 69
18 Implementing a planning process 70
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TABLES
Number Page
1 Characteristics of the aspen, oak, pine and northern
hardwoods sites 19
2 Soil survey legend of sludge fertilization study area....20
3 Pretreatment tree stocking, diameter and density at the
oak, pine and northern hardwoods sites... 21
4 Contractor cost breakdown for sludge transportation and
application 31
5 Assignment of cooperator benefits and costs 32
6 Average chemical concentrations in sludge applied on
forest sites 34
7 Heavy metal concentrations in commercial fertilizer and
wastewater sludges from Alpena and Detroit 35
8 Solids, nutrient and trace element loading
on forest sites 36
9 Heavy metal concentrations in greenhouse soils amended
with sludge or commercial fertilizer 38
10 Aspen foliar nutrient concentrations resulting from
sludge application 39
11 Red oak and white oak foliar nutrient concentrations
following sludge application 40
12 Jack pine and red pine foliar nutrient concentrations
following sludge application 40
13 Tree diameter growth at the oak, pine and northern
hardwoods sites 45
14 Basal area response factor summary for oak, pine and
northern hardwoods 45
15 Aspen stocking and mortality 48
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16 Nutrient and trace element content of the forest
floor, 1984 50
17 Forest floor retention of applied elements, 1984 51
18 Heavy metal concentrations in ryegrass grown on soil
receiving sludge or commercial fertilizer 61
19 Heavy metal concentrations in tissues of whitetail deer
harvested on aspen site, November 1982 62
20 Heavy metal concentrations in earthworms raised in soil
receiving sludge or commercial fertilizer 62
21 Cadmium concentrations in tissues of woodcock fed
earthworms raised in soil receiving sludge or
commercial fertilizer 62
22 Catagories of sludge chemical quality 76
23 Metal accumulation factors 76
24 Recommended rates for wastewater sludge application
in Michigan forests, assuming a five-year
retreatment interval 78
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ACKNOWLEDGEMENT
A multidisciplinary research-demonstration examining complex
land management, environmental and sociological questions requires
the cooperative interaction of numerous groups and individuals.
While responsibility for achieving final objectives rests with the
Project Manager, credit for success must be accorded those at the
federal, state and local levels whose participation made the
project possible. The author wishes to recognize and extend
appreciation to the following who contributed their funding,
ideas, time and labor.
This project was funded by the United States Environmental
Protection Agency, Great Lakes National Program Office in Chicago,
Illinois. Recognition is due Peter Wise, Madonna McGrath, Ralph
Christensen, Gregory Vanderlaan and Stephen Poloncsik for their
continuing support during the many phases of this study.
Special thanks is extended to members of the Montmorency
Township Board and Supervisor, Garry Boldery, for taking a chance
on success with a potentially controversial issue. Appreciation
is also due the members of the Montmorency County Planning and
Zoning Commission and Chairman, Orlen Zahnow, for their interest
and supp9rt throughout the project. Sincere gratitude is
expressed to the members of the Huron Pines Resource Conservation
and Development Area Council Forestry Committee and Chairman,
Merritt Clark, for the support and promotion which made possible
successful siting of the project in Montmorency County. Thanks
also to Randy Frykberg and Robert Koch of the Northeastern Council
of Governments, whose enthusiasm and local insight facilitated
project initiation and acceptance. Recognition is also due area
specialists, Jack Stegall of the Montmorency Soil Conservation
District, Richard Silver of District Health Department #4 and Mike
Wilson of the Montmorency County Cooperative Extension Service,
for their support during the project.
Recognition is due Tom Young of the Montmorency County
Tribune, Susan Grulke of the Alpena News, Dudley Pierson of the
Detroit News, Malcolm Johnson of the Lansing State Journal, Cheryl
Peck of the Leader and Kalkaskian and Mike Norton of the Traverse
City Record Eagle for their factual and objective news coverage
and reporting during all phases of this project.
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Appreciation is extended to wastewater treatment plant
Superintendents, Dale Goupell of Alpena and Dave McGlone of Rogers
City, and their staffs for furnishing the sludge utilized and for
their cooperation. Sincere thanks is expressed to William Mondor
and Erick Olsen of Sludge Management Corporation for their
professionalism, patience and perseverance in the transportation
and application of wastewater sludge to the forest sites.
Recognition is also due Peter Davis of Chenonquet Consulting
Foresters for his excellent service in site preparation.
Special recognition is owed Michigan State University
research scientists, Dr. James Hart, Dr. John Hart, Dr. Jonathan
Haufler, Dr. Phu Nguyen, Dr. Ben Peyton, Dr. Carl Ramm and Dr.
Dean Urie, and their research assistants, Andrew Burton, Henry
Campa, Larry Gigliotti, Thomas Lagerstrom, Dennis Merkel, Elena
Seon, Anne Thomas and David Woodyard. These individuals served
as the core group of this investigative effort. Most of that
contained herein is the product of their long hours in the field
and laboratory.
Special thanks to Robert Bastian of the U.S. Environmental
Protection Agency in Washington, D.C., Dr. William Sopper of the
Pennsylvania State University, Dr. Jack Corey of the Savannah River
Research Laboratory, Robert Burd of the U.S. Environmental
Protection Agency in Seattle, Charles Henry of the University of
Washington and Dr. Peter Machno of the Seattle Metro Authority for
their review of the manuscript and numerous constructive comments
which substantially improved the quality of the final report.
Sincere gratitude is expressed to Senator Nick Smith and
members of the Senate Agriculture and Forestry Committee, Senator
Vernon Ehlers and members of the Senate Natural Resources and
Environmental Affairs Committee, Representative Thomas Hickner and
members of the House Agriculture and Forestry Committee and
Representative Thomas Scott and members of the House Conservation
and Environment Committee for their continued support of MDNR
programs. Appreciation is also extended Chairman David Olson and
members of the Natural Resources Commission for their interest,
encouragement and support as MDNR staff continue to seek solutions
to Michigan's most pressing environmental and resource management
problems.
From several divisions of MDNR, numerous individuals deserve
recognition for the time and talent they contributed toward
project success: Gary Guenther of the Environmental Protection
Bureau, Director John MacGregor of Region II, Robin Stone and
XI
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Jackie Borden of the Office of Public Affairs, Tim Trasky of the
Office of Budget and Federal Aid, Jack Dibean and John Goodman of
the Environmental Services Division, Dr. Henry Webster, Michael
Moore, William Botti, Robert Borak, Robert Reddy, Eugene Phillips,
Dayle Garlock, Ned Caveney, Robert Ziel, Thomas Stone, Mike
Paluda, Robert Slater, Lynn Mohr and Dave Spalding of Forest
Management Division, Nels Johnson, Tom Carlson, Raymond Perez,
Joseph Vogt, Tom Jenkins, Carl Bennett, Gary Boushelle, Dick Elden
and Robert Strong of Wildlife Division, Harry Doehne, William
Bradford, Paul Blakeslee and Richard Sprague of Water Quality
Division and Wayne Denniston, Daniel O'Neill, Ross Dodge and
Robert Nowinski of Groundwater Quality Division.
Special appreciation is extended to William Marks of the
Environmental Protection Bureau whose informal discussions with
USEPA eventually led the author to preparation of the project
research grant proposal. Through his vision, the proper support
was paired with the specific expertise required to successfully
implement and complete this complex undertaking. For this
opportunity he has the author's sincere gratitude.
Finally, special thanks is due James Johnson of the Land
Application Unit for his many contributions to success of this
project. He was instrumental in initiating several contacts
which ultimately led to successful project siting and served as
Interim Project Manager during the author's two year assignment
with the USDA Forest Service in Vancouver, Washington. Jim
skillfully attended to numerous field, budget and reporting
duties during a very demanding period of the study. For his
friendship and overseeing orderly task progression, the author
extends his sincere appreciation.
XII
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INTRODUCTION
Production of wastewater sludge has become a problem of
growing proportion in the United States during recent decades.
Expanding industrialization, population growth in urban and
suburban areas and legislation requiring a higher standard of
treatment for wastewater have resulted in increased generation of
waste residuals which require periodic removal from treatment
facilities. National sludge production near 3.6 million Mg
(4 million dry tons) in 1970 (Walsh 1976) has increased to 6.4
million Mg (7 million dry tons) currently {Maness 1987) and is
expected to double again by the year 2000 (Bastian 1988). Total
discharge of domestic sewage in 1975 was 90.5 billion liters
(24 billion gallons), a volume which contained approximately 733
million kg (1.6 billion Ibs) of nitrogen, 674 million kg (1.5
billion Ibs) of phosphorus and 428 million kg (942 million Ibs)
of potassium (Freshman 1977). The value of these nutrients
amounted to 561 million dollars. Sludge is currently generated
as a byproduct of wastewater treatment in 15,378 facilities
nationwide (USEPA 1985).
Combined residential and industrial water use in Michigan
has resulted in the annual production of 202,500 Mg (223,218 dry
tons) of sludge by 199 municipal wastewater treatment plants
(MDNR 1986). While traditional strategies for managing this
residual waste have emphasized disposal options such as
incineration and landfilling, sludge management programs
developed since 1978 have increasingly identified nutrient
utilization through the practice of land application.
Approximately 57,200 Mg (63,000 dry tons) of wastewater sludge
are presently used throughout the state as a soil amendment.
Most of this residual byproduct is applied as a fertilizer of
grain and forage crops grown on farm land; however, an increasing
proportion is being recycled on forest land in northern regions
of the state where suitable farm sites are less available.
To facilitate proper implementation of forest land
application programs by communities and industries in northern
Michigan, federally sponsored research studies conducted during
the recent decade have aided in development of guidance criteria
which provide for productive utilization of nutrients and organic
matter contained in sludge and protection of the public health
and environment. This report summarizes much of that research
effort, documents conclusions which have been used as a basis for
regulatory guidance and outlines a strategy for implementation of
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forest land application technology within existing environmental
protection and resource management programs.
SUMMARY
In 1981, forest stands of aspen coppice, oak, pine and
northern hardwoods growing on sandy soils in Montmorency County
north of Atlanta, Michigan were selected in which to conduct a
five year, $1.1 million U.S. Environmental Protection Agency
(USEPA) sponsored research-demonstration project that examined
the technological, environmental and sociological aspects of
fertilizing forest land with wastewater sludge. This project
was an extension of research initiated (and later discontinued)
by the North Central Forest Experiment Station of the USDA Forest
Service. The project was intended to serve as a bridge between
the small plot studies of the Forest Service and the eventual
large scale implementation of operational programs by local
communities and industries.
Conduct of this multidisciplinary study required the
participation of numerous individuals and groups at a variety of
levels. Research studies were conducted by scientists from
Michigan State University (MSU) in the Department of Forestry and
Department of Fisheries and Wildlife. Research efforts were
overseen by and coordinated through staff of the Michigan
Department of Natural Resources (MDNR). Site selection was
coordinated through local units of government and regional
planning organizations. Site preparation and sludge application
were performed by private contractors and coordinated through
MDNR staff.
Following several years of study, we may conclude that
forest land application has been shown to be a cost-effective,
innovative management alternative for sludge generated as a
byproduct of wastewater treatment. When appropriate quality
control, application rates, site selection and program management
are utilized, forest land application provides numerous benefits
such as improving wildlife habitat and increasing forest
productivity, while providing adequate protection for the
environment and public health. Through these and related
research studies, forest land application has been developed into
an attractive silvicultural opportunity, especially when one
recognizes that this byproduct resource is typically furnished to
the land manager without charge.
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TECHNOLOGICAL
During the fall of 1981 and early summer of 1982, 3,679,311
liters (972,077 gallons) of liquid (2.6 to 5.1% solids)
anaerobically digested wastewater sludge were transported from
Alpena and Rogers City a distance of 80 km (50 miles) by tank
truck and applied to the forest floor of the four sites located
on the Mackinaw State Forest. Prior to application, access
trails at intervals of 20 m (66 feet) were created on each site
by removal of existing trees, those of merchantable size being
offered through the timber sale process. Sludge application was
conducted using an all-terrain tanker vehicle equipped with high
flotation tires, a standard pressure-vacuum pump and a series of
nozzles designed to laterally disperse liquid sludge in a uniform
pattern.
The sludge application rate received by the aspen site
averaged 10 Mg/ha (4.5 tons/acre) resulting in respective
nitrogen and phosphorus additions of 561 and 291 kg/ha (500 and
260 Ibs/acre). The oak site was treated with a sludge rate of
8 Mg/ha (3.6 tons/acre) resulting in respective nitrogen and
phosphorus additions of 401 and 272 kg/ha (358 and 243 Ibs/acre).
The sludge application rate delivered to the pine site averaged
8 Mg/ha (3.6 tons/acre) resulting in respective nitrogen and
phosphorus additions of 379 and 253 kg/ha (338 and 226 Ibs/acre).
The northern hardwoods site received an application rate of
9 Mg/ha (4 tons/acre) resulting in respective nitrogen and
phosphorus additions of 783 and 384 kg/ha (699 and 343 Ibs/acre).
Application rates of heavy metals were low on all sites.
The procedures developed for site preparation, sludge
transportation and sludge application were highly effective in
achieving the logistical aims of providing suitable site access
for the application vehicle, prompt sludge delivery to the
unloading area and uniform distribution of sludge upon the forest
floor. These tasks were accomplished at costs that were
comparable with those of other sludge management options.
Unavoidable mechanical difficulties were not encountered in
the process of applying sludge on these forest areas.
Costs for transportation and application of sludge totaled
$48,576 ($303.52 per Mg or $275.94 per dry ton). This amount
would be typically borne by the generator as an operational cost
for sludge management. Costs normally incurred by the land
manager would include those for site preparation. The land
manager, however, would realize a net gain from sale of timber
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plus a value added to his site from sludge nutrients. The
average value of the major macronutrients and trace elements
contained in the sludges used in this study was $46.07 per Mg
($41.88 per ton), which provided a value addition of $406.87 per
ha ($162.72 per acre). Benefit-cost ratios for full scale forest
land application programs are anticipated to exceed the 1.47
value computed for this demonstration.
ENVIRONMENTAL
Nutrients delivered with sludge application to the forest
floor were readily taken up by overstory trees and understory
vegetation. The nutrient status of trees was improved as seen by
increased levels of foliar nitrogen and phosphorus. Sludge
treatment resulted in increased growth in tree diameter (aspen
23%, oak 78%, pine 25%, northern hardwoods 48%), basal area
(aspen 48%, oak 56%, pine 36%, northern hardwoods 48%) and
biomass (aspen 57%). An average 29% increase in long term tree
volume growth (1.05 m^/ha/yr) was predicted to continue as
long as site nutrient levels are maintained by periodic
reapplications of sludge.
Aspen mortality from infections of naturally occurring
Armellaria, Fusarium and Cytospora fungi increased three fold
following sludge application. This increase was not a direct
result of sludge addition, but rather, a result of site
preparation leading to increased sunscald on.tree bark and
increased breakage of stems which were heavily browsed by elk
seeking foliage of higher nutrient value. These injuries
predisposed young aspen to infection by fungi.
Compositional changes in understory vegetation did not
result from sludge application. Sapling growth was improved on
the aspen and oak sites but not on the pine or northern hardwoods
sites. Seedling regeneration was increased on all treated sites,
indicating that increases in groundcover vegetation (forbs,
sedges, grasses) did not compete substantially with tree
seedlings.
Fluctuations in forest floor weight, resulting from loading
of sludge nutrients and organic matter, subsequent increases in
microbial decomposition and recycling of plant parts in
litterfall, were observed. Overall increases in forest floor
weight and nutrient and trace element levels were proportional to
sludge application rates. Significant increases for several
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elements in the 01 and 02 horizons were noted to persist
throughout the study. The total amount of heavy metals present
in the forest floor was quite small. The 02 horizon comprised
95% of the total forest floor mass and was the major repository
for nutrients and trace elements. Very little change was noted
in the chemical composition of surface and subsurface soils.
Three years following sludge application, most nutrients and
trace elements were either retained in the forest floor or had
been taken up by vegetation.
Soil water and groundwater data indicated that small
increases in nitrate-nitrogen movement below the plant rooting
zone occurred within 6 to 18 months following sludge application.
Nitrification of ammonia present in the sludge produced a modest
surplus of nitrate which, when not assimilated by vegetation, was
leached during periods of recharge. Average levels of nitrate
leaching during these periods generally were well below the USEPA
potable water standard of 10 mg/1 and declined rapidly to near
background in subsequent seasons. Minor leaching losses of
calcium, magnesium, potassium and sodium cations occurred along
with nitrate anion movement. However, leaching losses of zinc,
manganese, cadmium, boron, copper, nickel and chromium to
groundwater did not occur. The sludge application rates used in
this study balanced element addition with ecosystem assimilation
capacity and therefore posed no danger to the groundwater
resource.
The structural and nutritional properties of wildlife
habitat were significantly improved by sludge application.
Vertical cover increased in 88% of the plant species present in
the lower 2 m (6 feet) strata and horizontal cover (stem density)
increased in 56% of the plant species. Increases up to 200% were
measured in the annual primary production of herbaceous species.
Deer and elk were observed to browse more heavily on sludge
treated areas. Within one year following sludge application,
significantly increased levels of protein (20 to 50%) and
phosphorus were present in forage. Protein is a critical factor
in the nutrition of deer and may typically limit fawn production
in many areas. Population numbers of small mammals increased as
much as 100% following sludge application. Similar improvements
in habitat structure have been associated with increases in bird
species diversity in temperate climates.
Pood chain studies conducted in the field and laboratory
indicated that forest land application of good quality sludges
poses very little risk for biomagnification of heavy metals.
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Tissue bioassays of free ranging small mammals in the field
indicated that no accumulation of toxic metals was present.
Small mammals confined to a laboratory diet of sludge grown
forage showed very small, statistically nonsignificant
accumulations of cadmium and zinc in liver and kidney tissue.
Whitetail deer harvested from sludge treated field sites
possessed slightly elevated levels of cadmium and zinc in liver
and kidney tissue, but these were well below concentrations known
to be hazardous to vertebrates. Woodcock confined to a
laboratory diet of sludge-raised earthworms accumulated elevated
levels of cadmium in liver and kidney tissue; however, these
levels were below those hazardous to vertebrates. As sludge
application is excluded by regulation from lowland forests where
free ranging woodcock feed and liver and kidney tissues are
discarded prior to consumption, the food chain risk to humans is
minimal from forest land application.
SOCIOLOGICAL
A public opinion survey of forested counties in northern
Michigan indicated that, while two-thirds of residents believe
sludge generation to be a significant problem for cities and
industries, a major portion were undecided about the practice of
forest land application. The absence of strongly held opinions
was attributed to very little technical information concerning
the risks and benefits of various sludge management alternatives
being available to the public. Developing effective public
involvement on this issue may therefore be done through
remediating deficient rather than inaccurate knowledge.
With current public knowledge, human health and environmental
quality are of greatest concern and economics and esthetics of
least concern to residents. Public preference among sludge
management options is a direct result of the perceived impact
each will have first on human health and second on environmental
quality. Although forest land application is the second most
preferred sludge management alternative, incineration is most
preferred only because of the perceived human health protection
it offers. When the public becomes aware of the major health,
environmental and economic limitations inherent with incineration,
forest land application will likely become their principal sludge
management preference.
Forest land application of sludge is an emerging natural
resource management issue which has not reached disruptive status
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with development of strongly polarized interest groups. To
avoid its development to a disruptive level, forest land
application proposals must not be introduced into the planning
process as preformed alternatives to be accepted or rejected.
Rather, the public must recognize that no decision will be made
until they have had opportunity to learn about, participate in
evaluation of and influence the final selection among the full
range of options.
A booklet has been developed during this study, "The Sludge
Solution: Comparing the Alternatives", which discusses in
nontechnical terms the benefits and risks inherent in each sludge
management option. This document will aid the public in gaining
access to correct information concerning the issue. A second
booklet, "A Manual for Public Involvement in Planning Sludge
Management Programs", provides those groups planning sludge
management programs with guidance on how to facilitate effective
public input and makes available to the public background for
providing effective input in the planning process.
Citizens are willing to take responsibility for management
of sludge generated in their own communities, but most do not
wish to have their locale become a dumping site for distant
communities. Because of this prevailing view, forest land
application programs should restrict sludge use to that from
local sources. However, this attitude may change as education
programs persuade the public to perceive sludge as a byproduct
resource rather than waste.
REGULATORY SIGNIFICANCE
During the recent decade, MDNR Land Application Unit staff
have developed a statewide program which has produced solutions
for the effective management of residuals generated as byproducts
of waste treatment. Initially the program focused upon
agricultural land application of municipal wastewater sludges,
but eventually gained responsibility for recycling numerous waste
treatment byproducts on a variety of lands. With conclusion of
this research study, unit staff have set in place systematic
standards for the safe use of forest land as a waste management
option. Criteria have been developed for sludge quality, site
selection, sludge application rates and program management
procedures. Public participation has been identified as
essential to local program success.
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Studies in the Pacific Northwest, Southeastern and
Northeastern United States have demonstrated that sludge
application can be successfully practiced in a variety of forest
environments. However, characteristics of climate, topography,
soil and vegetation unique to each region-require that land
application techniques and regulations be tailored to meet the
needs of practitioners in a specific environment. Guidelines
developed from research in Michigan should therefore be used with
caution outside the Great Lakes Region and with special attention
to environmental conditions prevailing in each specific locale.
Forest land application represents to the waste generator an
additional sludge management alternative, but to the forest land
owner and manager it is a land management opportunity to
economically fertilize forest stands, increasing timber
production and improving wildlife habitat. Practice of forest
land application on public land will require the coordinated
effort of staff in Forest Management Division, Wildlife Division
and Environmental Protection Bureau with municipal or industrial
generators and local elected officials. Despite circumstances
which may complicate local program implementation, resource
managers have expressed interest in adding forest land
application to their array of land management tools.
Land Application Unit staff will continue their function in
providing technical assistance to waste generators and
disseminate information on forest land application to all
segments of the interested public. Cooperative Extension
workshops will continue as will agency training sessions and
informational seminars. The technical and sociological data from
local forest land application programs will be reviewed and used
to refine the statewide program. Funding will also be sought to
further research in the areas of long term site responses and
environmental fate of organic chemicals.
BACKGROUND
HISTORICAL DEVELOPMENT
Traditional approaches to sewage disposal have primarily
relied upon dilution via discharge into available surface waters.
Since the beginning of the industrial revolution, growing
populations have largely compounded the degree of water quality
degradation. Section 13 of the Rivers and Harbors Act of 1899
8
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represented the first attempt in the United States to prohibit
discharge of waste into navigable waters; however, this law
suffered*from lack of enforcement (Sullivan 1973). The Water
Pollution Act of 1948 gave states the primary enforcement
responsibility in water pollution cases with assistance provided
by the federal government. This law also lacked substance until
passage of the Federal Water Pollution Control Act of 1956 which
authorized large scale grants to assist states in planning and
building wastewater treatment facilities.
Growing public awareness of the national environmental
crisis resulted in passage of the National Environmental Policy
Act of 1970, which sought to eliminate the practice of sludge
discharge into surface waters (Sullivan 1973), and the Federal
Water Pollution Control Act Amendments of 1972 (PL 92-500), which
focused attention on the need to develop waste management
techniques that are cost-effective and environmentally sound
(Morris and Jewell 1977), While section 301 of PL 92-500 required
all wastewater to receive secondary stage treatment, thereby
increasing sludge production, sections 402 and 403 discouraged
sludge disposal in surface waters. Land application of wastewater
sludge was cited as a major alternative for eliminating nutrient
rich discharges into surface waters.
CURRENT ISSUE
Preliminary research and experience with sludge additions to
farm sites have identified land application as an innovative,
cost-effective technology for environmentally sound waste
treatment (Forster et al. 1977). Increased crop production,
improved soil fertility and a direct cost savings to farmers from
decreased dependence on petroleum-based commercial fertilizers
are nearly universal benefits of land application. As the
popularity of agricultural land application has grown, it is
likely that few individuals have not consumed foods produced on
sludge fertilized soil.
Although farm land is most often selected for sludge
application and has received more study in this regard, forest
land offers several unique advantages in terms of site
characteristics, ecological structure and mode of nutrient
cycling (Smith and Evans 1977). Numerous industries and
communities in northern Michigan have little farm land available
for sludge recycling. In this locale are millions of hectares of
forest land which could serve as sites where sludge nutrients and
-------
organic matter could be utilized to increase forest productivity
and improve wildlife habitat (Brockway and Nguyen 1986).
Forest crops, ie., wood products, are generally nonedible,
thereby diminishing the risk of human exposure to elements which
may be hazardous in the food chain. The long term accumulation
of biomass on a forest site provides substantial storage capacity
for elements applied in sludge over the length of a crop rotation.
The harvest of tree boles and whole trees offers a means of
removing sludge-applied elements from the treated forest site.
Forest soils are generally porous, resulting in minimal surface
runoff of applied nutrients, and usually nutritionally
impoverished, providing opportunity to substantially increase
soil organic matter and nutrient levels through sludge additions.
Native forest plants, though adapted to low ambient nutrient
levels in forest soils, have demonstrated their ability to
respond with nutrient and biomass increases following
fertilization with sludge (Brockway 1983, Henry and Cole 1983,
Zasoski et al. 1983, Wells et al. 1984). Forest sites are also
typically remotely situated from large population centers and
used for dispersed recreational activities, minimizing the
opportunity for direct human contact with recently applied sludge.
Despite the apparent benefits of recycling nutrients through
forest land application, numerous concerns have been raised about
the potential hazards to public health and the environment. The
possible presence of pathogens, heavy metals and toxic organic
compounds in sludge are leading health concerns. Nutrient
enrichment of groundwater and contamination of wildlife, soil and
groundwater by toxic metals and organic chemicals are major
environmental quality concerns. Prior to implementation of full
scale operational programs, a research assessment of numerous
forest types in Michigan was needed to establish suitable sludge
application rates based upon corresponding sludge composition and
evaluate application impacts upon wildlife, vegetation, soil and
water resources.
MANAGEMENT OBJECTIVES
A major function of the Michigan Department of Natural
Resources in carrying out its mission in environmental
protection and resource management is to encourage wise resource
utilization. When the two major components of that mission can
be coordinated in beneficial fashion, there exists a special
opportunity to serve the public interest. Sludge is generated as
10
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a potentially valuable byproduct of wastewater treatment, a
process which clearly serves to promote water quality and enhance
the environment. While wastewater sludge has in the past been
routinely discarded in landfills as a supposedly useless waste,
MDNR staff specialists have, in recent years, recognized the
numerous benefits to be gained by recycling sludge on land.
As fossil fuel costs rise, incineration has become
increasingly prohibitive technology for sludge treatment.
Recognition that potentially toxic constituents are directly
released as emissions to the atmosphere during incineration has
warranted further caution, as concern increases about the hazards
of cross media transfer. Landfill capacity for storage of
incinerator ash and dewatered sludge is also diminishing as
public agencies, local governments and residents have begun to
appreciate the risks involved in concentrating wastes in
structures built into geologic material which may be relatively
unstable or quite permeable over the long term.
Where sludge has been utilized as a soil amendment,
industrial and municipal wastewater treatment facility managers
have realized immediate savings, from their perspective as being
responsible for selecting least cost alternatives for residuals
disposal. Land owners and managers applying sludge on their soils
also receive a cost benefit in terms of dollars saved that would
have otherwise gone for the purchase of expensive petroleum-based
commercial fertilizers. The average nutrient value of each dry
Mg of a typical sludge is approximately $26.31 ($23.92 per ton).
At a 9 Mg/ha (4 tons per acre) application rate to the typical
40 ha (100 acre) farm an annual fertilizer savings of $9500 would
be realized by the land owner. Crop productivity and soil
fertility increases are additional benefits. As this nutrient
rich byproduct is prevented from reaching surface waters and
recycled on the land, the entire environment benefits.
Forest land application appears to hold a similar promise in
completing the nutrient cycle for the economic and environmental
benefit of society. It is also a special opportunity for MDNR to
encourage utilization of a byproduct of an environmental
protection program to the benefit of resource management programs
in forestry and wildlife. In 1980, MDNR initiated a cooperative
research-demonstration project with the U.S. Environmental
Protection Agency and the Department of Forestry and Department
of Fisheries and Wildlife at Michigan State University to
further evaluate forest land application as a technology for
operational use in Michigan. The major study objectives were
11
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to assess sludge constituent effects upon (1) plant productivity
and nutrition, (2) soil fertility, (3) water quality and
(4) wildlife habitat, nutrition and population dynamics.
Additional objectives included (1) evaluation of forest land
application methodology and equipment, (2) analysis of costs and
(3) assessment of public acceptance and need for educational
materials. Guidance criteria developed from this and related
research would be incorporated into agency environmental and
resource programs.
INVESTIGATIVE APPROACH
EARLY STUDIES
Advances in science and technology are typically built upon
the foundation of work which has preceded. The current state of
knowledge concerning forest land application is no exception.
The first studies which used wastewater sludge applications in
the forests of Michigan were conducted by the North Central
Forest Experiment Station of the USDA Forest Service near
Cadillac on the Manistee National Forest.
Beginning in 1975, aspen and pine forest types were
fertilized with a range of sludge rates up to 46 Mg/ha
(20 tons/acre) to determine maximum application rates which could
be safely used in these ecosystems (Urie et al. 1978). Vegetation
growth and chemical composition, soil fertility and leachate and
groundwater chemistry were carefully monitored on these sites
(Harris 1979, Brockway 1979). Regression analysis of soil
leachate and groundwater data with USEPA water quality standards
estimated safe maximum sludge application rates at 9.5 dry Mg/ha
(4.2 tons/acre) to 19 dry Mg/ha (8.5 tons/acre) depending upon
forest stand conditions and sludge chemical composition (Brockway
and Urie 1983). Improved foliar nutrition and increased
vegetation growth were noted in proportion to sludge application
rate (Brockway 1983, Urie et al. 1984).
As encouraging as these preliminary studies were, they were
conducted on small plots less than 0.2 ha (0.5 acre) in size and
left unanswered questions related to mass effects from treatment
of larger areas or entire watersheds as in the conduct of full
scale operational sludge recycling projects. Also left unanswered
were questions concerning the effects of repetitive sludge
applications and their long term impact upon forest growth,
12
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wildlife and water quality. In the early 1980s, a rearrangement
of funding priorities within the Forest Service led to termination
of this valuable environmental research effort.
RECENT STUDIES
Interest in forest land application continued into the decade
of the 1980s. However, numerous unanswered questions delayed
implementation of full scale operational programs. Municipalities
as well as industries (primarily involved in forest products)
requested assistance in developing this sludge management
alternative. In March 1980, MDNR applied to the Great Lakes
National Program Office of USEPA for an assistance grant which
would allow movement from small plot research to research-
demonstration on larger operational scale plots in continuing
development of forest land application technology. By mid-year,
approximately one million dollars was committed to a cooperative
research and development effort which was to span a period of at
least five years. The terms of funding were 75 percent federal
and 25 percent state awarded annually, based upon task
accomplishment during the previous year and availability of
federal funds. Michigan DNR staff from resource management as
well as environmental protection programs contributed to
completion of numerous project planning and design tasks. These
included Forest Management Division, Wildlife Division, Land and
Water Management Division and Water Quality Division. Several
research scientists from Michigan State University were retained
as principal investigators for their expertise in the disciplines
of forest ecology, soils, hydrology, biometrics, pathology,
wildlife ecology and citizen involvement in natural resource
issues. The efforts of these researchers and their assistants
and the use of the computer and laboratory facilities in the
Department of Forestry and Department of Fisheries and Wildlife
were crucial to completion of the research aspects of the project.
The comprehensive research-demonstration project sponsored
by USEPA was the only vehicle by which forest land application
technology could be further developed in Michigan. It represents
a complex cooperative effort of many levels of government as well
as educational institutions and citizen groups. Its findings are
interesting, in some ways surprising and provide, in combination
with other forest research, a solid basis for present regulatory
guidance. This project will serve as the focus for discussion in
subsequent sections of this report.
13
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METHODS
SITE SELECTION
In addition to a thorough chemical analysis of the sludge,
selection of suitable sites is of foremost importance to proper
implementation of any forest land application project.
Assessment of hydrology, physiography, soil physical and chemical
properties and the vegetation present are all essential components
of the site selection process. The proposed crop nutritional
needs and soil fertility levels are also the primary factors
determining sludge nutrient application rates. As this process
is undertaken in the context of protection for the public health
and environment, site selection must also be concerned with
proximity to dwellings, public highways, surface waters and water
supply wells.
Related Studies
As originally proposed, the research-demonstration was
conceived as a means of assessing the effects of forest land
application of a sludge which had previously received much study
as an amendment to agricultural soils. The value of this approach
would have been to diminish much of the variation inherent in
using sludges from different sources, use an already established
data base and facilitate comparisons between responses of farm
and forest sites to application of a single sludge. The original
candidate sludge source was the City of Jackson wastewater
treatment facility.
Jackson, with a population of approximately 40,000, contains
a moderate industrial base which results in production of a
wastewater sludge containing moderately elevated levels of heavy
metals. The City staff have for numerous years conducted a
carefully monitored farm land application program which, despite
the presence of heavy metals, was recognized for a record of
productive achievements and protection of health and environment.
Liquid sludge from the Jackson facility was to be transported by
tank truck to application sites on State Forest land in northern
Lower Michigan.
14
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Technical Criteria
The principal project aims were to evaluate the wildlife,
hydrological, soil and vegetation responses following sludge
application in forest types of major commercial importance in
Michigan. Application rates indicated as environmentally safe
yet biologically productive in earlier Forest Service research
were also to be tested on a larger scale in these forests. The
forest types identified as being of major commercial value in
this region were aspen, oak, pine and northern hardwoods.
Michigan DNR staff sought to locate an area of State Forest
where these four forest types occurred in reasonably close
proximity to one another to minimize planning and logistical
problems. The types also needed to be located on sites meeting
the criteria for physical environment which would ensure adequate
protection for health and environment. In addition, the forest
stands had to be of a condition where they were free of disease
and insect infestation, fully stocked and competitively free to
grow. Special attention was paid to access road system
suitability and personal concerns of local residents.
By late 1980, MDNR staff completed an evaluation of State
Forest land, screening candidate sites with reference to numerous
technical criteria suiting them to the study objectives. This
assessment included examination of maps, aerial photographs and
actual field sites on four State Forests in consultation with
Forest Management Division staff. At this time, sites in eastern
Kalkaska County were identified as best meeting the biological,
physical and logistical criteria. In January 1981, site
preparation and the process of citizen involvement began.
Public Involvement
In early January 1981, MDNR staff brought before the Kalkaska
County Board of Commissioners a proposal for fertilizing State
Forest land in the eastern county with sludge from Jackson,
Michigan. The proposal was well received by commission members
and complimented as being visionary and sound in concept. Soon
after that meeting, an article appearing in an area newspaper
initiated a public reaction against the proposal.
In early February, MDNR staff presented the project proposal
at a public meeting attended by residents of Garfield, Oliver and
Bear Lake Townships in eastern Kalkaska County. Citizen reaction
15
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to the study was less than enthusiastic. Resident concerns ranged
from fears about toxicant levels potentially present in the sludge
to general indignation about not being personally consulted prior
to tentative site selection. Eastern Kalkaska .County had also
been in the 1970s a burial site for PBB contaminated cattle, an
activity conducted by MDNR over the objections of many area
residents.
After weeks of attending numerous township meetings, it
became clear that while many area residents favored or did not
oppose the forest land application project, the political fallout
from previous experience with MDNR programs was yet an overriding
factor in the decision of most local elected officials. Township
decision makers did not trust MDNR to act in their best interest.
The northward transport of downstate sludge was also perceived as
of no direct benefit to county residents. In keeping with our
promise to conduct the research-demonstration only in consenting
townships and counties, MDNR staff turned in late April to the
process of selecting an alternative location for the project.
By early May, northern Montmorency County had been
identified as an area which also contained forest stands meeting
the technical criteria for the study. In addition, a decision
was made to only utilize sludge generated at wastewater treatment
facilities (Alpena and Rogers City) in the locale. Contacts were
initiated through local MDNR offices with members of the
Northeastern Michigan Council of Governments (NEMCOG), Huron
Pines Resource Conservation and Development Council, Montmorency
Township*and Montmorency County Planning and Zoning Commission in
seeking support for conduct of the research-demonstration project.
Michigan DNR staff presented audio-visual discussions of previous
land application research, conducted field trips to research
sites where sludge had previously been applied to forests,
engaged in numerous informal discussions with area leaders and
sought local advice in specific site selection. By August,
formal resolutions of support were obtained from local governments
and citizen groups. The relationship of trust and confidence
developed between local authorities and MDNR staff was largely
responsible for acquisition of support for the project and
assistance in final site selection in Montmorency Township. The
circumspect approach of local groups and individuals to the
germaine environmental and resource management issues resulted in
prudent action and avoidance of devisive polarization.
16
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SITE DESCRIPTION
Sites selected on which to conduct the forest land
application research-demonstration project were located in v
northern Montmorency County on the Atlanta Forest Area (Figure 1)
of the Mackinaw State Forest in northeastern lower Michigan
(45°Nr84o10'W). Site characteristics are summarized in Table 1.
Vegetation on each site was representative of the upland forest
types of major commercial importance in the northern portion of
the state. Permeable glacial drift materials formed the parent
material for the soils, which are low in native fertility and
allow rapid infiltration of excess precipitation falling on all
four of the forest sites. Annual precipitation in this area
averages 766 mm (30 inches), with the equivalent of 160 mm (6.3
inches) incident as snow from late November to early April (NOAA
1982). The mean annual temperature is 5.8°C (42.4°F) with average
extremes of -7.4°C (18.7°F) in January and 19.6°C (67.3°F) in July
(NOAA 1981). The sites are underlain by a phreatic aquifer which
is contiguous with the regional groundwater system. Elevation is
approximately 300 m (985 ft) above sea level.
The aspen site was occupied by a 10-year-old stand of coppice
regeneration which was predominantly bigtooth aspen (Populus
grandidentata Michx.) containing a secondary component of quaking
aspen (Populus tremuloides Michx.), northern pin oak (Quercus
ellipsoidallis L.), cherry (Prunus spp. L.) and other species.
Soils on this site generally belonged to the Grayling series
(Spodic Udipsammet) and the Rubicon series (Entic Haplorthod).
Grayling soils are excessively drained and developed on deep
glacial outwash sands (Table 2). Rubicon soils are deep,
excessively drained and formed in sandy glacio-fluvial deposits.
Surface runoff from the site does not occur as a result of high
soil permeability. Surface emergence of groundwater occurs in the
lowlands along Tomahawk Creek to the northwest of the site. Depth
to groundwater at the study site was 5 to 8 m (16 to 26 feet).
Oak Site
The oak site was occupied by a 70-year-old stand that was a
mixture of red oak (Quercus rubra L.) and white oak (Quercus
alba L.) with red maple (Acer rubrum L.), scattered pines (Pinus
spjp^ L.) and aspen. The stand (Table 3) contained 868 trees/ha
17
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00
C/Upper
Tomahawk Lake
MONTMORENCY
COUNTY
Cranberry
Laker"
Lake
Flooding
Figure 1. Sludge fertilization sites in northern Michigan.
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Table 1. Characteristics of the aspen, oak, pine and northern hardwoods sites
(Hart and Nguyen 1986).
Characterist ic
Aspen
Oak
Pine
Northern Hardwoods
ID
Phys iography
Geologic
material
Groundwater
system
Predominant
soil series
Soil group
Forest floor
Ground flora
Overs tory
trees
Stand age
Level to gently
roll ing
Sandy outwash
over till
Groundwater at
5 to 8 m
Rub icon
s andy mixed ,
frigid entic
Haplorthod
Mull
Panic grass,
brambles, sedge,
sweetfern,
bracken fern
Mixed bigtooth
and quaking
aspen
10 years
Gently rolling
overwash
moraine
Sandy deposits
over loamy
till
Groundwater at
over 25 m
Graycalm
mixed, frigid
alf ic
Ud ipsamment
Mull
Bracken fern,
wintergreen,
asters, Canada
mayflower
Mixed oak and
red maple
70 years
Level plain
Sandy outwash
Groundwater at
4 to 8 m
Grayling
mixed, frig id
typ ic
Udipsamment
Mor
Sedges,
bearberry,
lichens
Mixed red and
jack pine
50 years
Gently rolling
ground moraine
Sandy and loamy
till
Groundwater at
1 to 16 m
Mancelona and
Melita
sandy mixed,
frigid alfic
Haplorthod
Mull
Starflower,
asters, violets,
Canada mayflower
Red and sugar
maple, yellow and
white birch, beech
and hemlock
50 years, uneven
age distribution
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Table 2. Soil survey legend of sludge fertilization study area
(Hart and Nguyen 1986).
Map Symbol Soil Series Soil Characteristics
Gy
Gy-b
Gr-b
Rb
Rb-s
Rb-b
Mt-w
Mt
Ma
Me
MO
Kw
Sm
Grayling
Grayling
Graycalm
Rubicon
Rubicon
Rubicon
Montcalm
Montcalm
Mancelona
Melita
Menominee
Kawkawlin
Sims
Excessively drained soil developed on
deep glacial outwash sands
Same as above, but with faint banding
in the C horizon
Somewhat excessively drained soil
formed in deep glacio-fluvial sands
Deep excessively drained soil formed
in glacio-fluvial sands
Same as above, but with Bn^r horizon
Same as above, but with sandy loam
bands below 140 cm (55 inches)
Well drained soil formed in sandy and
loamy glacio-fluvial upland deposits
Same as above, but with modal amounts
of sand and loam in the C horizon
Deep excessively drained soil in sandy
and gravelly glacio-fluvial uplands
Deep somewhat excessively drained soil
formed in sandy materials over loam
Well to moderately well drained soils
in sandy material overlying loam at
50 to 100 cm (20-40 inches)
Deep somewhat poorly drained soil
formed in moderately fine textured
glacial tills and ground moraines
Deep poorly and somewhat poorly
drained soil formed in fine textured
glacial tills and ground moraines
20
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Table 3. Pretreatment tree stocking, diameter and density at the
oak, pine and northern hardwood sites (Hart and Nguyen
1986).
Site and Species
Stocking
(trees/ha)
DBH
(cm)
Density
(m2/ha)
Oak site:
All species 868
Red/black oak 287
White oak 228
Red maple 302
Other species 51
Pine site:
All species 680
Jack pine 441
Red pine 225
Other species 14
Northern Hardwoods site:
All species 720
Sugar maple 353
Red maple 161
Other species 206
17.11
18.88
14.33
11.07
20.62
18.71
19.13
19.06
16.67
10.14
21.48
9.32
5.83
4.73
1.60
23.38
12.95
10.07
0.36
22.23
9.66
4.53
8.04
(351/acre) and an average combined basal area of more than
21 m2/ha (94 ft2/acre). Soils were predominantly of the
Graycalm series (Alfic Udipsamment) with smaller areas of the
Rubicon series. Graycalm soils are somewhat excessively drained
and formed in deep glacio-fluvial sands (Table 2). Surface
runoff from the site does not occur as a result of high soil
permeability. The site location on a high sandy morainal hill
prevented successful drilling to the water table. Depth to
groundwater at this study site was in excess of 30 m (97 ft).
21
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Pine Site
The pine site was occupied by a 50-year-old plantation that
was a mixture.of jack pine (Pinus banksiana Lamb.) and red pine
(Pinus resinosa Ait.). The stand (Table 3) contained 680 trees/ha
(275/acre) and an average combined basal area of over 23 m2/ha
(102 ft2/acre). Soils on the site were of the Grayling series
with a smaller area of the Montcalm series (Eutric Glossoboralf).
Montcalm soils are deep, well drained and formed in sandy and
loamy glacio-fluvial deposits (Table 2). Surface runoff does not
occur on this site because of its flat surface and highly
permeable soils. The water table beneath this site slopes
uniformly toward the east where groundwater emerges at Grass Lake
1 km (0.6 mile) away. Depth to groundwater at this study site
was 6 to 7 m (20 to 23 feet).
Northern Hardwoods Site
The northern hardwoods site was occupied by a 50-year-old
stand that was predominantly red maple and sugar maple (Acer
saccharum Marsh.) with remnants of American beech (Fagus
grandifolia Ehrh.), yellow birch (Betula alleghaniensis Britton)
and white birch (Betula papyrifera Marsh.) and a minor number of
red oak, American basswood (Tilia americana L.), white ash
(Fraxinus americana L.) and eastern hemlock (Tsuga canadensis
(L.) Carr.). The stand (Table 3) contained 720 trees/ha
(291/acre) and an average combined basal area exceeding 22 m2/ha
(97 ft2/acre). Soils were primarily Mancelona series, Melita
series and Menominee series (Alfic Haplorthods) with minor areas
of the Kawkawlin series (Aquic Eutroboralf) and Sims series
(Mollic Haplaquept). Mancelona soils are deep, excessively
drained and formed in sandy and gravelly glacio-fluvial upland
deposits (Table 2). Melita soils are deep, somewhat excessively
drained and formed in sandy materials overlying loamy deposits.
Menominee soils are moderately well to well drained and formed in
sandy material overlying loamy deposits at 50 to 100 cm (20 to 39
inches). Kawkawlin soils are deep, somewhat poorly drained and
formed in moderately fine-textured glacial tills and ground
moraines. Sims soils are deep, poorly to somewhat poorly drained
and formed in fine-textured glacial tills and ground moraines.
This study site is situated upon an area of relatively high
elevation which is underlain by loamy sands and clay layers of
low permeability. These materials cause periods of temporary
flooding during spring snowmelt when the water table is at or
near the soil surface and account for a groundwater gradient
22
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which slopes steeply to the west from the plots. Depth to
groundwater at this study site ranged from 1 to 15 m (3 to 49
feet).
SITE PREPARATION
Prior to land application of wastewater sludge, each study
site was prepared for treatment. The sequential steps in this
process consisted of plot layout, baseline measurements and
construction of access trails which would facilitate movement of
application vehicles about each site.
Experimental Design
Three,replications of three experimental treatments were
assigned to completely randomized plots within each study site.
The treatments consisted of (1) a control group of plots left
undisturbed, (2) a group that underwent access trail development
but received no sludge application and (3) a group that underwent
access trail development and received a single application of
liquid sludge. Experimental plots were each 1.5 ha (3.8 acres)
in area and of a rectangular shape approximately 100 m by 150 m
(328 by 492 feet). The study plots covered an area of 54 ha
(132 acres), of which 18 ha (44 acres) were treated with nearly
4 million liters (1 million gallons) of wastewater sludge. The
sludge application rate averaged 9 Mg of dry solids per ha
(4 tons/acre). The design was suited to evaluate large scale
operational procedures, equipment and costs while affording
adequate area for a diverse array of environmental research
studies (Brockway and Nguyen 1986).
Sampling and Measurements
Vegetation, forest floor and soil data collection was
facilitated by use of a series of subplots designed in accordance
with the ecological characteristics of each site (Hart and Nguyen
1986). Because of a lack of vegetation uniformity on the aspen
site, twelve paired plots were installed across a range of tree
heights and densities. Trees on each pair were assessed by
species, diameter at breast height (DBH; 1.37m; 4.5 feet), crown
class, condition, presence or absence of disease, total height,
ground level diameter (GLD; 15 cm; 6 inches) and biomass.
Sampling design for the oak, pine and northern hardwoods sites
23
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allowed evaluation of within plot thinning effects which might
result from access trail construction. On subplots within each
plot, trees greater than 10 cm (4 inches) DBH were assessed for
species, DBH, crown class and condition. From these data,
estimates of basal area, gross growth, mortality and net growth
were calculated. Similar measurements were collected for
saplings, defined as greater than 1.8 m (6 feet) tall and less
than 10 cm (4 inches) DBH. Seedlings, defined as commercial
species less than 1.8 m (6 feet) tall, were measured on 1 m2
(11 ft2) circular subplots. Ground vegetation, defined as
grasses, forbs, shrubs or noncommercial tree seedlings, was
measured,as percent cover on 2 m2 (43 ft2) circular
subplots. Foliar samples were collected from the upper sunlit
crown of overstory trees during the fall season prior to leaf
abscission to assess nutritional status and response to sludge
nutrients. Forest floor samples partitioned into 01 (litter) and
02 (humus) layers were collected along with surface and subsurface
soil samples on subplots in all stands. In 1981, 6300 trees were
measured and tagged, 176 tree crown foliar samples collected, 1080
forest floor, surface and subsurface soil samples collected, 858
regeneration plots measured and 858 ground cover plots measured.
Data from these analyses indicated that no significant differences
existed among the study plots at each site prior to sludge
application. Posttreatment sampling was continued annually.
Hydrological monitoring of the sites was accomplished
through installation of a well network supplemented by pressure-
vacuum lysimeters (Urie et al. 1986). Monitoring wells were
inserted into the upper strata of the phreatic aquifer following
drilling in unconsolidated glacial drift. The groundwater
gradients were determined from static water table measurements.
Lysimeters were installed at a depth of 120 cm (4 feet) in the
soil. Water samples collected from the lysimeters represented
dynamic changes in percolate as it moved through the plant
rooting zone. Groundwater samples from the wells represented an
integrated effect of all upgradient treatments. Samples were
collected each week during spring and fall recharge periods and
monthly during the summer and winter seasons.
Chemical analyses of water, soil, sludge and animal and
plant tissues were conducted at the USDA Forest Service-Michigan
State University Cooperative Analytical Laboratory in East
Lansing. Concentrations of total Kjeldahl nitrogen, nitrate,
ammonia, phosphorus, potassium, sodium, calcium, magnesium,
sulfate, chloride, manganese, iron, boron, zinc, copper, nickel,
chromium, cadmium, aluminum and other parameters were measured
24
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via Technicon autoanalyzer or plasma emission spectroscopy
following various digestion and extraction procedures (Hart and
Nguyen 1986, Urie et al. 1986, Haufler and Woodyard 1986, Haufler
and Campa 1986). Data were unavailable for lead because of
difficulty encountered with analytical equipment. However,
previous work has shown lead to be strongly held in upland soils
and less mobile than other heavy metals studied in these forest
ecosystems. Laboratory participation in the USEPA quality
assurance program ensured consistently high quality results from
sample analysis.
Numeric analysis of data was performed using several data
reduction software programs including Knowledgeman (Micro Data
Base Systems 1984), Number Cruncher Statistical Systems (Hintze
1986) and Microstat (Ecosoft 1984). Analysis of variance and
covariance, multiple regression analysis, non-parametric analysis
and principal components analysis were among the data analysis
techniques employed.
Wildlife studies were conducted both in the field and
laboratory (Haufler and Woodyard 1986, Haufler and Campa 1986).
Vegetation was examined to determine changes in habitat structure
and species growth, composition and nutritive value. Nutritional
properties of primary concern were fiber, crude protein and
phosphorus levels. Small mammal (rodent) populations were
monitored using baited live traps. Representative proportions of
these populations were sacrified to allow chemical analysis of
liver, kidney, humerus and leg muscle tissues. Three female
whitetail deer (Odocoileus virginianus Zimmermann) were
harvested from the sludge treated plots to allow chemical
analysis of their liver, kidney, heart and skeletal muscle.
In the laboratory, two food chain studies were conducted.
The first study grew rye grass (Lolium perenne) upon sludge
treated soil and pressed the forage into food pellets which were
fed to white-footed mice (Peromyscus leucopus) which were to be
fed to great horned owls (Bubo virginianus) and red-tailed hawks
(Buteo jamaicensis). The second study raised earthworms in
sludge amended soil for 30 to 90 days then fed them to woodcock
(Philohela minor) over a period of 30 days. Each bird consumed
approximately 10,000 worms during this period. In the laboratory
studies, unlike the field studies, sludge from the City of Detroit
was substituted for the sludge from Rogers City. Sludge from the
City of Alpena was used in the field and laboratory studies.
Animals at all trophic levels of the food chain studies were
sacrificed to allow chemical analysis of their liver, kidney,
25
-------
skeletal muscle and bone for accumulation of potential toxicants.
In addition to studies of the much emphasized physical
environment, the social environment in relation to public
acceptance of forest land application was also of prime importance
to the success of this technology. Previous experience in the
difficulties of siting land application projects underscored the
need for a better understanding of citizen values, beliefs and
attitudes. This effort was approached in two phases (Peyton and
Gigliotti 1986). In phase I, public opinion surveys were
developed and distributed to citizens selected at random within
stratified groups residing in seven selected counties in northern
Michigan. These survey instruments were accompanied by and
followed up with correspondence explaining the purpose of the
study, the importance of each individual's participation and use
to be made of the information. Responses on returned
questionnaires were tallied, interpreted and summarized. In
phase II, the responses from the surveys were used to develop
materials for public education and effective public participation
in the forest land application planning process. The public
education materials are factual summaries which provide the
public with accurate information concerning land application and
related sludge management alternatives. The public involvement
manual will provide sludge generators and land managers with a
clear understanding of their responsibilities in promoting
constructive public participation and enlisting citizen support
for local sludge management programs.
Access and Treatment
Prior to sludge application, a grid of parallel trails at
20 m (66 feet) intervals was prepared to facilitate application
vehicle access and more uniform sludge distribution (Brockway
and Nguyen 1986). The spacing interval for access trails was
dictated by the maximum spray distance of the application vehicle
and resulted in removal of 20 percent of the stand volume. Had
equipment capable of discharging greater distances been available
as in the Pacific Northwest studies (Henry and Cole 1983) and
existing access used, little or no stand area would have been
removed from production. Trees harvested from oak, pine and
northern hardwoods sites were felled and removed as whole trees
from the stand using a rubber-tired skidder. Because of their
small unmerchantable size, trees on the aspen site were removed
at the groundline with a bulldozer blade. Chenonquet Consulting
Foresters of Hillman, Michigan worked in close cooperation with
26
-------
MDNR staff to complete this task.
Anaerobically digested sludges from the municipal wastewater
treatment facilities in Alpena and Rogers City were transported by
tank truck to the demonstration sites/ where single applications
of liquid were sprayed on the forest floor. Applications were
conducted in October and November 1981 on the oak and aspen sites
and in June and July 1982 on the pine and northern hardwoods
sites. An all-terrain vehicle, equipped with high flotation
tires, a standard pressure-vacuum pump and a modified three
nozzle spray system, was used for sludge application on each site
(Figures 2, 3, 4, 5). Sludge Management Corporation of
Washington, Michigan conducted both the transport and application
of sludge on all sites.
LOGISTICS AND ECONOMICS
Site preparation to provide vehicle access in the stand is a
major initial consideration in planning a forest land application
program for wastewater sludge. If stands consist of young,
unmerchantable age classes, site access may need be developed at
a net cost to the land manager. Such was the case with the aspen
coppice stand, in which trails were cleared at a cost of $1,485
($163.91/ha or $66.36/acre) using a bulldozer. In contrast, a
net income may be generated by harvest of timber growing in
proposed access trails when trees are of sufficient size and
quality. Following development of access trails on the pine, oak
and northern hardwoods sites, net respective returns from sale of
timber were $340 ($37.53/ha or $15.19/acre), $158 ($17.44/ha or
$7.06/acre) and $140 ($15.45/ha or $6.26/acre). Where the
services of consulting foresters were required in site
preparation, a rate of $21 per hour resulted in a total fee of
$3,973 ($109.63/ha or $44.38/acre) for the project.
Using one 32,000 liter (8,500 gallon) and two 23,000 liter
(6,000 gallon) tank trucks, sludge was transported from the
municipal wastewater treatment plants at Rogers City and Alpena,
a distance of 80 km (50 miles) to each of the forest sites.
Loading time at each treatment plant varied from 45 to 60 minutes
for each truck and one-way transport time on the highway was
approximately one hour. Onsite unloading for each truck ranged
from 30 to 40 mimutes, resulting in-a total delivery cycle of
three to four hours per load. During a working day without
mishap, each truck could complete three to four deliveries. More
27
-------
Figure 2. Sludge application on aspen site,
Figure 3. Sludge application on oak site,
28
-------
Figure 4. Sludge application on pine site.
Figure 5. Sludge application on northern hardwoods site,
29
-------
typically, because of operational delays, daily sludge delivery
rates averaged 147,615 liters (39,259 gallons) requiring a travel
distance of 950 km (590 miles) and 18 man-hours during the 26
days on which sludge was transported.
Sludge application was conducted using an Ag-Gator 2004,
manufactured by the Ag Chem Equipment Company of Minneapolis,
Minnesota. This application vehicle was equipped with high
flotation tires and a standard pressure-vacuum pump that was used
to fill and empty its 8,300 liter (2,200 gallon) tank. Liquid
sludge could be laterally discharged distances up to 10 m
(33 feet) from one side of the vehicle through a modified spray
system of three nozzles arranged to evenly cover near,
intermediate and distant bands of the forest floor. This system
can apply sludges approaching 12 percent solids, but was used
here to apply liquids containing only 2.6 to 5.1 percent solids.
Contractual costs for transport and application of 3,679,311
liters (972,074 gallons) of liquid sludge totaled $48,576
($303.52 per Mg or $275.94 per dry ton). This amount was equally
apportioned by the contractor for transportation, application and
administration (Table 4). Had this procedure been a sludge
reapplication to a previously treated site, the contractor
estimated a reapportionment of costs to 40% for transportation
and 30% each for application and administration. The resultant
lower total cost would be a product of less time needed in
planning and greater efficiency in reapplication based on
previous onsite experience.
While trafficability was satisfactory on most forest sites,
pit and mound microtopography and high stumps remaining in trails
at the completion of whole-tree skidding on the northern hardwoods
site complicated application vehicle operation. Stumps caused
the puncture of one high flotation tire and the generally rough
terrain contributed to the eventual rupture of the hydraulic unit
on the articulated steering mechanism of the application vehicle.
Repair costs for these breakdowns totaled $4,070.
The cost of initial sludge transport and application to the
four forest sites averaged 1.3 cents per liter (4.8 cents per
gallon). If the expenditures for equipment repair are added, the
total unit cost increases to 1.4 cents per liter (5.2 cents per
gallon). When care in site selection, stand preparation and
equipment operation are exercised, this cost increment for repairs
can be minimized. If the expenditures for site preparation and
service of consulting foresters are also added, the total unit
30
-------
Table 4. Contractor cost breakdown for transportation and
application (Brockway and Nguyen 1986).
Initial Application Subsequent Applications
Transportation $16,515.84 $16,515.84
Labor 1,651.58 1,651.58
Equipment 11,561.09 11,561.09
Fuel 3,303.17 3,303.17
Application 16,030.08 12,144.00
Labor
Equipment
Fuel
Administration
Totals
1,603.01
12,824.06
1,603.01
16,030.08
$48,576.00
1,214.40
9,715.20
1,214.40
12,144.00
$40,803.84
cost increases to 1.5 cents per liter (5.6 cents per gallon) of
sludge applied. When care is taken to select sites containing
merchantable timber that will be harvested and sold in the course
of developing access trails, this cost increase can also be
abated. Had the procedure been a sludge reapplication to forest
sites receiving periodic operational use, the total unit cost
estimate would have approximated 1.1 cents per liter (4.1 cents
per gallon).
These costs are comparable to those for sludge transport and
application to farm land. Because the expenditures reported are
for a research-demonstration project established to meet precise
scientific criteria, the forest sites were located 80 km
(50 miles) from the sludge source. Typical haul distances for
operational sludge fertilization programs would more likely
approximate 16 to 32 km (10 to 20 miles), proportionally reducing
transportation costs. This decrease in program costs below those
quoted above would make sludge application to forest land a
highly attractive alternative.
31
-------
Table 5. Assignment of cooperator benefits and costs.
Costs normally incurred by generator $52,646.00
Sludge transportation 16,515.84
Sludge application 16,030.08
Equipment repair 4,070.00
Costs normally incurred by land manager 5,458.00
Access trail development 1,485.00
Consulting forester fees 3,973.00
Value received by land manager 8,010.48
Sale of timber from access trails 638.00
Fertilizer value of sludge nutrients 7,372.48
Return from increased timber growth not estimated
Net value to land manager $ 2,552.48
Benefit-cost ratio 1.47
Further, the costs related to creating stand access trails
and those for repairing equipment subject to travel over stumps
could be eliminated by careful planning during the establishment
of a plantation scheduled to receive fertilizing applications of
sludge at some future time. This could be accomplished by
leaving one pair of unplanted seedling rows at 20 m (66 feet)
intervals when a forest site is planted. The resultant system
of parallel access trails would enable the stand to easily
accommodate sludge application vehicles in the future and
facilitate entry for intermediate silvicultural operations
throughout the rotation.
The above analysis may be somewhat misleading from the
standpoint of which parties normally bear which costs and derive
which benefits from operational land application programs. Costs
attributed to sludge transportation, application and equipment
repair are typically assumed by the industry or municipality
generating the waste byproduct (Table 5). These expenses are
paid by the generator, in the course of selecting the least cost
32
-------
alternative for sludge management, as a portion of facility
operation and maintenance. Costs incurred by the land manager
are typically for site preparation services required to assist in
access trail development. Benefits received by the land owner or
manager include revenues from timber sold during trail
construction, fertilizer value of sludge nutrients, improved
quality of wildlife habitat and increased timber productivity
which leads to greater revenue return when the stand is harvested.
The average value of the nutrients and trace elements contained
in these sludges was $46.07 per Mg ($41.88/ton), which provided
a value addition of $406.87 per ha ($164.72/acre). Full scale
operational forest land application programs would likely benefit
the land manager with an even more favorable benefit-cost ratio
than the 1.47 value estimated for this research-demonstration
project with its numerous special constraints.
SLUDGE APPLICATION
Liquid sludges from the wastewater treatment facilities in
Rogers City and Alpena were applied to the forest floor of the
aspen, oak, pine and northern hardwoods sites in northern
Montmorency County (Brockway and Nguyen 1986). These cities have
very light industrial input into each municipal waste stream.
Liquid sludges from Detroit and Alpena were applied to soils in
laboratory food chain experiments conducted at Michigan State
University. Detroit is widely known for its heavily developed
industrial base and has been long thought to generate sludge with
high levels of heavy metals and related contaminants.
SLUDGE COMPOSITION
The relative concentrations of macronutrients (N, P, K, Ca,
Mg), micronutrients (Na, B, Al, Fe, Mn, Zn, Cu) and heavy metals
(Zn, Cu, Ni, Cr, Cd) in the sludges applied to the four forest
sites are shown in Table 6. Sludges from Alpena and Rogers City
were both rich sources of nitrogen, phosphorus and calcium.
Other macronutrients and micronutrients were present at modest
levels. Concentrations of heavy metals were relatively low and
typical for sludge produced in cities with low levels of industry.
Because of the relatively low levels of potentially toxic
metals found in the sludges from Rogers City and Alpena, sludge
from the City of Detroit wastewater treatment facility was used
33
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Table 6. Average chemical concentrations in sludges applied on
forest sites (Hart and Nguyen 1986).
Element
AspenJ
Oak'
Oak-
Pine4 Northern Hardwoods5
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sodium
Boron
Aluminum
Iron
Manganese
Zinc
Copper
Nickel
Chromium
Cadmium
53,040
28,080
2,733
41,902
4,452
3,151
44
30,514
55,942
706
1,234
571
43
182
28
32,490
32,490
2,389
86,321
5,763
2,334
4
19,733
56,379
1,073
1,119
434
42
109
8
rag/
71,840
35,920
3,040
64,521
7,150
4,263
122
16,164
68,113
431
1,201
1,221
36
102
115
Kg
45,840
30,560
2,685
45,534
4,053
3,648
86
16,808
61,044
417
932
516
43
106
60
85,140
41,580
1,295
55,064
5,445
2,028
30
8,732
50,846
182
942
597
23
64
8
1Alpena sludge, October 1981
2Alpena sludge, November 1981 (plot 1)
^Rogers City sludge, November 1981 (plots 5 and 7)
4Alpena sludge, June 1982
^Rogers City sludge, July 1982
in the laboratory food chain studies in hopes of testing the
biomagnification potential of heavy metals in sludge from a
heavily industrialized source. A comparative chemical analysis
of the metal concentrations of Detroit sludge, Alpena Sludge and
a commercially available fertilizer (12%N-12%P-12%K) was
surprisingly revealing. The comparison showed that, while both
sludges contained higher levels of heavy metals than the
commercial fertilizer, the heavy metal concentrations in the
Detroit wastewater sludge were not substantially different from
those in the Alpena sludge (Table 7).
34
-------
Table 7. Heavy metal concentrations in commercial fertilizer and
wastewater sludges from Alpena and Detroit (Haufler and
Woodyard 1986).
Metal
Cadmium
Chromium
Copper
Nickel
Zinc
Fertilizer
3.2
24.0
115
5.6
401
Alpena
/i-
- -mg/Kg
7.5
48.8
1230
36.3
1125
Detroit
13.0
139
527
9.8
1718
SLUDGE LOADING AND DISTRIBUTION
Because of the variation in site characteristics, such as
microtopography and vegetation structure, and that encountered
in operation of application equipment, such as vehicle speed,
discharge rate and tank pressure, a substantial amount of
variation in solids, nutrient and trace element loading can be
anticipated on any sludge treated forest site. An overall
assessment indicated that this variation in loading and
distribution of sludge constituents was less than expected
(Table 8).
The aspen site was treated with 1,112,878 liters (294,023
gallons) of Alpena wastewater sludge. The average dry solids
content of the material was 3.2%, resulting in a mean sludge
loading rate of approximately 10 Mg/ha (4.5 tons/acre). The
loading rates of nutrients and trace elements were computed from
data on area of application, volume of sludge applied and
chemical analysis of sludge samples collected during the
application period. Loading rates for nitrogen and phosphorus
averaged 561 and 291 kg/ha (500 and 260 Ibs/acre), respectively.
Differences in loading rates for most major elements were
generally not statistically significant among plots.
35
-------
Table 8. Solids, nutrient and trace element loading on forest
sites (Brockway and Nguyen 1986).
Constituent
Solids
Nitrogen
Phosphorus
Potassium
Magnesium
Calcium
Sodium
Aluminum
Iron
Manganese
Copper
Zinc
Cadmium
Boron
Nickel
Chromium
Aspen
9,980
560.0
290.5
26.21
44.36
418.0
31.45
304.0
557.2
7.04
5.68
12.29
0.28
0.44
0.42
1.81
Oak
8,019
400.6
272.1
21.35
50.89
619.0
25.21
146.3
491.7
6.44
6.13
9.25
0.42
0.43
0.31
0.85
Pine Northern Hardwoods
— IT/-I /Via — —
n*^f lid
8,119
379.4
252.9
22.12
32.25
373.5
30.18
137.8
500.9
3.80
4.22
7.61
0.36
0.71
0.35
0.86
9,210
783.1
383.7
11.89
49.84
503.0
18.57
79.8
456.9
1.66
10.82
8.60
0.08
0.27
0.21
0.58
The oak site was treated with 264,971 liters (70,006 gallons)
of wastewater sludge from Alpena (plot 1) and 514,801 liters
(136,011 gallons) of wastewater sludge from Rogers City (plots 5
and 7). The average dry solids content of these materials was
3.4%, resulting in a mean sludge loading rate of approximately
8 Mg/ha (3.6 tons/acre). Plot 1 received the highest application
rate of 14 Mg/ha (6.2 tons/acre). Over the entire site, the
nitrogen loading rate averaged 401 kg/ha (358 Ibs/acre), while
that for phosphorus was 272 kg/ha (243 Ibs/acre). Nutrient
loadings for plot 1 were much higher than those for other plots.
Because of the different chemical characteristics of the two
sludges, significant differences were found between plot 1 and
plots 5 and 7 for most major elements, except nitrogen, copper
and boron.
36
-------
The pine site was treated with 1,112,878 liters (294,023
gallons) of Alpena wastewater sludge. The average dry solids
content was 2.6%, resulting in a mean sludge loading rate of
approximately 8 Mg/ha (3.6 tons/acre). The nitrogen loading rate
averaged 379 kg/ha (338 Ibs/acre) and that of phosphorus 253
kg/ha (226 Ibs/acre). Differences in the loading rates of most
elements were generally not statistically significant among plots.
The northern hardwoods site was treated with 673,783 liters
(178,014 gallons) of Rogers City wastewater sludge. The average
dry solids content was 5.1%, resulting in a mean sludge loading
rate of approximately 9 Mg/ha (4 tons/acre). Because of the
higher solids content of this sludge, nutrient additions to these
plots were higher than those on other sites. The nitrogen
loading rate averaged 783 kg/ha (699 Ibs/acre) and that of
phosphorus 384 kg/ha (343 Ibs/acre). Trace element additions
were lower on this site than on the other sites. Differences in
the loading rates of nutrients and trace elements were not
statistically significant among plots.
LABORATORY FOOD CHAIN STUDIES
In a study of a soil-plant-small mammal-raptor food chain,
sludges were manually applied to potted soils in a greenhouse
environment (Haufler and Woodyard 1986). Nitrogen application
rates for the Alpena and Detroit sludges were 584 kg/ha
(522 Ibs/acre) and 739 kg/ha (660 Ibs/acre), respectively.
Commercial fertilizer (12%N,12%P,12%K) was also applied as a
reference treatment using 600 kg N/ha (536 Ibs N/acre).
In the soil-macroinvertebrate detritivore-vertebrate
insectivore food chain study, Alpena and Detroit sludges were
mixed with soil in a 7:10 ratio to a depth of 7 cm (2.8 inches).
Commercial fertilizer was also mixed with soil as a test
comparison. The relative metal concentrations of these mixtures
indicated that significantly more metal was present in the soil
as a result of sludge addition (Table 9).
37
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Table 9. Heavy metal concentrations in greenhouse soils amended
with sludge or commercial fertilizer (Haufler and
Woodyard 1986).
Element Fertilizer Alpena Sludge Detroit Sludge
Zinc
Copper
Chromium
Nickel
Cadmium
78a
15. 2a
48. 8a
20. 6a
1.63a
mg/Kg - -
287b
41. 6b
56. 5b
24. 8b
3.73b
327b
34. 4b
58. Ob
19. Sab
4.50b
Means in the same row followed by the same letter are not
significantly different at the 0.1 level.
ENVIRONMENTAL STUDY RESULTS
Earlier studies in Michigan (Brockway 1983, Urie et al.
1984) and related studies in northeastern (Koterba et al. 1979),
southern (Richter et al. 1982, Wells et al. 1984) and western
(Bledsoe 1981, Henry and Cole 1983, Zasoski et al. 1983) forests
have shown a variety of changes in the ecosystem as a result of
sludge nutrient additions. Increased tree growth and improved
nutritional quality of wildlife forage plants were among the
benefits. Enrichment of groundwater with nitrate-nitrogen and
heavy metal biomagnification in the food chain may be potential
risks (Sidle and Kardos 1979, Brockway and Urie 1983, Zasoski et
al. 1984, Cole et al. 1986). Investigators working on this
research-demonstration project examined these processes and
related ecosystem dynamics.
FOREST VEGETATION
Plants present in the forest environment are often limited
in their growth by low levels of native nutrients. As such,
forest vegetation is a primary beneficiary of sludge applied
nutrients and organic matter. Woody vegetation is also likely to
assimilate and immobilize substantial quantities of trace
elements, effectively removing them from cycling in the ecosystem
for extended periods.
38
-------
Tree Foliar Nutrition
Sludge applied nitrogen and phosphorus were rapidly taken up
by aspen. Statistically significant increases in foliar N and P
were measured on the aspen site by the 1982 season and persisted
through the 1984 growing season (Table 10). On the oak site,
applied sludge nutrients did not cause increased levels of foliar
N and P in red oak and white oak (Table 11). The diminished
effect of sludge on this site was thought to be a result of
higher native nutrient levels. Sludge applied N and P were
rapidly taken up by jack pine and red pine trees. Significant
increases of foliar N and P measured in the pine were likely a
result of nutrient deficiency prior to treatment (Table 12).
Generally sludge applied nutrients were rapidly assimilated on
the forest sites and should accumulate in the standing vegetation
biomass. Responses from application continued through 1984 and
were.anticipated to persist for several years until the nutrients
became immobilized in woody plant tissue with its slower nutrient
cycling rate (Hart and Nguyen 1986).
Table 10. Aspen foliar nutrient concentrations resulting from
sludge application (Hart and Nguyen 1986).
Nitrogen Phosphorus
Year Control Treated Control Treated
1981
1982
1983
1984
l.SOa
1.97a
1.91a
2.04a
1.94b
2.40b
2.61b
2.43b
0.20a
0.21a
0.20a
0.20a
0.21a
0.22b
0.26b
0.23b
Means of the same element in the same row followed by the same
letter are not significantly different at the 0.05 level.
39
-------
Table 11. Red oak and white oak foliar nutrient concentrations
following sludge application (Hart and Nguyen 1986).
Red oak:
Nitrogen
Phosphorus
White oak:
Nitrogen
Phosphorus
Pretreatment Control Treated
1981 1984 1984
2.02 2.36a 2.35a
0.24 0.22a 0.24a
2.12 2.27a 2.38a
0.28 0.25a 0.25a
Means in the same row followed by the same letter are not
significantly different at the 0.05 level.
Table 12. Jack pine and red pine foliar concentrations following
sludge application {Hart and Nguyen 1986).
Jack pine:
Nitrogen
Phosphorus
Red pine:
Nitrogen
Phosphorus
Pretreatment Control Treated
1981 1984 1984
1.09 0.90a 1.47b
0.17 0.14a 0.16b
0.96 0.94a 1.13b
0.17 0.13a 0.14b
Means in the same row followed by the same letter are not
significantly different at the 0.05 level.
40
-------
Short Term Tree Growth
Over the four year post-treatment period on the aspen site,
ground level diameter (GLD) of trees increased 23%, from 9.31 mm
for controls to 11.41 mm for sludge treated aspen (Figure 6).
Over the same period a 48% increase in aspen basal area from
5.71 m2/ha (24.8 ft2/acre) to 7.75 m2/ha (33.7 ft2/acre) was
measured for control and treated groups, respectively (Figure 7).
Aspen biomass production increased 57% from 8.46 kg/m2 (37.7
tons/acre) for controls to 13.27 kg/m2 (59.1 tons/acre) for
sludge treated trees (Figure 8). As of 1985, no decline in this
response was observed (Hart and Nguyen 1986).
Significant increases in tree diameter (DBH) growth occurred
on the oak, pine and northern hardwoods sites between 1981 and
1985 as a result of access trail construction (thinning effect)
and sludge application (Table 13). On each site, the diameter
growth differentials between the control and sludge treated
groups were significant for the 1981-84 period. A similar
pattern of response was observed for basal area increases
resulting from treatment. The overall relative proportion of
these increases attributed to access trail construction was 24.5%
and sludge application was 20.4%, resulting in an average total
gain of 49.6% from the complete forest land application treatment
(Table 14). Diameter (48 to 78%) and basal area (36 to 56%)
growth responses reported here were similar to those of 40 to 60%
measured in high yielding Douglas-fir stands of the Pacific
Northwest (Zasoski et al. 1983).
Long Term Tree Growth
Levels of site nitrogen and phosphorus were related to
indices of stand growth on the oak site using multiple regression
analysis (Merkel et al. 1986). The resultant equation accounted
for 69% of the variability between stand growth and site nutrient
levels. Measurements from 29 oak stands in Manistee, Wexford,
Mason and Lake Counties were included in the analysis to serve as
a representative data base for untreated sites. Based upon the
site nutrient levels present as a result of sludge application, a
growth increase of 29% from 3.57 m3/ha/yr (51.1 ft3/ac/yr) for
control stands to 4.62 m3/ha/yr (66.1 ft^/ac/yr) for sludge
treated stands was predicted. This estimate closely corresponds
to the 21% basal area increase measured during the initial four
years following stand fertilization with sludge. Current
increases in stand growth from a single application are
anticipated to become statistically nonsignificant by 1990.
41
-------
N)
E
a
az
CD
a
CD
12.0
10.5
9.0
7.5
6.0
4.5
3.0
1.5
0.0
84-85
83-84
82-83
81-82
CONTROL
SLUDGE
Figure 6. Diameter growth responses of trees at the aspen site
(Hart and Nguyen 1986).
-------
to
9.0-1
8.0-
_ 7.0-
lo
^ G.O-
(M
Jg 5.0-
| 4.0-
a —
oc 3.0 -
LD
S 2.0-
1.0-
0.0-
oogg
W8
i
«
»
>
>
»
i
i
N
•
HI
* *
a E
1
1
S '84-85
§ 83-84
p
S 82-83
M 81-82
CONTROL
SLUDGE
Figure 7. Basal area growth responses of trees at the aspen site
(Hart and Nguyen 1986).
-------
CD
,
a
DC
en
en
15.0
13.5
12.0
10.5
3.0
7.5
6.0 -
3.0
1.5
0.0
84-85
83-84
82-83
81-82
CONTROL
SLUDGE
Figure 8. Biomass growth responses of trees at the aspen site
(Hart and Nguyen 1986).
-------
Table 13. Tree diameter growth at the oak, pine and northern
hardwoods sites (Hart and Nguyen 1986).
Year
DBH
Diameter Growth
Control Trails
cm
Sludge
Oak site:
1981
1982
1983
1984
1981-84
17.11
17.36
17.78
17.96
0.22a
0.30a
O.lla
0.63a
0.22a
0.41b
0.18b
O.Slb
0.32b
0.56c
0.24c
1.12c
Pine site:
1981
1982
1984
1981-84
20.62
20.82
21.48
0.24a
0.52a
0.76a
0.17b
0.71b
0.87ab
O.lSab
0.76b
0.95b
Northern hardwoods site:
1981
1982
1984
1981-84
19.06
19.35
20.12
0.29a
0.60a
0.88a
0.20a
0.75a
I.Ola
0.32a
0.98b
1.30b
Means in the same row followed by the same letter are not
significantly different at the 0.05 level.
Table 14. Basal area response factor summary for oak, pine and
northern hardwoods (Hart and Nguyen 1986).
Basal Area Increase
Trail Construction Sludge Application Combined
Oak
Pine
Northern hardwoods
Mean
29.3
26.6
ods 17.7
24.5
— ^ — — — — —
21.0
7.7
32.6
20.4
56.4
36.3
56.0
49.6
45
-------
However, successive sludge applications could maintain site
fertility at a higher level and ultimately lead to greater stand
productivity (Figure 9).
Tree Mortality
Aspen mortality following sludge application was reported at
14.5% for the control group and 41.4% for the treated group
(Table 15). The increased mortality was not a direct result of
sludge application, but rather the interaction of several factors
which predisposed quaking aspen and especially bigtooth aspen to
infection by Armellaria, Fusarium and Cytospora fungi that
naturally occur in this area. The construction of site access
trails in an east-west direction left the stem bark of young
aspen trees exposed to direct sunlight for long periods during
the day. This exposure often resulted in sunscald injury and
points of entry for infecting fungi. The increased nutrient
levels in aspen plant tissues resulting from sludge treatment
enhanced the palatability of leaves. Elk (Cervus canadensis
Erxleben) often damaged stems as they attempted to browse on this
highly desirable forage. Such injury created a major pathway for
fungal infection. Finally, the nitrogen in the sludge may have
prolonged the growing season for young trees, thereby
predisposing them to winter injury (Hart et al. 1986).
Substantial mortality occurred on the pine site across all
plots. This was a result of the normal suppression of saplings
which is typical of dry sites. No significant mortality
increases were observed on the oak or northern hardwoods sites.
Tree mortality, as reported above for aspen, might serve as an
economic disincentive for the land manager were it a likely
outcome of sludge application. However, such would be a very
rare occurance when good forest management practices are
otherwise followed.
Understory Vegetation
On the aspen site seedling regeneration and groundcover
vegetation were unaffected by sludge application (Hart and Nguyen
1986). However, some undergrowth suppression may have begun as
tree growth increased following sludge fertilization. Saplings
on the oak site increased significantly in number and basal area
following treatment; however, those on the pine and northern
hardwoods sites were unaffected. Seedling regeneration increased
46
-------
..••••' ..... o
•"
-A
A
i
C
»
B
Broken line indicates extrapolated prediction
•O
•O
•A
-e
8
Years from initial application
Figure 9. Hypothetical mean annual increment (MAI) curve for oak
showing growth resulting at (A) high, (B) low and (C)
moderate rates of nutrient retention (Merkel et al. 1986)
-------
Table 15. Aspen stocking and mortality (Hart and Nguyen 1986)
Year
Stocking Mortality
Control Treated Control Treated
1981
1982
1983
1984
1985
1981-85
9106
8923
8373
8206
7789
"
ere
9733
7633
6550
6161
5700
"•
es/na
183a
550a
167a
417a
1317a
2100b
1083b
389b
461a
4033b
Means in the same row followed by the same letter are not
significantly different at the 0.1 level.
on the oak and northern hardwoods sites, but these changes were
statistically nonsignificant. Increases in cover of grasses,
sedge, forbs and shrubs on the oak and northern hardwoods sites
were unrelated to sludge application. Grass and sedge cover on
the pine site increased while forb cover decreased, possibly
accounting for no increase in seedling regeneration there.
Overall understory changes related to sludge application were
minimal.
FOREST FLOOR AND SOIL
The forest floor (01 and 02 horizons) is the first ecosystem
component where the impact of sludge application is manifest
(Brockway 1983). It is believed to be the major repository for
applied nutrients and trace elements. These elements, if not
directly taken up by plants, may then enter the soil beneath the
forest floor through leaching and humus incorporation.
Forest Floor Weight
The initial effect of sludge application in the forest was
to increase the weight of the forest floor on each site, a result
of solids loading (Hart and Nguyen 1986). The 01 horizon on the
aspen site increased from 1453 kg/ha (1295 Ibs/acre) to 4348 kg/ha
48
-------
(3874 Ibs/acre). However, the 02 horizon decreased in weight
3000 kg/ha (2673 Ibs/acre) as a result of increased micrpbial
decomposition following fertilization. Over the subsequent three
years, forest floor weight on this site progressively increased
from increasing rates of dry matter production and recycling.
The 02 horizon comprised approximately 95% of the total forest
floor mass.
Forest floor weight on the oak site was initially increased
from 43 Mg/ha (19 tons/acre) to 56.6 Mg/ha (25.2 tons/acre) by
sludge application. Pine site forest floor horizons were
increased in weight from 31.2 Mg/ha (13.9 ton acre) to 41 Mg/ha
(18.3 tons/acre). Forest floor on the northern hardwoods site
was decreased by decomposition following application, but this
weight loss was not statistically significant.
Chemical Composition
On all sites fertilized with wastewater sludge, forest floor
nutrient and trace element levels increased in proportion to the
application rate (Hart and Nguyen 1986). Significant increases
in the 01 and 02 horizons were noted for several elements and
many of these differences persisted throughout the study period
(Table 16). The total amount of heavy metals present in the
forest floor was quite small, despite the relative differences
between control and treated plots. The 02 horizon was the major
repository for nutrients and trace elements.
Very little change was observed in the chemical composition
of surface and subsurface soils. Within the first year following
treatment on the aspen site, small increases in phosphorus and
sodium concentrations were measured in surface soils. By 1984
these levels declined to near background. Calcium and iron
concentrations did increase in the surface soil of the oak site
and calcium, magnesium and iron increased on the pine site
following sludge application. Chemical changes in the subsurface
soils on all sites were minor or absent.
Element Retention
Three years after sludge treatment, the forest floor on the
aspen site generally retained more than 50% of the applied
macronutrients, micronutrients and heavy metals, except calcium
and cadmium (Table 17). The oak forest floor retained less than
49
-------
Table 16. Nutrient and trace element content of the forest
floor, 1984 (Hart and Nguyen 1986).
Oak Site Pine Site Northern Hardwoods Site
Element Control Treated Control Treated Control Treated
• — — — ——kg/ha
01 horizon:
K
Ca
Mg
Na
Al
Fe
Mn
Cu
Zn
Cd
Ni
Cr
02 horizon:
6.4a
92. 7a
6. la
0.7a
3.7a
3.7a
15. 2a
0.06a
0.36a
0.006a
0.014a
0.012a
9.3a
136. 2a
9.9a
1.3a
14. 7a
67. 2c
21. 2a
0.59b
1.43b
0.022b
0.048a
O.lOOa
2.62a
28.85a
3.64a
0.24a
4.93a
3.04a
4.97a
0.04a
0.30a
O.Ola
0.02a
O.Ola
4.31b
43.95a
5.85b
0.28a
9.66b
33.25b
6.45a
0.22b
0.78b
O.Ola
0.03a
0.05b
6.29a
116. 95a
9.16a
O.SOa
3.72a
13.95a
6.84a
0.25a
0.46a
O.OlOa
0.017a
0.020a
6.80a
121. 40a
10.14a
0.52a
5.35a
38.50b
3.72b
0.74b
0.75a
O.Olla
0.021a
0.037b
K
Ca
Mg
Na
Al
Fe
Mn
Cu
Zn
Cd
Ni
Cr
36. 9a
261. la
48. 8a
5.2a
117. Oa
175. 6a
136. Oa
0.6a
3.8a
0.15a
0.31a
0.28a
43. 6a
590. 5a
73. 5b
7.0a
202. 5b
661. 9b
207. 7a
4.6b
10. 9b
0.26b
0.55b
0.92b
7.48a
47.80a
24.60a
1.22a
42.50a
37.50a
12.90a
0.13a
0.97a
0.04a
O.lOa
0.07a
14.72b
161. lOb
48.10b
2.00a
101. 20b
342. OOb
20.40a
1.99b
5.25b
O.OSb
0.29b
0.48b
54.00a
628. OOa
122. OOa
6.02a
214. OOa
236. 80a
181. OOa
0.68a
6.18a
0.24a
0.42a
0.39a
60. OOa
1169. OOa
188. OOa
7.64a
260. OOa
972. OOb
232. OOa
14.66b
18.36b
0.55b
0.72a
0.99b
Means in the same row and on the same site followed by the same
letter are not significantly different at the 0.05 level.
50
-------
Table 17. Forest floor retention of applied elements, 1984 (Hart
and Nguyen 1986).
Element Aspen Oak Pine Northern Hardwoods
Nitrogen
Phosphorus
Potassium
Calcium
Magnesium
Sodium
Aluminum
Iron
Manganese
Zinc
Copper
Cadmium
Nickel
Chromium
-
82
25
84
-
50
73
356
68
53
41
87
68
44
18
38
47
52
9
61
110
-
87
74
29
84
85
-
32
34
74
-
39
65
229
70
48
11
46
50
^
—
28
62
135
18
108
178
-
142
129
400
167
114
50% of the applied macronutrients but more than 50% of the
micronutrients and heavy metals, except cadmium. The forest
floor of the pine site retained less than 50% of the applied
macronutrients and approximately 50% of the micronutrients and
heavy metals, except cadmium. The northern hardwoods forest
floor retained more than 50% of all elements, except potassium
and sodium, which are very mobile (Hart and Nguyen 1986).
Because the forest floor, specifically the 02 horizon, acts
as the main reservoir for nutrients and trace elements, the
degree to which elements are retained has major management
implications concerning their availability for plant uptake and
leaching to groundwater. Elements with higher retention in the
forest floor are likely less mobile and therefore less problematic
in managing sites in an environmentally safe manner. Of those
elements showing generally lower retention, cadmium was thought to
have greatest potential as an environmental hazard through food
chain biomagnif ication. As few nutrients and none of the trace
elements were detected as moving into the soil or leaching to the
groundwater, it may be concluded that plant assimilation, and
denitrification or volatilization in the case of nitrogen, were
likely responsible for low rates of retention in the forest floor.
51
-------
WATER QUALITY
Prior studies have shown that when nutrients are added to
the forest ecosystem at rates which exceed its assimilation
capacity, the excess in solution are leached (Brockway and Urie
1983). Forest land application programs seeking to minimize the
loss of site nutrient capital and the risks of groundwater
enrichment or contamination should therefore seek to balance
sludge nutrient and trace element additions with the ecosystem
assimilation capacity for these constituents. The sludge
application rates, based primarily on total nitrogen, used in
this research-demonstration project were consistent with those
determined as acceptable by earlier USDA Forest Service studies
(Figure 10).
Monitoring
Although major episodes of leaching were not anticipated,
each study site was carefully monitored with a series of suction
lysimeters placed in the unsaturated zone to collect soil
leachate and wells installed in the upper saturated zone to
directly sample groundwater {Urie et al. 1986). Soil parent
materials were of sufficient permeability to prevent surface
runoff of water, ensuring that all measurements made in the
unsaturated and saturated flow systems of the regional
groundwater aquifer reflected the actual impact of sludge
addition. Lysimeters were sensitive to chemical changes in water
moving through the soil profile, as downgradient wells were
affected by dilution from mass movement.
Numerous sludge constituents have been of concern in land
application, including organic chemicals, pathogens, certain
nutrients and heavy metals. Organic compounds may become
volatilized or bound to soil particles. Bacteria and viruses may
pass through soil, but do so very poorly in well aerated soils.
Phosphate and trace elements are normally adsorped and
precipitated strongly in mineral soil. Nitrate, sulfate, chloride
and bicarbonate anions are poorly adsorped onto soil particles and
readily mobile. Calcium, magnesium, sodium and potassium cations
are leached from the soil in proportion with anions, primarily
nitrate, during the spring and fall periods of groundwater
recharge. The nitrate form of nitrogen is of principal importance
to public health, as concentrations exceeding the 10 mg/1 USEPA
potable water standard are known to cause methemoglobin disease
in humans.
52
-------
Undigested Sludge on Pine
Digested Sludge on Pine
•••• Digested Sludge on Aspen
•Itllll
• Y = .02 x" -»- 2.65
Y = .04 x2 + 6.41
Y = .04 x2 - 1
Computed
"Safe" Rates
10 20 30 40
SLUDGE APPLICATION RATE (Mg/ha)
Figure 10. Relation of sludge application rate to nitrate
leaching (Brockway and Urie 1983).
53
-------
Nitrate Leaching
Nitrate-nitrogen is generated as the end result of organic
nitrogen mineralization to ammonia and further nitrification to
nitrite and nitrate (Figure 11), Nitrate which is not
immobilized, denitrified or taken up by vegetation is then
subject'to leaching loss to groundwater. In sludge amended
ecosystems, nitrate is the dominant anion and, because it adheres
weakly to soil particles, is highly mobile.
During the first year following sludge application, soil
water samples collected from lysimeters on all treated sites
showed nitrate levels elevated above those on control plots (Urie
et al. 1986). On the aspen site, nitrate levels less than 1 mg/1
increased to 4 mg/1. On the oak site, nitrate concentrations
between 1 and 2 mg/1 increased to 6 mg/1. On the pine site,
nitrate levels increased from less than 1 mg/1 to 13 mg/1. On
the northern hardwoods site, nitrate levels increased from less
than 1 mg/1 to 4 mg/1. These increases were the result of rapid
nitrification of the ammonia present in the sludge which led to a
modest surplus in site nitrate levels. Soil water nitrate levels
rapidly decreased to near background levels following this
initial pulse (Figure 12).
In subsequent years, organic nitrogen was more slowly
mineralized to ammonia and nitrified to nitrate (Urie et al.
1986). The impact of nitrate on groundwater wells was thus
delayed and muted by dilution. On the aspen site, peak nitrate
concentrations of 5 mg/1 were measured in groundwater during the
fall of 1983. On the pine site, nitrate levels peaked at 4.9 mg/1
in November 1983. On the northern hardwoods site, peak nitrate
concentrations of 3.9 mg/1 were recorded in September 1985. The
one to two year delay in peak arrival between soil water from
lysimeters at 120 cm (4 feet) in the unsaturated zone and
groundwater from wells several meters in the saturated zone is
typical for nitrate movement in these ecosystems. Such delays
result from differential rates of nitrification, rainfall and
snowmelt events closely associated with the local climate.
Nitrate leaching among the forest sites was highest on the
aspen and pine sites, followed by the oak site and least on the
northern hardwoods site. These differences appear to be a
complex interaction of sludge type, time of application, depth
to water table, soil textural properties and the manner in which
different plant communities were able to utilize sludge nutrients.
The Alpena sludge applied to the aspen, pine and oak sites did
54
-------
NH3
A.
N2
NoO
Denitrification
Volatilization
Organic
Nitrogen
Leaching
Figure 11. The sludge nitrogen cycle (Burton 1986)
55
-------
6.0
5.0 -
4.0 -
D Control
+ Sludge Treated
E
c
s
I
3.0 -
Z 2.0 -
1.0 -
0.0
Nov-81 May-82 Dec-82 Jul-83 Jan-84 Aug-84 Feb-85 Sep-85
Figure 12. Soil water pattern for nitrate (Urie et al. 1986)
-------
have higher levels of available nitrogen than did the Rogers City
sludge. The aspen site contained a juvenile stand with an
irregular distribution across the area. Young stands are noted
for high rates of nutrient uptake, but also for less efficiency
in retaining nutrients in an internalized nutrient cycle than
more mature forests. Soils on the northern hardwoods site
contained textural bands which could have served as temporary
sites of denitrification in the soil profile, leading to less
nitrate leaching. The timing of sludge application, during the
summer growing season on pine and northern hardwoods and the fall
dormant season on aspen and oak, may have also provided a
differential impact.
Groundwater nitrate concentrations measured throughout this
study remained well below the USEPA 10 mg/1 potable water
standard, indicating that temporarily elevated soil water nitrate
levels in the unsaturated zone do not directly translate to
equivalent levels of groundwater enrichment in the saturated zone.
The overall movement of nitrate-nitrogen to groundwater was minor
on all sites. The sludge application rates, based on total
nitrogen, used in this study were therefore demonstrated to be
environmentally suitable for these and similar forest ecosystems.
Leaching of Other Elements
Unlike nitrate, ammonia-nitrogen exhibited no significant
increases in leaching following sludge application (Urie et al.
1986). Ammonia ions are typically bound tightly to soil particles
by cation exchange and were mostly taken up by plant roots as
they became available. The leaching of nitrate did cause an
accompanying leaching loss of cations from the soil. This process
maintains the electrovalent equilibrium in soils subject to
leaching. Cation losses were highest during peak nitrate leaching
episodes and declined as nitrate leaching decreased (Figure 13).
The respective declines in soil water concentrations for calcium,
magnesium, potassium and sodium were from 15 to 5 mg/1, 5 to
1 mg/1, 2 to 0.4 mg/1 and 6 to 1.5 mg/1. Soil water data
indicated that no significant leaching losses of zinc, manganese,
cadmium, boron, copper, nickel or chromium to groundwater
occurred. These elements remained largely in the forest floor or
were taken up by vegetation.
57
-------
c
o
at
VJ
8
o
8
20i
15
10
5
0
6--
4--'
2-
0
81
2-
Calcium
Magnesium
Potassium
•
.1
Sodium
Sept
1983
July
1984
May
1985
Figure 13. Concentrations of calcium, magnesium, potassium
and sodium in soil water (Urie et al. 1986).
58
-------
WILDLIFE
Sludge nutrient additions which result in greater levels of
vegetation production and higher levels of soil fertility were
found to enhance the quality of wildlife habitat and generally
benefit wildlife populations. Studies showed an increase in the
nutritional quality of wildlife food plants. The potential for
transmission of potentially toxic heavy metals in the food chain
was minimal when proper sludge quality controls, application rates
and site selection procedures were used in program planning.
Habitat
Although species composition of the plant community was
unaffected, sludge application resulted in significant changes in
the vegetation structure on all four study sites (Haufler and
Woodyard 1986). Both the quantity of total cover and vertical
distribution of cover increased following sludge addition.
Increases of vertical cover were measured in 88% of the plant
species present in the lower 2 m (6 feet) strata (Haufler and
Campa 1986). Horizontal cover (stem density) also increased for
56% of the species present. Increases in annual primary
production were mostly observed in herbaceous species (Haufler
and Woodyard 1986). Herb production increased 200% on the aspen
site in 1982, then declined to levels 50% greater than controls
by 1984. A similar but less pronounced pattern was observed on
the other study sites.
Structural improvement in habitat was greatest in the pine,
aspen and oak sites and least on the northern hardwoods site.
Responses were greater when sludge was applied during the dormant
season. In the northern hardwoods stand, sludge was applied
after the flush of spring leaves, resulting in increased seedling
mortality from smothering by solids. The generally richer soils
on the northern hardwoods site may have further contributed to
the muted understory response to sludge application (Haufler and
Woodyard 1986).
Ungulates, such as deer and elk, were observed to browse more
heavily on sludge treated areas. Browse utilization was highest
on sludge treated plots on the aspen site and progressively less
on the northern hardwoods, pine and oak sites. This activity was
closely associated with the presence of access trails which
provided greater ease of movement and higher levels of nutrients
contained in key forage plant species (Haufler and Campa 1986).
59
-------
Within one year following sludge application, significantly
increased levels of protein (20 to 50%) and phosphorus were
measured in forage. This improvement in the nutritive quality of
wildlife food persisted until the third growing season when
nutrient levels decreased to near background (Haufler and Woodyard
1986). Protein is a critical factor in deer forage, with low
background levels normally limiting population growth. Higher
protein levels in forage may have accounted for increased deer
use, resulting in a higher rate of fawn production in sludge
fertilized areas.
Populations
Habitat changes in vertical and horizontal cover and
nutritional improvement in food plants have been favorably
associated with wildlife population dynamics. Bird diversity in
temperate climates is known to increase in response to such
habitat enhancement. Small mammal populations responded in
positive fashion to habitat improvements resulting from sludge
application, within one year of sludge fertilization, small
mammal populations on the aspen site increased 100%, then
declined to near background by 1984 as nutrients became
assimilated into unavailable woody vegetation (Haufler and
Woodyard 1986).
Food Chain Assessments
At the sludge application rates used in this research-
demonstration, a heavy metal toxicity hazard to wildlife consuming
vegetation grown on sludge amended sites or to higher trophic
groups (carnivores and man) consuming prey species did not exist
(Haufler and Woodyard 1986). Concentrations of heavy metals found
in forage plants on sludge treated plots were well below maximum
safe levels (Underwood 1977). As with all other field studies of
free ranging small mammals, native species here did not accumulate
toxic metals in their body tissues.
In the laboratory small mammal-raptor food chain study/
significantly increased concentrations of cadmium, chromium and
zinc were found in ryegrass grown on soil amended with Alpena
sludge and Detroit sludge (Table 18). Tissue bioassays of small
mammals consuming the ryegrass revealed that relatively small,
statistically nonsignificant accumulations of cadmium and zinc
occurred and were restricted to liver and kidney tissues. While
60
-------
Table 18. Heavy metal concentrations in ryegrass grown on soil
receiving sludge or commercial fertilizer (Haufler
and Woodyard 1986).
Treatment Cadmium Chromium Copper Nickel Zinc
Fertilizer (12-12-12)
Alpena sludge
Detroit sludge
0.32a
0.78b
0.93b
0.47a
0.91b
0.95b
— my/ K.y
3.6a
3.7a
3.0a
l.la
l.Oa
l.la
44a
73b
60b
Means in the same column followed by the same letter are not
significantly different at the 0.1 level.
cadmium and zinc concentrations in the laboratory were twice those
found in the field studies, they were not considered hazardous to
the health of small mammals or raptors at higher trophic levels
(Haufler and Woodyard 1986).
Liver and kidney tissue taken from whitetail deer harvested
on the sludge treated aspen site contained slightly elevated
levels of cadmium and zinc (Table 19). Concentrations of 3 mg/kg
and 31 mg/kg were well below the 200 mg/kg level of cadmium
considered hazardous to vertebrates. Zinc levels as high as 858
mg/kg were also in the nonhazardous range of less than 1000 mg/kg.
Heavy metal toxicity was an unlikely event in this study, because
the metal application rates with sludge were well below those
found to produce chronic toxicities in laboratory tests (Haufler
and Campa 1986).
In the laboratory detritivore-insectivore food chain study,
earthworms raised in soil amended with Alpena and Detroit sludge
accumulated approximately five times more cadmium, chromium,
copper and zinc in their tissues than did the control group
(Haufler and Woodyard 1986). These significant increases were
the result of direct ingestion of sludge and assimilation of the
heavy metals present (Table 20). Woodcock fed an exclusive diet
of these earthworms for 30 days accumulated twice the cadmium in
their liver and kidney tissues than did the control group (Table
21). However, the cadmium concentrations of 6 to 36 mg/kg were
well below the 200 mg/kg threshold considered hazardous to
vertebrate health. On an exclusive diet of sludge-raised
61
-------
Table 19. Heavy metal concentrations in tissues of whitetail
deer harvested on aspen site in November 1982
(Haufler and Campa 1986).
Tissue
Muscle
Heart
Kidney
Liver
Cadmium
1.08
0.81
31.36
3.13
Chromium
1.26
0.43
0.85
1.59
Copper
/I ^ _
9.39
19.57
21.16
474
Nickel
1.70
0.60
1.00
1.53
Zinc
399
397
858
688
Table 20. Heavy metal concentrations in earthworms raised in
soil receiving sludge or commercial fertilizer
{Haufler and Woodyard 1986).
Treatment
Cadmium
Chromium Copper
Nickel Zinc
Fertilizer (12-12-12)
Alpena sludge
Detroit sludge
5.0a
19. 2b
27. 4b
16. 5a
67. 4b
47. 7b
rag/ *.g —
9.6a
37. 9b
24. 9b
21. la
35. 4a
19. 8a
21. Oa
85. 4b
117b
Means in the same column followed by the same letter are not
significantly different at the 0.1 level,
Table 21. Cadmium concentrations in tissues of woodcock fed
earthworms raised in soil receiving sludge or
commercial fertilizer {Haufler and Woodyard 1986),
Treatment
Control
Fertilizer (12-12-12)
Alpena sludge
Detroit sludge
Liver
3.12a
l.Slb
7.38c
6.21c
Kidney
17. 9a
12. 6b
30. 4c
36. Ic
Heart
/\
— mg/Kg —
0.78a
0.57a
0.61a
0.56a
Muscle
1.25a
0.69a
0.97a
1.12a
Bone
O.OSa
0.02a
0.04a
0.02a
Means in the same column followed by the same letter are not
significantly different at the 0.1 level.
62
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earthworms, two years would be required to reach kidney cadmium
levels which may be lethal to woodcock. In free ranging and
migratory species such as woodcock, confinement to such a narrow
diet is extremely unlikely. Heart, muscle and bone tissue showed
no accumulation of heavy metals during this very intensive feeding
trial. Minimal risk to human consumers from woodcock is
anticipated because lowland forests which serve as the primary
habitat for woodcock are systematically excluded from sludge
application because of higher water tables and liver and kidney,
the only tissues shown here to accumulate cadmium, are discarded
by hunters prior to consuming their game.
Nutrition and Sludge Quality—
Sludge application in the forest provides the plant and
animal community with numerous nutrients and trace elements
needed for growth and related physiological processes. Nitrogen,
phosphorus, potassium, calcium, magnesium, sodium, chloride,
sulfur, boron, silicon, iron, manganese, cobalt, molybdenum, zinc
and copper are essential for proper plant nutrition. Animals
also require many of these elements plus iodine, selenium and
chromium in trace amounts.
Certain heavy metals present in sludge at modest levels
may be beneficial in plant and animal nutrition. However,
several {lead, nickel, cadmium and mercury) are toxic and of no
known value and others (zinc, copper, chromium and molybdenum),
while needed at lower levels, may be toxic at higher
concentrations. Among these, cadmium represents the greatest
hazard to animals in that it has previously been found to
accumulate at levels which do not injure plants but may be
deleterious to animals (Baker et al. 1977).
Because of the toxicity hazard to animal (and human) health
from high levels of heavy metals, poor quality sludges containing
these are best excluded from consideration for land application
in forests. When adequate sludge quality control is combined
with appropriate sludge application rates, the heavy metals
present in sludge are a minimal risk for plant, wildlife and
human populations. Given prudent planning and monitoring, upland
forests can be recommended as sites for sludge recycling while
posing little risk to wildlife or humans consuming wildlife
(Haufler and Woodyard 1986).
63
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SOCIOLOGICAL STUDY RESULTS
This study and previous research have demonstrated that the
biological, physical and economic challenges of forest land
application can be adequately addressed through prudent sludge
quality -control, site selection and project management. However,
natural resource and environmental programs of today must often
be conducted in highly visible fashion under the watchful eyes of
a frequently skeptical public. Citizen interest in the conduct
of these programs is a natural extension of the normal curiosity
and concern residents have about activities which may affect
their quality of life.
Public agencies and, to a lesser degree, private industry
must be sensitive to these sociological dynamics in order to
reassure residents about the potential risks, enlist citizen
support in beneficial endeavors and achieve program goals which
represent a social good for local and regional publics. Citizen
participation in the planning process of forest land application
programs will not guarantee success, but neglecting public input
will most certainly doom any project proposal to failure. The
survey of public beliefs and opinions conducted in this study
greatly aided agency staff in understanding the nature of
information needed for public education materials developed to
foster effective citizen participation in planning local forest
land application programs.
PUBLIC OPINIONS AND CONCERNS
A public opinion survey conducted in the forested counties of
northern Michigan indicated that, while two-thirds of residents
believe sludge generation to be a significant problem for cities
and industry, a major portion were undecided (Figure 14) about
the practice of sludge application on forest land (Peyton and
Gigliotti 1986). Very little technical information concerning
the risks and benefits of various sludge management alternatives
was previously available to the general public and largely
accounted for the absence of strongly held opinions. The major
task in developing effective public involvement is one of
remediating deficient rather than inaccurate knowledge. Further,
a large segment of the public (87%) indicated an interest in
learning more about sludge management practices.
64
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CO
c
0
TJ
c
o
a
CO
a>
oc
80
60
40
20
en
«
m
I
I
opposed
undecided
favor
m
m
m
1
•V«V«
m
m
-»x-
opposed undecided
favor
General Public
Public Officials
Fi9ure
land
-------
In the context of current public knowledge, human health
and environmental quality are of greatest concern and economics
and esthetics of least concern to residents considering sludge
management options (Figure 15). Public preference among numerous
options is a direct result of the perceived impact each will have
on human health and second on environmental quality (Peyton and
Gigliotti 1986). Although forest land application is the second
most preferred sludge management alternative (Figure 16),
incineration is most preferred only because of the perceived
human health protection it offers. When the public becomes aware
of the major health, environmental and economic limitations
inherent with incineration which restrict its availability to
very few large generator facilities, forest land application may
become an increasingly attractive sludge management option.
Forest land application of sludge is an emerging natural
resource management issue which has not reached disruptive status
with development of strongly polarized interest groups (Peyton
and Gigliotti 1986). To minimize opportunity for its development
to a disruptive level, forest land application proposals must not
be introduced into the planning process as preformed alternatives
to be accepted or rejected. Rather, the public must recognize
that no decision will be made until they have had opportunity to
learn about, participate in evaluation of and influence the final
selection among the full range of options. Schematic
representations for developing and implementing a planning
process are depicted in Figures 17 and 18, respectively. These
illustrations, from a public involvement manual (Gigliotti and
Peyton 1986) developed during this study, outline steps
appropriate to conducting a program for effective citizen
participation in the sludge management planning process.
PUBLIC EDUCATION MATERIALS
Public officials (Figure 14) and members of environmental-
outdoor organizations are substantially more favorable toward
forest land application than the general public. Recreationists
who anticipated a loss in the quality of their outdoor experience
were much less favorable. Educational programs must therefore
make a factual distinction between perceived and actual loss in
quality. It should be emphasized that land application programs
typically affect relatively small acreages and few individual
forest users. Education programs should also convey information
to nonresident users of candidate forest sites.
66
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O
CO
UJ
•o
0)
(0
•H*
c
O
70
60
50
40
30
20
10
HEALTH ENVIRONMENTAL ECONOMIC ESTHETIC
QUALITY
Concerns
Figure 15. Public priority of concerns about sludge management
practices (Gigliotti and Peyton 1986).
67
-------
40
•o
o
£
1
2 o 30-
o>
CO
c
o
•o
c
o
a
(0
0)
o o.
^ o
20
10-
incineration forest
application
HH
landfills
agricultural
application
no opinion
Figure 16. Public preference for sludge management alternatives
(Gigliotti and Peyton 1986).
-------
FO
Criteria:
Nigh Credibility
Olvarsa Expertise
Representative
Reasonable Group Size
IM STEERING GOMMinEE
Select tram:
local Planners
University / SUte Expertise
tocol Technical Wests Manegament Expertise
local Officials
Citizens at large
News Media Representatives
DEFINE THE PROBLEM
ASSEMBLE FACTS.
Niture at sludge (O.B., chemicals, pathogens)
Quantities, prelected disposal needs
Alvnatlves
Fined Constraints
legal Constraints
dotes
Planning Rudgat
E1C.
IDENTIFY INFORMATION NEEDS
Bi unfits, costs, risks ol altarnetlves
Public perceptions, preferences
ETC.
DEVELOP TIME FRAME
Planning Period
Hiplementationoate
rc.
I
STAT: 60ALS OF PLANNING PROGRAM
examples;
Inloi
od public-, benefits, costs, risks of alternatives.
Rapri tentative public Input In comparing and selecting alternatives.
Credibility with public.
OE
f
;LOP PUtUHNB STRATEGIES FOR
examples:
Educating the Public
Identification of Public Segments
Obtaining Representative Public Input
Developing, Evaluating, and Selecting Alternatives
I
IMPLEMENT THE PUNNING PROCESS
Figure 17.
Developing a planning process (Gigliotti and Peyton
1986).
69
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MEASURE PUBLIC PERCEPTIONS
General Public
— Surveys
Public Meetings
Levels of Understanding
Values
Concerns
Preferences
Public Education
News Media
Pamphlets
Survey
RESEARCH AND PLAN ALTERNATIVES
Representative Public
..Citizen Advisory
Councils Review
Panels Task Forces
ibiic
—*4
Plan A
1 Benefits:
Costs:
Risks:
PlanB
Benefits:
Costs:
Risks:
PlanC
Benefits:
Costs:
Risks:
h1
Public Education
EVALUATION PROCESS
'General Public I Communicate alternatives to public
Information Campaign _ |Pub|ic evaluation and comparison of
- Public Meetings M bej)efjts cosls and f|sks
I Public expression of preferences
Workshops
Surveys
Public Ecucation
f
SELECTION PROCESS
.Representative Public
Advisory Council
Agency and representative public
evaluate public responses and
select appropriate plan.
Feed Back
To Public
Figure 18. Implementing a planning process (Gigliotti and Peyton
1986).
70
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Educational materials developed to improve public
understanding of sludge management practices will be most useful
if information on risks and benefits of all options is provided
(Peyton and Gigliotti 1986). Because citizens who feel most
influential in the outcome of a planning process are more likely
to become involved, these materials should also teach members of
the public how to become effectively involved. The planning
process is best approached without preselected options and should
involve the public in simultaneous evaluation of each possible
sludge management alternative. To increase citizen perception of
influence as well as familiarize individuals with new technology,
the public should be provided with constant feedback before,
during and after forest land application programs are developed
and implemented.
Recognizing that forest land application of wastewater
sludge is a relatively unfamiliar practice to a large segment of
the population, public involvement early in the planning process
is essential to program success, especially when proposals
include fertilization of publicly owned forests. Citizens are
willing to take responsibility for management of sludge generated
in their own communities, but most (73%) do not wish to have
their locale become a dumping site for distant communities
(Peyton and Gigliotti 1986). Because of this prevailing view,
forest land application programs should restrict sludge use to
that from local sources. However, this attitude may change as
education programs persuade the public to perceive sludge as a
resource rather than waste.
In consideration of the above, public education materials
developed during this project focused upon two major areas.
First, emphasis was placed upon development of a booklet which
provides basic background information on wastewater treatment
technology and compares the relative benefits and risks of
numerous sludge management alternatives (Assaff et al. 1986).
The document uses nontechnical language to discuss the advantages
and disadvantages of traditional and innovative sludge management
options. Second, emphasis was directed toward developing a
guidance manual which would aid local units of government,
industries and others in conducting a program planning process
which would effectively incorporate public input (Gigliotti and
Peyton 1986). Through these publications, the public can have
access to accurate information about sludge management
alternatives and to a planning process which produces outcomes
agreeable to its interest.
71
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SIGNIFICANCE TO AGENCY PROGRAMS
Development of technology which affords new waste management
alternatives has had effects both upon agency regulatory programs
and the regulated community. Numerous consultants and contractors
who service the regulated community have taken note of recent
developments and responded with requests for additional
information about the new technology. Individual citizens,
public interest groups and media representatives have also sought
technical information concerning the benefits and risks of land
application. Further, because forest land application may
involve the use of public as well as private forests, agency
natural resource and land management programs must be prepared to
deal effectively with an increasing number of requests to utilize
State Forest land as recycling sites in the future.
EXISTING LAND APPLICATION PROGRAM
Currently in the MDNR Bureau of Environmental Protection,
divisions exist which focus primary attention upon air quality,
water quality, pollution clean up and waste management. Local
programs for recycling waste upon farm, forest and disturbed
lands are coordinated through and authorized by the staff of the
Land Application Unit. Unit staff is comprised of scientists and
engineers whose expertise includes the fields of waste treatment
technology, toxicology, biochemistry, soil chemistry, soil
management, crop science, geology, hydrology, forest ecology,
silviculture and forest management. The principal wastes
regulated by the unit are wastewater sludges generated by
municipalities and industries and waste residuals produced as
byproducts of commercial enterprises. Recycling of the nutrients,
trace elements and organic matter present in these materials is
permitted on land under authority of NPDES permits or Public Act
245 groundwater discharge permits.
The basic principle which guides land application programs
statewide is that of balancing nutrient additions with crop
nutrient demands, while not exceeding the trace element
assimilation capacity of the soil. Following this guide has
typically resulted in increased crop yields, improved soil
fertility and, with periodic crop removal, avoidance of
undesirable accumulations of nutrients and trace elements in the
soil. With proper management, land application represents a
unique opportunity to recycle with 100% efficiency wastes which
72
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would be potentially troublesome in landfillsr groundwater or
surface water but are valuable fertilizers on the land.
Considering the widespread generation of recyclable waste
treatment byproducts and the variety of sites on which they are
applied, the Land Application Program ranks as one of the most
important in protecting public health and environmental quality
in Michigan. While entire divisions have been formed to protect
air and water resources, the Land Application Unit is the sole
entity in MDNR responsible for protecting our most basic resource,
the soil and its productive potential. The degree to which
program management is conducted on a sound scientific basis has
direct and profound implication for the safety of the human food
chain.
DEVELOPMENT OF TECHNICAL GUIDANCE
The Land Application Program was established in 1978 in the
Water Quality Division of MDNR to provide technical assistance in
managing the increasing volumes of sludge generated by municipal
wastewater treatment facilities. At that time, landfill space
was dwindling and fuel costs for sludge incineration continued to
rise to prohibitive levels. Independent attempts at land
application of sludge met with only intermittent success as a
great deal of uncertainty surrounded proper site selection,
application rates and management procedures.
Initial staff efforts in program development focused upon
farm land application because the greatest portion of sludge was
generated in the predominantly agricultural region of southern
Michigan and a great wealth of scientific data existed from
studies of sludge application on agricultural soils. In
consultation with research scientists in the Department of Crop
and Soil Sciences at Michigan State University and the USDA
Cooperative Extension Service, preliminary guidance for sludge
application on farm land was adopted. The guiding principles
were firmly based upon scientific findings and reflected a
conservative approach in protecting public health and
environment. Emphasis was placed upon nutrient addition, trace
element accumulation, pathogen control, site selection and
proper sludge handling procedures.
In 1980, Land Application Unit staff conducted a sampling
survey of sludges produced at all municipal wastewater treatment
plants in Michigan. Samples were analyzed by researchers at
73
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Michigan State University for content of nutrients, trace
elements and potentially to#ic organic chemicals (Jacobs et al.
1981). These results further strengthened the data base upon
which the Land Application Program was developing.
By 1982, the preliminary guidance for sludge application on
agricultural land was consolidated under single cover in "The
Michigan Municipal Wastewater Sludge Management Program" (MDNR
1982). In 1984, this booklet was revised to reflect
administrative changes within MDNR, including specifics related
to permitting procedures, preparation of approvable sludge
management plans and inclusion of all recyclable wastes suitable
for application to the soil {MDNR 1984). In 1986, sludge
application methods for forest and minespoiled land were
incorporated into the basic program document, "Guidance for Land
Application of Wastewater Sludge in Michigan" (MDNR 1986).
Criteria for proper management of sludge application on
forest land have been developed from the results of this and
related studies in Michigan and numerous research efforts in
other regions. Research studies in the Pacific Northwest
(Bledsoe 1981, Henry and Cole 1983, Zososki et al. 1983, 1984,
Cole et al. 1986), Southeastern (Richter et al. 1982, Wells et
al. 1984) and Northeastern United States (Sopper and Kerr 1979,
Koterba et al. 1979, Sidle and Kardos 1979) have shown that
sludge application can be successfully practiced in a variety of
forest environments. However, differences in climate,
topography, soil and vegetation characteristic of each region
demand that application techniques and regulations be tailored to
meet the needs of practitioners in a specific environment.
Guidelines developed from our research in Michigan should
therefore be used with caution beyond the Great Lakes Region and
with special attention to environmental conditions prevailing in
each specific locale.
The presence of tree roots in the forest environment under
most circumstances rules out the direct subsurface injection of
sludge into the soil. Rather, sludge must be typically applied
upon the forest floor. Liquid sludges have proven in previous
research to make better contact with the biologically active
portion of the forest floor and soil, as they rapidly infiltrate
these components and are readily covered by litterfall during
subsequent periods of senescence. Dewatered sludge cake, by
contrast, remains perched upon the forest floor for longer
periods in a manner which does not allow as rapid decomposition
and incorporation of nutrients into the ecosystem (Richter et al.
74
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1982). Persistence of dewatered sludge cake upon the forest
floor may also represent a real or perceived threat to human
health. For these reasons, best management practices dictate
that only liquid and rewatered sludge should be land applied in
Michigan forests.
The" use of wastewater sludge as fertilizer in the forest is
largely to increase production of nonfood chain commodities (ie./
wood products). However, numerous food plants consumed directly
by wildlife and directly or indirectly by humans also come from
forest land. Two concerns associated with sludge applications
have been persistence of pathogenic microorganisms and
bioaccumulation of heavy metals in the food chain.
Pathogens are always present in wastewater sludge and
represent a potential hazard for disease transmission to those
who come into direct contact with this material. To minimize
this risk, unstabilized raw sludges may not be applied to land in
Michigan. Rather, federal and state guidance requires that all
land applied sludges undergo a "process to significantly reduce
pathogens" such as anaerobic digestion, aerobic digestion, air
drying, composting and lime stabilization to effectively reduce
pathogen numbers. For an added level of protection, a "process
to further reduce pathogens" may be used to decrease the
likelihood of disease transmission. When the resulting sludges
are land applied, die off of the remaining pathogens is quite
rapid from the effects of solar radiation, desiccation and
interaction with native soil microorganisms.
The presence of potentially toxic materials in sludge, such
as heavy metals and organic chemicals, represents another area of
concern in forest land application. While zinc, copper, lead,
nickel, chromium and cadmium have been shown to be toxic at high
concentrations to agricultural crops, their toxic effects have
not been observed in forest plants, perhaps because these
wildtypes have retained greater genetic plasticity in adapting to
the widely variable chemical environments of forest soils.
Because these elements reach animal consumers indirectly through
vegetation and are largely in organically bound forms, documented
food chain transmission has not been reported in Michigan.
Sludges, based upon the presence of heavy metals, have been
partially categorized into low level (Class 1), moderate level
(Class 2) and elevated level (Class 3) groups (Table 22). While
sludges in all categories may be applied to land, increased
levels of sludge and site monitoring are required for Class 2 and
Class 3 land application. Sludge application rates are ultimately
75
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Table 22. Catagories of sludge chemical quality (MDNR 1986).
Constituent
Cadmium .
Chromium
Copper
Lead
Mercury
Nickel
Zinc
Selenium
Molybdenum
Arsenic
PCB
Class 1
< 5
< 50
<250
<250
< 2
< 25
<750
< 10
< 10
<100
< 1
Class 2
- -mg/kg
5-125
50-5000
250-2000
250-2000
2-10
25-1000
750-5000
10-80
10-50
100-2000
1-10
Class 3
> 125
>5000
>2000
>2000
> 10
>1000
>5000
> 80
> 50
>2000
> 10
Table 23. Metal accumulation factors (MDNR 1986).
Element
Metal Accumulation Factor (MAP)
Lead
Zinc
Copper
Nickel
100
50
25
10
limited by allowable maximum annual and lifetime site metal
accumulations. The maximum lifetime site metal accumulation
(Ibs/acre) is the product of soil cation exchange capacity (CEC)
at a specific site and the metal accumulation factor (MAF) seen
in Table 23. Each MAF represents the relative mobility of a
specific heavy metal in soil as determined from research findings.
The maximum annual site metal accumulation is one-twentieth of
the lifetime maximum, assuming a useable site life of at least 20
years. Standards have not yet been established for land
application of most organic chemicals and research in this area
76
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is continuing.
Sludge application rates for forests have been primarily
based upon nitrogen (not including losses from volatilization or
denitrification), as it is most frequently limiting to growth
(Table 24). These have been determined by balancing nutrient
additions with site nutrient assimilation capacity, a principle
similar to that used for agricultural land application. Because
forests are complex ecosystems and nutrients may be stored in the
forest floor for substantial periods/ forest sites may receive
sludge applications which supply sufficient nutrients to last an
interval of up to five years. Application rates of total
nitrogen up to 445 kg/ha (500 Ibs/acre) have been demonstrated to
benefit forest growth while ensuring adequate protection for
groundwater quality.
In Michigan, stands of all ages appear to respond well to
sludge application. Forests of varying age will, however
present a different set of structural and biological challenges.
In each case, it is essential that adequate care be taken to
minimize injury to the forest site. Precautions such as use of
high flotation tires on sludge application vehicles are
considered mandatory on all sites to avoid soil damage from
compaction.
In established forest stands, sludge delivery systems that
have proven most effective are all-terrain tank vehicles which
travel a set of prepared parallel trails and distribute liquid
sludge from fixed or rotating spray guns. These provide uniform
coverage, confine traffic to established trails and are
demonstrated cost-effective. The stand density and effective
spray distance of the guns determines the distance interval
between trails. On most sites, adequate access can be achieved
by removal of some existing trees or use of existing fire control
lanes.
In recently established stands (ie., plantations), sludge
may be applied as in older stands. However, because of the
shorter stature of newly planted trees, sludge will be sprayed
upon tree foliage. Because of the danger of solarization of
sludge coated leaves, application is best conducted prior to or
during rainfall events or during the dormant season. As physical
structure of such a forest site is quite open, greater advantage
is afforded in ease of sludge distribution over greater distances,
hence more cost efficient application vehicle operation.
77
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Table 24. Recommended rates for wastewater sludge application in
Michigan forests assuming a five-year retreatment
interval (MDNR 1986).
Sludge Application Rate
Forest Type
Aspen
Aspen
Aspen
Northern Hardwoods
Northern Hardwoods
Northern Hardwoods
Oak-Hickory
Oak-Hickory
Oak-Hickory
Elm-Ash-Cot tonwood
Elm-As h-Co t tonwood
Elm-Ash-Cot tonwood
Scrub oak
Scrub oak
Red, White, Jack Pine
Red, White, Jack Pine
Red, White, Jack Pine
Spruce-Fir
Spruce-Fir
Spruce-Fir
Northern White-cedar
Northern White-cedar
Age
(years)
0 to 5
5 to 20
over 20
0 to 10
10 to 30
over 30
0 to 10
10 to 30
over 30
0 to 5
5 to 20
over 20
0 to 20
over 20
0 to 10
10 to 30
over 30
0 to 10
10 to 30
over 30
0 to 20
over 20
Available Total
(Ib/A/yr) (lb/A/5 yrs)
50
100
50
40
80
40
50
100
50
50
100
50
20
40
50
40
20
40
30
20
40
20
250
500
250
200
400
200
250
500
250
250
500
250
100
200
250
200
100
200
150
100
200
100
78
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On recently clearcut harvested sites appears the greatest
opportunity for operational ease of sludge application. However,
unique problems are also encountered in this environment.
Studies in the Pacific Northwest measured significant effects on
tree survival, competition from weeds (Archie and Smith 1981) and
deer browsing (West et al. 1981) following sludge application.
Although- standing trees may no longer be present to interfere
with sludge distribution, application vehicle access to and
movement about newly clearcut sites can be hindered by the
presence of logging slash.
Of the factors which contribute to program success, careful
selection of land application sites is of major importance.
Sites selected for land application of sludge should be located
where they are not permanently or periodically influenced by
flooding. Bottomlands containing alluvial plains or swamps are
best avoided. The water table must be maintained no less than
76 cm (30 inches) below the soil surface at the time of sludge
application. Soils classified as poorly drained are generally
not suitable for forest land application. In Michigan, the
maximum slope limitation for surface applied sludge is 6%;
however, steeper sites may be used if no significant surface
runoff hazard exists. Although the potential for sludge solids
runoff during a rainfall event is recognized, the moderate
rainfall, high infiltration capacities of forest soils and
regulatory limitations on slope steepness greatly decrease the
likelihood of such an incident. Sludge has been successfully
applied on slopes up to 30% in the Pacific Northwest,
underscoring the differing management practices appropriate for
various forest environments. Minimum isolation distances of
152 m (500 feet) to homes and commercial buildings and 46 m
(150 feet) to wells, surface waters, public roads and property
lines must be observed. No sludge may be applied within 610 m
(2000 feet) of a municipal water supply well.
For each proposed forest land application site, the
following information must be provided to MDNR: (1) a site
management history indicating stand age, previous and planned
harvest and stand improvement activities, previous fires and
importance as wildlife habitat or recreational area, (2) a plat
map showing general site location by township and section and
land ownership including name and address of land manager, (3) an
air photo showing site proximity to structures, roads, streams
and lakes, (4) a soil survey map showing soil type, drainage
class, surface slope and topographic position of the site, (5) a
vegetation cover type map showing species composition, age class,
79
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basal: area and stocking of the forest stand and (6) a computation
of sludge application rate and the nutrient and trace element
loading rates. The proposed rate must be based on recent chemical
analyses of the sludge and soil. The interval between sludge
reapplications on the same area should be specified.
In regions of milder winter climate, such as the Pacific
Northwest, little if any restriction is necessary for winter
season application. At lower elevations, nearly all
precipitation is received as rainfall and frozen soils are
nearly unknown. Under such conditions, sludge application in
the forest may continue unimpeded throughtout the year.
In Michigan, sludge application in winter when the soil is
frozen or snow covered is always done with increased risk to the
environment or public health. Applied sludge remains perched
above the forest floor for long periods where unanticipated heavy
rainfall or sudden thawing may result in lateral movement of
solids off the site. The fact that granular rather than concrete
frost forms beneath the canopy over forest soils minimizes this
risk to large extent. However, as with agricultural lands,
winter season sludge application should only be undertaken when
no other reasonable option remains. The following standards are
to be met in site selection and program operation when winter
season sludge application is proposed.
(1) Surface slope of the site must not exceed 2% and pose no
reasonable probability for surface runoff of applied sludge
solids.
(2) Soils on the site should be classified as well drained or
moderately well drained.
(3) The forest stand present must be fully stocked with canopy
cover no less than 60%.
(4) A minimum isolation distance of 152 m (500 feet) to homes,
commercial buildings, wells, surface waters, public roads
and property lines must be observed.
(5) Liquid sludge applications must be limited to a maximum of
93,490 liters per ha (10,000 gallons per acre).
(6) No established winter recreation uses (eg. resorts) are
allowed on the site.
80
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(7) Each site must be submitted to MDNR by September 15th prior
to the winter during which it is proposed for sludge
application.
(8) Each site must be clearly identified by signs which indicate
that the area has been fertilized with wastewater sludge to
increase tree growth and improve wildlife habitat.
Ultimately, application sites will be selected as part of
the local program planning process. When programs are targeted
for use of publicly owned lands, each citizen may feel the need
to be consulted or at least represented somewhere in the planning
process. Very early in the planning phase of a sludge management
program the sludge generator should meet with the forest land
manager to screen candidate land application sites. Discussion
should also thoroughly address the issues of conflicts with
public user groups and compatibility with silvicultural
objectives of the land manager. Because of the high nontimber
values of Michigan forests, recreational user groups are most
likely to be in conflict with sludge application. This may not
always be so, as fertilization of forests enhances certain
amenities considered desirable by recreationists. However,
recreational users are most likely to feel displaced by a recent
sludge application and preliminary screening of candidate sites
should consider this factor.
IMPACT ON ENVIRONMENTAL PROGRAMS
The major effect of developing forest land application
technology has been to afford generators of wastewater sludge an
additional alternative for utilization of this byproduct. This
option is of particular importance to communities and industries
located in the forested northern two-thirds of Michigan and
similar regions in neighboring states. Now that guidance is
available for properly conducting forest land application
programs, these communities and industries may soon gain access
to an expanded land base which was previously unavailable for
this purpose. Also of major importance to forest land owners and
managers will be the availability of an essentially free source
of nutrients and organic matter with which to enhance forest
sites. The total fertilizer value of Michigan's sludge resource
has been estimated to exceed five million dollars.
To ensure that information concerning forest land application
81
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technology is disseminated in timely fashion, increased levels of
staff time and agency financial resources will be required in
local program planning, training sessions, informational meetings
and travel. Interest-expressed in transporting downstate sludges
to northern forest sites is likely to be met with opposition from
local residents. This situation will continue until the public
begins to perceive sludge as a resource rather than waste. Some
individuals are anticipated to maintain a skeptical view of land
application/ as all possible questions concerning risks have not
been answered and research is continuing on several fronts.
IMPACT ON RESOURCE PROGRAMS
A major effect of developing forest land application
technology has been to provide private forest land owners and
public forest land managers with an economical means of using
fertilization as a silvicultural treatment. The nutrient
resources available allow opportunity for increasing forest
productivity and enhancing the quality of wildlife habitat. The
ultimate impacts of these uses will be increased income from sale
of increased timber volumes and increased carrying capacity for
game and nongame wildlife populations. Benefits will accrue for
commercial and recreational users of the land. Forest land
application represents the linkage between a compelling waste
management need and a profitable land management opportunity.
Private landowners and agency forest and wildlife managers have
expressed interest in utilizing this technology to the benefit
of their respective resource management objectives.
As in any matter which is new or potentially controversial,
incorporation of forest land application technology into the
existing administrative framework has proceeded with caution.
Existing workloads, personnel ceilings and budgetary limitations
slow the process of integration. Sludge fertilization is also
perceived as one more use competing with a vast array of more
traditional forest uses. Recreational users of the forest who
perceive a loss in the quality of their experience from forest
land application may greatly add to the scheduled workloads of
forest managers. Relations between agency staff and local
government officials may be strained as the result of forest
land application proposals on public forest land within their
jurisdiction. Despite these complications, agency resource
managers appear generally favorable toward forest land application
and seem committed to incorporating this technology into their
selection of land management tools.
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INFORMATION DISSEMINATION
A major function of Land Application Unit staff has been to
provide technical assistance to sludge generators who wish to
develop land application programs. These regulatory contacts
with municipalities and industries will increasingly involve
evaluation of the forest land alternative for treatment of waste
byproducts. A growing number of these meetings will also involve
direct contact with forest land managers from the private and
public sectors who share a common interest with the waste
generator. At such meetings the technical guidance criteria will
be reviewed and public participation in planning discussed.
As part of statewide program development, information
sharing sessions have been conducted for the public at
Cooperative Extension Service sponsored workshops and a MDNR
sponsored conference. These meetings have reviewed technical
study findings, discussed application technology, encouraged
public involvement and visited sludge fertilized sites. In the
future, agency sponsored training sessions will be conducted for
regulatory and resource management staff, consultants, local
officials and interested citizens. Seminars organized to discuss
forest land application information with numerous public interest
groups are also planned.
FUTURE DIRECTION
With the current state of the art in forest land application,
a technology which is firmly based in sound scientific research is
at hand. The major task at this time is to disseminate accurate
information concerning its benefits and risks to all interested
groups, public or private, regional or local. Technical
assistance provided to waste generators and land managers will
also include information on the forest land application
alternative.
This agency will continue to monitor the results of local
programs which involve forest land application and public opinion
that develops and evolves in response to program conduct. Staff
will continually refine statewide program criteria as new
technical and sociological data become available. The Land
Application Unit will continue seeking funds to develop research
studies which address (1) the long term and retreatment effects of
forest land application and (2) the environmental fate of organic
chemicals land applied in the forest.
83
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REFERENCES
Archie, S.G. and M. Smith. 1981. Survival and growth of
plantations in sludge-treated soils and older forest growth
studies, p. 105-113. Iri C.S. Bledsoe (ed.) Municipal Sludge
Application to Pacific Northwest Forest Lands. Institute of
Forest Resources Contribution No. 41, University of Washington,
Seattle.
Assaff, E., R.B. Peyton and L.M. Gigliotti. 1986. The sludge
solution: comparing the alternatives. Dept. of Fisheries and
Wildlife, Michigan State University, East Lansing. 24 p.
Baker, D.E., M.C. Amacher and W.T. Doty. 1977. Monitoring
sewage sludges, soils and crops for zinc and cadmium, p. 261-281.
Iri R.C. Loehr (ed.) Land as a Waste Management Alternative. Ann
Arbor Science Publishers, Ann Arbor, Michigan.
Bastian, R.K. 1988. Overview of sludge Management in the United
States. Office of Municipal Pollution Control, U.S. Environmental
Protection Agency, Washington, D.C. 12 p.
Bledsoe, C.S. (ed.). 1981. Municipal sludge application to
Pacific Northwest forest lands. Institute of Forest Resources
Contribution No. 41, University of Washington, Seattle. 155 p.
Brockway, D.G. 1979. Evaluation of northern pine plantations as
disposal sites for municipal and industrial sludge. Ph.D.
Dissertation. Dept. of Forestry, Michigan State University, East
Lansing. University Microfilms, Ann Arbor, Michigan (Diss.
Abstr. 40-2919B).
Brockway, D.G. 1983. Forest floor, soil and vegetation responses
to sludge fertilization in red and white pine plantations. Soil
Science Society of America Journal 47:776-784.
Brockway, D.G. and D.H. Urie. 1983. Determining sludge
fertilization rates for forests from nitrate-nitrogen in leachate
and groundwater. Journal of Environmental Quality 12:487-492.
Brockway, D.G. and P.V. Nguyen. 1986. Municipal sludge
application in forests of northern Michigan, a case study.
p. 477-496. In D.W. Cole, C.L. Henry and W.L. Nutter (eds.) The
Forest Alternative for Treatment and Utilization of Municipal and
Industrial Wastes. University of Washington Press, Seattle.
84
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Burton, A.J. 1986. Nitrogen transformations and nitrate
leaching following sludge application to four Michigan forest
types. M.S. Thesis. Dept. of Forestry, Michigan State
University, East Lansing. 141 p.
Cole, D.W., C.L. Henry and W.L. Nutter (eds.). 1986. The
forest alternative for treatment and utilization of municipal
and industrial wastes. University of Washington Press, Seattle.
582 p.
Ecosoft, Inc. 1984. Microstat, an interactive general purpose
statistical package. Release 4.0. Ecosoft, Inc., Indianapolis,
Indiana.
Porster, D.L., T.J. Logan, R.H. Miller and R.K. White. 1977.
State of the art in municipal sewage sludge landspreading.
p. 603-618. I_n R.C. Loehr (ed.) Land as a Waste Management
Alternative. Ann Arbor Science Publishers, Ann Arbor, Michigan.
Freshman, J.D. 1977. A perspective on land as a waste
management alternative, p. 3-8. Iji R.C. Loehr (ed.) Land as a
Waste Management Alternative. Ann Arbor Science Publishers, Ann
Arbor, Michigan.
Gigliotti, L.M. and R.B. Peyton. 1986. A manual for public
involvement in planning sludge management programs. Dept. of
Fisheries and Wildlife, Michigan State University, East Lansing.
78 p.
Harris, A.R. 1979. Physical and chemical changes in forested
Michigan sand soils fertilized with effluent and sludge.
p. 155-161. Ijn W.E. Sopper and S.N. Kerr (eds.) Utilization
of Municipal Sewage Effluent and Sludge on Forest and Disturbed
Land. Pennsylvania State University Press, University Park.
Hart, J.B. and P.V. Nguyen. 1986. Ecological monitoring of
sludge fertilization on state forest lands in northern Lower
Michigan. Final Project Report. Dept. of Forestry, Michigan
State University, East Lansing. 285 p.
Hart, J.H., J.B. Hart and P.V. Nguyen. 1986. Aspen mortality
following sludge application in Michigan, p. 266-271. ITI D.W.
Cole, C.L. Henry and W.L. Nutter (eds.) The Forest Alternative
for Treatment and Utilization of Municipal and Industrial Wastes.
University of Washington Press, Seattle.
85
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Haufler, J.B. and H. Campa. 1986. Deer and elk use of forages
treated with municipal sewage sludge. Final Project Report.
Dept. of Fisheries and Wildlife, Michigan State University, East
Lansing. 112 p.
Haufler, J.B. and O.K. Woodyard. 1986. Influences on wildlife
populations of the application of sewage sludge to upland forest
types. Final Project Report. Dept. of Fisheries and Wildlife,
Michigan State University, East Lansing. 288 p.
Henry, C.L. and D.W. Cole (eds.). 1983. Use of dewatered sludge
as an amendment for forest growth: Volume IV. Institute of
Forest Resources, University of Washington, Seattle. 110 p.
Hintze, J.L. 1986. Number cruncher statistical system (NCSS).
Version 4.21. Kaysville, Utah.
Jacobs, L.W., M.J. Zabik and J.H. Phillips. 1981. Concentrations
of selected hazardous chemicals in Michigan sewage sludges and
their impact on land application. Final Project Report. Dept.
of Crop and Soil Sciences and Pesticide Research Center, Michigan
State University, East Lansing. 195 p.
Koterba, M.T., J.W. Hornbeck and R.S. Pierce. 1979. Effects of
sludge applications on soil water solution and vegetation.
Journal of Environmental Quality 8:72-78.
Maness, D.J. 1987. Economic analysis of sludge disposal
alternatives, p. 7-10. In Proceedings of the 17th National
Conference on Municipal Sewage Treatment. HMRCI Publications,
Silver Spring, Maryland.
Merkel, D.M., J.B. Hart, P.V. Nguyen and C.W. Ramm. 1986.
Municipal sludge fertilization on oak forests in Michigan:
estimation of long-term growth responses, p. 292-300. In D.W.
Cole, C.L. Henry and W.L. Nutter (eds.) The Forest Alternative
for Treatment and Utilization of Municipal and Industrial Wastes.
University of Washington Press, Seattle.
Michigan Department of Natural Resources. 1982. The municipal
wastewater sludge management program. Sludge Management Unit,
Water Quality Division, Lansing. 13 p.
Michigan Department of Natural Resources. 1984. Guide to
preparing a residuals management plan. Land Application Unit,
Groundwater Quality Division, Lansing. 17 p.
86
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Michigan Department of Natural Resources. 1986. Guidance for
land application of wastewater sludge in Michigan. Land
Application Unit, Groundwater Quality Division, Lansing. 32 p.
Micro Data Base Systems (MDBS). 1984. Knowledgeman reference
manual. Version 1.07. Micro Data Base Systems, Inc., Lafayette,
Indiana..
Morris, C.E. and W.J. Jewell. 1977. Regulations and guidelines
for land application of wastes: a 50 state overview, p. 9-28.
ITI R.C. Loehr (ed.) Land as a Waste Management Alternative.
Ann Arbor Science Publishers, Ann Arbor, Michigan.
•.
National Oceanographic and Atmospheric Association (NOAA). 1981.
Climatological data, annual summary, Michigan. Volume 96.
National Oceanographic and Atmospheric Association (NOAA). 1982.
Climatological data, annual summary, Michigan. Volumes 96 and 97.
Peyton, R.B. and L.M. Gigliotti. 1986. Public perceptions and
acceptance of sludge application to state forest lands in
Michigan. Final Project Report. Dept. of Fisheries and Wildlife,
Michigan State University, East Lansing. 20 p.
Richter, D.D., D.W. Johnson and D.M. Ingram. 1982. Effects of
municipal sewage sludge-cake on nitrogen and phosphorus
distributions in a pine plantation, p. 532-546. In Fifth Annual
Madison Conference of Applied Research and Practice on Municipal
and Industrial Waste. Dept. of Engineering and Applied Science,
University of Wisconsin, Madison.
Sidle, R.C. and L.T. Kardos. 1979. Nitrate leaching in a
sludge-treated forest soil. Soil Science Society of America
Journal 43:278-282.
Smith, W.H. and J.O. Evans. 1977. Special opportunities and
problems in using forest soils for organic waste application.
p. 429-454. j[n L.F. Elliott and F.J. Stevenson (eds.) Soils for
Management of Organic Wastes and Waste Waters. American Society of
Agronomy, Madison, Wisconsin.
Sopper, W.E. and S.N. Kerr (eds.). 1979. Utilization of
municipal sewage effluent and sludge on forest and disturbed
land. The Pennsylvania State Universtiy Press, University Park.
537 p.
87
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Sullivan, R.H. 1973. Federal and state legislative history and
provisions for land treatment of municipal wastewater effluents
and sludge, p. 1-7. rn D.R. Wright, R. Kleis and C. Carlson
(eds.) Recycling Municipal Sludges and Effluents on Land.
National Association of State Universities and Land Grant
Colleges, Washington, D.C.
Underwood, E.J. 1977. Trace elements in human and animal
nutrition. Academic Press, New York. 545 p.
United States Environmental Protection Agency. 1985. The 1984
needs survey, a report to Congress. Office of Municipal
Pollution Control, U.S. Environmental Protection Agency,
Washington, D.C.
Urie, D.H., A.J. Burton, J.B. Hart and P.V. Nguyen. 1986.
Hydrologic and water quality effects from sludge application to
forests in northern Lower Michigan. Final Project Report. Dept.
of Forestry, Michigan State University, East Lansing. 131 p.
Urie, D.H., A.R. Harris and J.H. Cooley. 1984. Forest land
treatment of sewage wastewater and sludge in the Lake States.
p. 101-110. In Research and Development Conference Proceedings,
T.A.P.P.I. Press, Atlanta, Georgia.
Walsh, L.M. 1976. Application of sewage sludge to cropland:
appraisal of potential hazards of heavy metal to plants and
animals. Council for Agricultural Science Technical Report No.
64. Iowa State University, Ames.
Wells, C.G., K.W. McLeod, C.E. Murphy, J.R. Jensen, J.C. Corey,
W.H. McKee and E.J. Christensen. 1984. Response of loblolly
pine plantations to two sources of sewage sludge, p. 85-94. In
Research and Development Conference Proceedings, T.A.P.P.I.
Press, Atlanta, Georgia.
West, S.D., R.D. Taber and D.A. Anderson. 1981. Wildlife in
sludge-treated plantations, p. 115-122. Iri C.S. Bledsoe (ed.)
Municipal Sludge Application to Pacific Northwest Forest Lands.
Institute of Forest Resources Contribution No. 41, University of
Washington, Seattle.
Zasoski, R.J., D.W. Cole and C.S. Bledsoe. 1983. Municipal
sewage sludge use in forests of the Pacific Northwest, U.S.A.:
growth responses. Waste Management and Research 1:103-114.
88
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Zasoski, R.J., R.L. Edmonds, C.S. Bledsoe, C.L. Henry, D.J. Vogt,
K.A. Vogt and D.W. Cole. 1984. Municipal sewage sludge use in
forests of the Pacific Northwest, U.S.A.: environmental
concerns. Waste Management and Research 2:227-246
PROJECT PUBLICATIONS
Assaff, E., R.B. Peyton and L.M. Gigliotti. 1986. The sludge
solution: comparing the alternatives. Dept. of Fisheries and
Wildlife, Michigan State University, East Lansing. 24 p.
Brockway, D.G. and P.V. Nguyen. 1986. Municipal sludge
application in forests of northern Michigan, a case study.
p. 477-496. In D.W. Cole, C.L. Henry and W.L. Nutter (eds.) The
Forest Alternative for Treatment and Utilization of Municipal and
Industrial Wastes. University of Washington Press, Seattle.
Brockway, D.G., D.H. Urie, P.V. Nguyen and J.B. Hart. 1986.
Wastewater and sludge nutrient utilization in forest ecosystems.
p. 221-245. _In D.W. Cole, C.L. Henry and W.L. Nutter (eds.)
The Forest Alternative for Treatment and Utilization of Municipal
and Industrial Wastes. University of Washington Press, Seattle.
Burton, A.J. 1986. Nitrogen transformations and nitrate leaching
following sludge application to four Michigan forest types. M.S.
Thesis. Dept. of Forestry, Michigan State University, East
Lansing. 141 p.
Burton, A.J., D.H. Urie and J.B. Hart. 1986. Nitrogen
transformations in four sludge-amended Michigan forest types.
p. 142-153. In D.W. Cole, C.L. Henry and W.L. Nutter (eds.) The
Forest Alternative for Treatment and Utilization of Municipal and
Industrial Wastes. University of Washington Press, Seattle.
Campa, H. 1982. Nutritional responses of wildlife forages to
municipal sludge application. M.S. Thesis. Dept. of Fisheries
and Wildlife, Michigan State University, East Lansing. 88 p.
Gigliotti, L.M. 1983. A public assessment of concerns and
beliefs about forest application of sludge. M.S. Thesis. Dept.
of Fisheries and Wildlife, Michigan State University, East
Lansing. 252 p.
89
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Gigliotti, L.M. and R.B. Peyton. 1986. A manual for public
involvement in planning sludge management programs. Dept. of
Fisheries and Wildlife, Michigan State University, East Lansing.
78 p.
Hartf J.H., J.B. Hart and P.V. Nguyen. 1986. Aspen mortality
following sludge application in Michigan, p. 266-271. In D.W.
Cole, C.L. Henry and W.L. Nutter (eds.) The Forest Alternative
for Treatment and Utilization of Municipal and Industrial Wastes.
University of Washington Press, Seattle.
Haufler, J.B. and S.D. West. 1986. Wildlife responses to forest
application of sewage sludge, p. 110-116. rn D.W. Cole, C.L.
Henry and W.L. Nutter (eds.) The Forest Alternative of Treatment
and Utilization of Municipal and Industrial Wastes. University
of Washington Press, Seattle.
Lagerstrom, T.R. 1983. Comparison of citizen reaction to a
proposed sludge demonstration project in two Michigan counties.
M.S. Thesis. Dept. of Fisheries and Wildlife, Michigan State
University, East Lansing. 184 p.
Merkel, D.M., J.B. Hart, P.V. Nguyen and C.W. Ramm. 1986.
Municipal sludge fertilization on oak forests in Michigan:
estimations of long-term growth responses, p. 292-300. Ijti D.W.
Cole, C.L. Henry and W.L. Nutter (eds.) The Forest Alternative
for Treatment and Utilization of Municipal and Industrial Wastes.
University of Washington Press, Seattle.
Nguyen, P.V., J.B. Hart and D.M. Merkel. 1986. Municipal sludge
fertilization on oak forests in Michigan: short-term nutrient
changes and growth responses, p. 282-291. In D.W. Cole, C.L.
Henry and W.L. Nutter (eds.) The Forest Alternative for Treatment
and Utilization of Municipal and Industrial Wastes. University
of Washington Press, Seattle.
Peyton, R.B. and L.M. Gigliotti. 1986. Planning for the public
dimension in forest sludge and wastewater application projects.
p. 341-348. In D.W. Cole, C.L. Henry and W.L. Nutter (eds.) The
Forest Alternative for Treatment and Utilization of Municipal and
Industrial Wastes. University of Washington Press, Seattle.
Seon, E.M. 1984. Nutritional, wildlife and vegetative community
response to municipal sludge application of a jack pine/red pine
forest. M.S. Thesis. Dept. of Fisheries and Wildlife, Michigan
State University, East Lansing. 75 p.
90
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Thomas, A.M. 1983. First-year response of wildlife habitat to
sewage sludge application in a northern hardwoods forest. M.S.
Thesis. Dept. of Fisheries and Wildlife, Michigan State
University, East Lansing. 81 p.
Orie, D.H. and D.G. Brockway. 1986. Relating research results
to sludge guidelines for Michigan's forests, p. 383-389. Ir\
D.W. Cole, C.L. Henry and W.L. Nutter (eds.) The Forest
Alternative for Treatment and Utilization of Municipal and
Industrial Wastes. University of Washington Press, Seattle.
Woodyard, D.K. 1982. Response of wildlife to land application
of sewage sludge. M.S. Thesis. Dept. of Fisheries and Wildlife,
Michigan State University, East Lansing. 64 p.
Woodyard, D.K. 1986. Risk evaluation for sludge-borne elements
to wildlife food chains. Ph.D. Dissertation. Dept. of Fisheries
and Wildlife, Michigan State University, East Lansing. 188 p.
PRINCIPAL INVESTIGATORS
Dr. James B. Hart, Associate Professor
Dept. of Forestry
Michigan State University
East Lansing, Michigan 48824
(517) 355-9528
Dr. Jonathan Haufler, Associate Professor
Dept. of Fisheries and Wildlife
Michigan State University
East Lansing, Michigan 48824
(517) 355-4477
Dr. R. Ben Peyton, Associate Professor
Dept. of Fisheries and Wildlife
Michigan State University
East Lansing, Michigan 48824
(517) 355-4477
Dr. John H. Hart, Professor
Dept. of Botany and Plant Pathology
Michigan State University
East Lansing, Michigan 48824
(517) 355-4687
Forest fertilization,
soils and hydrology
Wildlife ecology,
populations, habitat
and food chains
Citizen participation
in the public
planning process and
related sociological
dynamics
Forest tree pathology
91
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Dr. Carl W. Ramm, Associate Professor
Dept. of Forestry
Michigan State University
East Lansing, Michigan 48824
(517) 355-2399
Dr. Phu ,V. Nguyen, Assistant Professor
Dept. of Forestry
Michigan State University
East Lansing, Michigan 48824
(517) 355-1836
Dr. Dean H. Urie, Research Associate
Dept. of Forestry
Michigan State University
East Lansing, Michigan 48824
(517) 355-7740
Dr. Dale G. Brockway, Project Manager
Dept. of Natural Resources
P.O. Box 30028
Lansing, Michigan 48909
(517) 373-8750
Forest biometrics,
tree growth, site
productivity
Nutrient cycling,
forest soils and
silviculture
Forest hydrology and
water quality
Forest ecology,
forest soils,
silviculture, forest
fertilization and
nutrient cycling
RESEARCH ASSISTANTS
Michigan State University, Dept. of Fisheries and Wildlife:
Larry M. Gigliotti
David K. Woodyard
Henry Campa
Anne H. Thomas
Elena M. Seon
Thomas R. Lagerstrom
Public participation planning
Wildlife food chains
Deer and elk
Wildlife habitat and populations
Wildlife habitat and populations
Public opinion assessment
Michigan State University, Dept. of Forestry:
Dennis M. Merkel
Andrew J. Burton
Tree growth and site productivity
Forest hydrology and water quality
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
1. REPORT NO.
EPA-905/9-91-003
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Sludge Fertilization of State Forest Land
in Northern Michigan
5. REPORT DATE
April 1988
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
Dale G. Brockway, Ph.D.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Michigan Department of Natural Resources
P.O. Box 30028
Lansing, Michigan 48909
10. PROGRAM ELEMENT NO.
A42B2A
11. CONTRACT/GRANT NO.
S005551
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency, Region V
230 South Dearborn
Chicago, Illinois 60604
13. TYPE OF REPORT AND PERIOD COVERED
Final 6/80 to 3/86
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Stephen Polonscik, USEPA Project Officer
Ralph G. Christensen, Section 108A Coordinator, GLNBO
16. ABSTRACT '——~~~—' "
A five-year research-demonstration project to examine the logistical, economic, environ-
mental and sociological aspects of municipal wastewater sludge application was conducted
on State Forest land occupied by forest types of major commercial importance in northern
Michigan. Sludge applications of 9 Mg/ha resulted in increased levels of nutrients in
forest floor and vegetation and increased tree growth and understory productivity.
Improvement in the structural complexity of wildlife habitat and the nutritional quality
of important wildlife food plants was observed. Wildlife numbers and browse utilization
increased on sludge treated areas. Food chain biomagnification studies found no
significant risk of heavy metal transfer to wildlife or humans. Public preference among
various sludge management alternatives is a direct result of the perceived level of
protection each affords public health and environmental quality. While forest land
application was the second most preferred option, as the public comes to recognize the
environmental hazards and economic limitations inherent with incineration and the value
of sludge as a byproduct resource, forest land application should receive increasing
attention as a preferred sludge management alternative. State regulatory and resource
management authorities are committed to use of this newly developed technology in
addressing waste management and land management issues.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIRERS/OPEN ENDED TERMS C. COSATI Field/Group
Wastewater sludge, land application,
ilviculture, forest productivity,
groundwater quality, wildlife habitat,
wildlife nutrition, food chain, forest
fertilization, public involvement,
mblic education.
Ecology
Forestry
Soil Science
Hydrology
Wildlife Biology
Sociology
8. DISTRIBUTION STATEMENT
Public Information
19. SECURITY CLASS (This Report)
Unrestricted
21. NO. OF PAGES
104
20. SECURITY CLASS (Thispage/
22. PRICE
EPA Form 222Q-! (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
93
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