EPA 910/9-77-042
DEVELOPMENT OF A MODEL
SANITARY LANDFILL SITE DESIGN
FOR SNOHOMISH COUNTY, WASHINGTON
by
Snohomish County Department of Public Works
Solid Waste Division
County Administration Building
Everett, Washington 98201
Prepared for
U.S. Environmental Protection Agency
Region X
Air and Hazardous Materials Division
Solid Waste Management Program
1200 Sixth Avenue
Seattle, Washington 98101
Grant Number: S-801761
October 1975
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EPA 910/9-77-042
DEVELOPMENT OF A MODEL
SANITARY LANDFILL SITE DESIGN
FOR SNOHOMISH COUNTY, WASHINGTON
by
Snohomish County Department of Public Works
Solid Waste Division
County Administration Building
Everett, Washington 98201
Grant Number: S-801761
EPA Project Officer: Tobias A. Hegdahl
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Region X
Air and Hazardous Materials Division
Solid Waste Management Program
1200 - Sixth Avenue
Seattle, Washington 98101
October 1975
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This report was furnished to the Environmental Protection Agency
by the Snohomish County Department of Public Works, Solid Waste Division
in fulfillment of Grant No. S-801761. The contents of this report are
reproduced herein as received from the Grantee. The opinions, findings,
and conclusions expressed are those of the authors and not necessarily
those of the Environmental Protection Agency- Mention of company or
products names is not to be considered as an endorsement by the Environ-
mental Protection Agency.
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PREFACE
In March of 1973, Snohomish County, Washington, was awarded
$150,000 under Section 204 of the Solid Waste Management Act as
amended. The purpose of the award was to provide partial support to
the County in the development of a regional solid waste management
system. The funds provided by the EPA marked the beginning of a compre-
hensive, six year solid waste management implementation program.
The primary objective of the grant program was to develop and
make available for public examination an operating, model sanitary landfill,
together with the associated design plans, reports, and environmental
impact statement. As of this date, the County has not been successful in
achieving an operating landfill. However, the design plans, reports, and
an environmental impact statement have been completed. These documents,
h
in themselves, should serve as a valuable resource to other persons con-
fronted with the need to develop final disposal sites for solid waste.
To provide for the dissemination and public review of this informa-
tion, a series of three reports has been prepared. These reports are as
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follows:
1. "Development of a Regional Solid Waste Management System
For Snohomish County, Washington."
2 . "Development of a Model Sanitary Landfill Site Design For
Snohomish County, Washington."
3. "Development of a Sanitary Landfill Environmental Impact
Statement For Snohomish County, Washington."
Each report relates to a specific area of interest and stands alone
in that regard. At the same time, each report discusses only one aspect
of a broad planning and implementation effort. Readers interested in a
more thorough analysis of any of the specific reports, or a more general
analysis of the Snohomish County Solid Waste Management Implementation
Program, should review all three of the reports.
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ACKNOWLEDGEMENTS
The Snohomish County Comprehensive Solid Waste Management
Implementation Project has benefited from considerable information and
support supplied by various governmental, private, and citizen organiza-
tions. The special assisstance of the following persons and organizations
is gratefully acknowledged:
Board of Snohomish County Commissioners
C. Earl Torgeson
N. Richard Forsgren
Charles Hill
Snohomish County Solid Waste Management Steering Committee
Snohomish Health District, Clarice Hyatt, M.D., Director
Snohomish County Department of Public Works, Harry D0 Martin,
P. E., Director
Snohomish County Planning Department, George Sherwin, Director
Snohomish County Prosecuting Attorney's Office
Stevens, Thompson and Runyan, Inc., Dirk Van Woerden, P.E.
Project Manager
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The primary authors of this report have been as follows:
Rodney G. Hansen, Director, Solid Waste Division, Snohomish
County Department of Public Works
Byron D. Robertson, Environmental Specialist, Solid Waste
Division, Snohomish County Department of Public Works
Ronald J. Owes, Partner, Harper-Owes
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TABLE OF CONTENTS
Section Page
Number Section Titles Number
Preface 3
Acknowledgements
Table of Contents 7
Summary 8
I. Introduction
12
II. Background Information
III. Initial Site Selection 14
IV. Final Site Selection 18
V. Development of Final Design 25
VI. Content of the Appendices
VII. Appendix 35
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SUMMARY
The purpose of this report is to aid agencies and municipalities in
selecting and designing a modern sanitary landfill site. This report will be
most useful to those persons desiring to select and design a landfill in areas
of historically high rainfall and high groundwater tables.
This report will also describe to the reader a method by which a
sanitary landfill site can be selected and designed concurrent with the
preparation of the environmental impact statement. By utilizing this process,
as environmental impacts are identified, the design can be modified to
mitigate those impacts. The report describes those criteria which should
be utilized for selecting a sanitary landfill site. These criteria tend to
emphaisze minimization of these environmental impacts.
The design of this sanitary landfill has several unique features which
might be of interest to the reader. These include a background water quality
monitoring program conducted far in advance of construction of the sanitary
landfill; extensive precautions for the prevention of groundwater contamination,
leachate collection, and treatment. The design of the sanitary landfill is
•
phased or staged to minimize environmental impacts and to afford flexibility
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in terminating the operation if so desired.
It can be concluded from this report that a modern sanitary landfill
can be selected and designed to operate in areas of high groundwater tables
and high net annual rainfall without contaminating surface or ground water
and minimizing ancillary impacts .
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I. INTRODUCTION
This report will describe how Snohomish County. Washington,
selected a sanitary landfill site and arrived at an ultimate design.
Appended to this report is Volume I and Volume II of the sanitary land-
fill Design Report. Volume I (Appendix A) is the site design showing
location and construction of most of the major features of the landfill.
Volume II (Appendix B) contains supportive data for Volume I, such as
water quality monitoring data, soils investigations, geological research,
and percolation testing of the bedrock. Close scrutiny of.the appendices
will provide the reader with an opportunity to examine those features
necessary for the operation of a sanitary landfill in an area of high rain-
fall. These documents depict a landfill built to very high standards of
environmental protection.
Anyone contemplating construction of a sanitary landfill in an area
where protection of groundwater quality is paramount will find the appended
designs useful. Because the expertise required to design a sanitary land-
fill to these high standards was not possessed by Snohomish County, an
engineering consultant was retained to aid in the site selection and develop
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the site design. The consultant's obligation was to produce: 1)
Evaluations of the sites selected by Snohomish County as candidates
for the sanitary landfill; 2) Once final selection had been made, the
consultant was to produce an acceptable design; 3) And the consultant,
together with the County, was to write a draft and final environmental
impact statement. Additionally, the consultant was to have recognized
experts in the field of solid waste management available for permit hearings,
if needed. The contract negotiated with the general consultant was a "cost
plus" to a maximum ceiling type. It was felt by the County that more
quality work could be obtained with this arrangement than by a "fixed price"
contract.
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II. BACKGROUND INFORMATION
Snohomish County, located in the western half of the State of
Washington, is approximately 1900 square miles and has a population of
about 260,000 people. On the eastern side of the County are located the
rugged Cascade Mountains, which make approximately one third of the
land area unusable for urbanization. On the western perimeter of the County
is located Puget Sound, a major port for shipping lines to the Orient.
Because Snohomish County is relatively close to the Pacific Ocean and is
backed on the east by high mountains, moist, humid air coming from the
west off the ocean tends to deposit the majority of the precipitation in
Snohomish County rather than carrying it on further to eastern areas of the
state. As a result, Snohomish County is typified by areas of high rainfall
to areas of extremely high rainfall and has warm, moderate temperatures
throughout both the summer and winter.
Geologically, Snohomish County is underlain by soil strata of a
relatively impermeable nature. Because the County has high rainfall and
relatively impermeable soils, high groundwater tables throughout the area
typify Snohomish County's groundwater situation. Obviously, when
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determining the selection of the proposed sanitary landfill site and designing
that site, high groundwater tables played a very serious role in this process.
Fortunately, the County is served by a major transportation route in
the form of an interstate highway running north and south from border to bor-
der in the western portion of the County. One major mountain pass is served
by an all-weather, heavy-duty highway originating from the interstate highway
and heading to the east. The County has developed a "corridor" type demo-
graphic distribution running parallel to and adjacent to the major interstate
highway with the most dense populations found in the southwest portions of
the County between the interstate highway and the bay.
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III. INITIAL SITE SELECTION
In 1971, Snohomish County initiated development of a solid waste
management planning effort, funded in part by the Department of Housing
and Urban Development and conducted by the Snohomish County Planning
Department. This planning effort, WASH-USE-1, addressed the problem of
solid waste disposal in the County. It determined that the existing dis-
posal system consisting of fourteen open dumps and/or improperly operated
landfills was not capable of serving the County in an environmentally
suitable manner. In addition, the landfill which served the City of Everett,
the major metropolis in the County, was determined to be nearing capacity
with no replacement available. The conclusion was then arrived at that
new solid waste disposal facilities would have to be developed in the im-
mediate future if the County was to prevent a crisis because of the unavaila-
bility of a means of waste disposal.
The planning effort concentrated on selecting an appropriate means
for solid waste disposal that would serve the County in the most cost/
effective and environmentally suitable manner. A number of potential alter-
natives were evaluated, including incineration and various resource recovery
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techniques. The conclusion reached in the evaluation was that sanitary
landfills were the most cost/effective alternative for waste disposal at
that time for the conditions existing in Snohomish County.
The planning effort, then, attempted to identify potential sanitary
landfill locations. Many individuals, recognizing the County's need for
a solid waste disposal site, came forward and offered potential sites of
their own. These people included land speculators. County employees
who knew of potential sites, and, in some cases, independent disposal
site operators. The County decided to utilize the services of real estate
brokers to identify parcels of land which were or might be available for
purchase. This was necessary since the County did not have condemna-
tion authority for obtaining land for a sanitary landfill. Criteria were
developed for identifying available parcels as potential sanitary landfill
sites. The criteria included requirements that the site must be readily
accessible by a major County roadway and that the site, if developed as
a sanitary landfill, would not conflict with existing and forecasted land
use in the vicinity. In addition, identified sites were assessed as to
topography and soils characteristics using available maps provided by the
United States Coast And Geodetic Survey and the Soil Conservation Service.
Using this process, seventeen sites were identified as potential locations
for sanitary landfills.
The WASH-USE-1 planning program analyzed the seventeen potential
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landfill sites by comparing operations, implementation, and transport costs
through use of a computer program. The results of this analysis, then,
enabled the sites to be ranked according to least cost. While expense is
a very important parameter to consider in the site selection process, it
should not be the sole criterion. It's important to consider other parameters
during the site selection process such as the aesthetic impact on surrounding
property owners, ability to control pollutants produced by the landfill site,
visual and noise obscuring buffers, and other items principally relating to
environmental impact. However, in this particular case, these other items
were not considered during initial selection. The County was looking for
a least cost solution solution primarily, and the site which was recommended
as being least costly was located near Paine Field, an airport used by private
aircraft and by the Boeing Company in conjunction with the 747 production
facility.
The implementation effort appeared to be straightforward as the Paine
Field location was initially judged to be acceptable for a sanitary landfill.
Considerable opposition developed almost immediately, however, when it
became known that the Paine Field site was being considered for a sanitary
landfill. The Boeing Company requested a meeting with County staff and
consultants. At the meeting, Boeing attorneys and technical staff questioned
the location because of potential danger to aircraft using Paine Field. They
felt that a sanitary landfill in the vicinity would attract birds, specifically
seagulls, and that these birds would endanger aircraft because of the
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potential for collisions. In response to these concerns, an evaluation
was made of the ability to control birds at the landfill site. The evaluation
determined that while it was possible to keep birds away from a sanitary
landfill operation, it was not possible to guarantee that birds would never
be attracted to the site. This meant that there was the possibility that the
County could be held liable if there was an aircraft accident. Because of
this, the Paine Field location was dropped from further consideration as a
sanitary landfill.
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VI. FINAL SITE SELECTION
Up to this point, the initial site selection process had been conducted
principally by the Snohomish County Planning Department. During the period
of time when the Paine Field site was under consideration, a Department of
Public Works, with responsibility for solid waste management in Snohomish
County, was created. One of the tasks of the Department of Public Works
was to complete the site selection process. The Department of Public Works,
being the agency which was going to have to implement the landfill when it
was finally selected, had certain criteria in mind which they would like to
have in any sanitary landfill site located in Snohomish County. Primarily,
these criteria were design oriented. The Department of Public Works wanted
to find a landfill site which contained these certain criteria so that they
would not have to be developed as part of the design later. Additionally,
solid waste management legislation, which was either adopted or on the
horizon, was starting to impinge upon the site design characteristics and,
therefore, on the site selection criteria. By identifying these regulatory
constraints and desirable operating characteristics, additional site selection
criteria were developed to re-evaluate the sites previously selected in the
planning study in order to select a preferred one for conducting engineering
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feasibility studies. These desired characteristics included the following:
On-site soils must be available for cover during landfill
operations and with characteristics which would enable ample
compaction for vector control and not hinder operations during
wet weather.
An impervious sub-strata should be present to afford
protection of groundwater contamination by leachate.
A defined on-site drainage pattern should exist, preferably
draining to the site's center to enable diversion of surface waters
and collection of leachate generated from the landfill.
Site topography and size should be sufficient to enable
maintenance of a buffer area to shield landfill operations from
adjacent areas and from public view during the site's operational
life.
Site topography and soils conditions should allow develop-
ment of the sanitary landfill in short time increments to afford
flexibility and minimization of environmental impacts.
The site must be located above major flood plains and
outside the vicinity of densely populated areas during its
operational life.
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To re-evaiuate potential landfill sites, assistance was obtained from
the United States Soils Conservation Service. This assistance included on-
site reconnaissance surveys in which soils and topography were examined.
In addition, sub-surface soils characteristics were determined in a prelimi-
nary nature by digging test pits with shovels and pesthole diggers.
The re-evaluation of available sites culminated with the selection
of two preferred candidate locations which could be developed as sanitary
landfills to serve the urban portion of Snohomish County. A special con-
sultant with expertise in soils and geology was then retained to assist in
selecting between the two. After preliminary field examinations by the
special consultant, it was determined that neither site was ideal for devel-
opment as a sanitary landfill. In particular, both sites contained fine soils
which could present operational problems during wet weather. Field examina-
tions also indicated that groundwater surfaced occasionally on both sites in
the form of springs and seeps, making drainage control and leachate attenua-
tion difficult. It was decided that a more thorough site evaluation was
required for both sites in order to selected either for design.
The evaluation of the two candidate landfill sites emphasized soils
and geologic analyses „ Backhoe test pits were utilized to examine sub-
surface conditions, including defining soils types and strata locations and
groundwater flow patterns. On the basis of these evaluations, one site was
found to be completely unacceptable for a sanitary landfill. This conclusion
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was reached when sub-surface examinations found that the site was
underlain by alternating strata of clay and sandy soils intersected by the
site's surface. Groundwater then flowed through the sandy soil strata
atop the clay materials and could surface on the site at a variety of
locations as seeps and springs. It was determined that it would be extremely
difficult, if not impossible, to prevent this water from discharging into a
sanitary landfill area and thus increase the generation of leachate and
polluted water. The second site under evaluation, referred to as the Winter-
mutes Corner site, was found to also contain sandy soils atop more impervious
strata. The location of the soil strata and associated surfacing of ground-
water could permit containment of surface and groundwaters, however,
preventing contamination by solid waste placed at the site. It was deter-
mined that containment of surface and groundwaters would add considerable
cost to development of the Wintermutes Corner site, however. In addition,
the cost of purchasing the site was found to have increased substantially
above that initially estimated. The initial cost estimate was based on a
verbal understanding; and when actual negotiations began for purchase or
lease of the site, the cost was considerably higher. Thus, serious reserva-
tions developed as to the suitability of the Wintermutes Corner site for a
sanitary landfill.
Because of high costs associated with development of the Winter-
mutes Corner site, another alternative location was selected for detailed
evaluation. This site, referred to as the Cathcart site, had been identified
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previously in the planning effort. The Cathcart site had not been seriously
considered, however, because waste transport distances were greater for
it than for the other sites considered, thus making it appear to be uneco-
nomical because of haul costs. It was determined that a cost comparison
should be developed for the Cathcart and Wintermutes Corner sites to make
a final site selection. This comparison was needed to determine cost trade-
offs associated with the greater haul distances to the Cathcart site but
possible higher development and operations costs of the Wintermutes Corner
site. To complete this cost comparison, the Cathcart site was first evalua-
ted in the same manner that the Wintermutes Comer site had been, including
a detailed analysis of site drainage and sub-surface characteristics. A
preliminary engineering design was completed for each site which emphasized
design features which would differ between the two sites. This preliminary
design included development of site layouts, soil excavation requirements,
and preliminary selection and sizing of drainage and leachate control facili-
ties. In addition, a preliminary environmental impact assessment was
prepared for each site to assist in final evaluation.
The preliminary engineering studies first addressed site descrip-
tions and locational considerations. Included in the locational considera-
tions was a determination of the applicability of zoning and land use of
the site and its vicinity. The availability of required access roads and
utilities was also determined. A preliminary soils and geologic
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investigation was conducted for each of the sites using the services of
a qualified soils engineer and geologist. These investigations included
visual site surveys and preliminary sub-surface analyses utilizing test
pits excavated by a backhoe. The purposes of the soils and geologic
investigations included a determination of the workability of soils located
at the sites for use as cover during sanitary landfill operations. In
addition, a preliminary determiniation of the natural hydrology of the sites
was made using the geologic data. This enabled a prediction of potential
problems associated with leachate contamination of surface and ground
waters.
A preliminary site layout was completed for each site to serve as
the basis for estimates of the costs associated with site development. The
layout also enabled estimates of the landfill operation life for each of the
sites. The preliminary layout established requirements for site facilities
and equipment and presented preliminary locations of design features „ Also
of importance was the determination of the need for site buffer areas to serve
as a screen and containment for certain environmental impacts associated
with sanitary landfill operations. Finally, a preliminary cost estimate was
made for developing and operating sanitary landfills at each site.
A summary of the information developed in the preliminary site
designs was then presented for use in the final selection of a sanitary land-
fill site. This information was divided into four categories: locational
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considerations, environmental considerations, operational considerations,
and economic considerations. Locational considerations included waste
transport distances and land use compatibility. Environmental considera-
tions included defining the potential for water pollution at each site,
hydrology and drainage effects, gas and odor considerations, noise con-
siderations , and the ability to control vectors. Operational considerations
included describing differences in site workability, differences in flexi-
bility in developing or terminating operations at each site, and landfill
life estimates. Finally, economic considerations included differences in
initial costs and operational costs.
Based on the results of the final evaluation, the Cathcart site was
selected for design as a sanitary landfill to serve the urban portion of
Snohomish County. The site was found to have the lowest total annual
cost of all sites analyzed and had the lowest potential for adverse envi-
ronmental impact. The process undertaken to arrive at the final site
selection involved considerable time and effort. The selection has
resulted in considerable opposition from property owners in the vicinity
of the Cathcart site, as can be expected in most instances when a new
waste disposal location is sought. Without the time and effort that went
into the site selection process, it would be impossible to convince the
citizens of the County that the selected location was in fact the best
alternative available.
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V. DEVELOPMENT OF FINAL DESIGN
The final design process for the Cathcart Sanitary Landfill site
included building on the efforts from the preliminary design process and
refining design features in conjunction with the development of the
environmental impact statement. As impact analyses were conducted,
design features were developed or refined to reduce or eliminate
identified adverse impacts.
The initial step in carrying out the final site design was the
development of more complete and accurate soils and geologic informa-
tion. This was done through the analysis of soil borings taken at the
Cathcart site. Of special importance in these analyses was the defini-
tion of locations of various soils strata and a definition of their properties.
This information then enabled an analysis of the leachate attenuating
properties of the materials at the site, their workability, and the estab-
lishment of elevations for excavating soils for construction of the sanitary
landfill.
It was determined early in the design process that the least
amount of area possible would be developed and operated as a landfill
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at any one time. This would be done to minimize environmental impacts
and to afford flexibility in terminating the operation if so desired. The
landfill would then be developed in stages whereby operations could
be conducted in one area as another area was being prepared. It was
then necessary to define the locations and sizes of each staged opera-
tional area. In order to do this , the desired dimensions of landfill cells
were established. These dimensions were based on the length required
to provide needed access by waste transport vehicles and on a calculation
of the dimensions which would require the least amount of cover material.
Boundaries of the overall sanitary landfill area within the site were estab-
lished based on buffer area, site access, and facility requirements. The
dimensions of the staged operational areas were then established within
the overall sanitary landfill area to complement the established cell dimen-
sions and to allow for required access to the landfill operation by waste
haul vehicles. The lower elevation of the landfill area was established
based on soils and geologic information and on drainage requirements for
collecting leachate which would form at the bottom of the landfill.
On-site facility requirements were then established and designed.
These include access roads, buildings, a truck washing facility and
utilities. Of primary emphasis was the design of drainage and water
pollution control facilities as this effort was deemed critical for minimi-
zation of environmental impact. It was determined that two separate
systems should be developed for drainage control—one for drainage entering
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the site at its perimeter (off-site surface run-off), and one for drainage
within the site perimeter (on-site surface run-off drainage). The
purpose of the off-site surface water collection system is to divert
drainage around the site, thereby minimizing the amount of water which
could potentially be contaminated through contact with waste deposited
at the site. This was done through the design of an intercepting and
diversion ditch which would transport drainage around the site in a manner
which would have a low erosion and sedimentation potential. The on-site
drainage system design consists of a pipe network eventually to be
located under the fill areas to transport surface run-off waters off-site.
The pipe network would be protected with an impervious material to
prevent leachate contamination and would only function during the life
of the sanitary landfill operations. After completion of the landfill, the
off-site drainage collection system would serve as the collector for all
drainage.
The development of methods for preventing leachate contamination
of ground and surface waters was approached in a conservative manner.
The Cathcart site is located in an area of high net annual rainfall where
a history exists of water quality problems associated with solid waste
disposal sites. It was thus determined that all practicable means would
be developed to prevent water quality degradation. The concept of di-
verting all drainage around the landfill area is the first step in this process,
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aimed at allowing the least amount of water possible to enter the fill
area and thus become contaminated. The second design concept involves
establishment of a barrier for preventing any leachate generated at the
site from migrating through the bottom soils into the groundwater.
Soils investigations indicated that materials on the site were relatively
impervious and would afford a certain degree of leachate attenuation.
It was determined, however, that an additional barrier would be necessary.
Testing of available materials for use as a barrier is recommended prior
to selection of the specific sealant material.
The final concept in the prevention of water quality degradation
is the development of a leachate collection and treatment system. It is
anticipated that the attenuation provisions will result in the lack of
leachate movement out of the area. A monitoring program was developed
(and is described in Appendix A) to determine if leachate generation could
present a potential water quality problem, however. In the event that
leachate generation is detected, a system was designed to collect and
treat the pollutant. This system consists of a collection pipe located at
the lowest elevation of the fill area. Leachate would flow along the
impervious lower level of the fill area, be collected in the pipe and trans-
ported to a treatment facility. The treatment facility would consist of an
aerated lagoon and physical chemical treatment system. A monitoring
program is also recommended to establish that the treatment system is
adequate since little information exists to enable prediction of treatment
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efficiencies when leachate is being handled. If the treatment system is
found to be inadequate, storage and off-site transport of polluted waters
is recommended.
The final step in the design was the determination of the site
development process. This process consists of site preparation, the
sanitary landfill operation, and the development of the final site use. Each
sequence is described in order to enable the site to be developed in the
appropriate manner, resulting in a final topography desired for potential land
uses.
Certain features in the design of this landfill are unique and are
considered to be significant. The first of these is the background water
quality monitoring program which was begun so that at least 24 consecutive
months of data could be accumulated prior to the landfill becoming opera-
tional. This was achieved by boring six wells down to the first impervious
sub-strata. The wells are distributed throughout the site. These sampling
wells are two inches in diameter, made out of polyvinyl chloride pipe,
and have the well points designed such that water can pass into the wells
but surrounding silt and sediment cannot. The wells were then sampled
by a simple vacuum hand-pump every two weeks for the first 18 months
and once a month thereafter. The samples collected were subjected to an
extremely wide range of analyses so as to cover all possible or probable
contaminants which might be expected from the landfill once it's opera-
tional. The data derived from the background water quality monitoring
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program appears in Appendix B of the attached appendices. Once the
landfill becomes operational, the water quality monitoring program will
be continued via peripherally located groundwater monitoring wells. The
data derived during the ongoing water quality monitoring program will be
continually compared to the background quality data which was obtained
prior to the opening of the landfill. During operation of the landfill,
groundwater samples will be subjected to a variety of analyses with
different sampling schedules for different parameters. The proposed ongoing
water quality monitoring program is described in detail in Volume I of the
appended Design Report (Appendix A).
Another unique attribute of the design of the Cathcart Sanitary
Landfill is the drainage and pollution control facilities. Basically, the
drainage and pollution control facilities are designed to do three things:
1) Reduce the net infiltration of water into the solid waste; 2) Collect
the net ex-filtration of water coming out of the solid waste and treat it;
and, 3) Provide the basic facilities that could later be modified for use
in a park-like setting. Reduction of the net infiltration of water into the
solid waste was accomplished by diverting the off-site surface run-off
water via channelization of an on-site stream and by application of an
impermeable final cover to the solid waste. To enable the County to
collect the ex-filtrated water as it percolates from the solid waste, a
complex system of perforated pipe underdrains, in situ impermeable soil
strata, and artifically applied impermeable seals under the solid waste
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are used. To provide a park-like setting compatible with the final use of
the landfill and to divert surface water away from the landfill, the chan-
nelized on-site stream was dammed at one point to provide a large
reservoir facility. The stream running from the reservoir was diverted to
keep it away from the active solid waste working area, and flows over
several manmade waterfalls. On-site surface water will be collected
behind a dam at the downgrade end of the property to form a second
permanent reservoir on the site. This reservoir will act as a settling
pond for sediment removal during the active life of the landfill and as a
potential recreation area during the final use stage.
The final feature about this landfill that's considered unique is
the gas control system. Gases produced by the decomposing solid waste
will be allowed to move laterally through the landfill by the construction
of gravel-filled ditches at the highest point of each daily cell. The gas
from the entire fill will be collected through a gravel wall on the north,
east, and west side of the fill. The top of the gravel wall will be sealed
with impervious soils to keep water from running down the gravel wall into
the solid waste.
Penetrating down through the impervious soils and into the top of
the gravel wall will be aluminum vent pipes which will allow the accumu-
lated gases to disperse into the atmosphere. If it is found at a later date
that these gases are producing a nuisance because of their odors or a
hazard because of their flamability, they can then be collected via a
31
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header and burned safely similar to the manner in which methane gas
produced at a sewage treatment plant is burned.
32
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VI. CONTENT OF THE APPENDICES
Volume I of the Design Report explains the design and operation of
the landfill in depth. It begins by describing the design criteria initially
set down which led to the ultimate design of the Cathcart Sanitary Landfill.
Certain assumptions are made regarding the average daily traffic volume
and the average daily waste load. Decisions were arrived at which deter-
mined the controlling cell dimensions. Based on this initial data, typical
solid waste cells could be designed for the sanitary landfill.
Certain items necessary for the operation of the sanitary landfill are
identified in Volume I and includes such buildings and facilities as the gate-
house and scale, truck washing facility, the necessary utilities such as
power, water, telephone, radio, and sewage disposal facilities.
Volume I provides the information necessary to conduct a very
comprehensive groundwater quality monitoring program. Specific parameters
for analysis are discussed as well as sampling frequency. The site develop-
ment sequence section of Volume I of the Design Report describes in general
terms the step by step process through which the sanitary landfill site is
prepared, operated, and put to its final use. It is very important in that it
-------
contains soil volume estimates. Without these soil volume estimates,
it would be impossible to adequately predict the volume of various soils
necessary to operate the landfill through to its conclusion.
Finally, Volume I contains the actual design drawings of the landfill,
stage by stage, plus all of the ancillary facilities which will be constructed
to operate the landfill.
Volume II of the Design Report attached in the appendices contains
most of the supportive documentation necessary to design the landfill.
Primarily, this information is oriented around the soil and geological char-
acteristics of the site. Cross sections are shown, as well as depth to
groundwater, impervious sub-strata, and percolation rates. The water
quality data accumulated over the first 18 months of the water quality
monitoring program will be found in Volume II of the Design Report. The
sample point designations in the water quality reports correspond to the
boring location shown in Volume I, Page 2.
The "heart" of this report is in the attached appendices Volume I
and Volume II. If the reader desires to learn the details of sanitary landfill
construction in wet weather situations, it is recommended that the Design
Report be carefully perused.
34
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Appendix "A"
35
-------
. t ..**.'.'> -*~r .£ •*""iii""- -''.•"'-'• --' . v,"1, i","*.'. ' *. ^i. • -„ "' ' •""".'.. - ,'
" -v • — *• s '-', . ^'. S." • •• i-/* - - • " •.. . ' _.. -.- r.,.,».. ',~ -; - * ?:if "•
Jt .-" '- "., . '."'••- - "' _"'- • A '\ .'.p'-/," - '",- " - ,
-.'•-«:,•. ":"&-;'
.;^?:^^
K^fe^ii
'^v;
•"-Y^-'S;^;^^ ^!'^:-^-^
•'-;;'^-^M'~*SyJi^ ^
-------
SOLID WASTE DISPOSAL SYSTEM
SNOHOMISH COUNTY
CATHCART LANDFILL
DESIGN REPORT
VOLUME I
AUGUST, 1975
Stevens, Thompson & Runyetn, inc.
Engineers / Planners
PORTLAND • SEATTLE • BOISE • SPOKANE
37
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TABLE OF CONTENTS
Page No.
PURPOSE AND SCOPE, 40
EXISTING CONDITIONS 40
FACILITY DESIGN CRITERIA 40
Waste Disposal Area 42
Access Roads 43
Buildings and Facilities 45
Truck Washing Facility 45
Utilities 46
Drainage and Pollution Control Facilities 48
Water Quality Monitoring Program 59
Gas Control Systems 63
Landfill Equipment 64
Buffer Zone and Reserve Areas 64
Fencing 65
Future Considerations 65
SITE DEVELOPMENT SEQUENCE 66
General Approach 66
Phase I - Initial Site Preparation 67
Phase II - Sanitary Landfill Operation 70
Phase III - Final Use 78
APPENDIX A - SOLID WASTE DISPOSAL SYSTEM Volume II
Snohomish County - Facility & Operational Plan
Design - Phase I - Report No. 2
APPENDIX B - WATER QUALITY MONITORING DATA Volume II
APPENDIX C - FINAL DESIGN DRAWINGS Volume I
APPENDIX D - REE'S CORNER SANITARY LANDFILL SITE: Volume II
W-1035-62
APPENDIX E - CATHCART SANITARY LANDFILL SITE: Volume II
SNOHOMISH COUNTY; W-1035-64
APPENDIX F - SUBSURFACE INVESTIGATIONS AND PERCO- Volume II
LATION TESTING OF BEDROCK; LANDFILL
SITE; CATHCART, WASHINGTON; W-1035-66
38
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LIST OF TABLES
Page No.
1. Estimated Solid Waste Design Quantities 42
2. Utilities Required at Cathcart Site 47
3. Characteristics of Proposed Off-Site Runoff 52
Holding Pond
4. Cathcart Site Development Sequence 66
5. Summary of Quantities at End of Landfill 72
Development Stage
LIST OF FIGURES
Page No.
1. Location of Water Monitoring Stations 41
2. Typical Cell Section 44
3. Rainfall Intensity Duration Frequency 50
4. Time of Concentration of Small Drainage Basins 51
39
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PURPOSE AND SCOPE
The purpose of this report ts to summarize the design effort to date,
present the criteria used in the design and identify the steps to be
taken to implement operation of the facilities.
EXISTING CONDITIONS
The 200-acre Cathcart site is located along State Highway No. 9 approxi-
mately 3-1/2 miles south of the City of Snohomish. The existing conditions
at the site are described in the report entitled, "Solid Waste Disposal
System, Snohomish County Facility and Operational Plan Design, Phase I -
Report No. 2," a copy of which is included in this report as Appendix A.
Since the previous report was prepared, additional information regarding
existing conditions has been obtained. This information includes more
detailed soils information and existing ground and surface water quality.
The soils information is presented in three reports (W-1035-62 dated
October 15, 1973; W-1035-64 dated February, 1974; and W-1035-66 dated
August 9, 1974) by Geolabs - Washington, Inc. Copies of the reports are
attached as Appendices D, E, and F.
The State of Washington Department of Ecology has analyzed samples of
ground and surface water surrounding the Cathcart site since the end of
March, 1974. The samples have been taken bi-monthly at the locations
shown on Figure 1. The test results are shown in Appendix B. These data
show that the groundwater has higher concentrations of total organic car-
bon, chemical oxygen demand, turbidity, and dissolved solids than the
surface waters on the site. The quality of the surface waters appears
to be relatively high. These data will provide background information to
detect possible future changes in water quality caused by landfill oper-
ations .
FACILITY DESIGN CRITERIA
Preliminary design drawings and development plan are shown in Appendix C.
These drawings show the location and preliminary design of the following
functional elements:
Waste disposal area
Roads
Buildings and facilities
Utilities
Drainage and pollution control facilities
Water quality monitoring stations
Gas control systems
Landfill equipment
Buffer zone and reserve areas
Fencing
40
-------
»0"«4t"
•OX CULV.-
off site
J«" OIA. CULV.
/T;
«•• 1
7 ;•!
'/ ' .
' '
»
8 i
\
, \
k
?*•- *
LOCATION OF WATER MONITORING STATIONS
41
Figure 1
-------
Detailed descriptions of each element are. presented in following sections.
Waste Disposal Area
Approximately 56 acres of the. site will Be developed as a waste disposal
area as shown on Sheet 1 in Appendix C. The disposal area will be developed
in six stages. Based on the estimated solid waste q-aantities listed in
Table 1, the life of the landfill will be seven to ten years.
Table 1
Estimated Solid Waste Design Quantities
Year Tons per Year
1975 147,000
1980 161,000
1985 178,000
1990 196,000
The area of each stage will vary from eight to twelve acres. The first
stage of approximately 11 acres will be cleared, excavated, and prepared
for receiving the solid wastes and the second stage of approximately 10
acres will be cleared and excavated as part of the initial site prepara-
tion. Part of the excavated soil will be stockpiled in the second stage
area for use as daily cover during the first stage landfill operation.
Before the first stage is filled with four lifts of solid waste, the sec-
ond stage area must be prepared for receiving solid wastes and the third
stage area must be cleared and excavated. The first stage area can be
only partially filled with four lifts of solid waste because truck man-
euvering space will become limited at higher elevations. The second
stage area will then be filled to the same elevation as the first stage,
and both areas can be filled to final elevation. Time to complete the
first and second stage areas is estimated at approximately 3 years. Truck
maneuvering space should not be restricted in other stages. The same basic
sequence of conducting the sanitary landfill operation in the first stage
while preparing the second stage and excavating the third stage will be
followed for the remaining stages. As each stage is completed to final
elevation, the area will receive the final cover material, final grading,
gas controls, and be seeded with grass.
The landfill operations have been developed in accordance with the follow-
ing design criteria:
42
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1. Average Daily Waste Load « 535 tons per day on average weekday of
average month in year 1975, based on a 6 day work week.
2. Average Daily Traffic Volume - 50 trucks per day or 10 trucks per
peak hour on average weekday of average month in year 1975.
3. Basic Cell and Lift Construction Criteria
a. Intermediate cover - 12-inch thickness each day
b. Working face cover * 6-inch thickness each day
c. Slope of working face - 3 horizontal to 1 vertical
d. Slope at end of cell - 3 horizontal to 1 vertical
e. Compacted waste density = 1,000 Ib/cu. yd. (average)
f. Cover loss factor » 1.5
4. Controlling Cell Dimensions
a. Length of open working face should not exceed 75 feet. Incoming
traffic will require 45 feet of unloading length for the
average weekday load condition, 45 feet of unloading length
for peak month average weekday load condition, and 75 feet of
length on peak days.
b. Maintain a constant height of compacted waste (cell height) at
9 feet and a constant thickness of compacted waste (cell
thickness) of approximately 22.6 feet. Allow the working face
length to vary with the daily waste load and corresponding
traffic.
Figure 2 shows a typical cell section. Final contours of the completed
landfill are presented in Appendix C.
Approximately 80 percent of weekday wastes will arrive by transfer truck
with average payload of 16.5 tons per truck. The remaining 20 percent
of weekday wastes will arrive by collection vehicles with average pay-
loads of 3.75 tons per truck. Transfer trucks only are expected on
weekend days.
Access Roads
The access to the site will be off of State Highway No. 9. The all-
weather, permanent site access road will extend approximately 5,200 feet
from the highway to the north end of the landfill area as shown in
Appendix C. The design of the site access road should be for use by
large trucks and tractor-trailer combinations. ~
Preliminary design indicates that the road should have a twenty-eight
foot wide paved section with four foot wide shoulders.
-------
INTERMEDIATE COVEF
WORKING FACE COVER
3
0.5'
COMPACTED WASTE
NOTE: THE DAILY CELL CONSISTS OF THE COMPACTED SOLID WASTE PLUS
THE DAILY COVER (WORKING FACE COVER PLUS INTERMEDIATE COVER)
A SERIES OF ADJACENT CELLS MAKE UP A LIFT.
TYPICAL CELL SECTION
Figure 2
-------
Maximum roadway grade, should be s-ix percent and the minimum centerline
radius should b,e 10.0! feet.
Temporary unpaved access roads to the waste disposal area must be con-
structed as- required. These temporary roads should be twenty-eight feet
wide for two lanes, or eighteen feet wide for a single lane.
Buildings and Facilities
Approximate location of the miscellaneous- buildings and facilities are
shown on the location plan in Appendix C.
Gate House and Scale
The gate house and scale location near the top of the ridge will provide
approximately 1,000 feet of on-site road for traffic backup, which suffic-
iently exceeds the minimum requirement of 400 feet. Tbe location also
allows existing trees and topography to act as screening to the highway
and adjacent residences.
Buildings
The operation of a landfill at the site will require two buildings and
related features such as parking areas. Approximately two acres have
been designated for the buildings as indicated on Sheet 1 in Appendix C.
The employee and office facility will include a lunchroom, a washroom,
lockers, an office area, and adjacent parking for visitors. The
facility could be either a permanent building or a prefabricated, mobile
unit. The location designated will provide a permanent site using land
less suited for general waste disposal. An office building located near
the top of the ridge will allow visual observation over nearly all of the
site. The location is also reasonably close to the existing utilities and,
in addition, this location would keep visitors away from the landfill oper-
ations .
A covered storage shed should be provided for routine maintenance of the
landfill operating equipment. The proposed location of the vehicle stor-
age shed is in a portion of the building area. This location would reduce
the utility construction cost and keep the building in the same general
area as other buildings. Another consideration would be to provide a
portable shed that could be initially located near the landfill area and
possibly moved as stages of the landfill are developed. It is anticipated
that approximately one-half acre would be required.
Truck Washing Facility
It is desirable that a facility be provided for external cleaning of the
collection vehicles and other trucks before they return to State Highway
45
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No. 9. This would help assure, the cleanliness of the public roadways near
the landfill site.
The truck washing facility should b.e located back from the highway as
far as possible to reduce the amount of water tracked on the public high-
way by wet trucks. The. facility will require a permanent area of approx-
imately 7Q feet wide by 3QQF feet long alongside the exit lane of the per-
manent access road. A location just past the gate house is recommended
for reasons of permanency, nearness to water supply, consolidation of fac-
ilities into one area and advantages of the gate house personnel being
able to visually monitor operation. This location, however, may be poorly
suited for disposal of large volumes of wastewater by drainfield. The
facility design should, therefore, include means for reusing the waste-
water to minimize quantities for disposal. Wastewater disposal methods
will depend upon the type of truck wash facility selected. Methods of
wastewater disposal could include a drainfield, storage facilities with
trucking of the wastewater to the leachate treatment facility, or piping
to the leachate treatment facility. Sludge and litter could be placed in
the sanitary landfill.
Utilities
Utility requirements of the different locations on the site are summarized
in Table 2. All public utilities, except sanitary sewers, are available
and located along State Highway No. 9.
Power
The controlling power requirements will be those for the leachate treat-
ment facilities (described later). The aerator in the leachate aerated
lagoon will require a three-phase, 480-volt power supply. This is avail-
able from an existing overhead powerline on the west side of State High-
way No. 9. Power will be supplied to the sanitary landfill site by an
underground cable which will be installed as part of construction of the
permanent access road.
Domestic Water
Domestic water, including water for fire protection, is available from
the existing waterline along State Highway No. 9. Domestic water supply
and fire flow will be supplied by a four and six-inch pipe constructed
in association with the permanent access road.
Telephone
Telephone service is available from existing facilities located along
State Highway No. 9. Telephone lines to the site would be installed by
the General Telephone Company.
46
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Table 2
Utilities Required at Cathcart Site
Location on Site Power
Gate House & Scale Yes
Office & Employee Building Yea
Vehicle Storage Shed Yes
Collection Vehicle Wash Facility No
Waste Disposal Area No
(near working face)
Leachate Treatment Facility Yes
Yard
Lights*
Yes
Yes
No
Yes
Yes
Yes
Domestic
Water
No
Yes
Yes
Yes
No
Yes
Fire Hydrant
& Water Line
Yes
Yes
No
No
Yes
No
Telephone Radio Other
Yes No
Yes Yes Septic tank and
drainfield
No No
No No Septic tank and
drainfield
No Yes Portable toilets
No No
*Light on pole or building light with switch boxes.
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Radio
Snohomish County has a radio system to which operations at the landfill
site may be connected. It is proposed that radio communications be estab-
lished between the locations shown on Table 2 to facilitate the communi-
cation required for the operation of the landfill.
Other Utilities
A septic tank and drainfield will be installed for the disposal of waste-
water from the office and employee building and the collection vehicle
wash facility. Prior to construction, a drainfield area must be selected
and percolation tests must be performed. The septic tank and drainfield
should be designed and constructed in accordance with Manual of Septic
Tank Practice, U. S. Department of Health, Education and Welfare, Public
Health Service, latest edition and the standards and criteria promulgated
by Snohomish County Health District.
If a suitable drainfield site is not available in the immediate vicinity
of the facilities, a site within reasonable piping distance from the fac-
ilities must be selected. Drainfield sites along the hill east of the
holding pond area and creek should be avoided. Areas east and southeast
of the proposed facilities should be investigated. A temporary drainfield
could be established in the southern end of the waste disposal area until
the area is excavated, at which time the wastewater could be piped to
drain into the leachate collection system.
A portable toilet of the type generally used at construction sites should
be supplied at the waste disposal area near the working face. The waste
accumulated in the portable toilet will have to be pumped periodically and
can be dumped in the leachate lagoon.
Drainage and Pollution Control Facilities
The drainage and pollution control facilities are shown on Sheets 3 through
12 in Appendix C. The facilities consist of off-site surface water runoff
detention and diversion facilities, on-site surface water runoff diversion
and treatment facilities, and leachate collection, treatment and disposal
facilities.
Off-Site Surface Water Runoff Facilities
The purpose of the off-site surface water runoff detention and diversion
facilities is to maintain or improve water quality and use of the inter-
mittent creek that presently runs through the proposed waste disposal area by:
o Intercepting and diverting surface water from south and west of
the waste disposal area around the disposal area and back into the
natural creek channel north of the disposal area.
48
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o Reducing stream flows during storms.
o Detaining storm flows to allow settlable materials to settle out
of the stream water. Occasional maintenance dredging will be
required to remove settled material from the holding pond. Dredged
material can be stockpiled and/or wasted on-site.
o Storing late spring storms for maintaining stream flow during a
portion of the normally dry summer months.
o Adding no new stream blockages.
o Providing basic facilities that could later be modified for use in
a park setting.
The detention and diversion facilities were designed for the 100-year, 60-
minute storm using the rational formula:
Q = CIA
where
Q = design flow (cfs)
C = coefficient of runoff (dimensionless)
I = rainfall intensity (inches/hour)
A = drainage area (acres)
The coefficient of runoff has been assumed to be 0.3 which is typical for
hilly, unimproved areas.
Rainfall intensity is assumed to be dependent on storm duration (time of
concentration) and the design storm frequency as shown in Figure 3. The
nomograph in Figure 4 was used to establish the time of concentration for
small drainage basins. The time of concentration for the drainage area
(approximately 420 acres) contributing to the proposed holding pond at the
south end of the Cathcart site is 60 minutes.
The 100-year storm design flow for off-site surface runoff into the hold-
ing pond is estimated to be 140 cubic feet of water per second, using the
rational formula. To minimise the effect of this relatively high flow
on the diversion channel and downstream natural channel, the holding pond
outlet weir has been designed to reduce the 100-year storm flow to 80
cubic feet per second which is equivalent to a 5-year, 60-minute storm flow.
Regulating the downstream flows during the 100-year storm to flows lower
than 80 cfs would require a higher dam for the holding pond and the water
level would inundate more land area south of the proposed holding pond
site.
The holding pond will be formed by constructing an earth dam across the
existing creek channel and excavating south of the dam to provide a pond
even during times of no upstream flow (permanent water level). A weir
49
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Z5
H
m
z
un
n
en
0
ora
c
—t
0)
OJ
0
100 YEAR FREQUEI
0
10
20
30
40 50 60
DURATION IN MIN.
70
80
90
RAINFALL INTENSITY DURATION FREQUENCY
-------
LU
o
LU
>
o
m
O
a.
LU
O
C/3
O
u_
O
H
X
CO
H(FT.)
— 500
1-400
I- 300
- 200
- 150
- 100
50
- 40
- 30
— 20
— 10
- 5
- 4
— 3
—— O
!— 1
Note:
Use nomograph TC for natural
basins with well defined channels,
for overland flow on bare
earth, and for mowed grass road-
side channels.
For overland flow, grassed sur-
faces,, multiply Tc by 2.
For overland flow, concrete or
asphalt surfaces, multiply Tc
by 0.4.
For concrete channels, multiply
Tc by 0.2.
LU
QC
H
LL
O
X
LIFT.)
f=r 10,000
- 5,000
- 3,000
- 2,000
• 1,500
~— 1,000
• 500
• 300
200
150
— 100
cc
f-
z
LU
O.
O
o
u_
O
LU
TC(MIN.)
200
150
100
80
60
50
40
30
25
20
15
10
8
6
5
4
3
I— 2
TIME OF CONCENTRATION OF SMALL
DRAINAGE BASINS
51
Figure 4
-------
with a 6 ft. wide by 3 ft. high control section will regulate downstream
flow. A terrace around the perimeter of the pond is necessary for main-
tenance of the pond and public safety.
Details for the holding pond, dam and outlet weir are shown on Sheet 12 of
Appendix C. The upstream face of the dam and the pond bottom and sides
will be lined with impervious soils to minimize seepage of water into
the waste disposal area north of the dam. The sides of the waste disposal
area will later be lined with a leachate barrier which will provide addi-
tional protection against water seepage. Characteristics of the proposed
holding pond and weir at the various design water level elevations are
listed in Table 3.
Design criteria for the outlet weir of the holding pond includes:
o Maintain minimum water level in the pond at elevation 307.0 feet.
o Control discharge to 80 cfs at water level elevation of 310.0 feet.
o Provide an emergency spillway into the diversion channel that will
discharge a minimum of 140 cfs at water level elevation 311.0 feet.
o Weir height should be adjustable between elevations 307.0 and 310.0
feet.
o Weir with height at elevation 307.0 feet should not block the stream.
Table 3
Characteristics of Proposed Off-Site Runoff Holding Pond
1.
2.
3.
4.
5.
6.
7.
Water Surface Elevation (Ft.)
Total Pond Volume (Cu. Ft.)
Storage Volume above Elevation
307.0 feet (Cu. Ft.)
Pond Surface Area (Acres)
Depth of pond; range (Ft.)
Freeboard to top of Dam at
Elevation 312.4 feet (Ft.)
Discharge at weir (cfs)
307.0
174,000
0
0.
4
5.
0
8
to 8
4
310.0
306,000
132,000
1.5
up to 11
2.4
80
311.0
-
-
up to
1.4
150
12
Design criteria for the holding pond includes the following:
o Minimum water depth at permanent water level should be 3 feet to
prevent growth of weeds plus 1 foot additional depth for sediment
accumulation.
52
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o Side slopes should be no steeper than 3H:1V for slope stability
and no steeper than 4H:1V for grassed areas that will be mowed.
o A terrace, located one foot above permanent water level, should
be 12 feet minimum width for equipment access and 5 feet minimum
width for walkway purposes.
o The terrace and areas above the terrace should be seeded with grass
for slope stability and aesthetic purposes.
o The pond should have 130,000 cu. ft. storage capacity between ele-
vations 307.0 and 310.0 feet.
o Pond bottom and sides up to elevation 308.0 feet should be lined
with an impervious material as the site is less suitable for con-
struction of a dam with an impervious core.
o Minimum freeboard of 2 feet should be provided for the 100-year
storm.
The diversion channel will be constructed from the holding pond outlet
weir, along the southern and western sides of the permanent site road and
then down the steep hill to the natural creek channel at the north end of
the site as shown on Sheets 3 and 12 of Appendix C. Total length of the
proposed diversion channel is approximately 3,560 feet which is equal to
the length of natural channel bypassed by the diversion channel.
The final 240 foot downstream segment of the diversion channel is very
steep (approximately 30% slope). A 4-foot wide concrete chute with a
concrete stilling basin at the natural stream channel has been selected
as the type of channel for withstanding the large velocities and erosion.
An open channel was considered to be more consistent with future use of the
site than a pipe. Another option that could be considered is a series of
waterfalls.
A trapezoidal channel section with 2H:1V side slopes and with chemically
stabilized and grassed bottom and sides was selected for segments with
gentle grades in the 0.10 to 0.14% range to minimize erosion in the easily
eroded soils and to minimize construction costs. A manning roughness
coefficient of 0.025 was assumed. Channel lengths are approximately 1,460
feet of 4 feet wide channel, 130 feet of 6 feet wide channel, and 180 feet
of 8 feet wide channel.
A trapezoidal channel section with 2H:1V side slopes and with rock riprap
along the bottom and sides was selected for steeper segments with grades
up to 6% and for transition areas. A manning roughness coefficient of
0.035 was assumed for 1 foot nominal rock diameter and 0.038 for 2 foot
nominal rock diameter. Channel lengths would be approximately 1,380 feet
of 4 feet wide channel, 50 feet of 6 feet wide channel, and 120 feet of
transitions between different channel widths.
53
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A culvert will be required at the access road to the permanent excess soil
stockpile area. Two 48-inch diameter corrugated metal pipe or two 42-inch
diameter concrete pipe would be required to pass the 140 cfs flow without
backing the water up over the road base. The pipes could be installed
when the diversion channel is constructed or during the summer prior to
construction of the excess soil stockpile area.
Design flows for the diversion channel were 140 cfs and 80 cfs. The
channel should be able to carry 140 cfs with 1 foot minimum freeboard to the
top of the permanent site road base without causing excessive damage. Max-
imum permissible velocities of 15 feet per second in rock riprap (2 feet
nominal rock diameter) channels or 5 feet per second in chemically stab-
ilized and grass-lined channels would be allowed. Some overflows into
suitable sections of the buffer area may be allowable, but will be deter-
mined after final survey.
The diversion channel should be able to carry 80 cfs without overflow into
the buffer area and velocities should not exceed 10 feet per second in
rock riprap channels or 3 feet per second in chemically stabilized and
grass-lined channels.
A computer program for backwater analysis was run for the diversion chan-
nel profile and sections indicated on Sheet 12 of Appendix C to check the
design concept. Results indicated that a 5 foot channel depth was adequate
for the 140 cfs design flow and that velocity criteria could be met. After
the channel route is surveyed, the design of the concrete chute and still-
ing basin can be finalized and design of the trapezoidal channel segments
can be finalized to minimize excavation depths and rock riprap.
On-Site Surface Water Runoff Diversion and Treatment Facilities
The on-site surface runoff diversion and treatment system is shown in
Appendix C. During operation of the landfill, the system will consist
of a pipe collection system located under the fill. These pipes will be
placed in trenches excavated into the underlying sandstone or dense glac-
ial till. The trenches will be backfilled with the most impervious on-
site soils available and the top of the trenches will be covered with the
leachate barrier to prevent leachate from entering the pipe.
The collection system will be developed in stages as indicated on Sheets
13 through 20 in Appendix C.
This collection system will convey the on-site surface runoff to a settling
pond prior to discharge to the existing drainage channel north of the site.
When landfill operations are completed, the runoff will drain into a ditch
on the east side of the permanent access road. This ditch will also dis-
charge into the settling pond prior to discharge into the existing creek
channel. The underground pipe system will then be diverted into the leachate
collection system in event that the abandoned pipeline ever starts to
collect leachate.
54
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The piping system and ditch are designed to accommodate the 10-year
storm at a runoff coefficient of 0.2 over 80 acres. This results in a
design flow of 17 cubic feet of water per second. The settling pond is
designed to provide for 10 days detention time at an annual average rain-
fall of 45 inches over 365 days which results in a volume of 360,000
cubic feet.
The on-site surface runoff settling pond will be constructed by install-
ing a small dam across the existing creek channel north of the site.
Treated runoff will be discharged through an 18-inch corrugated metal pipe
to the existing creek channel north of the site.
Leachate Collection, Treatment, and Disposal Facilities
The leachate collection, treatment, and disposal facilities consist of
the following components:
Leachate barrier
Leachate collection system
Raw leachate pumping system
Aerated lagoon
Physical chemical treatment system
Outfall
Soil tests of the south end of the site indicate that the dense sandstone
could provide a natural barrier to movement of leachate or gases out of
the waste disposal area or to reverse movement of groundwater into the
disposal area. However, detailed soils tests have not been conducted in
the northern and western portion of the waste disposal area to confirm this
conclusion. Therefore, the following approach has been chosen for pro-
viding a leachate and gas barrier along the bottom and sides of the waste
disposal area.
1. The bottom and sides of the fill area will be lined with a leachate
barrier material that will have a permeability less than 1 x 10
cm/sec, and will not be degraded by leachate or gases for a minimum
of 40 years. The leachate barrier material will also not be suscep-
tible to damage by vehicle traffic or solid waste materials. Methods
being considered include membrane liners (i.e. PVC), asphaltic con-
crete, clay liners, and a chemical resin that stabilizes and seals
the surface soils. Protective layers of sandy soils would be placed
over the membrane, clay or chemical resin liners. The leachate bar-
rier will extend up to the top of the road berm along the south and
west sides of the fill area, and will extend a minimum of 15 feet
vertically up the excavated eastern and northern side slope. The
barrier material will be selected after subsurface soils investigations
are completed in the northern and western ends of the fill area.
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2. The northern and eastern side slopes in the excavated fill area
will be sealed with the chemical resin material (or other appro-
priate material) wherever the excavated soils have a permeability
greater than 1 x 10 cm/sec. This will be necessary to seal
porous soil lenses to force leachate to drain to the bottom of
the fill area and to provide a gas barrier. A layer of gravel will
be placed along the northern, western and eastern side slopes to allow
unrestricted movement of leachate and gas. Most leachate should drain
away from the eastern side slope as the top surface of each lift will
drain to the west.
3. The bottom of the fill area will be excavated to drain the short-
est distance (east and west) to the center of the fill area which
will be sloped to drain to the northern end. A perforated pipe
covered with a berm of gravel will be placed along the center
drainage (from south to north) to provide positive drainage to the
leachate collection system at the north end of the fill area. This
will minimize the depth of leachate accumulation in the fill area
and will minimize leachate loss should a local area of the leachate
barrier fail.
The unweathered sandstone, underlying the site, could be used as a nat-
ural leachate barrier provided that fractured areas can be identified and
sealed and provided that the excavated or repaired surface has a perme-
ability less than 1 x 10 cm/sec. Soils testing to date indicate a
high probability that the unweathered sandstone will meet the above require-
ments. However, additional subsurface soils investigations in the north-
ern portion of the waste disposal area will be required as an intermediate
step to verify the sandstone as a natural leachate barrier. Also, a large
area of sandstone should be exposed by excavation to inspect for fractures,
determine the feasibility and reliability of sealing fractures, and to
finalize the design selection.
The excavation depths and grades presently specified in Appendix C are
expected to expose some sandstone across the northern end of the stage 1
area. However, much of the waste disposal area will be excavated only
into glacial till and other porous soils overlaying the dense sandstone.
The till and other porous soils will require a layer of leachate barrier
material to prevent leakage of leachate out of the waste disposal area.
If the unweathered sandstone proves to be an adequate natural leachate
barrier, it would be possible to modify the depths and grades along the
bottom of the waste disposal area to excavate through the porous soils
into unweathered sandstone. This would increase landfill life by approx-
imately one year, increase excess soil quantities by approximately 160,000
cubic yards, and may substantially reduce cost of the leachate barrier.
56
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The leachate collection system is shown in Sheets 7 and 8 in Appendix C.
The leachate collection system consists of an eight-inch perforated pipe
placed in a trench excavated into the sandstone. The trench will be lined
with an impervious membrane liner to prevent leakage of leachate into the
sandstone and will be backfilled with gravel. The side cut at the north
toe of the landfill will be sealed with an impervious material to prevent
leachate from escaping the landfill to the north. The bottom of the fill
area will be sloped to drain leachate to the leachate collection system.
The leachate collection system will drain to the leachate pump station
located at the low point on the northern periphery of the waste disposal
area.
The pump station will have a capacity of fifty gallons per minute at
approximately twenty-five feet of total dynamic head, and will discharge
through a four-inch diameter force main into the aerated lagoon.
The pump station will be a factory-fabricated, package type and will
include two submersible pumps, each capable of handling the entire design
flow.
The leachate treatment facility must provide adequate treatment to allow
effluent discharge to the on-site surface runoff holding pond and even-
tually to the existing creek north of the site. To meet this requirement,
the average concentration of specific effluent constituents should not
exceed the following:
Biochemical Oxygen Demand 5 mg/1
Suspended Solids 5 mg/1
Chemical Oxygen Demand 10 mg/1
Phosphates (as phosphorus) 1 mg/1
Total Coliform Bacteria 20/100 ml
pH within limits
of 6.0 to 9.0
Based on this, the leachate treatment facility should consist of the
following units:
Aerated Lagoon
Flash mixing unit with chemical addition
Flocculation unit
Sedimentation unit
Activated carbon reactors
Pressure filter
Chlorine contact chamber
Dechlorination unit (activated carbon)
pH adjustment unit
Sludge holding tank
57
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The following are specific design criteria for each of the units:
Aerated Lagoon
Design BOD removal
Detention Time
Oxygen requirement
Aerator oxygen transfer
Flash Mixing Unit
Detention time
Flocculation Unit
Detention time
Sedimentation Unit
Overflow rate
Detention time
Weir rate
Activated Carbon Reactors
Hydraulic loading
Pressure Filter
Hydraulic loading
Chlorine Contact Chamber
Detention time
Dechlorination Unit
Same as activated carbon reactors
pH Adjustment Unit
Detention time
Sludge Holding Tank
Storage capacity
80-85%
11 days
1.5 Ibs 0 /lb BOD
2 Ibs 0 /HP hr.
60 seconds
20 minutes
600 gpd/sf.
2 hours
1,000 gpd/LF
2 gpm/sf.
3 gpm/sf.
60 minutes
60 minutes
15 days
All units, except the aerated lagoon and the sludge holding tank, can be
supplied as a package treatment plant by one manufacturer. A site layout
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and schematic flow diagram of the leachate treatment facility are shown
on Sheet 10 in Appendix C.
The aerated lagoon is designed to provide 80 to 85 percent removal of
Biochemical Oxygen Demand (BOD). It has previously been assumed that the
influent BOD will average 2,000 milligrams per liter. This will result
in an effluent BOD concentration of 300 to 400 milligrams per liter, pri-
marily as suspended solids.
The lagoon will be constructed prior to landfill operations and will have a
volume of 400,000 gallons. This will correspond to a detention time of
11 days at a flow of twenty-five gallons per minute.
The aerated lagoon will be an earthen basin sealed with an impervious
membrane. The aerator will be twenty horsepower, highspeed floating unit,
based on an oxygen transfer rate of two pounds of oxygen per horsepower-
hour, and an oxygen requirement of 1.5 pounds of oxygen per pound of BOD.
Generally, leachate does not have adequate nutrients for proper biological
treatment. If this is the case at Cathcart, consideration should be given
to the addition of nutrient feeding equipment to optimize the operation
of the aerated lagoon.
The effluent from the aerated lagoon will be pumped to the package treat-
ment plant discussed previously. This package plant will require a sur-
face area of approximately 37 feet by 10 feet. It is recommended that the
package plant be housed in a 48 feet by 16 feet building. This would
provide covered storage for chemicals, aerated lagoon, and leachate pump
station motor control center and sludge holding tank. The sludge holding
tank will be periodically emptied and the sludge will be wasted with the
solid waste.
The chemicals to be utilized in the flocculation-sedimentation part of
the leachate treatment plant would have to be determined from actual ana-
lyses performed on the aerated lagoon effluent.
The effluent from the pH adjustment unit of the package treatment plant
will be discharged to the on-site surface runoff ditch through an eight-
inch outfall pipe. The treated leachate will receive further treatment
(at least ten days detention time plus dilution) in the on-site surface
runoff holding pond prior to discharge to the existing creek north of the
landfill site.
Water Quality Monitoring Program
Baseline monitoring will be conducted at groundwater monitoring wells and
on the creek flowing through the Cathcart site to document water quality
characteristics prior to landfill development and operation. Ground and
59
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surface water monitoring that is currently being conducted by Department of
Ecology (DOE) at six locations shown in Figure 1 will provide part of the
required baseline information. Data on fecal coliform, pesticides, oil and
grease, and stream sediment samples should be obtained to complete the base-
line data requirements.
Routine monitoring will be accomplished throughout the operation of the
landfill and should not be discontinued until it can be positively proven
that the generation of leachate has ceased. Routine monitoring would be
conducted at six groundwater monitoring wells and four stream monitoring
stations (refer to locations on sheet 2 of Appendix A), the leachate
treatment facility and the on-site runoff settling pond. All on-site
monitoring should be performed by Snohomish County Department of Public
Works and the data should be submitted to the Snohomish Health District
for review. All tests should be performed in accordance with Standard
Methods for the Examination of Water and Wastewater, latest edition,
published by the American Public Health Association.
The Snohomish Health District should periodically monitor private wells
in the vicinity of the Cathcart site for materials indicating the pres-
ence of leachate (i.e. chloride and sulfate). The wells within one mile
of the waste disposal area are indicated on Sheet 1 of Appendix C and
in the Final Environmental Impact Statement - Cathcart Sanitary Landfill.
The purpose of the water quality monitoring program is to detect changes
in the environmental conditions at and surrounding the site in its early
stages and provide a sound basis for implementation of remedial measures
before the changes become uncontrollable. The recommended scope for each
part of the program are described in following paragraphs. It may become
necessary to modify the scope of monitoring at a later date based on data
trends observed after the first few years of monitoring. Large quantities
of high strength leachate are not expected until after one to three years
of landfill operation.
Groandwater Monitoring P/ells
Two of the monitoring well locations used for current DOE sampling program
(locations 1 and 6 on Figure 1) are used in the monitoring well network
shown in Appendix C. The other DOE well locations would be destroyed by
development of the waste disposal area or are not located to intercept
groundwater flow from the waste disposal area.
Baseline monitoring should be conducted for at least one year prior to
operation of the sanitary landfill. Parameters to be monitored should
include materials found in leachate which are moderately to highly mobile
in subsurface soils and materials which are important to water quality for
agricultural (irrigation and livestock) and domestic water uses. The
following parameters and sampling frequency are recommended for baseline
monitoring of groundwater wells:
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Monthly Sampling (One Year Baseline)
Quarterly Sampling
pH*
Color*
-Total Solids*
Total Volatile Solids*
Total Dissolved Solids*
Conductivity*
COD*
Total Hardness*
Chloride*
Sulfate*
Nitrate & Nitrite (as N)*
Ammonia (as N)*
Total Phosphorus
Total Coliform*
Fecal Coliform*
Sodium*
Potassium*
Calcium*
Manganese*
Iron*
Cadmium*
Chromium*
Copper*
Lead*
Mercury
Nickel*
Zinc*
*Has been monitored by
D.O.E. and should be
used for baseline.
Routine monitoring of groundwater wells would be conducted for materials
that would indicate leakage of leachate out of the waste disposal area.
The wells would be sampled monthly for conductivity, chloride, sulfate,
sodium, and calcium which represent leachate materials that are mobile
in soils.
If routine monitoring indicates the presence of leachate (significant increase
in indicator materials) in wells outside the waste disposal area, then other
monitoring may be necessary to isolate the source and quantify the extent
of the problem.
Stream Monitoring Stations
One of the surface water monitoring stations (location 3 on Figure 1) cur-
rently used by DOE will be used in the stream monitoring network shown in
Appendix C. The other DOE locations will not be suitable after diversion
of the creek.
Baseline monitoring should be conducted for at least one year prior to
extensive clearing and earthwork at the DOE monitoring locations. Para-
meters to be monitored should include the materials expected in leachate
and on-site surface runoff, the parameters used in the Department of Ecol-
ogy Water Quality Standards for Class A streams, and materials which are
important to water quality for agricultural, domestic, aquatic life, and
aesthetic water uses. Sediment samples should also be taken from a loca-
tion where sediment deposition downstream of the waste disposal area
would be expected in future years. A benthic survey would be most useful
to monitor long-range impacts on the creek. The University of Washington
should be contacted to determine their interest in developing and conduct-
ing a series of benthic surveys on the creek.
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The following parameters and sampling frequency are recommended for baseline
stream monitoring:
Monthly Sampling (One Year Baseline)
Flow
Temperature
Turbidity*
Color*
Conductivity*
Total Solids*
Total Dissolved Solids*
Suspended Solids*
Total Volatile Solids*
pH*
Dissolved Oxygen
Total Coliform*
Fecal Coliform
Nitrate & Nitrite
(as N)*
Ammonia (as N)*
Organic Nitrogen (as N)
Total Phosphorus (as N)
BOD
COD*
Chloride*
Sulfate*
Sodium*
Potassium*
Calcium*
Magnesium*
Manganese*
Iron*
Oil & Grease
Quarterly Sampling
Cadmium*
Chromium*
Copper*
Lead*
Mercury
Nickel*
Zinc*
Chlorinated Hydrocarbons
*Has been monitored by
D.O.E. and should be
used for baseline.
The following parameters are recommended for sampling of sediments every
two years: total solids, total volatile solids, heavy metals (Cd, Cr, Cu,
Pb, Hg, Ni, Zn), and pesticides.
Routine monitoring of the creek would include a sampling at station S-l,
concurrently with sampling of discharge from on-site surface runoff settl-
ing pond, to determine the impact of treated wastewaters on the creek plus
monitoring of the creek upstream and downstream of the waste disposal area
for materials that would indicate leakage of leachate or on-site surface
runoff into the creek.
The following parameters and sampling frequency are recommended for routine
monitoring at station S-l:
Quarterly
All baseline stream monitoring para-
meters except heavy metals and chlor-
inated hydrocarbons which would be
sampled once in summer and once
in fall.
Monthly
Stream flow
PH
Temperature
Turbidity
Dissolved Oxygen
Color
Conductivity
Total Coliform
COD
Chloride
Sulfate
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The following parameters are recommended for routine sampling every month
at Stations S-2, S-3 and S-4: pH, temperature, turbidity, dissolved
oxygen, color, conductivity, total coliform, COD, chloride and sulfate.
If routine monitoring indicates leakage of leachate or on-site surface
runoff into the diverted creek, investigations necessary to define the
problem should be undertaken.
The sediment sample should be taken every two years from the same location.
Treatment Facilities Monitoring
Monitoring of treatment facilities should include the on-site surface
runoff settling pond influent and effluent, raw leachate, aerated lagoon
effluent, and completely treated leachate prior to discharge into the
settling pond. The purposes of this monitoring is to measure the effec-
tiveness of the treatment facilities and to monitor discharges to the
creek for verification of discharge requirements.
The following parameters and sampling frequency are recommended to pro-
vide research data for evaluating performance of unit operations, if a
funding source becomes available. Parameters necessary for basic
operational control are noted, and should be routinely monitored as a
minimum requirement.
Monthly Sampling
Flow*
Temperature
Color*
Turbidity*
Total Solids
Total Dissolved Solids
Total Suspended Solids*
Total Volatile Solids
pH*
Dissolved Oxygen
Oil & Grease
Nitrate (as N)*
Nitrite (as N)
Ammonia (as N)*
Organic Nitrogen*
Total Phosphorus*
Ortho Phosphate (as P)
Total Coliform*
Fecal Coliform*
BOD*
COD*
Chloride
Sulfate
Sodium
Potassium
Calcium
Magnesium
Manganese
Iron
Conductivity*
Quarterly Sampling
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Zinc
Chlorinated Hydrocarbons
*Routine monitoring
for operational
control.
The following parameters are recommended for weekly sampling of discharge
from the on-site surface runoff settling pond: flow, BOD, COD, suspended
solids, total coliform, pH, total phosphorous, total nitrogen, dissolved
oxygen, chloride, sulfate, color and conductivity.
Gas Control Systems
Gases will be allowed to move laterally through the landfill by the con-
struction of gravel-filled ditches at the highest point of each daily
cell. The gas from the entire fill will be collected through a gravel wall
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on the north, east and west side of the fill, as shown on Sheets 15 and
16 in Appendix C. The top of the gravel wall will be sealed with impervious
soils to keep water out of the landfill. Vents to the atmosphere will be
installed through this impervious seal along the east and west sides of
the fill area.
Gas vents are sized to handle 10% of total gas generation within one
year as a peak rate at a velocity of 1 foot per second. Gas generated
over the total degradation cycle is estimated at 12 billion cubic feet
at one atmosphere of pressure based on 15 cubic feet per second of vola-
tile solids, 35% volatile solids and total landfill capacity of 1,140,000
tons of waste.
If the release of gases to the atmosphere results in a significant odor
problem, the installation of a gas header and burners should be con-
sidered.
Landfill Equipment
Equipment will be required for two distinct operations in the general
waste disposal area; (1) site preparation, including excavating and
stockpiling cover material, and (2) cell development, including moving
and compacting waste and cover to form the cell. The equipment required
for the site preparation operation will be used on an intermittent basis
for a few months as each landfill stage is prepared. Large quantities of
earth will be excavated and stockpiled. Equipment required will include
large track-type tractors with rippers for excavation, large scrapers,
graders and equipment necessary for construction of pipeline, ditches,
roads, earthen dams, and the leachate barrier.
The daily landfill operation will require a large sized track-type tractor
modified for landfill operations or a landfill compactor. A second
tractor would be utilized on large waste load days and a medium sized
scraper would be used to transport daily cover material.
The availability of a water truck would be required during dry-weather
operations for dust control. It is also desirable to have a truck-mounted
litter vacuum available for site maintenance and litter control. A
general maintenance half-ton truck should be available.
Buffer Zone and Reserve Areas
The purpose and general requirements for the buffer zone are discussed in
Appendix A. Since a large part of the vegetation on the site consists of
alder, additional evergreen trees and shrubs will be required to obtain
the desired screening effect. The extent of additional planting will be
determined by the county after the site is cleared.
The buffer zones and reserve areas are shown on Sheet 1 in Appendix C.
The buffer along the east side of the landfill would be approximately
180 feet wide. This buffer zone would be left in its natural condition
with the addition of planting of evergreens and shrubs as required.
The buffer along the west side of the landfill is approximately 200 feet
wide to the center of the permanent access road. This area would contain
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the access road and the drainage diversion channel. The remaining width
of 100 to 150 feet, depending upon depth of channel cuts, would be left
in its natural condition. Since there are no homes on the west side of the
landfill, planting of additional vegetation in the west buffer zone may
not be rquired.
Considerable reserve area, approximately 110 acres, has been designated
for the total 200 acre Cathcart site. The southeastern 40 acre area of
the site presently contains a residence and out buildings. The area
would be left in its present condition, except for the access road and
service facilities along the access road, such as the scale, gate house,
collection vehicle wash facility and employee and office facility.
Trees in this area must be retained, wherever and whenever possible, to
provide screening. For future development of the site, this area would
be physically suitable for buildings, bulky waste disposal and special
facilities such as resource recovery. The area would be less suitable
for general or special waste disposal because of proximity to the high-
way and residences and subsurface soil conditions.
Approximately 7 acres directly south of the landfill area would be used
for stockpiling cover materials during landfill operations. In the
future, the landfill operation could be extended into this area or the
area could be developed as part of the future use plan and not be filled
with waste.
Approximately 40 acres at the north end of the proposed landfill area
would be reserved in its natural condition, except for very limited
development in the vicinity of the on-site surface runoff settling pond
and leachate treatment facilities.
Fencing
Fencing locations will be determined by the county after the site is
cleared. Six-foot high chain link fence with three strands of barbed
wire on top should be considered along the eastern side of the waste
disposal area for litter control and because of deep cuts. The rest of
the waste disposal area perimeter should be enclosed with a six-foot high
wire mesh fence for litter control and to provide a barrier to animals
and people. This fence should be installed between the site road and
the creek diversion channel to keep litter out of the creeks, and should
also enclose both holding ponds. A wooden fence or chain link fence
with wooden slats should be considered along the southern property line
for approximately 1,100 feet to help reduce noise impact on the existing
mink farm.
Warning signs will be posted on the fence at intervals governed by local
topography. An access gate with lock will be provided at the entrance
from State Highway No. 9.
Future Considerations
Possible facilities to be added at a future date include nutrient feeding
equipment for the aerated lagoon and gas header and burners. These
facilities would be designed from data obtained during operation of the
landfill over an extended period of time.
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SITE DEVELOPMENT SEQUENCE
General Approach
The Cathcart site.will be developed, operated and prepared for future
use in three separate phases, as outlined in Table 4. In Phase I, the
site will be prepared for receiving solid wastes through a three-stage
approach which will include, 1) clearing, surveying, subsurface soils
investigation and water quality monitoring, 2) finalization of design,
and 3) initial site construction.
In Phase II, a sanitary landfill operation will be conducted in the 56-
acre waste disposal area which will be filled to final contours and ele-
vations in six stages over an estimated time period of approximately
seven years. The sanitary landfill operation will start at the north
end of the waste disposal area, as indicated on Sheet 13 in Appendix C.
In Phase III, the site will be maintained after the sanitary landfill
operation has ceased and the site will be planned and prepared for final
use. Development for final use may be accomplished during later stages
of the sanitary landfill operation, as portions of the 56-acre waste
disposal area will be developed to final contours and elevation as soon
as possible.
Table 4
Cathcart Site Development Sequence
PHASE I; INITIAL SITE PREPARATION
Stage 1 - Initial Site Preparation - Clearing and site investigations,
Stage 2 - Construction Plans and Specifications
Stage 3 - Initial Site Construction
PHASE II: SANITARY LANDFILL OPERATION
Stage 1
Stage 2
Stage 3
Stage 4
Stage 5
Stage 6
Landfill and
Landfill and
Landfill and
Landfill and
Landfill and
Landfill
Stage 2 Preparation
Stage 3 Preparation
Stage 4 Preparation
Stage 5 Preparation
Stage 6 Preparation
PHASE III: FINAL USE
Stage 1 - Maintenance and operation after landfill closure
Stage 2 - Final use development
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Phase I - Initial Site Preparation
It will be necessary to prepare the first portion of the waste disposal
area for receiving solid wastes and to construct the related site facil-
ities in three stages. Clearing must be accomplished as a first step
to open up portions of the site for survey and subsurface soils investi-
gations in the northern and western sides of the site. The survey and
soils information are required to allow finalization of the design of
the various site use facilities. The last stage of Phase I will be
preparation of the waste disposal area and construction of facilities
required to initiate the sanitary landfill operation.
Stage 1 - Site Preparation - Clearing and Site Investigations
Clearing: Approximately 54 acres of the Cathcart site will be logged,
cleared and grubbed in the locations shown on Sheet 2 of Appendix C.
Areas reserved for buffer zones and reserve areas must not be disturbed.
Prior to the clearing operation, the county should: 1) obtain approval
from the State of Washington Department of Natural Resources (owner) to
use the site, 2) obtain a logging permit from the Department of Natural
Resources, and'3) advertize and award a contract for logging, clearing
and grubbing. Other permits may be necessary depending upon methods
used by the contractor.
The construction period for the clearing contract should be approxi-
mately 90 days. Construction supervision should be performed by Sno-
homish County.
Final Design Survey: Because of inaccessibility and heavy vegetation,
design surveys have not yet been performed on portions of the landfill
site. The site preparation discussed above will provide the necessary
accessibility to complete the design survey in these areas. Areas of
particular concern include portions of the site to be utilized for
initial landfill operations, the on-site surface runoff holding pond
area, the leachate treatment facilities area, the permanent road, and
the off-site surface runoff diversion channel route. Other areas where
additional surveys may be needed will be defined during finalization of
design.
The final design survey can begin whenever the areas of concern have
been cleared. The final design surveys should be performed by personnel
from Snohomish County.
The final design survey should also include an analysis, by Snohomish
County Department of Public Works, of screening capacity of the buffer
zones and reserve areas. A noise consultant should be retained and noise
abatement regulations being adopted by Department of Ecology, should be
considered. The analysis would determine the visual screening and noise
attenuation capacity of the buffer zones and reserve area and would
determine the extent of new planting in these areas to obtain the desired
screening capacity.
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Subsurface Soils Investigation: Heavy vegetation has prevented soils
investigations from being conducted on the northern portion of the site.
Areas of concern include:
o Waste Disposal Area: Landfill Stages 1, 2 and part of 3 should be
investigated to determine soil conditions to dense sandstone,
location of dense sandstone and groundwater, and permeability of sandstone,
o On-Site Runoff Holding Pond: The location for the dam requires
investigation for soil types, depth to bedrock, bearing capacity
of bedrock, and soil permeability.
o Off-Site Runoff Holding Pond: The location for the holding pond
requires similar investigations as for the on-site holding pond dam.
o Off-Site Runoff Diversion Channel: The location where the channel
joins the natural streambed needs to be investigated for soil
types and depth to bedrock.
o Leachate Treatment Facility: The location of the leachate lagoon
and treatment plant requires investigation for soil type and
bearing capacity.
o Permanent Site Road: The road location along the western side of
the waste disposal area should be investigated for soil type,
groundwater location, and hard sandstone location to determine the
feasibility of using the off-site runoff drainage channel for
intercepting groundwater movement towards the waste disposal area.
The above soils investigations should be accomplished after the various
areas have been cleared and surveyed.
Water Quality Monitoring: Six groundwater monitoring stations around
the waste disposal area, a stream monitoring station downstream of the
waste disposal area and three stream monitoring stations along the
disturbed area should be installed, as shown on Sheet 2 of Appendix C,
to monitor water quality during site construction, landfill operation
and landfill maintenance after the waste disposal operation has ceased.
Baseline water quality conditions should be established over at least a
one year period. The baseline stream monitoring should be initiated
prior to site clearing and/or any extensive site development work near
the stream. The baseline groundwater monitoring should be initiated as
soon as possible after the site has been opened up enough to allow
installation of the groundwater monitoring wells.
Water quality monitoring should be performed by the Snohomish County
Department of Public Works.
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Stage 2 - Site Preparation - Penalization oZ D
Finalization of design will include development of final construction
features and requirements of the following elements:
o Earthwork in waste disposal area - excavation, grading and stock-
piling
o Earthwork for permanent access road - cut, fill, and rough grades
o Groundwater monitoring wells (per recouiaaiidations of Snohomish
Health District)
o On-site water quality monitoring
o Leachate collection, treatment and discharge facilities
o Leachate barrier
o On-site runoff drainage and holding pond
o Off-site runoff drainage and holding pond
o Gas controls and monitoring
o Final cover on landfill
o Access at Highway 9
o Permanent site roads - final grades, surfacing and maintenance
o Fencing
o Buffer zones and reserve areas
o Buildings and related site preparation
o Scale
o Utilities
o Overall site operations - including sanitary landfill operation (per
regulations and review recommendations of Snohomish Health District)
Stage 3 - Site Preparation - Initial Site Construction
Facilities to_ be Constructed: Facilities to be constructed during this
stage, shown on Sheets 3 through 12 in Appendix C, include the following:
o Site entrance at State Highway No. 9
o Permanent Site Road
o Buildings
Gate house and scale
Employee and office building
Vehicle storage shed
o Utilities - power, outdoor lighting, water supply, telephone, radio,
septic tank and drainfield, and portable toilet facility.
o Buffer
Screening
Fencing
o Preparation of Stage 1 Landfill Area
Excavation and grading
On-Site runoff drainage pipeline
Leachate collection pipeline and pump station
Leachate barrier on bottom and sides
Gas venting gravel layer on east and west sides
Temporary access road
o Preparation of Stage 2 Landfill Area
Excavation and rough grading for drainage
Stockpile for daily cover
o Excess Soil Stockpile
69
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o Temporary Road to Excess Soil Stockpile for Excavation Equipment
o Off-Site Runoff Controls
Drainage diversion channel
Holding pond, sam, and spillway
o Treatment Facilities
Leachate lagoon and treatment plant
Outfall for treated leachate
o Settling pond for on-site runoff
Basic Work Elements: it is anticipated that the required construction
would include the following basic elements:
o Earthwork: This work element would consist of the necessary
excavation, earthmoving, stockpiling, compaction, rough grading,
final grading and riprap operations related to site entrance
road, permanent site road, temporary road to excess soil stockpile,
temporary road to Stage 1 Landfill area, off-site runoff diver-
sion channel, on-site runoff pond including outlet, dam and holding
pond for off-site runoff, excavation of Stages 1 and 2 landfill
areas (21 acres), daily cover stockpile, excess soil stockpile,
earthfill north of waste disposal area, leachate lagoon, building
areas, and other facility areas designated by the county.
o Site Improvements: This work element would include surfacing of
roads, installation of utilities, construction of drainage
channels and culverts outside of the waste disposal area, instal-
lation of buffer zone improvements, and installation of fencing
and gates.
o Buildings and Facilities: This element would include construction
of the gate house, employee and office building, vehicle storage
shed, and scale foundation. Also included would be vehicle
parking areas, vehicle wash facility and any other facilities or
buildings designated by the county.
o Installation of Mechanical Equipment: This work element would
include installing the liner and aerator for the leachate lagoon,
leachate treatment plant, leachate pump station, truck scale, and
any other equipment designated by the county.
o Waste Disposal Area Preparation: This work element would include
installation of the leachate collecting pipeline network, instal-
lation of on-site surface runoff drainage pipeline network, con-
struction of a leachate barrier on the bottom and sides of the
excavated pit, and placement of the gas venting gravel layer
along the eastern and western cut slopes. Only the Stage 1 landfill area
(approximately 7 acres) would be prepared.
Phase II - Sanitary Landfill Operation
Approach
The waste disposal area will be filled with solid wastes and cover
materials of on-site soils using sanitary landfill operating procedures
70
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to be developed by Snohomish County. The county will conduct the sani-
tary landfill operations.
The 56-acre waste disposal area should be prepared and filled to final
elevations and grades in six stages, as indicated on Sheets 13 through
20 in Appendix C. Basically, each stage of operation consists of con-
ducting a sanitary landfill operation in the first stage area, preparing
the second stage area for receiving solid waste and excavating the third
stage area to stockpile daily cover and other on-site soils for future
sanitary landfill operations in the second stage area. This basic se-
quence of operations would be continued until the total 56-acre waste
disposal area is filled to final elevations. The major portion of ex-
cavation and stockpiling operations should be accomplished during dry
weather because the bulk of the on-site soils are moisture sensitive.
The total time of operation of the sanitary landfill is estimated to be
approximately seven years based on waste generation forecasts by the
county and on excavation depths and final contours shown in the drawings
for each stage of operation. Estimates of excavation volumes, cover
material requirements, waste capacity and time periods for completing
each stage of landfill are summarized in Table 5.
Typical details and sections on Sheets 15 and 16 in Appendix C indicate
the basic concepts recommended for each task. Details will be finalized
after completion of surveys and other site investigations in Phase I.
Soils Classification
To facilitate this discussion, the soils to be utilized on the site have
been classified into five groups according to their limitations and uses:
1) Soils Group A: Top of final cover.
Uses: Top 0.5 to 1.0 feet of final cover.
Purpose: Top soils as base for seeding.
Soil Types: Forest duff (usually top 0.5 feet) and loose, very
silty sands or silty fine to medium sands normally
found in rooting zone (top 2 feet).
Volume Required: Approximately 70,000 cubic yards total.
Stockpile Placement: Uncompacted berms with 3 horizontal to
1 vertical side slopes.
Weather Protection: Plant with grass as each segment of berm
is completed to prevent erosion.
2) Soil Group B: Wet weather cover.
Use: Daily cover for landfill during wet weather.
Purpose: Source of dry, lower moisture-sensitive on-site soils.
Soil Types: Weathered sandstone (silty fine to medium sands, silty
sands) and excavated dense sandstone.
Volume Required: Approximately 200,000 cubic yards total.
Stockpile Placement: Excavate only during dry weather and place
in berms with 3 horizontal to 1 vertical
side slopes. Compact the top and side surfaces.
Weather Protection: Cover with sheet plastic or other suitable
material. Divert surface runoff away from berm.
71
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Table 5
Summary of Quantities at End
Cathcart Sanitary Landfill
Item
Solid Waste + Daily Cover
(Cubic Yard)
Compacted Solid Waste
Volume (C.Y.)l
Weight (Tons @ 1,000
(Ib/C.Y.)
Estimated Life (accum. Yrs)
Excavation
Location
Approx. Surface Area (Ac)
Top Soil Material (C.Y.)2
Top Cover (C.Y.)3
Other Soils (C.Y.)
Total Cubic Yard
Required Cover
Acres of Final Cover
Top Soil @ 6" depth (C.Y.)
Top Cover @ 18" depth (C.Y
Daily Cover1 (C.Y.)
Total Cubic Yard
Soil Stockpile At End of
Stage
Daily Cover (C.Y.)
Top Soil (C.Y.)
Top Cover (C.Y.)
Other Soils (C.Y.)
Total C. Y.
of Landfill Development Stage
Initial Site Stage of
Construction
0
0
0
—
I S II areas
21
17,000
51,000
370,000
438,000
0
0
.) 0
0
0
65,000
17,000
51,000
305,000
438,000
I
319,
"4,
127,
1 yr
III
6,
20,
141,
168,
65,
65,
156,
23.
71,
290,
541,
000
000
000
area
8.4
800
200
000
000
0
0
0
000
000
000
800
200
000
000
Sanitary I
II
759,000
604,000
302,000
3 yrs .
IV area
8.4
6,800
20,200
169,000
196,000
15.5
16,000
46,000
156,000
218,000
116,000
14,600
45,400
343,000
519,000
.andfill Operation
III
566.000
450,000
225,500
4 . 5 yrs.
V area
8.4
6,800
20,200
255,000
282,000
8.9
8,200
25,800
116,000
150,000
90,000
13,200
39,800
508,000
651,000
IV
443,000
352,000
176,000
5.5 yrs.
VI area
10.2
8,300
24,700
280,000
313,000
8.4
8,000
24,000
90,000
122,000
78,000
13,500
40,500
710,000
842,000
V
385,
307,
154,
6.5
none
9,
27,
78,
114,
89,
4,
13,
621,
728,
000
000
000
yrs.
0
0
0
0
0
9.3
000
000
000
000
000
500
500
000
000
VI
437,000
348,000
174,000
7 . 3 yrs .
none
0
0
0
0
0
14.3
13,800
41,200
89,000
144,000
0
(-9,300)
(-27,700)
621,000
584,000
Total
2,909,000
2,315,000
1,158,000
7.3 vrs.
56.4
45,700
136,300
1,215,000
1,397,000
56.4
55,000
164,000
594,000
813,000
(-9,300
(-27,700
621,000
584,000
C.Y.
C.Y.
T.
AC
C.Y.
C.Y.
C.Y.
C.Y.
AC
C.Y.
C.Y.
C.Y.
C.Y.
C.Y.)
C.Y.)
.Y.
.Y.
1 Based on 3.9:1 waste to cover ratio for 10 ft. lift.
2 Based on 6" top soil and 18" of top cover as average over site
3 Based on 6" top soil and 18" top cover with factor of 1.2.
-------
3) Soil Group C: Temporary site road.
Use; As surface and base material for the temporary site roads.
Purpose: Source of lowest moisture sensitive on-site soils.
Soil Type: Excavated dense sandstone (some blocks and clods are
allowable) and any clean or relatively clean sands
or gravels.
Volume Required: Approximately 30,000 cubic yards total.
Stockpile Placement: Excavate during any season and place in berms
with 3 horizontal to 1 vertical side slopes.
Compact the top and side surface areas.
Weather Protection: Cover with sheet plastic or other suitable
material. Divert surface runoff away from
berm.
4) Soil Group D: Final intermediate cover.
Use: One foot thick intermediate cover on top of final lift and
exposed final side slopes of all lifts.
Purpose: Impervious barrier to keep water out of the landfill.
Soil Types: Excavated dense glacial till.
Volume Required: Approximately 110,000 cubic yards total.
Stockpile Placement: Excavate during dry weather and place in
berm with 3 horizontal to 1 vertical side
slopes. Compact the top and side surfaces.
Weather Protection: Cover with plastic sheeting or other suitable
material.
5) Soil Group E: Dry weather cover.
Use: Daily cover for landfill during dry weather.
Purpose: Source of moderately dry on-site soils during dry weather
operations.
Soil Type: Dense, glacial till and weathered glacial till (gravelly
silty sands, silty gravelly sands).
Volume Required: Approximately 600,000 cubic yards total.
Stockpile Placement: Use directly from excavated materials or
stockpile in uncompacted berms with 3 hori-
zontal to 1 vertical side slopes. Top and
side surfaces of berms should be compacted.
Weather Protection: Drain surface runoff away from berm.
The soil groups A through D will require that minimum volumes be stock-
piled for future time periods of use. These volumes should receive first
priority.
Very little of the clean sands and gravels for Soil Group C are expected i:o
he available on-site and may be difficult to excavate without being contami-
nated. Imported soils or other on-site soils (i.e., excavated dense sand-
stone) .may have to ba used.
Imported gravels or other substitutes (wood chips, ashes, etc.) may have
to be used for temporary road surfaces during wet weather conditions.
The predominant on-site soils are expected to be the dense glacial till,
and weathered sandstone or till. Surplus volumes of dense till and
weathered till are expected.
73
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Stagre 1 Landfill and Stage 2 Preparation
Tasks to be accomplished during the first stage of sanitary landfill
operation, indicated on Sheet 13 in Appendix C, include:
o Sanitary Landfill in Stage 1 Area (approximately 11 acres):
Fill with four lifts.
Drain on-site runoff by moving inlet along 8-inch pipeline.
Obtain daily cover from stockpile in Stage 2 and Stage 3 areas.
o Operate and Maintain Site Facilities:
Off-site surface runoff diversion system.
On-site surface runoff drainage system.
Leachate collection and treatment system.
Water quality monitoring system.
Buildings, gate house and scale, roads, fencing, buffer strips,
and other features in accordance with procedures developed by
the county.
o Preparation of Stage 2 Area (Approximately 7 acres):
Final grading after depletion of soil stockpile.
Extend on-site drainage pipeline.
Construct leachate barrier where required.
Construct temporary site road.
Place gravel for gas vent and leachate drain.
o Excavate Stage 3 Area (Approximately 8.4 Acres):
Clear approximately 7.5 acres.
Excavate approximately 168,000 cubic yards.
Stockpile approximately 165,000 cubic yards of daily cover
(Group B and E soils) in Stage 3 area.
Stockpile remaining soils in excess soil stockpile area.
Stage 2 Landfill and Stage 3 Preparation
Tasks to be accomplished during the second stage of sanitary landfill
operation, indicated on Sheet 14 in Appendix C, include:
o Sanitary Landfill in Stage 1 and Stage 2 Areas (Approximately
15.5 Acres):
Fill Stage 2 area with four lifts.
Continue filling both Stage 1 and Stage 2 areas to final elevations.
Drain on-site runoff by moving inlet along 8-inch pipeline.
-------
Obtain daily cover from Stage 3 and Stage 4 areas.
Complete gas venting system along east and west side of landfill.
Apply final cover, grade, and seed with grass.
Construct drainage channel for storm runoff from the completed
landfill.
Install 8-inch clean-outs on end of on-site drainage pipeline
and leachate pipeline.
Obtain soils for final cover from excess soil stockpile.
o Operate and Maintain Site Facilities:
The same site facilities as in Stage 1 landfill would continue to
be operated and maintained.
o Preparation of Stage 3 Area (Approximately 7 Acres):
Final grading.
Extend on-site drainage pipeline.
Construct leachate barrier where required.
Construct temporary site road.
Place gravel for gas vent and leachate drain.
o Excavation of Stage 4 Area (Approximately 8.4 Acres):
Clear approximately 7.5 acres.
Excavate approximately 196,000 cubic yards.
Stockpile approximately 123,000 cubic yards of daily cover
(Group B and E soils) in Stage 4 area.
Stockpile remaining soils in excess soil stockpile area.
Stage 3 Landfill and Stage 4 Preparation
Tasks to be accomplished during the third stage of sanitary landfill
operation, indicated on Sheet 17 in Appendix C, include:
o Sanitary Landfill in Stage 3 Area (Approximately 8.9 Acres):
Fill Stage 3 area with 5 to 6 lifts to final elevations.
Drain on-site runoff by moving inlet along 8-inch pipeline.
Obtain daily cover from Stage 4 and Stage 5 areas.
Complete gas venting system along east and west side of landfill.
Apply final cover, grade and seed with grass.
Extend drainage channel along permanent site road for on-site
runoff.
Install clean-out on end of 8-inch on-site drainage pipeline.
Obtain soils for final cover from excess soil stockpile.
o Operate and Maintain Site Facilities:
The same site facilities as in Stage 1 landfill would continue to
be operated and maintained.
75
-------
o Preparation of Stage 4 Area (Approximately 7.3 Acres):
Final grading.
Extend on-site drainage pipeline.
Construct leachate barrier where required.
Construct temporary site road.
Place gravel for gas vent and leachate drain.
o Relocate Excess Soil Stockpile Area:
Prepare a permanent excess soil stockpile area (approximately 7
acres) outside of the waste disposal area. Work items will involve
clearing, rough grading, drainage, and an access road across the
off-site runoff diversion channel.
Relocate soil stockpiles of special soil groups (Group A, B, C, and
D) to the newly prepared area.
Relocate, sell, or give away excess Group E soils not needed for
future landfill operations. Approximate excess after completion of
the fill area is estimated at 350,000 to 450,000 cubic yards.
However, this volume is subject to monitoring of waste to daily
cover ratios during initial stages of landfill operation. This
material could be used to develop the future use contours or to
extend the life of the waste disposal area.
o Excavation of Stage 5 Area (Approximately 8.4 Acres):
Clear approximately 7.5 acres.
Excavate approximately 282,000 cubic yards.
Stockpile approximately 96,000 cubic yards of daily cover in
Stage 5 area.
Stockpile remaining soils in newly prepared excess soil stockpile
area.
Stage 4 Landfill and Stage 5 Preparation
Tasks to be accomplished during the fourth stage of sanitary landfill
operation, indicated on Sheet 18 in Appendix C, include:
o Sanitary Landfill in Stage 4 Area (Approximately 8.4 Acres):
Fill Stage 4 area with 4 to 5 lifts to final elevation.
Drain on-site runoff by moving inlet along 8-inch pipeline.
Obtain daily cover from Stage 5 and Stage 6 areas.
Complete gas venting system along east and west side of landfill.
Apply final cover, grade and seed with grass.
Extend drainage channel along permanent site road for on-site
runoff.
Install cleanout on end of 8-inch on-site drainage pipeline.
Obtain soils for final cover from excess soil stockpile.
o Operate and Maintain Site Facilities:
The same site facilities as in Stage 1 landfill would continue to
be operated and maintained.
76
-------
o Preparation of Stage 5 Area (Approximately 7.6 Acres):
Final grading.
Extend on-site drainage pipeline.
Construct leachate barrier where required.
Construct temporary site road.
Place gravel for gas vent and leachate drain.
o Excavate Stage 6 Area (Approximately 10.2 Acres):
Excavate approximately 313,000 cubic yards.
Stockpile approximately 83,000 cubic yards of daily cover (Group
B and E soils) in Stage 6 area.
Stockpile remaining soils in excess soil stockpile area.
Stage 5 Landfill and Stage 6 Preparation
Tasks to be accomplished during the fifth stage of sanitary landfill
operation, indicated on Sheet 19 in Appendix C, include:
o Sanitary Landfill in Stage 5 Area (Approximately 9.3 Acres):
Fill Stage 5 area with 3 to 4 lifts to final elevation.
Drain on-site runoff by moving inlet along 8-inch pipeline.
Obtain daily cover from Stage 6 area.
Complete gas venting system along east and west side of landfill.
Apply final cover, grade and seed with grass.
Extend drainage channel along permanent site road for on-site
runoff.
Install cleanout on end of 8-inch on-site drainage pipeline.
Obtain soils for final cover from excess soil stockpile.
o Operate and Maintain Site Facilities:
The same site facilities as in Stage 1 landfill would continue
to be operated and maintained.
o Preparation of Stage 6 Area (Approximately 10.2 Acres):
Final grading.
Extend on-site drainage pipeline.
Construct leachate barrier where required.
Construct temporary site road.
Place gravel for gas vent and leachate drain.
Stage 6 Landfill
Tasks to be accomplished during the sixth stage of sanitary landfill
operation, indicated on Sheet 20 in Appendix C, include:
o Sanitary Landfill in Stage 6 Area (Approximately 14.3 Acres):
Fill Stage 6 with 2 to 3 lifts to final elevations.
Drain on-site runoff by moving the inlets along 8-inch pipeline.
77
-------
Obtain daily cover from excess soil stockpile.
Complete gas venting system along east and west side of landfill.
Apply final cover, grade and seed with grass.
Extend drainage channel along permanent site road for on-site
runoff.
Install clean-outs on end of 8-inch on-site drainage pipeline.
Obtain soil for final cover from excess soil stockpile.
o Operate and Mainatain Site Facilities:
The same site facilities as in Stage 1 landfill would continue
to be operated and maintained.
o Divert On-Site Drainage Pipeline to Leachate Collection System:
After clean-outs are installed on the two 8-inch on-site drainage
pipelines, the 18-inch pipeline north of the waste disposal area
should be diverted into the leachate pump station.
Phase III - Final Use
Maintenance and Operation after Landfill Closure
Upon completion of the sanitary landfill operation, the waste disposal
area should have been developed to the final elevations and grades shown
on Sheet 21 in Appendix C. The following items should be operated
and/or maintained for a minimum period of five years, unless otherwise
noted.
Final Cover: Cracks, depressions or erosion marks that develop in the soil
cover as the landfill settles should be filled with soil (Group A or D
soils), graded and reseeded with grass. Approximately 50,000 cubic yards
of soil should be retained in the excess soil storage area for maintenance.
On-Site Runoff Drainage Channel: The channel should be periodically
inspected for adverse erosion which should be corrected by reconstructing
the channel with Group A or D soils and reseeding with grass or by
reconstructing the channel and lining it with rock, asphalt or other
suitable materials.
Leachate Collection and Treatment System: The leachate collection pipe-
line and pump station should be maintained and the leachate treatment
facility should continue to be operated until monitoring of the raw
leachate quantity and quality indicates that the treatment facility can
be eliminated. This may require many years of leachate treatment facility
operation and maintenance. If leachate generation tapers off, it may be
possible to store leachate in the lagoon for periodic batch treatment
and discharge to the on-site runoff holding pond.
On-Site Runoff Holding Pond: Water quality should continue to be moni-
tored prior to discharging pond water into the intermittent creek.
78
-------
Off-Site Runoff Holding Pond and Drainage Channel; Both facilities
should be maintained.
Gas Venting System: The vents should be maintained to prevent plugging
and gases should be periodically monitored to determine the need for
odor control.
Permanent Site Road: The road should be maintained for access to the
leachate treatment facility.
Utilities: Utility service to the leachate treatment facility will be
required.
Excess Soil Stockpile Area: Group A and D soils will periodically be
required for maintenance of the final cover on the landfill. Other
soils could be used for future site development.
Water Quality Monitoring: The routine water quality monitoring procedure
should be continued by Snohomish County Department of Public Works until
results indicate that monitoring is no longer required.
Final Use Development
Final use of the site is presently undefined. However, the final ele-
vations and contours (refer to Sheet 21, Appendix C) have been selected
to provide large gently sloped areas suitable for development of active
recreation facilities (such as tennis courts, ball parks, soccer fields,
archery range, golf course and bicycle pathways) and/or passive recre-
ation facilities (such as parks, picnic areas, gardens, walkways or open
space). As only 56 acres of the site would be filled with solid waste,
considerable area will be suitable for structures. Large areas will be
left in their natural condition. The holding ponds and the diverted
creek could be developed to enhance the visual aesthetics of the site.
The double lane service road will provide vehicle access to much of the
site.
79
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-------
INDEX TO DRAWINGS
No. Title
1 GENERAL SITE PLAN
2 PHASE I: Initial Site Preparation - Clearing and Site Investigations
3 PHASE I: Initial Site Construction Plan
4 PHASE I: Site Roads - Details
5 PHASE f: Stage 1 and 2 Excavation Sections
6 PHASE I: Stage 1 Leachate Collection and On-Site Runoff Drainage Plan
7 PHASE I: Leachate and Drainaqe Pipelines at North End of Stage 1
B PHASE I: Leachate Collection System Details
9 PHASE I: On-Site Runoff Drainage System Details
10 PHASE I! Leachate Treatment Facility
11 PHASE I: Off-Site Runoff Holding Pond
12 PHASE I: Off-Site Runoff Diversion Channel
13 PHASE II: Stage 1 Landfill and Stage 2 Preparation Plan
14 PHASE II: Stage 1 and 2 Landfill and Stage 3 Preparation Plan
1 5 PHASE II: Stags 1 and 2 Landfill and Stage 3 Detail
16 PHASE II: Daily Cover. Final Cover and Gas Control Details
17 PHASE II: Stage 3 Landfill and Stage 4 Preparation Plan
18 PHASE II: Stage 4 Landfill and Stage B Preparation Plan
19 PHASE II: Stage 5 Landfill and Stage 6 Preparation Plan
20 PHASE II: Stage 6 Landfill
21 PHASE III: Base Site For Future Use
SNOHOMISH COUNTY
CATHCART SANITARY LANDFILL
JANUARY I975
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INITIAL SITE PREPARATION
CLEARING AND SITE INVESTIGAIION
F71
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SNOMOM1SM COUNTY
TAIHCART SAMtlARY LANT1HI I
F1IASE 1
HIIIAI. SITE CONSTRUCTION PLAN
-'21
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CATHCARt SANITARY LANnrilL
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-------
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•r
LF5CHATE 8 DRAINAGE
AT NORTH END OF MAGF I
CAUICART SANITAnY LANDriLL
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21
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DETAILS
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OFF-SITE RUNOFF HOLDING POND
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PREPARATION PLAN
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• 21
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STAGE l&? LANUFILL AW STAGE 3 PREPARATION PI.AN
-------
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SNOHOMISM COUNTY
CATMCART SANITARY LANDFILL
STAGE 1 9 2 LANDFILL AND STAGE 3
PREPARATION DETAILS
^21
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FILL DEPRESSIONS AMD To MATCM puist
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INTERFACE BETWEEN PERMANENT SITE ROAD Q LANDFILL. ''
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" SOILS D'JRING DRV WEAT
OR GPOUPT3" SOIL.5 DUUtN^
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3OLIP WA57F.-
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ITING SYSTEM - EAST'SIDE OF FILL AREA
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SNOHOM1SH COUNTY
CATHCAUT SftNlfARY LftNDFILL
DAILY COVER, FINAL COVER 8
GAS CONTROLS
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/ 21
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«Bn.r.T-
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AS SHOWN. |r"t JW.Y 79
SNOHOMISH COUNTY
CAIHABT SANITARY LANDFILL
PHASE H
STAGE 5 LANDFILL AMD STAGE 6 PREPARATION PLAN
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COMPLETED WASTE DISPOSAL AREA
56 ACRES
-' r
-------
Cathcart Sanitary Landfill
Design Report
"\folume II
SnohomislL County
Public 'Works Department
Stevens, Thompson & Runyan, Inc.
103
-------
SOLID WASTE DISPOSAL SYSTEM
SNOHOMISH COUNTY
CATHCART LANDFILL
DESIGN REPORT
VOLUME II - APPENDICES
AUGUST, 1975
Stevens, Thompson &, Rvinyan, inc.
Engineers / Planners
PORTLAND SEATTLE BOISE • SPOKANE
104
-------
TABLE OF CONTENTS
No. of Pages
APPENDIX A - SOLID WASTE DISPOSAL SYSTEM 106
Snohomlsh County - Facility & Operational Plan
Design - Phase I -' Report No. 2
APPENDIX B - WATER QUALITY MONITORING DATA 129
APPENDIX C - FINAL DESIGN DRAWINGS
(See Volume I)
APPENDIX D - REE'S CORNER SANITARY LANDFILL SITE: W-1035-62 161
APPENDIX E - CATHCART SANITARY LANDFILL SITE: SNOHOMISH 179
COUNTY; W-1035-64
APPENDIX F - SUBSURFACE INVESTIGATIONS AND PERCOLATION 227
TESTING OF BEDROCK; LANDFILL SITE; CATHCART,
WASHINGTON; W-1035-66
105
-------
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-------
APPENDIX A
FACILITY & OPERATIONAL PLAN DESIGN
PHASE 1 - REPORT NO. 2
This appendix includes excerpts from the Phase 1 - Report No. 2 which
was a preliminary report to Snohomish County from Stevens, Thompson
& Runyan, Inc. concerning an early evalution of the Wintermutes and
Cathcart sites as potential sanitary landfill sites. The appendix
contains general landfill requirements, alternative approaches for meet-
ing the requirements and a description of the Cathcart site.
The information taken from the preliminary report supplements the final
design report, except where quantities have been substantially revised
in final design. These quantities are noted in this Appendix.
107
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APPENDIX A
SYSTEM REQUIREMENTS
CELL DIMENSIONS
The design of the daily cell development in the sanitary landfill is one of the most important
design considerations of the facility. The cell development must be designed in such a
way as to assure that the following criteria are met:
1. Unrestricted access is provided to the sanitary landfill working face by the
vehicles depositing waste at the site.
2. The working face is kept as small as is practical to satisfy environmental and
aesthic considerations.
3. The slope of the landfill working face and the thickness of layers in which
waste is applied to the working face are designed to assure maximum waste
in compaction.
4. The working face slope and cell height are designed to assure the safety of
the landfill operators.
5. The daily cover material usage rate is minimized.
6. Sufficient cover is provided to meet the health and aesthetic requirements
of the sanitary landfill.
The cell development should also be designed to obtain cover for the fill operation through
excavation on the site. Thus, when more than one cell lift is placed on the site, sufficient
soils excavation must be made to provide for future cover requirements, since the cell
layer will cover the source of materials. The determination of cover requirements and
cell development is therefore important to assure proper design of fill development and
cover excavation.
A typical daily cell development is presented in Figure 1 in order to define terminology.
The working face length of the daily cell for the urban sanitary landfill must be a minimum
of 110* feet in order to allow adequate access by the number of vehicles transporting
waste to the site. The actual working face length would vary so that the cell thickness
could be kept constant to control the landfill development. A working face slope of 3
to 1 should be maintained for minimum cover usage and maximum waste compaction.
The cell would require a daily cover of 6 inches of compacted soil. A depth of 12 inches
would be required for the top of the cell when it is to be left uncovered for more than
6 months.
A cell height of 9 feet with a lift height of 10 feet is recommended for operational ease
and safety. However, a higher cell height would reduce cover usage rates. Using these
'Revised to 45 feet in final design.
108
-------
o
•TYPICAL CELL DEVELOPMENT-
AREA METHOD SANITARY LANDFILL
FIGURE-1
-------
cell dimensions, and assuming that it would require 1 1/2 cubic yards of excavated soil
to obtain 1 cubic yard of compacted cover because of soil loss during the cover operation,
the excavations required for daily cover for the urban sanitary landfill are tabulated in
Table 3.
Year
1975
1980
1985
1990
TABLE 3
DAILY COVER REQUIREMENTS
Excavation Required for Daily Cover
vd3
LITTER CONTROL
A potential problem associated with the operation of a sanitary landfill is the blowing
of loose material from the working face. On windy days, the amount of loose material
can be great and the litter can be blown off the site.
The normal method of litter control is the construction of fences as close to the working
face area of the fill as possible. The fences are normally constructed of a fine mesh screen
to allow air movement through the fence so that litter is less likely to be carried over
the fence. The screen must be of mesh fine enough to trap the litter.
A strict site maintenance program is also required, whereby personnel continuously collect
litter which is scattered on site and trapped by the fences. Specific manpower and
equipment requirements for this operation will be dependent on weather conditions and
the ability of the site operators to compact incoming refuse within the shortest possible
time. Methods for collecting litter include hand pickup by site personnel and mechanical
pickup by truck-mounted vacuum systems.
Initial costs for portable litter control fencing are approximately $15 per foot, with the
total cost being $3,000 $5,000*. Costs for a maintenance program for litter pickup and
moving of portable fencing are dependent on the performance of site operations. A
minimum program would include one individual with a small truck assigned periodically
to site cleanup and maintenance, including some landscape and repair work. This program
would result in costs of approximately $10,000 per year.
* Revised to under $3,000 for final design.
110
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NOISE CONTROL
The noise produced by equipment operating a sanitary landfill and by vehicular traffic
transporting waste to the site can present problems to individuals living near the facility.
The noise levels associated with operating equipment which might be utilized at the site
are presented in Table 4. These noise levels are for distances of 50 feet from the
equipment. The actual noise levels attributed to site operations or refuse haul that would
occur at any specific location near the landfill are a function of a number of variables.
These variables include background noise levels already present at that location, the distance
from the location to the landfill operation noise source, topography including trees and
structures between the noise source and the location, and meteorological conditions at
that time. It is therefore difficult to forecast specific impacts which may be generated
by noise developed at a landfill. However, noise attenuation caused by peripheral barriers
and ground absorption can be assumed to be over 40dB for distances greater than 500
feet from the operation. This attenuation combined with feasible noise controls placed
on equipment should meet a desired noise level of below 40dB which will result in minimal
impact to the surrounding areas, as shown in Table 5.
TABLE 4
EQUIPMENT NOISE LEVELS
in dB(A) at 50 Ft.
Present
Noise With Feasible
Equipment Level Noise Control 1
Front loader 79 75
Backhoes 85 75
Dozers 80 75
Tractors 80 75
Scrapers 88 80
Graders 85 75
Truck 91 75
Source: "Noise from Construction Equipment and Operations, Building Equipment,
and Home Appliances" U.S. EPA, 1972
111
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TABLE 5
ESTIMATES OF MAGNITUDES OF NOISE EFFECTS
/In dB(A)7
Effect Moderate Level Appreciable Level
Hearing Damage Risk 70 90
Speech Interference 45 60
Sleep Interference 40 70
Physiological Stress * 90
Startle * 110
Annoyance 40 60
Task Interference 55 75
ODOR AND GAS ATTENUATION
A problem associated with a poorly operated solid waste landfill is the presence of odors
near the site. This problem is primarily caused by allowing air to be in contact with
decaying garbage because of improper or inadequate soil covering. Thus, the daily
compaction and covering of the waste are critical. Odor can be controlled only if the
covering operations are continuously maintained.
In the sanitary landfill, organic waste is converted into inorganic materials, water, and
gases through biodegradation. In the presence of oxygen, the biological activity is carried
out by aerobic bacteria, and C02 is the primary gas produced. After the available oxygen
has been utilized by this process, which normally takes several months, the biodegradation
is carried out by anaerobic bacteria. In the anaerobic process, C02 methane, ammonia,
hydrogen sulfide, nitrogen, and hydrogen gases are produced. The volume of gas produced
is theoretically 15 cubic feet at atmospheric pressure per pound of volutile solids. Thus,
in the landfill it can be assumed that 35 percent of the waste is originally reducable,
the density is 1000 pounds per cubic yard, and the gas production potential over the
life of the landfill is approximately 190 cubic feet of gas at atmospheric pressure per
cubic foot of landfill space. While the potential gas production can require a number
years to take place, gas production rates are significant and the gas produced can contain
up to 50 percent methane.
The gas produced at the landfill can have several effects. If concentrated when vented
to the atmosphere, odors can result. Since the methane and hydrogen portions of the
gas are flamable, fires may occur either in the fill itself or at points where gas is
concentrated when vented to the atmosphere. Cases have been recorded where gas has
112
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migrated horizontally for considerable distances in the subsurface soils and caused
explosions in the basement of structures. The ammonia and C02 gases can dissolve in
the moisture present in the fill. The C02 in part forms a weak acid (carbonic acid) in
solution which will react with metals, especially iron, causing the metals to enter the
solution. The C02 in solution also readily reacts with limestone, greatly increasing the
Ca COS hardness of the solution.
The control of gas generated at a sanitary landfill is important. This is especially true
for a landfill at the proposed alternative locations in Snohomish County, since the silty-clay
materials available for cover have a low permeability. This will tend to trap the gases
in the cells and could create explosions, fires or horizontal movement of the gases from
the site through subsurface soils. Control of the downward movement of gases is not
critical, however, because of the |ow permeability of the subsurface silty-clays.
A system will be required for venting the gas produced in each individual cell. The venting
can be accomplished with the use of a pipe collection network. The gas collected in the
pipe may have to be burned prior to release to the atmosphere for odor control and
prevention of any uncontrolled fire. The development of a pipe network would be difficult,
however, because of possible interference with daily operations, especially in multi-lift
landfill operations. Pipe network would also be difficult to maintain because of settlement
in the landfill.
A more practical method of gas control would be the construction of a gravel-filled ditch
in the top of each cell. This ditch would act as a gas vent because of the porous gravel.
A ditch backfilled with gravel should also be constructed, at the site perimeter to assure
that gas did not migrate laterally from the site. This control system would then be
monitored to assure that gas was venting properly. If it were found that gas were
accumulating in the cells and not venting properly, a negative pressure pipe network could
then be constructed to vent gas from the cells.
VECTOR CONTROL
The presence of health vectors including flies, rodents and seagulls is often associated
with improperly operated solid waste disposal operations. The daily covering and
compaction of the refuse with soil in a properly operated sanitary landfill does much
to correct this potential problem. If the refuse is frequently covered, it is no longer a
source of food or harborage for rodents. The soil cover, if well compacted, will prevent
the emergence of flies from the refuse. A potential will exist for birds to feed from the
refuse before it is covered with soil. This problem can be alleviated by keeping the working
fact of the fill as small as possible.
> A program should also be
established for rat baiting on the site to assure that a rodent problem does not occur.
This baiting program should result in costs of less than $100 per month.
113
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WATER POLLUTION AND DRAINAGE CONTROL
In Report No. 1, the four types of ground and surface waters normally appearing at a
sanitary landfill were described and discussed. These were:
1. Off-site surface runoff: Surface waters originating from precipation off the site and
entering the site through overland flow.
2. On-site surface runoff: Surface waters originating from precipitation on the site.
3. Off-site groundwater: Ground waters entering the site through pervious soil strata
and quite often appearing on the site as springs.
•
4. Leachate: On-site groundwater polluted by percolation through solid wastes.
The first three types of water are potential sources of leachate if not properly managed,
and the volume of leachate to be treated depends greatly on the drainage control systems
developed on the landfill site. Therefore, the attenuation of leachate starts with the
diversion of off and on-site surface runoff and off-site groundwater in their unpolluted
state.
The following is a discussion of specific design requirements and objectives for drainage
control for the purpose of minimizing the volume of leachate.
Off-Site Surface Runoff
Off-site surface runoff may enter a landfill site in two forms: either continuously as a
relatively large, discrete, flowing body of water (rivers, creeks), or intermittently, during
and subsequent to precipitation, as indiscrete overland flow. Of these two forms of runoff,
the latter is the most difficult to control.
Rivers and creeks of the magnitude affected by any landfill operation covered in this
study can be controlled by the installation of impervious liners in the channel bottom and
sides. This would prevent river or creek water from intruding the surrounding soil and
becoming leachate as well as preventing leachate from polluting the river or creek.
Intermittent overland flow must be collected and transported to a body of receiving water.
This would be accomplished by the construction of peripherial ditches intercepting any
overland flow before it reaches the fill areas.
For sizing these ditches, the rational method will be used. This method gives a relationship
between the size of the drainage area, characteristics of the drainage area, precipitation
114
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intensity and the resulting flow as expressed by the following equation:
Q = Ci A
Where
Q = flow in cubic feet per second
C = Dimension less number ranging from 0 to 1 expressing surface characteristics
of the drainage area
i = Rainstorm intensity in inches per hour
A = Drainage area in acres
To determine a design flow for which to size interceptor ditches, the following parameters
will be used.
C = 0.2
i = .75 inches per hour
This will give a design peak hour flow of 0.15 cubic feet per second per acre of contributing
drainage area.
These parameters and resulting flows will be refined when more knowledge of topography
and surface characteristics of the contributing drainage areas are known.
On-Site Surface Runoff
On-site surface runoff will be similar to the intermittent overland flow as described under
off-site surface runoff, and the same design criteria will be used, i.e. peripheral ditches
and a design peak hour flow of 0.15 cubic feet per second per acre.
On-site surface runoff is generally relatively unpolluted. Experience has shown that BOD
concentrations of these waters generally range from ten to twelve milligrams per liter
(mg/L). The runoff usually contains a high concentration of inorganic solids due to erosion
of cover materials. Occasionally, the runoff may also have a high concentration of coliform
bacteria.
Based on these parameters, the installation of a settling basin for the removal of inorganic
suspended solids is usually provided. Since there is some biological activity in such settling
ponds that may have a removing effect on coliform bacteria, a monitoring program should
be initiated to determine if a disinfection system is required.
115
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To minimize the suspended solids concentrations in the on-site surface runoff, the
completed parts of the landfill should immediately be seeded with grass.
Off-Site Groundwater
Off-site groundwater is the most difficult to control for the purpose of attenuation of
leachate and general prevention of pollution. Because both flow directions and volumes
vary greatly with the depths and permeabilities of soil strata, it is imperative that thorough
soils investigations be performed before any systems are designed or constructed.
Four different methods may be employed to divert off-site groundwater:
1. Vertical impervious peripheral barriers diverting the groundwater in the ground itself.
2. Peripheral drain pipes intercepting the groundwater before it enters the landfill site.
3. Overexcavation of the off-site storm runoff ditches to also collect off-site
groundwater in case the off-site groundwater is perched on a relatively shallow
impervious soil stratum.
4. Drain pipes at or immediately below the ground surface where springs occur and
an impervious barrier on top of these drain pipes preventing leachate from entering
the spring drain pipes.
Vertical impervious barriers are used for groundwater control in several types of
construction projects. However, in numerous cases, the groundwater tables have risen
behind such barriers. This, in turn, has caused flooded basements and inoperative septic
tank drainfields behind these barriers. Therefore, vertical, impervious peripherical barriers
are not recommended unless it can be accurately predicted that no harmful effects result
from a higher groundwater table behind the barriers.
In cases where shallow perched watertables are encountered, peripheral drain pipes
removing the groundwater before it enters the landfill site would probably be the best
solution. These pipes could drain into nearby receiving waters by gravity if the ground
surface allows. Otherwise, the groundwater will have to be pumped.
The volumes of off-site groundwater that will be diverted cannot be estimated until the
system is in operation. However, a rough estimate can be made when the permeability
of the surrounding soils are known.
In cases where the off-site groundwater appears on the landfill site as springs and the
depth at which it enters the site is too great to economically divert with peripheral drain
pipes or overexcavated off-site runoff ditches, the most feasible method will be to divert
the springs where they appear on the site.
116
-------
This kind of situation usually occurs in ravines and the collection and transportation of
springs can usually be done entirely by gravity.
Although some measurements of spring flows can be made before a collection system
is designed and constructed, reliable flow data cannot be obtained until after the system
is placed in operation.
Leachate
The proposed methods of landfill operations and the drainage improvemetns are all designed
to minimize and possibly eliminate the generation of leachate. However, in case a problem
occurs, a standby system for the collection and treatment of leachate is recommended.
The only practical method of collecting leachate is by the means of drain pipes at those
parts of the periphery where detailed on-site groundwater studies have shown that leachate
may be expected to occur. These drain pipes will be perforated and placed in a trench
backfilled with gravel. The invert of the leachate collection pipe will be placed
approximately at the same elevation as the lowest depth at which leachate contamination
is likely to occur.
The leachate collection system would convey the leachate to a leachate treatment and
disposal facility.
Table 6 lists characteristics of leachate reported for sanitary landfills throughout the
country. As can be seen, a wide spread of concentrations of the different pollutants can
be anticipated.
For the purpose of this study, a Biochemical Oxygen Demand (BOD) of 2,000 milligrams
per liter (mg/L) is assumed for the purpose of estimating costs.
Four types of systems are considered feasible for the treatment and disposal of leachate.
These include 1) teriary treatment and disposal to a local creek, 2) secondary treatment
and disposal to a river, 3) intermediate (somewhat less than secondary) treatment and
spray irrigation of the effluent on the completed, seeded parts of the landfill, and
4) disposal to a municipal sanitary sewerage system.
A tertiary leachate treatment facility has recently been installed at the Hidden Valley
Sanitary Landfill, Bucks County, Pennsylvania. This facility consists of physical-chemical
treatment process units that have proven themselves to provide a high quality effluent
through numerous pilot plant studies, and the same treatment processes are recommended
for Snohomish County if the discharge of the treated leachate to a local creek is required.
In case the discharge of the treated leachate to a stream with a relatively high flow (river)
is feasible, a secondary biological treatment process will probably be the most feasible
alternative.
117
-------
TABLE 6
TYPICAL LEACHATE CHARACTERISTICS
oo
PARAMETER
ph
Dissolved Oxygen
Total Coliform-MPN
BOD
COD
Total Solids
Suspended Solids
Volatile Solids
Alkalinity (CaCO3)
Total Hardness (CaCO3)
Calcium
Magnesium
Total Nitrogen
Organic Nitrogen
Ammonia - N
Nitrate - N
Total Phosphate
Ortho-Phosphate
Total Iron
Sodium
Potassium
Sulfate
Sulfide
Chloride
Copper
Zinc
Nickel
Chromium
Mercury
Lead
CEDAR
HILLS
F-C-R (1)
5.8-6.2
00.1
23-1600
1150-7000
1 760-8870
0.92.4
0-0.1
0.03-0.12
KENT-
HIGHLANDS
F-C-R (1)
6.0-6.9
0-2.1
8- 2400
820-7,300
1240-8,940
31-447
0-20
00.026
00.017
0.1-0.6
00.3
00.0004
0.01-0.319
KENT
HIGHLANDS
MILLER (2)
6.3-6.5
0
7000-17,500
1010-2240
1250-3095
916-2045
48-311
341-1103
548 1571
480750
110-192
214-333
26.4-124.0
1.5-30.5
12.2-102.2
.20-2.50
.36-. 72
0-.16
27.7-143.8
16-35
2
0-65
2.4-3.6
0
CALIFORNIA
(3)
6.06.5
21,700-30,300
730-9,500
890-7,600
240-2,330
64-410
2.4-465
.22-480
.3-29
6.5-220
85-1,700
28-1,700
84-730
96-2,350
FUNGAROLI
(4)
3.7-8.5
800-50,700
1326,500
2005500
8-482
2.1-177
2-130
.12 1,640
127-3,800
20-450
47-2,340
0-7.6
0.03-129
00.81
NOTE: See following page for references, i.e., (II.
-------
REFERENCE LIST
1. Food, Chemical, and Research Laboratories, Inc.
2. Miller, Joseph R., "Characteristics of a Sanitary Landfill Leachate and Its Treatability
in an Aerated Lagoon," a Master's thesis, University of Washington, 1971. A study
conducted at the City of Seattle's Kent Highlands landfill.
3. California State Water Pollution Control Board. Report on the investigation of
leaching of a sanitary landfill. Publication No. 10. Sacramento, 1954.
4. "Pollution of Subsurface Water by Sanitary Landfills." United States Environmental
Protection Agency, Solid Waste Management Research Grant EP-000162, Drexel
University, Pennsylvania, (1971)
119
-------
Although numerous pilot plant studies of biological leachate treatment have been
performed, the only full scale biological leachate treatment facility in operation, as far
as is known, is an aerated lagoon at the City of Seattle sanitary landfill at the
Kent-Highlands. This lagoon has not performed adequately, probably because of
unanticipated increases in flows and a lack of nutrients.
However, efficiency studies have proven that the aerated lagoon can convert the dissolved
pollutants generally present in leachate into a suspended state which in turn could be
removed by conventional solids removal facilities (i.e., clarifiers, sand filters, etc.)
Since the characteristics of leachate vary from landfill to landfill, it is recommended that,
if this alternative is selected, the aerated lagoon be constructed first. While the lagoon
is in operation, an extensive monitoring program would determine the type of solids
removal facilities to be employed to further treat the aerated lagoon effluent. In addition,
disinfection facilities will be required.
In case the distance to any receiving water or municipal sewerage system is large enough
to cause economic difficulties, the alternative of intermediate treatment and land disposal
on the completed, seeded parts of the landfill should be considered.
The treatment facility would consist of an aerated lagoon discharging into a combined
polishing/storage lagoon. The dual purpose of this system would be to settle out
the solids and to provide storage during rainy days. Based on rainfall records from the
Everett-Monroe area, the polishing/storage lagoon should have a detention time of
approximately 30 days.
Research on land disposal of wastes has shown that if a waste is allowed to flow overland
for a distance of a few 100 feet, relatively good treatment may be accomplished.
The treated leachate will, therefore, appear as on-site surface runoff, be further treated
while flowing overland, be collected with other on-site surface runoff by the on-site surface
runoff collection ditch, and be further treated on the on-site surface runoff settling pond
before being discharged to the receiving water.
Operation of the sprinkler facilities during days with rainfall is not recommended.
The alternative of pumping the leachate to a municiapl sewerage system would be selected
if such a system is located in the vicinity of the landfill. In this case, final agreements
would have to be made with the municipality regarding acceptance, pre-treatment
requirements, and user charges.
120
-------
Water Quality Monitoring
It is imperative that a water quality monitoring program of surface waters as well as ground
water be undertaken approximately 12 months prior to initiation of landfill operations.
The monitoring program should not be completed until it can be positively proven that
the landfill has stabilized.
BUFFER AND RESERVED AREAS
Ten acres in the southeast corner of the site have been designated a
reserve area, as it contains the only residence and building presently
located on the site. Retention of the on-site residence and the 10-acre
reserve (660 feet by 660 feet) would provide an excellent buffer be-
tween the site and the residences overlooking the site.
The site buffer should screen the landfill from view, block access to
the area and attenuate noise generated on the site. The buffer area
would be left in a natural state and be provided with additional plantings
of evergreen trees and shrubs. In this way, the site would blend in
with the surrounding area and a natural screen would be present through-
out the year. A fence would be constructed in the buffer adjacent to the
landfill area to prevent access by animals and unauthorized individuals,
also blocking any litter generated during high wind periods. Soils
excavated for future cover could be stockpiled to provide additional noise
attenuation.
121
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CATHCART SITE
SITE DESCRIPTION AND LOCATIONAL CONSIDERATION
SITE LOCATION
The Cathcart Site is being considered to serve the urban landfill service area and the South
County rural landfill service area. It is located along the Woodinville Cutoff Road (State
Highway 9} approximately 3 1/2 miles south of the town of Snohomish. The general
location is shown on Figure 2.
GENERAL DESCRIPTION
The Cathcart site is approximately 160* acres in size, most of which lies in a moderately
sloping gully between two ridges. The southeastern 40 acre portion of the site slopes
moderately from a ridge down to Highway 9. The surface water drainage in the gully
is intermittent.
The western 120** acre portion of the site is completely undeveloped. The southern 40
acres has been recently logged and is covered with young alder, stump and considerable
slash. The remaining portion of the western 120** acres has a dense cover of second growth
fir and alder trees.
The eastern 40 acres contains only a few trees and light brush. A house and three
outbuildings are also located on this portion of the site.
The entire site is owned by the State of Washington Department of Natural Resources.
ZONING AND LAND USE
The Cathcart Site is located in a predominantly rural area. Several houses and small farms
are located south and east of the site along 152nd Street east and along Highway
9 as shown in Figure 3. The north and west sides of the site have no residences or roads
for a considerable distance.
At least one and possibly three residences are located immediately adjacent to the south
property line near Highway 9 and overlook the eastern portion of the site. Other residences
south of the site are located over 700 feet from the site and are separated from the
site by a dense stand of trees.
'Revised to 200 acres in final design.
**Revised to 160 acres in final design.
122
-------
CATHCART DISPOSAL
SITE LOCATION
-------
RR-12500
AG-IOocre-F*1!
CATHCART
SITE »
PRESENT ZONING
CATHCART SITE
SCAI E IN FEET
ooo o" oob xoo jcoo
-------
Properties to the east of the site include residences along both sides of Highway
9. The houses between the site and Highway 9 are located over 700 feet from the site
and are separated from the site by a densely wooded ridge. Residences along the east
side of Highway 9 are downhill of the site. However, the eastern 40 acre portion of the
site may be visible from some of the residences.
Properties to the north of the site have residences along the Lowell-Cathcart Road. The
residences are at least 2,000 feet from the site* and are separated from the site* by dense
woods and an elevation drop of approximately 160 feet. Surface water drainage from
the 120** acre portion of the site flows to these properties.
Properties to the west of the site are completely undeveloped (no roads or houses) for
at least one mile. The area is heavily wooded.
The present landuse zoning in the vicinity of the Cathcart site is shown on Figure
3. As can be seen from Figure 3, the site is presently zoned for rural use (RU). Under
this zoning classification, sanitary landfill operations are permitted only upon issuance
of a conditional use permit, in accordance with Section 18.18.030 of the Snohomish
County Zoning Resolution.
SITE ACCESS
Major access to the Cathcart site is provided by State Highway 9 along the eastern 40
acre portion of the site. Access to the southern end of the site is possible from State
Highway 9 along the paved 152nd Street East to an unimproved road which leads to
the southeast corner of the site. The speed limit on Highway 9 is 60+miles per hour. The
speed limit on 152nd St. E. is 35 miles per hour.
State Highway 9 provides direct access to the disposal site from portions of the service
area located north and south of the site. Service areas to the east and particularly to
the west, would probably use less direct routes travelling through the City of Snohomish
via Highway 9, Lowell-Cathcart Road, Vine Street, and Maltby Road.
AVAILABILITY OF UTILITIES
The Cathcart Site is served by water, fire hydrants, power and telephone which are present
along State Highway 9. Thus, the site has good access to these utilities.
'Revised to waste disposal area for final design.
**Revised to 160 acres in final design.
+Speed limit is now 55 m.p.h.
125
-------
SOILS AND GEOLOGY
Subsurface Characterises
The Cathcart site appears to have two basic soil types overlying a sandstone bedrock.
The moderately hard sandstone, lying below the eastern ridge is fairly shallow, and
apparently slopes downwards to the west. Glacial till caps the high ground on both sides
of the gully. This material is a medium dense to dense mixture of sands, silts and some
gravels. Saturated sands were encountered within the gully overlying the impervious glacial
till. This material is a loose mixture of gravels, silts and mostly sands.
The dense glacial till, the loose sands and the weathered sandstone contain a relatively
large percentage of fines. Preliminary soil analysis indicated that the glacial till contaminates
about 45 percent fines, the loose sands contains 20 to 30 percent fines, and the weathered
sandstone contains approximately 18 percent fines.
Water was encountered in the sands along the gully bottom and in an isolated pond near
the top of the west ridge.
General Effect Upon Site Utilization
Additional soils investigations are necessary to supplement limited information describing
subsurface characteristics, especially in the areas of bedrock location and slope, glacial
till-bedrock contact, permeability of bedrock and surface soils, and groundwater flow.
However, the present information allows some general observations on the Cathcart Site.
The glacial till materials should serve as suitable cover materials during dry weather. The
till also contains sufficient fine materials so that, if it were used as cover material, the
fill would prevent surface runoff from penetrating into the fill and become leachate.
Excavation will require heavy equipment. The sands also contain considerable fines and
should be suitable cover material. However, they would be a less efficient barrier to water
movement than glacial till.
The sandstone bedrock may be an excellent leachate barrier depending upon its location,
slope, and permeability. The sandstone may limit the depth of excavation in some areas
of the site and may eventually limit the life of the site due to lack of on-site cover
material.
The abundance of fines in all of the soils indicates difficulty in using the soils for cover
and roads during wet weather. On-site dry soils could be stockpiled for use as wet weather
cover. Other soils or materials may be needed for road surfaces during wet weather.
126
-------
HYDROLOGY AND DRAINAGE
Surface Runoff
The majority of the Cathcart site is located in a draw draining northward. A small creek
with seasonal flow runs northerly in the bottom of the draw. This creek has a drainage
area of approximately 380 acres before it enters the site and peak flows of 57 cubic
feet per second can be anticipated.
Several drainage facilities have been constructed in conjunction with road construction.
These drainage facilities are shown on Figure 4 and include a 24-inch diameter culvert
under Virginia Street and an 18-inch and a 24-inch under 152nd Street.
The creek draining through the site eventually enters the flat Snohomish River Valley
through a 30 inch by 42 inch box culvert under Bluff Road.
Groundwater
Very little information is available on groundwater movements. Preliminary soils
investigations indicate that groundwater generally moves in the same direction as surface
waters. The location of certain soil strata indicates that groundwater movements may also
take place in a westerly direction. This must be investigated further before a definite
conclusion can be made.
General Effect Upon Site Utilization
The major problem appears to be diversion of the seasonal creek flowing through the
site. Because of the topography of the site, this creek will have to be partly diverted
Another problem may be the disposal of treated leachate. The only body of water having
any assimilative capacity is the Snohomish River which is located approximately 2 miles
to the northeast. If the treated leachate were discharged to the seasonal creek, extremely
advanced treatment equipment would be required to protect the water quality of this
creek.
127
-------
BOX CULV.
36 DIA. CULV.
& 24 //"• 18 DIA. CULV. :•
I A. CULV. 37
38£ ACRES A'
l^°4y
Existing Drainage Facilities
Jf( 'CATHCART SITE ^;rv
•;/•
i'i
Stevonw. Thompson 61 Ilunyan. inc.
Engineer i / Planner t
PORTLAND • SEATTLE • BOISE • SPOKANE
128
FIGURE 4
-------
) <"
'lS^':»M^»'v-v44if1niii"
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\ '4,- M , j. :i f;.,'
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'•*' V- '" '
,.,' I ' " '
V : .' '• r '"'^
-------
APPENDIX B
WATER QUALITY
MONITORING DATA
130
-------
MEMORANDUM
April 3, 1974 StellCOf
Washington
Department
, ol Biology
TO: 'Robert McCormick, Stewart Messman, Robert Aggas, Files
n Tf/Z.
FROM: John H. GlynnV *'*'
//
SUBJECT: PROPOSED CATHCART SANITARY LANDFILL,
SNOHOMISH COUNTY
On March 28, 1974, Bob McCormick, Bob Aggas, and I visited the proposed
Cathcart Sanitary Landfill with Byron Robertson of the Snohomish County
Health District and John Heneghan of Geolabs to look at the site and
take background surface water samples.
The site is owned by the Department of Natural Resources. It is a
moderately sloped gully. Bogs wera noted throughout the site. Much of
the vegetation was typical of wet sites. Surface water samples were taken
near borings # 1, 3, 5 and 7, and ground water levels were measured as
noted below:
PIEZOMETER # DEPTH TO WATER
1 5.5 ft.
2 5 ft.
3 2.5 ft.
4 2 ft.
5 5 ft.
6 11 ft.
7 5 ft.
8 3 ft.
In addition, on March 31, 1974, surface flows were measured in the creek near
the indicated piezometer stations as noted below:
PIEZOMETER # DISCHARGE
3 3.0 cfs
7 6.9 cfs
According to county estimates "peak flows of 57 cfs can be anticipated" in the
creek. A preliminary facility plan proposes the following water pollution and
drainage control:
1. Off-site Storm Runoff
a. Peripheral diversion using 48" pipe.
b. Impervious pipe through fill.
131
Northvvest Regions; Office, 15345 N.E. 26!h Slreet, Redmond, Washington 9805"
Tpkichnns: C20R') 68S-1900
-------
MEMORANDUM
TO:.
FROM:.
SUBJECT:.
DATE:-
John H. Glynn, Files ,,
Laurence Ashley
CATHCART - SNOHOMISH COUNTY PROPOSED LANDFILL
May 7, 1974
State of
\\osliington
Department
of Ecology
Five surface water samples were delivered. The samples were collected
on March 28, 1974, from various sites around the proposed landfill site
at Cathcart in Snohomish County. The results are attached on the following
page.
LA: js
6-7-74 dt
cc: Snohomish County Health Department
132
Daniel J. Evans, Governor John A. Biggs, Director Olympi-i, Washington 9S504 Telephone (206) 753-2800
-------
SNOHOMISH COUNTY
March 28,-1974
TOTAL DIS-ORTIIO N-NC>3 (oh.-n cm) FTU
SAMPLE Ph TOC Cl SO4 TS HARDNESS Na K Mg Ca Fa Mn Cu COD Pb Cd Cr Zn N-NH3 P N02 COND. TUEB. COLOR
B-1S
8-15
B-5S
B-7S
B-9S
5*. 9
6.5
6.5
6.6
NA
18
a
10
9
7
4
5
6
5
S
9
8
9
9
7
76
66
62
63
NA
6
10
10
10
NA
3.2
3.0
3.0
3.0
3.5
0.3 0.7
1.0 1.5
0.9 1.7
0.9 1.5
0.8 1.6
1.8
2.6
2.8
2.8
2.8
0.5
0.1
0.1
0.1
0.1
.01
.01
.01
.01
.01
IWJ/ 1
.01
.01
O.'Ol
.01
.01
4.0
0.8
0.4
1.2
0.4
.2
.2
.2
.2
.2
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.01
.02
.01
.02
.01
.01
0.01
.01
.01
.01
.01
.01
2.2
1.9
1.9
2.0
31
55
50
49
55
2
1
1
1
1
.20
4
8
7
a
CO
CO
-------
MEMORANDUM
CHECK
INFORMATON.
FOR ACTION _
PERMIT
OTHER
TO:.
FROM:
SUBJECT:.
DATE:.
suite of
\\cishinj4ton
Department
i-.v-.v
Daniel J. Evans. Governor John A. Biggs D/rec.'or oiyrr
ympia, Washington 98504 Telephone (206) 753-P800
-------
MEMORANDUM
TO:-
John Glynn and Files
FROM:.
Laurence Ashley^g
SUBJECT:
SNOHOMISH COUNTY CATHCARD LANDFILL SITE
DATE:-
May 20, 1974
CHECK
INFORMATION
FOR ACTIOM
PERMIT
OTHER
State of
Washington
Department
of Ecology
Ten background surface and ground water samples taken on April 8,
1974 from various locations around the proposed Cathcard Landfill
site were delivered to the laboratory for chemical and physical
analyses. The samples were collected by the personnel of the Sno-
homich County Health Department.
The results:
See the attached data sheet.
LA:mk
5-20-74 at
cc: Snohomish County HeaIfV Department
Daniel J. Evans, Governor John A. Biggs, Director Olympia, Washington 98504 Telephone (2061 753-2800
135
-------
SNOHOMISH COUNTY
April 8, 1374
Collected By Snohomish County Health Department Personnel
SAMPLE * pH TOC Cl SO4 TS TNVS
B-l-G . 8.2 450 340 100 1938 1558
B-l-S 7.3 24 31 3 NA NA
B-3-G 7.8 310 12 44 473 323
:-S 6.7 11 25 11 NA NA
B-4-G 8.7 330 20 14 1734 1510
B-5-G 7.8 200 29 24 443 288
B-5-S 6.9 10 6 12 NA NA
B-7-G 7.6 19 16 40 714 598
— • B-7-S 6.9 9 32 8 NA NA
CO
cr>
OFF SITE S 7.5 8 24 12 140 90
SAMPLE tf
B-l-G
B-l-S
B-3-G
B-3-S
B-4-G
B-5-G
B-5-S
B-7-G
B-7-S
OFF SITE
TVS
__ /"I
380
NA
150
NA
224
155
NA
116
NA
50
Pb
-.05
.05
.05
.05
.05
0.10
.05
< .05
-. .05
S ..05
N-NOj
0.004
0.004
•- . 001
0.002
0.002
^ .001
0.002
0.015
0.002
0.003
Cd
-.01
v.Ol
,.01
.01
..01
.01
.01
.01
* .01
-..01
N-NII-j
160.0
0.06
0.36
0.02
1.2
0.13
0.03
0.09
0.03
0.03
Cu Fe
mg/1-
0.19 1.4
0.05 0.5
.01 1.6
0.11 <..!
0.25 17.0
1.90 1.5
0.05 -,1
0.31 3.2
0.07 -:.l
0.06 - .1
N-NO3
20.0
0.01
<.0i
2.0
0.08
0.01
1.6
1.3
1.6
1.8
Zn
0.06
0.02
0.07
0.01
0.23
0.49
0.01
0.15
0.04
0.01
COD COMD. TURB.
ohm cm FTU
21 3150 10
7.2 49 4
38 440 22
2.4 128 1
80 400 112
15 560 6
4.4 60 <1
7 220 3
3.2 157 1
-
•-1 128 1
Cr Mn
-.01 0.52
..01 0.02
- .01 1.0
^.01 -.02
.10 0.66
.01 4.0
r.Ol -.02
--.01 0.44
'.01 -.02
- .01 ...02
COLOR Na K Ca Kg
— _ nig/1—
100 440.0 114.0 12.0 11.0
155 26.0 0.4 1.5 0.9
5 58.0 1.8 32.0 11.0
5 20.0 1.1 1.7 1.2
15 145.0 5.1 0.5 15.0
5 59.0 3.4 32.0 20.0
5 25.0 1.0 1.4 1.2
5 32.0 2.0 2.2 7.5
5 23.0 1.0 1.4 1.2
5 26.0 1.0 1.5 1.2
-------
.MEMORANDUM
TO:-
FROM:.
SUBJECT:_
DATE:-
John Glynn, Files/
Laurence Ashley
PROPOSED CATHCART LANDFILL - SNOHOMISHCOUNTX
June 3, 1974
CHECK
INFORMATON-
FOR ACTION_
PERMIT
OTHER
Stale of
Wasliington
Department
of Ecology
Water samples from various sites around the proposed Cathcart Landfill
and the proposed Byrant Landfill were delivered to the laboratory for
chemical and physical tests. The samples were collected by personnel
at the Snohomish County Health Department on April 23, 1974. The
samples are for background information. The results are on the
attached page.
LA: js
6-3-74 dt
cc: Snohomish County Health Department
137
Daniel J. Evans, Governor John A. Biggs, Director Olympia, Washington 98504 Telephone (206) 753-2800
-------
SNOHOMISH COUNTY
4-23-74
SAMPLE
B-l-G
B-l-S
B-3-G
B-3-S
B-3-G (B)
B-4-G
B-4-G(B)
— • B-5-S
CO
00
B-5-G
B-6-G
b /-S
B-7-G
OFF SITE(S)
PH
8.0
5.5
6.8
7.2
7.1
3.0
7.4
7.6
7.4
7.7
6.5
7.0
6.7
CONDUCTIVITY
u ronos
1430
33
310
58
155
335
180
49
500
270
49
144
58
COD
21
4
38
1
4
58
28
2
15
27
2
2
2
TOC
--mg/
70
20
80
5
10
90
40
10
49
55
a
17
5
Cl
460
13
16
14
18
16
16
14
14
22
14
10
10
S04
55
4
35
8
8
13
3
•a
8
75
8
50
2
TURBIDITY
CWnfl
r \ u
12
1
21
-1
30
24
15
27
8
*l
16
^1
COLOR
'60
160
5
5
2
25
2
3
8
2
5
5
5
mg/1 CaCO3
as
HARDNESS
78
32
136
56
395
24
108
23
188
108
27
148
28
K
65.0
0.1
1.6
0.8
2.2
3.5
1.6
0.7
3.5
5.0
0.8
2.5
0.8
Na
180
3.0
40.0
3.0
6.1
95.0
4.5
3.0
46.5
50.0
3.0
5.0
3.5
Ca
10.0
1.6
32.0
3.2
8.0
7.0
15.0
3.0
38.0
9.0
3.0
11.0
3.2
Me,
C
0.
7.
1.
7.
6.
13.
1.
17.
2.
1.
5.
1.
1
7
0
2
0
0
0
5
5
2
5
0
6
Fe
0.9
0.7
1.5
0.1
2.9
16.0
3.6
0.1
4.5
C.3
*0.1
2.9
*0.1
Kn
0.50
0.02
0.01
-.01
O.JO
0.40
3.0
-C.01
6..0
0.01
^•'.01
0.51
-.01
-------
CO
UD
SNOHOMISH COUNTY
4-23-74
(continued)
SAMPLE
B-l-G
B-l-S
B-3-G
B-3-S
B-3-G (B)
B-4-G
B-4-G(Bj_
B-5-S
B-5-G
B-6-G
B-7-S
B-7-G
OFF SITE(S)
Criv
0.25
<0.01
0.06
<0.01
4.0
<0.01
0.23
0.05
0.65
0.40
••^o.oi
0.20
<0.01
Zn
0.12
0.01
0.10
-'.01
2.3
0.20
0.37
0.01
0.37
0.47
•C.Q1
0.13
<01
Pb Cd Cr Ni
mg/1
<0.1 --.01 '-.01 '-.I
<0.1 <.01 <.01 -..1
CO.l <.01 •; .01 < .1
< o.l < .01 •, .01 ;.l
0.1 < .01 ^.01 v.l
<-0.1 "=-.01 -..01 -v.l
<0.1 <.01 \.01 "^.l
<0.1 <.01 -..01 -.1
<0.1 ...01 <.01 -.1
<0.1 <.01 '-.01 Ol
<0.1 -.01 ^.01 <-.!
--0.1 <.01 ".".01 <.l
<,o.i <;.oi <.oi x-.i
-------
MEMORANDUM
July 16, 1974
SfcllCOf
Washington
Department
of Frology
TO:
FROM:
SUBJECT:
John Glynn and Files
Laurence Ashley pCf?
CATHCART, SNOHOMISH COUNTY'S PROPOSED
LANDFILL SITE
Eight water samples from various points around the proposed landfill site
called Cathcart, in Snohomish County, were collected and delivered June 5,
1974 tothe laboratory for chemical and physical analyses. The results of
the analyses are attached.
The nutrient values for samples of April 23, 1974 and May 8, 1974 are listed
below:
Samples for April 23, 1974
Sample # NON
B-I-G (c)
B-I-S (c)
B-3-S (c)
B-3-G (c)
B-3-G (B)
B-4-G (B)
B-4-G (C)
B-5-S (C)
B-5-G (C)
B-6-G (C)
B-7-G (C)
mg/l
ND
0.08
ND
ND
ND
ND
ND
ND
ND
ND
ND
NOy-N
mg/l
0.02
12.0
0.32
0.46
0.26
0.28
0.22
0.34
0.34
0.18
0.22
0-P04-P
mg/l
0.03
4.2
0.03
0.04
0.05
0.05
0.03
0.04
0.03
0.03
0.06
140
Nortnwest Regional Office, 15345 N.F.. 36th Street, Redmond. Washington 96C52
Telephone: '?OG) 835-1900
-------
MEMORANDUM to John Glynn and Files July 16, 1974
Samples from May 8, 1974 -
Sample * N02-N N03-N 0-P04-P
UV:sc
cc: Snohomish County Health Department
mg/l mg/l mg/l
B-I-G NO 0.17 0.04
B-I-S ND 0.20 0.03
B-3-G ND 0.12 0.02
B-3-S ND 0.40 0.20
B-4-G 0.02 4.70 3.0
B-5-G ND 0.22 0.33
B-5-S ND 0.10 0.28
B-6-G ND 0.06 0.20
B-7-G ND 0.15 0.16
B-7-S ND 0.27 0.14
Offsite ND 0.57 0.14
141
-------
ro
' *.
SNOHOMISH COUNTY : j
5-8-74 . *• T
SAMPLE
-I-*-
B-l-S
B-3-S
B-3-G
B-4-G
B-5-S
B-5-G
B-6-G
B-7-S
B-7-G
OFF SITE
PH
8.0
5.7
6.5
7.2
8.1
6.6
7.1
7.2
6.7
6.5
S 6.8
u mhos
CONDUCTIVITY
940
34
52
350
320
49
490
*>
266
48
128
- 57
FTU
TURBIDITY
12
2
1
30
33
1
24
9
24
41
COLOR
30
190
2
1
25
3
15
1
3
2
1
HARDNESS
mg/las CaCo-j
56
24
20
96
16
20
228
40
20
76
16
COD
19
6
3
29
53
8
11
34
8
10
8
TOC Cl
116 2(
55 ]
28 3
1-80 1
230 1
24 X
i
85 1
160 i
27 1
40 :
27 :
-------
SNOHOMISH COUNTY
5-8-74
CO
FTU HARDNESS
ITY TURBIDITY COLOR mg/las CaCo3 COD TOG Cl~
so4
Na K
L/"~*3 ft •'-.'Vtf
» i * V"V*
c*" ''
r^
9£i[A '*Pd'
,__ my/ A
12 30 56 19 116
2 190 24 6 55
1 2 20 3 28
>;•
30 1 96 29 180
4 1
33 25
L6 53 230
1 3 20 8 24
24 15 228 11 85
'.9 1 "40 34 160
<:i 3
20 8 27
24 2 76 10 40
*1 I 16 8 27
260
14
18
16
18
16
12
20
14
14
12-
23
'-1
8
24
10
3 .
1
69
8
36
9
110.0
3.6
3.7
40.0
90.0
3.6
43.0
50.0
3.7
5.8
4.2
35.0
0.5
1.0
1.6
3.4
0.9
3.8
5.0
0.9
2.6
1.1
14.0
1.7
3.2
37.0
0.7
2.9
60.0
1 * ,
11.0
2.8
4 . -
12.0
3.2
5.6
1.0
1.3
10.0
7.0
1.5
13.0
2.3
1.3
6.0
1.5
0.64 <-.!
^.01 <.l
<.01 <.l
0.23 < .1
0.50 <.l
-------
C A1 \-( C rt £. T S l Tc-
V? £• , 1^7^
S/WPLE I
B-I-S
B-3-S
B-3-G
B-4-G
D-5-S
B-5-G
B-7-S
CFFSITE
SAMPLE *
B-I-S
E-3-S
B-3-G
B-4-G
E-5-S
B-5-G
B-7-S
OFFSITE
pH COLOR
5.5 210
6.7 5
7.5 2
7.6 40
6.5 15
7.3 15
6.4 15
6.6 7
Mg Cu
1.0 <.OI
1.5 <^.OI
9.0 0.25
3. 7 0. 30
1.3 < .01
26 2.0
J.3 < .01
1.4 <.OI
FTU
TURBIDITY
1
1
6
50
1
39
1
1
Pb
<.oi
^.01
^•01
<.OI
<.OI
^".01
^.01
<.OI
HARDNESS
mg/l as CaCOj
32
20
140
52
28
324
20
20
mg/l
Cr Ca
-------
SAMPLE 1
B-I-S
B-3-S
B-3-G
B-4-G
B-5-S
B-5-G
B-7-S
OFFSITE
TS
72
62
276
457
54
493
56
61
TVS
63
25
98
160
20
195
22
25
IDS
68
59
233
269
46
333
51
55
mg/l
TSS
14
3
43
188
8
160
5
6
NO?-N
0.06
0.65
0.06
0.10
0.28
0.36
0.33
0.62
0-P04-P
0.20
0.20
0.20
0.14
0.18
0.08
0.18
0.16
N03-N
NO
ND
ND
ND
NO
ND
ND
NO
en
-------
TO:-
FROM:-
SUBJECT:.
DATE:.
CHECK
INFORMATON-
FOR ACTION-
PERMIT
OTHER
John Glynn and Files
Laurence Ashley <-j
CATHCART, SNOHOMISH COUNTY
State of
Wasliington
Department
of Ecology
PROPOSED LANDFILL SITE
July 19, 1974
Nine water samples were collected from various points around the proposed
landfill site called Cathcart In Snohomlsh County, on June 19, 1974.
The samples were delivered by the Snohomlsh County Health Department per-
sonnel. The samples were analyzed for chemical and physical components and
the results are as follows:
LArsc
%
UJ
Q-
00
B-I-S
B-I-G
B-3-S
B-3-G
B-4-G
B-5-S
B-5-G
B-7-S
OFFSITE
CL
7.1
6.5
7.1
6.3
7.1
7.2
6.0
6.9
6.9
on
3
8
220
7
4
2
35
7
20
3
3
1
£
•w
D
— ID
1-
1
43
1
36
53
<,
33
<,
<.!
8
in
to in
LU IO
§ —
x e
64
10
36
156
66
40
280
26
28
K
^^
H"
^
Q in
z O
O JC
O E
31
400
52
290
280
61
520
45.
55
—
U)
E
Q
O
0
8
9
1
27
57
2
17
1
1
~
O)
=
8
65
74
48
160
220
29
132
31
49
—
O)
0
2
43
3
4
7
3
5
3
3
—
O}
£
rT
to
5
3
2
16
14
10
5
9
13
^
D)
a>
u_
1.5
3.0
/l.l
3.7
7.5
-C.I
9.0
<.l
<-.!
Olympla
Daniel J. Evans, Governor John A. Biggs, Director Olympla Washington 98504 Telephone (206) 753-2800
-------
/IORANDUM
'age two
T0:_
FROM:.
SUBJECT:-
OATE:.
John Glynn and Ftles
Laurence Ashley
CATHCART, SNOHOMISH COUNTY
PROPOSED LANDFILL SITE
July 19, 1974
CHECK
INFORMATON_
FOR ACTION-
PERMIT
OTHER
State of
Washington
Department
of Ecology
*Jfc
LJ
i
Q_
^>
to
B-I-S
B-I-G
B-3-S
B-3-G
B-4-G
B-5-S
B-5-G
B-7-S
OFFS ITE
*••»
en
£
c
2:
0.20
0.70
v^
CO
E
*
O.I
9.0
0.9
1.6
2.5
0.8
3.7
0.8
1.0
—
CD
E
CO
I.I
5.0
1.5
9.0
3.5
1.5
25
1.5
1.7
•v.
en
E
8
1.5
1 1.
2.2
25
3.2
2.0
36
2.2
2.4
CO
E
^
C\J
i
ND
ND
ND
ND
ND
ND
ND
ND
ND
en
E
^.
co
g
0.18
0.14
0.04
0.13
0.13
0.08
0.22
1.05
0.07
1
o.
i
0*"
Q_
1.42
0.12
0.04
0.34
0.02
0.02
0.02
0.02
0.02
147
Daniel J. Evans, Governor .. o*,r-A B-^gs. Director Olympic, Washington 9250-1 Tclcct-.onc (205) 753-28QU
-------
SNOHOMISH COUNTY
CATHCART SITE
7-24-74
00
SAMPLE
/*•
B-l-S
B-2-S
B-2-G
B-3-G
B-5-S
B-5-G
B47-S
B-7-G
OFFSITE
PH
7.2
6.5
6.2
6.6
6.^9
6.2
7.3
7.1
7.0
COLOR
150
3
2
35
25
7
3
15
4
TURBIDITY
NTU
7
5
18
34
1
22
1
16
1
CONDUCTIVITY
u horns
35
114
290
380
59
490
66
144
84
HARDNESS
MgCaCo3/l
20
H6
94
24
22
202
26
73
26
COD
mg/1
15
5
16
40
2
12
1
NA
1
COLOR
i
150
3
2 •
35
25
7
3
15
4
TURBIDITY
NTU
7
5
18
34
1
22
1
16
1
-------
SNOHOMISH COUNTY
CATHCART SITE
7-24-74
CONDUCTIVITY
u horns ii.
35
114
290
380
59
490
66
144
84
HARDNESS
MgCaCo,/!
20
.16
94
24
22
202
26
73
26
COD
mg/1
15
5
16
40
2
12
1
NA
1
CHLORIDES
mg/1
4
7
6
7
5
7
5
NA
6
SULFATES
mg/1
1
5
11
10
5
2
5
NA
9
NO3-N
0.012
0.068
0.140
ND
ND
ND
ND
ND
ND
(H°?l"
ND
ND
ND
ND
ND
ND
ND
ND
ND
OP04-P
0.04
0.04
ND
ND
0.02
.ND
ND
ND.
ND
-------
SNOHOMISH COUNTY
CATHCART SITE
7-24-74
en
o
SAMPLE
B-l-S
B-2-S
B-2-.G
B-3-G
B-5-S
B-5-G
B-7-S
B-7-G
OFFSITE
COPPER
-------
SNOHOMISH COUNTY
CATHCART SITE
7-24-74
SODIUM POTSIUM SODIUM POTSIUM CHROMIUM
1
5
25
93
4
46
4
6
5
.0
.4
.0
.5
.7
.5
.5
.4
.5
0
2
1
2
0
4
1
2
1
.7
.1
.6
.2
.9
.0
.2
.8
.3
1
5
25
93
4
46
4
6
5
.0
.4
.0
.5
.7
.5
.5
.4
.5
0
'2
1
2
0
4
1
2
1
.7
.1
.6
.2
.9
.0
.2
.8
.3
<.01
<.01
C.01
-------
x LA/mk 9-24-74
tMOHOMItiH COUNTY CATHCART SITE, 8-7-74
m
g/l
SAMPLE
B-1-S
B-1-G
B-3-S
- B-4-G
B-5-G
B-6-G
B-7-S
Offsite
Samp 1 e
B-1-S
B-1-G
B-3-S
B-4-G
B-5-G
B-6-G
B-7-S
Offsite
&
6.4
6.0
6.7
6.4
6.3
6.7
6.0
6.0
Copper
0.36
1.40
0. 16
0.44
1.28
3.80
,-0.01
Z0.01
<*&
240
20
3
15
25
60
2
1
Manage-
nese
0.17
1.10
0.67
0.11
9.00
0.25
^0.01
*0.01
Turbi-
dity
NTU .
3
185
21
64
55
50
^1
^
So tub
1 ron
2.3
25.0
1.6
3.5
31.0
3.10
0.1
0.1
Hardness
mg as
CaC03/ I
90
84
130
46
350 -
71
28
30
Conduc-
tivity ^
, hom^
34
29
300
330
7oa
280
80
80
ccpo)
9
7
12
42
20
37
^
1
e Concentrations (mg/l)
Sod i urn
0.6
60.0
36.0
90.0
50.0
50.0
4.3
5.4
Magne-
si urn
1 .9
16.0
10.0
2.8
40.0
4.6
2.8
3.2
Ca lei urn
3.5
30.5
37.0
7.5
60.0
13.0
6.5
7.5
Cl
3
37
6
6
6
9
6
6
of Metal
Lead
*0.1
0. 1
^0.1
*0.1
0.1
-£0.1
-------
MEMORANDUM
September 25. 1974
»
Siaieof
\Aas!iin$o
Department
TO: John Glynn and Files
FROM: Laurence Ashley <7\-
SUBJECT: CATHCART - PORPOSED SNOHOMISH COUNTY
LANDFILL SITE
Two background water samples from the proposed Snohomish County Landfill
site called Cathcart were mailed to the laboratory August 23, 1974. The
samples were collected by Snohomish County Health Personnel on August 21,
1974.
The results:
\
Parameter B-I-S Off-site*
Chromium
Zinc
Copper
Iron
LA:sc
9-25-74'dt
153
Northwest Regions' OJH.-r •"r?".? »! «• 26»h Slreet. Redmond.
Telephone: (206) 885-1900
pH 5.7 6.7
Total Hardness as mgCaC03/l 55 40
Conductivity - ynhoms 43 92
COD (mg/l) II ^1
Sulfate (mg/|) ^1 10
Chloride (mg/l)
Turbidity - NTU
Color
Ammonia (NH3)
Orthorphosphate (0-P04)
Nitrate (N03)
Sodium
Potass I urn
MagnesI urn
Calcium
Manganese
-tead
4
6
240
mg/1 0.08
/
>
0.01
0.03
2.1
0.7
1.7
5.0
0.14
^0.01
^0.01
r 2.0
7
1
2
0.05
0.01
0.46
5.8
1.5
2.8 , ^
8.0 '?•
0.05
-------
en
Sculogy
ilAfE OF WAS.MING'fON
DEPARTMENT OF ECOLOGY
WATER QUALITY LABORATORY
DATA SUMMARY
.. I..^/.H vcy..
COPIES TO:
LAB FILES
rce
5 *
Ce>.
e Collected //-?- 7*|j /2- Y-7"j I-?-?/
Collected By
Goal, Pro./ObJ.
No. Station
7*7
711
R-r-G
8-7-6-
M
16.
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8
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6.03
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119
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21
2.
-------
(Jl
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717
7**
B-l-6
B-I-&
B-S-S
B-M-fr
B-r-S
Station
77C
7*7
72?
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37.
All results are in PPM unless otherwise specified. ND is "Hone Detected"
-icAnm M Jre* i* l
M«mu*S (u^4iL« Suranary by Vfi^x $>. /I/
Date
65-.
5"-
3I2S
-3
-------
DEPARTMENT OF ECOLOGY
WATER QUALITY LABORATORY
DATA SUMMARY
-z
Collected 2- £7 -7}"
Collected By SCffD
Goal, Pro./Obj.
'o. Station
C.
S/>.
T-
•£• D.
,n
^
to
c ^
'M
if
a
;.->
Cr
£1
7.
?,
72
S-I-S •
ff-l-£-
8-3-5*
S-VCr-
B-MS.
5-5T-V
R-c-fr-
S-6-6-.
B-7-S'
g-7-
i.l
<*!
?.o
o.l
<^.l
1.0
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-2.0
J.O.]
^l.
/o.l
1.
1.
1.
/j
2.
3.
Z.
t
J.
-------
TO:
FROM:
N.
ynn, .Fi
.
ohn Glynn, .Files
Laurence Ashley
SUBJECT:.
DATE:
CATHCART LANDFILL, SNOHOMISH COUNTY
State of
Washington
Department
ofB '
June 30, 1975
Sample set for 4-2-75 remaining data listed below:
SAMPLE
CONDUCTANCE
(uhmos/cni)@250C
pH
TOTAL ORGANIC CARBON
(mg/liter)
M-l
M-2
M03
M-4
B-l-S
B-l-6
B-3-3
B-3-G
B-4-G
B-5-S
B-5-G
B-7-S
B-7-G
B-9-S
B-6-G
30
110
170
50
30
130
70
320
320
70
990
65
170
75
280
7.0
6.4
6.7
6.7
6.4
6.7
7.3
6.9
7.6
6.6
6.9
6.5
6.3
6.4
7.2
3
10
8'
6
12
8
3
11
38
3
33
3
11
4
41
LA: js
6-30-75 d5
157
I 0'
Daniel J. Evans. Governor John A. Biggs, Director Olympia, Washington 98504 Telephone (2C6) 753-2800
-------
DEPARTMENT OF ECOLOGY
X
WATER QUALITY LABORATORY
DATA SUMMARY
tfce
Collected By £.C.
Date Collected H- 2-7]
Goal, Pro./Obj.
T-
Loe No. Station
7r/l75
7S
7C
»
)8
„
?•
?l
t?
«5
*v
rr
n
?7
B-l-*-
r^-i-G-'
R- 3-fr*
R-M-A-
R-r-s-
R-s-.fr-
R- 4.-G-*
G-7-.S-
6-7-6-
B-f-S--
n-i •
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^^? -
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1.
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2.
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2,
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25.
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36.
12-
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x
$
ote: All results are in PPM unless otherwise specified. ND is "None Detected"
158
Summary by // Z./-^ 9- /iff/ Date 6 "//' 7J"
-------
MEMC.
CHECK
INFORMATON-
FOR ACTION _
PERMIT
OTHER
TO:.
John Glvnn. Files
FROM:
Laurence Ashley'
DATE:.
CATHCART LANDFILL SITE, SNOHOMISH COUNTY
July 24, 1975
State of
\\ashington
Department
ofBoology
Several water samples taken at the various points at the Cathcart site
by Snohomish County Health Department personnel on 11-6-74, 12-9-74,
and 1-7-75 were analyzed and the findings are as follows:
12-9-75
some results
SAMPLE #
M3
• B-l-S
, B-5-G
. B-3-G
< OFFSIDE
»B-3-5
, B-7-6
,B-5-5
- B-l-G
c B-4-G
* B-7-S 11-6 SET
« B-4-G 11-6 SET
pH
6.6
5.9
6.9
7.0
7.0
6.3
5.1
6.2
6.2
NA
6.0
7.5
COND.
165
65
885
355
105
105
310
95
165
410
85
390
TURBIDITY
NTU
78
1
78
5
1
1
16
1
18
80
1
35
TOC
(mg/1)
43
43
170
23
7
6
22
5
9
112
6
127
. B-l- S
.B-5-G
• M-l
-B-l-G
» B-6-G
0-2
0-1
• B-3-S
• B-5-5
B-3-G
• M-4
• M-3
• B-7-S
•B-7-G
.'B-4-G
6.0
7.0
6.6
6.4
6.8
7.0
6.5
6.
6.
7.
6.
6.6
6.9
6.2
7.4
1-7-75
SET
40
1030
46
150
305
60
180
90
80
305
80
170
80
50
410
1
180
15
25
18
20
30
1
1
15
1040
8
1
18
54
Daniel J. Evans. Governor John A. Biggs, Director Olyrrpia. Washington 98504 Telephone (206) 753-2800
Snohomish County Health Department '59
-------
UJfireR
(too
fir
J4L
M£.
(loo
<~IOO
? too
-------
^f'illli^lMll^psifp^, -.
jmw&m®^'•
m^'-imm^^
^m^m^mmr:''
-------
APPENDIX D
REE'S CORNER SANITARY LANDFILL SITE
W-1035 -62
162
-------
-WASHINGTON, Ino.
K'ou.n.cia.tion and Soils Engineering, O- e o 1 o g y
12893 N.E. 15th PL ' Bellevue, Washington 98005 • (206) GL 5-2018
502 So. llth St. ' Tacoma, Washington 98402 • (206) 272-8363
Telex 32-9424 3416 Everett Avenue ' Everett, Washington 98201 ' (206) 259-0817
October 15, 1973 W-1035-62
Stevens, Thompson & Runyan, Inc.
700 Plaza 600
Seattle, Washington 98101
Attention: Mr. Ron Owes
Subject: Ree's Corner Sanitary Landfill Site
Gentlemen:
Based upon our prelininary subsurface investigation, we have deter-
mined that the site is underlain by a dense, gray, silty Sand and Sand (Glacial
Till) and at greater depth, a moderately hard, brown Sandstone. On the east
edge of the site, adjacent to Highway 9, below an approximate elevation of 325,
the sandstone is at shallow depth and the till is not present. To the west, the
high ground on both sides of the draw are capped by sandy, glacial till. With-
in the draw, saturated sands were encountered overlying impervious till and
possibly bedrock.
A large quantity of water was encountered in the sands along the stream
bottom and in an isolated pond atop the high ground at the west side of the
property.
DESIGN CONSIDERATIONS
1. General
The site appears to be well suited for use as a sanitary landfill. The
majority of the site soils, however, do not appear to be acceptable for use
in construction of haul roads during wet weather. Therefore, importation
of some granular material may be necessary. The site soils and rock are
moderately dense to very dense and may require the use of relatively heavy
equipment (D-7 or D-8 Cat) for their excavation. The majority of the soils
are relatively impervious and percolation of leachate into the groundwater
table should not be a serious problem. As an exception to this, saturated
BRANCH OFFICES IN MOST PRINCIPAL CITIES
163
-------
Stevens, Thompson & Runyan, Inc. W-1035-62
October 15, 1973 Page Two
permeable sands in the bottom of the draw, may permit loss of leachate
downs lope to the north, if the sands are not removed or provided with some
sort of a seepage cutoff system.
2. Groundwater Conditions
Some groundwater was encountered in a depression atop the knoll
near the southwest corner of the site, while considerable quantities occur
along the drainage course through the center of the property. Along the
drainageway, the water appeared to be perched atop the relatively imper-
meable sandstone or till. The material which is causing the water to remain
atop the high ground was not reached during our exploration; however, we
suspect that this impermeable stratum is either sandstone or glacial till.
We anticipate, based upon experience at similar sites, that during wet wea-
ther considerable seepage will be encountered along the upper surface of
the glacial till or sandstone. On the other hand, we do not anticipate that
appreciable quantities of seepage will flow along the till - sandstone contact.
3. Groundwater and Leachate Control
The upper surface of the sandstone appears to be higher on the east
side of the site than near the center (Cross Section, Plate 2). As a result,
we believe that there is little chance of leachate loss toward Highway 9.
Additionally, we do not expect leachate to migrate readily along the till -
sandstone contact to the south or west. In those areas where we have
exposed this type of surface, the till has been tightly bonded to the underlying
material. At this particular site, however, we did not reach this contact
with our relatively shallow backhoe pits.
4. Grading
Due to their density, the site soils below depths of roughly eight or
ten feet may prove to be difficult to excavate, except with relatively heavy
equipment (D-7 or D-8 Cat). The overlying materials, however, probably
can be excavated with considerably lighter equipment. The excavated dense
soil may contain numerous blocks or clods, especially if excavated during
dry weather. These lumps would need to be broken down prior to or during
placement for refuse cover. In the same manner, the sandstone will probably
require breaking up with the earthmoving equipment, prior to use.
Due to their relatively fine grain, the on-site materials, soil or
rock, may be difficult to compact during wet weather. Therefore, it may
be necessary to import granular materials during the rainy season.
a- H: o L.A.B e. IN*c.
164
-------
Stevens, Thompson & Runyan, Inc. W-1035-62
October 15, 1973 Page Three
Permanent cut and fill slopes constructed with the on-site soils or
sandstone should be designed with an angle of no more than 2H:1V. Addi-
tionally, drainage berms, benching and planting should be included wherever
they would be appropriate.
5. Access Roads
During dry weather, service roads crossing the site should remain
relatively stable with only minor amounts of grading, however, due to the
presence of appreciable quantities of silt in the soils, roadway sprinkling
for dust control may be necessary during dry weather. On the other hand,
these same soils will become soft, rutted and unstable during wet weather.
Therefore, it may be advisable to gravel the roads or use some sort of
impervious seal coat surfacing.
6. Recommended Additional Studies
The site features of most critical importance are: A) The configur-
ation and condition of the till - bedrock contact; B) the in situ permeability
of the site soils; C) groundwater conditions; and, D) detailed stability
analysis of the downstream face of the completed site.
A. Due to the thickness of till and other overburden materials,
the surface of the sandstone appears to a large extent, to
be beyond the reach of a backhoe. An evaluation of the con-
dition of this surface, however, is considered necessary
because of the possibility that permeable soils may be present
between the glacial till and underlying sandstone.
B. In order to understand and anticipate what may happen to any
leachate generated by the landfill, it would be necessary to
know the permeability characteristics of the sandstone, over-
burden and the contact between these deposits. As in the case
of the above mentioned bedrock - overburden study, this work
should be performed as part of the final subsurface drilling
program. These two programs should effectively locate and
outline any zones of potential leakage. They should also provide
alternate design criteria for controlling such leakage if it does
present a problem.
C. Due to the exceptionally dry weather conditions experienced
during the past year, groundwater information obtained during
this initial study may be misleading. For this reason, it would
BS. I 1ST C.
165
-------
Stevens, Thompson & Runyan, Inc. W-1035-62
October 15, 1973 Page Four
be appropriate to re-evaluate the shallow groundwater
conditions during the coming rainy season with a tractor
mounted backhoe.
D. Due to the inherent instability of the refuse, the con-
figuration of the downstream (north) face of the planned
embankment should be evaluated. In this manner, approp-
riate safe slope angles can be established based upon a
reasonable factor of safety and the strength characteristics
of the various materials used.
It should be born in mind that any further subsurface investigations will
require the use of a relatively larger dozer to carve access roads through the
brush, young second growth timber and numerous stumps found on the site.
We appreciate having this opportunity to serve you. If you have any
questions, please call.
Respectfully submitted,
GEOLABS-WASHINGTON/^INC.
"Tom Bekey, Engineering Geolpgist
TB/mh
166
H: o L.A.33 e. i isr a.
-------
Legend
T*»+
W Cros^ Se^t-ort L.it.
Sco.le 1*=400'
1 I 1 I 1
GB3OLA.BS. I N C.
GEOLOGY AND SOILS ENGINEERING
p. a.
PLATE 1
-------
350-1
«• o
2 5
I '
«
-»
•* 250 -
i''--*' **
A
Scale;
,o. Gla.oa.1 T.ll
17/ = 4-OO'
1" ' 100'
-300
-250
-200
A'
CROSS SECTION A- A'
-------
APPENDIX A
EXPLORATION PROGRAM
GJ- HJ O L.A. BO. I XT C.
169
-------
SUBSURFACE INVESTIGATION
Our subsurface soils investigation for the Ree's Corner Sanitary
Landfill Site was performed by excavating a series of backhoe test pits into
the site soils at various locations on the site. Due to the very dense brush
cover and numerous stumps, access during this study was restricted to the
south, southwest, and east margins of the property. The materials en-
countered in the test pits were logged by our engineering geologist at the
site. The approximate pit locations are shown on Plate 1, Site Plan. The
material logs are presented in Table A. Laboratory test results of
selected soil or rock samples are presented in Appendix B.
C3-H30LA.B Q.
170
-------
W-1035-62
TABLE A
TEST PIT LOGS
Depth - ft. Soil Classification
Test Pit No. 1
0.0-0.5 Soft, moist, brown Topsoil.
0.5 - 2.0 Medium dense, moist, tan, silty Sand.
2.0 - 6.0 Dense to very dense, moist, brown Sand with angular rock
fragments. (Weathered Sandstone) Refusal on moderately
hard Sandstone. Dry hole.
Test Pit No. 2
0.0-0.2 Soft, moist, brown Topsoil.
0.2 - 2.0 Medium dense, moist, tan, silty Sand.
2.0 - 4. 0 Medium dense, moist, tan Sand with rock fragments.
4.0 - 9.0 Moderately hard, brown to gray Sandstone.
Dry hole.
Test Pit No. 3
0.0-0.5 Soft, moist, brown Topsoil.
0.5 - 2.5 Medium dense, moist, brown, silty Sand.
2.5 - 4.5 Medium dense, moist, brown, silty Sand with rock fragments.
4.5 - 8.0 Moderately hard, brown to gray Sandstone.
Test Pit No. 4
0.0- 0.5 Soft, moist, brown Topsoil.
0.5 - 4.0 Medium dense, moist, tan, silty Sand. (Weathered Till)
4.0 - 10.0 Dense, moist, gray, gravelly, silty Sand. (Glacial Till)
Dry hole.
Test Pit No. 5
0.0- 1.0 Soft, moist, brown Topsoil.
1.0- 3.0 Medium dense, moist, tan, silty Sand. (Weathered Till)
3.0 - 11.0 Dense, moist, gray, gravelly, silty Sand. (Glacial Till)
Dry hole.
S, IKTC.
171
-------
TEST PIT LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 6
0. 0 - 0.5 Soft, moist, brown Topsoil.
0.5 - 5.0 Medium dense, moist, tan, silty Sand with rock fragments.
5.0-8.0 Dense, moist, gray-brown, silty Sand. (Glacial Till)
Dry hole.
Test Pit No. 7
0.0 - 1.0 Organic debris and logs.
1.0 - 3.5 Medium stiff, moist, gray Silt with organic debris. (Fill)
3.5 - 4.5 Stiff, moist, tan Clay with organic fragments.
4.5 - 5.0 Stiff, moist, gray Silt.
5.0 - 11.0 Medium dense, wet, gray, silty Sand with organic fragments.
Water below five feet. Test pit is adjacent to swamp.
Test Pit No. 8
0. 0 - 0.7 Soft, moist, brown Topsoil.
0.7-5.0 Medium dense, moist, tan, gravelly, silty Sand with
occasional cobbles.
5.0-6.5 Stiff, moist, gray Silt.
6.5 -8.0 Dense, moist, gray, silty Sand.
Dry hole.
Test Pit No. 9
0.0-1.0 Soft, moist to wet, peaty Topsoil.
1.0-3.0 Medium dense, moist, gray-brown Sand with gravel.
3.0-6.0 Medium dense, moist, brown, silty Sand.
6.0-8.0 Loose, wet, gray, silty, gravelly Sand.
Water below four feet.
Test Pit No. 10
0.0- 0.5 Soft, moist, brown Topsoil.
0.5 - 2.0 Medium dense, dry, tan, silty Sand with gravel.
Q.
172
-------
TEST PIT LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 10 (continued)
2.0 - 3.5 Medium dense, moist, tan, gravelly Sand.
3.5 - 6.0 Medium dense, moist, red-brown to gray, fine Sand with
gravel.
6.0 - 10.0 Dense, moist, gray, gravelly, silty Sand. (Glacial Till)
Dry hole.
Test Pit No. 11
0.0- 1.0
1.0- 4.0
4.0- 7.0
7.0 - 10.0
10.0 - 11.0
Soft, moist, brown Topsoil.
Medium dense, moist, brown, silty Sand with roots.
Dense, moist, brown, gravelly Sand with occasional cobbles.
Medium dense, moist to wet, red-brown, gravelly Sand.
Dense, moist, blue-gray, silty Sand.
Water between nine and ten feet.
O- H! OX--A.B S. I1STC,
-------
APPENDIX B
LABORATORY TEST RESULTS
Q- H3OLA.B Q. I XTC.
174
-------
BORING NO TP-1
DEPTH
LJ
CO
or
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2
LJ
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cr
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1000
6.0'
. I NO.
OBOCOOV AND BOIL. BMaiNHMIN*
wo. 1035-62
PROJECT Ree's Corner Landfill Site
PLATE
B-l
1 O n n
9 O
80
7 O
/ U
6 0
^ n
i r> ,
1 U
n .
U.
3in
i
S. STANDARD SIEVE SIZE
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i i ii i iii i
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w.O. 1035-62
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US. STANDARD SIEVE SIZE
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-------
BORING NO TP-9
DEPTH 7-°' " 8-°'
a e. INC.
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PROJECT Ree's Corner Landfill Site
W.O. 1035-62
PLATE B-3
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-------
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BORING NO TP-10
DEPTH 0.5' - 3.0'
. IISTC.
Oi.OOV AMD *OIL. •NOINHKINCi
PROJECT Ree's Corner Landfill Site
W.O. 1035-62
PLATE B-4
U.S. STANDARD SIEVE SIZE
3in l.5in. 3/4in.yein.-*4 10 20 40 60 100 20O
HYDROMETER
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-------
APPENDIX E
CATHCART SAHITARY LANDFILL SITE
SNOHOMISH COUNTY
W-1035 -64
180
-------
CATHCART SANITARY LANDFILL SITE
SNOHOMISH COUNTY
W-1035-64
FOR
STEVENS, THOMPSON & RUNYAN, INC.
700 Plaza 600
Seattle, Washington
FEBRUARY 1974
By
GEOLABS-WASHINGTON, INC.
Soils Mechanics and Foundation Engineers
12893 N. E. 15th Place
Bellevue, Washington
181
-------
SUMMARY
This report presents the results of our final subsurface investigation
of the proposed Cathcart Sanitary Landfill Site. The site is located four miles
south of the town of Snohomish, on the west side of State Highway 9 (Woodin-
ville Cut-off). Except for approximately ten acres which have been cleared
and used as pasture, most of the site is covered by young second growth timber
and logging slash, overgrown by berry vines. The most northerly eighty acres
are covered by older second growth timber, some of marketable size.
The entire property comprises roughly two hundred acres of which
the most northerly forty would be a buffer zone and site for a sanitary treat-
ment plant, if required. Buffer zones would also be provided around the
periphery of the site to protect adjacent landowners and their property. The
sanitary landfill, according to preliminary plans, would be a cut and cover
operation in which each day's refuse would be covered by soil.
The site is underlain by soft to moderately hard, gray, silty Sandstone
at depths ranging from six inches to forty -two feet. Atop bedrock, beneath
the ridges which flank the two sides of the property, are very dense, moist
to wet, brown or gray, silty, gravelly Sands (Glacial Till). Within the swale,
between the two ridges, are stream deposited, loose to dense and very dense,
wet, brown or gray, silty, gravelly Sands and soft Silts over the bedrock
stratum. Water was noted on the site, in a pair of northward flowing streams,
which join roughly 3200 feet north of the south property line. Groundwater was
observed in the borings at depths ranging from one and one -half to twenty -four
G B: O I_^A-B Q. IlsTC.
182
-------
feet below the ground surface. Backhoe test pits encountered seepage at
various depths, up to within six inches of the ground surface, in winter time.
In all of the borings, upon penetrating into the silty sandstone bedrock,
surface waters were cut off, resulting in dry holes during drilling.
This report presents specific recommendations concerning excavation
and use of the site soils in the landfill, ground and surface water management
and leachate control, and other appropriate design considerations. Included
with the report are descriptions of the site geology and soil conditions, hydro-
logy, a description of the exploration methods utilized and the laboratory test
program results.
DESIGN CONSIDERATIONS
I. General
The proposed Cathcart Sanitary Landfill site appears to be well suited
for solid waste disposal. The two most critical considerations in the develop-
ment of a landfill are separation of leachate from ground or surface waters
and soils suitable for use as cover material. Due to the relatively impervious
nature of the till and underlying sandstone, loss of leachate should be relatively
easy to control. Due to their density and high silt content, the till and rock
may, however, be difficult to excavate and place, especially during wet weather,
El. Groundwater and Leachate Control
The silty sandstone and glacial till are, based upon our drilling,
laboratory testing and inspection of the property during rainy weather, rela-
tively impervious. As a result, it would be possible to intercept the perched
a- :EC o I_-A. B s. ICTC.
183
-------
ground-water and surface runoff on the site with a system of perimeter drains
around the property. The drainage system may be designed as an open ditch,
a ditch lined with an impervious membrane on the side closest to the landfill,
a ditch filled with a coarse, granular, free draining material, or a combina-
tion of the above. Where installed adjacent to the south property line, such
an interceptor would need to extend from five to ten feet below the existing
ground surface to pick up water flowing atop the impervious sandstone or
glacial till.
In order to further minimize infiltration of water (rainfall), the daily
cover should, if possible, be constructed with the relatively silty, onsite
soils. By compacting and sloping this cover to improve drainage, infiltration
into the refuse may be reduced.
Leachate which is generated, should be intercepted downs lope from
the refuse in an appropriate system of drains and collectors. This leachate
may require treatment and/or dilution prior to disposal.
In isolated areas along the west side of the site, thin permeable sand
beds, on the order of two feet thick, may be encountered between the surface
of the sandstone and the base of the impervious till. This sand may form the
east edge of a widespread, permeable aquifer. In order to prevent loss of
leachate through this stratum, it will be necessary to provide an impervious
cutoff or blanket across each sand exposure, as it is encountered. The leach-
ate barrier may be constructed of suitably compacted silty soils, if blanketing
can be performed during dry weather. Otherwise a membrane such as PVC
or asphalt may be necessary.
G- E: o L.A. Be.
184
-------
If soil is used for the leakage barrier, the material used should be
glacial till or any other silty onsite soil. Grading should be performed during
dry weather, with the soil as close to optimum moisture content as possible.
The soil should be placed in eight-inch thick layers, loose depth, and com-
pacted to at least 90% of laboratory maximum density using ASTM Method:
D-1557-70 or AASHO: T-180 as a standard. Compaction should be performed
with a sheepsfoot type roller rather than a vibratory or smooth drum, to pre-
vent the development of planes of greater and lesser compaction. Compaction
should be performed under the supervision of a qualified soils engineer.
The width of the leakage barrier should be based upon laboratory
permeability determinations made on recompacted glacial till. Typical rates
of 1 to 2.5 x 10~5 cm/sec were measured on till samples obtained from boring
B-6. In any case, due to equipment size limitations, a minimum barrier
width of eight feet (dozer or compactor width) should be considered.
m. Soils
Due to their density and high silt content, difficulty may be encountered
in excavating and utilizing the till and sandstone. These materials will require
relatively heavy equipment for excavation (D-7 or D-8 Cat). They may also
tend to remain in blocks or clods when excavated, so that satisfactory com-
paction may be difficult, requiring several passes of the equipment to break
up. The high silt content of most of the onsite materials, from fifteen to
fifty-one percent, will cause these soils to be moisture sensitive. This means
that, if the soil contains more water than two or three percent over optimum,
it will be impossible to adequately compact it. This becomes especially critical
S. I3STC.
185
-------
with the till which normally is at or slightly over optimum moisture.
Due to the relatively impervious nature and high silt content of the
onsite soils, some method of gas collection and release will be necessary.
This may be accomplished by importing a granular soil (sand or gravel) and
placing it as a continuous cover atop the refuse. Otherwise, a network of
gas collectors or vents of some type should be installed. A review of gravel
sources, including test results on the material available has been reported
previously. (Geolabs Report: W-l035-65 dated January 22, 1974)
IV. Slopes
Temporary excavations in the till or sandstone, when not subject to
seepage or flowing water, should be stable at slopes approaching 1H:1V,
although localized sloughing in deep excavations may occur. The less dense
stream deposits, if dewatered, should remain stable at slopes of 2H:1V.
When continuously wet or subject to seepage, any of the cut slopes will
become unstable and may slough back to slopes flatter than 3H:1V in till or
10H:1V in soft silts and loose sands.
Temporary uncompacted stockpiles of soil, if protected from rainfall,
should stand with slopes of 3H:1V. If they are not protected from the weather,
they will gully and erode severaly possibly resulting in slopes of 5H or 10H:
IV, or flatter. Compacted fill slopes, especially the refuse cover, should
remain stable at slopes of 3H:1V or flatter. These permanent slopes should,
however, be protected from gullying by drainage benches and berms, planting,
and if deemed appropriate, a covering such as plastic sheeting or a thin film
binder such as Land Lock (TM) by the 3M Company.
S. IITC.
186
-------
V. Roads
The site roads will require some surface treatment at all times of the
year. During wet weather, the soils, if unprotected, will rut, gully, and
pump under traffic until they become impassable. In summer, the same soils
will produce dust unless they are stabilized. Stabilization may include gravel
surfacing, seal coatings or wood waste (hog fuel) fills.
HYDROLOGY
Rainfall in the vicinity of the site is reported to be in excess of thirty
inches per year, concentrated during the winter months. This heavy rainfall
is incapable of penetrating into the till and sandstone in appreciable quantities,
but instead, flows downslope to collect in the various kettles and potholes,
or to the two streams which cross the site. These northward flowing streams
represent the surface of the perched groundwater table which is trapped atop
the glacial till and sandstone.
Groundwater and surface water rise during winter and spring to their
highest levels and drop during the summer. Based upon surface area calcu-
lations from the USGS Quadrangle sheet, we have determined that the surface
area providing groundwater recharge is in excess of 985 acres. Due to the
generally impermeable nature of the soils within the drainage basin, most
of the rainfall should reach and/or flow through the site, rather than pene-
trating into a deep aquifer.
A review of all of the water well logs submitted to the State of Washington,
Department of Ecology and contacts with local well drillers, indicate that wells
Q H3 O L-A.B O. INC.
187
-------
in the immediate vicinity of the site obtain water from perched sources atop
the glacial till, from permeable lenses within the till, or from floodplain
deposits of the Snohomish River valley. Only one well is reported to obtain
water from the basalt underlying the sandstone. This well for the Cathcart
School, is located approximately one mile north of the site and draws water
from a fractured horizon about 140 to 150 feet below the surface. With some
500 feet of sandstone stratigraphically overlying the basalt, entry of leachate
into this aquifer is unlikely.
GEOLOGY
The Cathcart site is underlain at depths ranging from six inches to
forty-nine feet by a soft to moderately hard, gray, silty Sandstone, which
weathers to a brown or tan color. The sandstone is massive, with poorly
developed bedding, although occasional shale partings were observed in
some backhoe pits and boring samples. The sandstone, according to the
county geologic report, is of Oligocene age, and may be on the order of
500 feet thick. Beneath it are older basaltic rocks.
Overlying the sandstone, atop the high ground, is a very dense,
moist, brown to gray, silty, gravelly Sand (Glacial Till). This material
was deposited by glacial ice, as the glacier traveled southward through the
area. The till is a lodgement till, having been smeared or plastered across
the underlying sandstone. Glaciation and till emplacement occurred some
13, 000 to 15, 000 years ago.
West and south of the site, fine to coarse sands of the Esperance
C3-HI O 3L..A. B S. X2TG.
188
-------
sand, have been encountered between the base of the glacial till and the sur-
face of the Sandstone. This sand may extend in an isolated area along the
west margin of the site onto the property. The material represents the
outwash sands, carried by meltwater streams issuing from the approaching
glacier. With passage of the ice sheet, these soils were consolidated and
compacted along with the overlying glacial till.
As the ice sheet melted and wasted away, streams issuing from the
ice front and from remnant blocks of ice left behind on the uplands, coupled
with rain and snow, carved a draw through the till to bedrock. This breach
through the till has subsequently been partially filled by post glacial, reces-
sional, loose to dense, brown or gray sands, silty sands and silty, gravelly
sands with some silt beds.
Localized kettles or potholes in the till surface exist, especially near
the west margin of the property. These relatively small isolated basins con-
tain soft silts and clays, with saturated sands and a near surface mat of peat
or highly organic soil.
SUBSURFACE CONDITIONS
The basal material underlying the entire site is a soft to moderately
hard, gray, silty sandstone, which, near the ground surface, weathers to
light tan and brown. This rock is a massive to thin bedded sediment with
scattered thin shale partings. Test drilling and onsite water level observa-
tions in the borings indicate that the sandstone is only slightly permeable.
BQ. INC.
189
-------
Overlying the sandstone is a cap of glacial till atop the high ground
along the east and west sides of the parcel. The till is a nearly impervious,
very dense mixture of gravel, silt and sand, which has been thoroughly com-
pacted and consolidated by more than 3500 feet of glacial ice.
In the draw between the two low ridges are loose to dense, wet, gray,
brown or reddish brown, silty sands and silty, gravelly sands and some soft
to medium stiff silts. Within localized, small kettles and potholes atop the
till are loose, wet, blue-gray sands, soft silts and clays, and very soft,
brown peat and organic debris.
Along the west margin of the site, a two foot thick layer of medium
dense, medium to fine sands was encountered in one of the backhoe pits.
This sand may be part of the surficial, weathered bedrock, or may be a
portion of the Esperance sand formation. If these soils are part of the
Esperance sands, they would represent the easternmost edge of a wedge
shaped formation which extends for a considerable distance to the south and
west, and is, in some areas, utilized as an aquifer to supply water wells.
Groundwater is present perched atop the relatively impermeable
sandstone and glacial till, saturating the granular surficial materials.
During the winter rainy season, groundwater levels rise to the surface
creating a series of ponds and swamps, plus a pair of north flowing streams.
The drainage area feeding towards the site covers 785 acres. The steeply
descending slopes, north of the site, effectively prevent backup of ground-
water levels. Instead, waters, both surface and subsurface, are capable
of draining across the site.
O-HJO L-A.B Q. I 1STC.
190
-------
SUBSURFACE INVESTIGATION
During this phase of our investigation, we have drilled a total of eight
test borings across the site with a truck-mounted, hollow stem auger. The
borings range in depth from eleven to forty-nine feet. In each of the borings,
Standard Penetration Test samples were obtained at five foot or shorter
intervals. The Standard Penetration Test consists of driving a two-inch O.D.
split spoon sampler eighteen inches into the soil with a 140-pound hammer
free falling a distance of thirty inches. The number of blows required to
drive the sampler the last twelve inches is termed the Standard Penetration
Resistance (N value) and gives an indication of the in situ density or consis-
tency of the soil.
The materials obtained by this method were visually classified in the
field and representative portions were placed in airtight glass jars and re-
turned to our laboratory for testing. Each of the borings was provided with
a one and one-half inch diameter piezometer to permit monitoring of ground-
water level fluctuations and water sampling.
Coupled with the test drilling program, a series of twenty-five
backhoe test pits were excavated to more accurately delineate the nature,
depth and condition of the bedrock, glacial till and near surface soils.
The approximate boring and test pit locations are presented on Plate
1, Site Plan. The boring logs, showing materials encountered, sample
locations, N values, and depths to water are presented on Plates A-l
through A-9. The test pit logs are presented in Table A.
O EC O L-A. B S. I IT C.
191
-------
LIMITATIONS
Due to restrictions placed upon our exploration program by the
property owners, test drilling and backhoe work was not performed at the
north end of the landfill site. Upon completion of clearing and development
of adequate access, we will perform additional test drilling in this area to
verify the condition of the soils, the depth to impervious strata, and the
depth to bedrock. We are confident, based upon our visual inspection and
review of available data, that conditions beneath the area in question will
be similar to the explored portions of the property to the south.
We appreciate this opportunity to be of service. If you have any
questions regarding this report, please feel free to call us.
Respectfully submitted,
GEOLABS-WASHINGTON, INC.
Tom Bekey, Engineering Geologist
JJH/mh
: HeiMfghaii,
O-BJOL-A.BS. INC.
192
-------
LEGEND
APPROXIMATE
BORING LOCATIONS
APPROXIMATE TEST
PIT LOCATIONS
(OCT. 15, 1973)
APPROXIMATE TEST
PIT LOCATIONS
(THIS STUDY)
CROSS SECTION LINE
N
Note:
Redrawn by Stevens, Thompson, and Runyan, Inc.
from Geolabs, Inc. Plate 1 dated Feb. 7, 1974 to
fit report format.
SOIL PROFILE LOCATIONS
PLATE 1
193
-------
LANPFILL
GHOL-A.BS. INC.
OKOLOOV AND SOIL. CN
OATI .
SCAll
. WO.
1035 -
194
PLATE 1A
-------
600
o —'
pprwimzfc
6AN TAKY
UNPFILL 6ITE
\\nt&
GEOLOGY AND SOILS ENGINEERING
12893 N E. I5TH PLACE
BCLi-EVUE, WASHINGTON 98005
{ 206) 455-201 8
502 SOUTH 1 1TH STREET
TACOMA. WASHINGTON 98402
|206| 272 4347
OFFICES IN MOST PRINCIPAL CITIES
W.O.
BY _
1-74
DATE .
V: I' = 2.5O'
SCALE N: i• a i mite
195
2
-------
- 75
V/6INITY-
LAINPPILL
0- EC O L-A. B
a«oi_oav AMD •on.
. IITC.
OATI
YT
tCAll ±11
ITfnilc.
. if _
VKO.
196
PLATE 2 A
-------
A A
LANDFILL SITE
£
-^ 320-
C 2i°
0
_c
> 5^H
V
•^
ZOo —
t6O—
7.70—
. I WC.
-------
•:*•";?• "TV V Y -*'•%?--'•& 77" 7T
SECTION
U.HDFILL SITE
a;
r>f- tvtl
-fa^t" p f" \cc3i-\pn^
-h <>cd\n line.
r
If 7 OrflS- t /"/
. I3STCX
OATI _
tCAit
-------
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L^C
LANDFILL £>ITE
330-
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780
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if?
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.^ f if T p m ^ ^<
0 L -A. B S. I IT C.
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APPENDIX A
EXPLORATION LOGS
B2 O L-A.B S. I1STC.
201
-------
j
r"
0,
UJ
aa _
5.
•10-
•15-
•20
-
-
O
3
SM
GM
GM
^
SOIL DESCRIPTION
Surface Elevations - ^^5'
Loose to medium dense, moist, brown,
silty SAND.
Very dense, moist, brown, silty, gravelly
SAND.
Very dense, moist, brown to gray, silty,
gravelly SAND.
Top of Rock 14.5 ft.
Rock.
Bottom of hole at 16.5 ft.
SAMPLES
DEPTH.fMt
STANDARD
PENETRATION RESISTANCE
(14016. w«lght, 30"drop)
A Blowi p«r foot
0 25 50
V
\
•
e
50/4"^
50/5" A
100/3" A
LEGEND ° . %wgr oont.nt 5°
X 2.0"O.D. .plit tpoon sampl. xp Impervious MO|
IT 3.0" O.D. fhin-woiisompi. la. wat.r i.v.i Cathcart Sanitary Landfill Site
•* Sampl. not r.cov.r.d | Pi.zom.t.r tip
Att.rb.ro limit.: P SomP,.rp«h.d LOG OF BORING NO. B-1A
h- •— |-*-Llquid limit USC Unlfi.d Soil W-1035-64
V ^— — Natural wat.r cont.nt Cloiilflcotion Q- S3 O 'L+A.'B S, I N C.
>• • PlOltlC limit .OIL MCCMANIC. • rOUNCJATION INQINflN.
Dl it
-------
«•
I*
Q.
U
Ji
•5 •
• 10-
•15-
•
-
-
u
M
3
SM
GM
SM
/M
SOIL DESCRIPTION
Surface Elevation: - 320'
Medium dense to dense, moist, brown,
silty, gravelly SAND.
Very dense, moist to wet, gray, silty
SAND. Top of rock at 11.0ft.
Bottom of hole at 11 . 0 ft.
SAMPLES
DEPTH,f..t
2
-rJ?
JjL
STANDARD
PENETRATION RESISTANCE
(I40lb.w«lght, 30"drop)
A Blow* p.r foot
0 25 50
1/15/74
1/2/74
9
50/1" A
•
i • FRF Kin 0 «25 50
LtbtNU • % Wat«r eont.nt
I- 2.0"0.0. split ipoon tampl* # Imp.rvloui Mai
H 3.0" o.o. thin-wan sampi* J2L wat«r i«v«i Cathcart Sanitary Landfill Site
*• Sompl* not r«cov«r»d | Pi«zom«t«r tip
Att.rb.rg limit.- P S Nature Iwot.rcofittnt Cla.ilflcation O HI O 3Li J^ B fl. I XT C.
"> -PlO.tlC limit »OIU MICHANIC. * rOUNQATION INOINIIK*
203
-------
I
af
QL
UJ
_a _L_
-
r
•10-
I15
r
•20
•25
-
u
M
O
GM
GM
lk>k
SOIL DESCRIPTION
Surface Elevation: — 335'
Medium dense, moist, brown, gravelly
SAND.
Very dense, moist to wet, reddish brown,
silty, gravelly SAND. (Weathered Rock)
Top of Rock 9.0 ft.
Soft to moderately hard, gray SANDSTONE.
Bottom of hole at 22.5 ft.
SAMPLES
DEPTH,t««t
T
_J
V
V
I
STANDARD
PENETRATION RESISTANCE
(I40lb.w«lght, 3O"drop)
A Blow* p«r foot
0 25 50
1/2/74
V
1/15/74
54/12" A
50/5" A
87/10" A
50/3" A
100/1" A
i errrwn ° 0, 25 50
LtbtNU • % Wottr content
X. 2.0"O.D. split tpoon »omplt # lmp«rv(ou» MQ|
H 3.0" o.o. thin-waiMompi* pZ- wot«r i«vti Cathcart Sanitary Landfill Site
•*<• Sompl« not r«covtr«d | Pi«zom«t«r tip
Ati.rb.rg limit.. P SampUr p«.h.d LOG OF BORING NO. B-2
h-« |-*-Llquid limit USC Unlfl.d Soil W-1035-64
VV_ — Natural «rat«rconttnt CloMlflcotlon O SI O X_t.A. B Q. I XT O.
\ PlQtt It limit •OIL MtCHANICt » FOUHOATION INOINIIR*
204
PI -.f«
-------
J
r"
ll
UJ
j0
5.
•10-
•15 •
•
•
-
o
CO
=>
SM
SM
M
SOIL DESCRIPTION
+ 940'
Surface Elavation: - °^u
Medium dense, wet, brown, silty,
gravelly, fine SAND.
Dense, wet, gray, gravelly, silty, fine
SAND.
Top of Rock 11.0 ft.
Soft to moderately hard, gray
SANDSTONE.
Bottom of hole at 19. 0 ft.
SAMPLES
D
DEPTH.fe.t
V
v
L
STANDARD
PENETRATION RESISTANCE
(140 Ib. weight, 30"drop)
A Blow, per foot
0 25 50
1/15/74
1/4 /74\
\
\
100/5" A
LEGEND • % Water content
J- 2.0"O.D. split ipoon sample >& Impervious teal
J 3.0" O.D. thin- wan sample Is. water level Cathcart Sanitary Landfill Site
?t Sample not recovered | Pi«iom»t«r tip
Ati.rb.rg limit.. P Samp ,.r p«.h.d LOG OF BORING NO. B-3
(—• |-*-Llquid limit USC Unified Soil W-1035-64
VV__ — Natural water cont.nt Cloiilflcotion O HI O H«^L 13 S. T XT C.
N PlattlC limit »0\L. MtCHANIC. k rOUNDATION IN«IN(ln«
Plttf
-------
PEPTH.f*«t
•5 •
—
•10-
•15-
^BMHHH
^••MM
•20-
•
•25-
-30-
•••••••«•
-35-
40
Z
IE
*•
Aft*
^
U
V)
3
SM
GM
SM
SM
&#
SOIL DESCRIPTION
Surface Elevation: — 325'
Medium dense, moist, brown, gravelly,
silty SAND.
Very dense, moist, tan, gravelly, silty,
fine SAND.
Very dense, moist, gray, gravelly, silty,
fine SAND. (Till)
Top of Rock 21.5 ft.
Soft to moderately hard, gray
SANDSTONE.
Bottom of hole at 33.0 ft.
SAMPLES :
OEPTH.fMt
S
li.
STANDARD
PENETRATION RESISTANCE
(140 Ib. weight, 30"drop)
A Blowi p«f foot
0 25 50
1/15/74
•
•
•
9
9
9
9
50/3" A
50/5" A
50/411 A
50/3" A
53/6" i
83/12" A
134/12" A
i crPMn 0 25 bU
LEGEND • % Wof»r cont.nf
2.0"O.D. split tpoon tompl* ^ lmp«rvlou« Mai
3.0" O.D. thin- wan sompi* lsz_ wat.r i«v«i Cathcart Sanitary Landfill Site
Sompl« not r«cbv«r*d § Pi«iom«t«r tip
rb.rg limit.: P Sompl.rpumd LOG OF BORING NO. B-4
•— -|-*-Llquid limit USc Unlfl.d Soil W-1035-64
^— — Natural watvrconttnt Clo«»lf!cotlon O HI O X_i Ji. B 6. I XT C.
V . PlQttlC limit (OIL MtCHANICfl * FOUNDATION INQINIIM*
Plain A
-------
:
«•»
I*
L
UJ
•10-
•15
•
•
-
O
M
3
SM
GM
^
SOIL DESCRIPTION
+ 9Q9 '
Surface Elevation* - ^az
Very loose, moist to wet, brown, silty
SAND.
Very dense, moist, brown, gravelly,
silty SAND.
Top of Rock 11.0 ft.
Soft to moderately hard, gray
SANDSTONE.
r
Bottom of hole at 14. 0 ft.
SAMPLES
DEPTH,t««t
_l_ S
li_
STANOAHD
PENETRATION RESISTANCE
(14016. weight, 3O"drop)
A Blow* p«r foot
0 25 50
41 /1 5/74
•
•
52/6"j
100/2'K
i crcMn ° 2* DU
LtbtNU • % Wot«r content
X 2.0"O.D. iplit ipoon tampl* & Impervious MO!
IX 3.0" O.D. thin- won v,mpi« ls_ wat.r i.v.i Cathcart Sanitary Landfill Site
•tr Sample not r«cov«rtd || Pi«zom«t«r tip
Attarb.rg li.il.. P SompLr^.d LO <* OF BORING NO. B-5
I— • (^-Liquid limit USC Unlfl.d Soil W-1035-64
VV^V_ — Natural woUrconttnt Clasilflcatlon O ID O X^jJL B S. I XT C.
\ -P|a*tlC limit pp.7 «OIU M»CHAN|C» » FOUNDATION INQ1NIIIMI
Plate ^ c
-------
+-
:
i"
a.
UJ
a
• 5 •
•10-
•15 •
•20-
•25-
-30-
-35-
40
O
M
3
SP
SM
SP
SM
SOIL DESCRIPTION
Surface Elevation' - 340'
Very dense, moist, brown, gravelly
SAND.
Very dense, moist, tan to gray, gravelly,
silty SAND.
Very dense, moist, gray, gravelly, sandy
SILT. (Till)
SAMPLES
DEPTH.fMt
I
T
T
v
STANDARD
PENETRATION RESISTANCE
(140 Ib. weight, 3O"drop)
A Blow* per foot
0 25 50
•
•
9
9
1/15/74
•
•
51/6" A
54/6" i
50/4" A
50/5" A
50/4" A
53/6" A
50/4" A
50/3" <
Lc f* c n r\ L' ^ ^ *^ L
EG END • % Wot»r content
J- 2.0"O.D. split ipoon »ompU ^ Impervloui teal
H 3.0" O.D. thin-won sample TEL. water level Cathcart Sanitary Landfill Site
•*<• SampU not r«cov«r«d • Pi«/om«t»r tip
A«.,b.rg ...i... P S...p..rpMMd LOG OF BORING NO. B-6
1— « |-«-L!<|uid limit USC Unified Soil W-1035-64
V V— — Natural water coflttnt CloMlflcotion O XO O I_t JV. B S. T XT O.
PlOltlC limit SOIL. MI.CHANIC* k KOUNOATIOM (NQINIin*
208
Plate A-7
-------
1
r"
0.
UJ
^Q
•45-
M^H^^H
•50-
-
•
-
0
(A
3
/M
SOIL DESCRIPTION
+ q^fji
Surface Elevation-- - °^
Top of Rock 42.0 ft.
Soft to moderately hard, gray
SANDSTONE .
Bottom of hole at 49. 0 ft.
SAMPLES
OEPTH.feet
T!
STANDARD
PENETRATION RESISTANCE
(140 Ib. weight, 30"drop)
A Blow, per foot
0 25 50
•
50/5" A
100/5" A
i prPMn 0 25 50
LEGEND • % Woter content
I. 2.0"O.D. split ipoon sompls <& Impervious seal
H 3.0" O.D. thin-won sample 1.5L. water level Cathcart Sanitary Landfill Site
•**• Sampls not r»cov«r»d f Pi»iom»t»r tip
Aft.rb.rg limit.. P Sompl.r pu.h.d LOG OF BORING NO. B-6 (cont.)
H • l^-Llquid limit USC Unified Soil W-1035-64
V V__ — Natural water content Classification OHJOL-A.BQ. I J>T O.
^ -Plastic limit SOIL MSCHANICS • FOUNDATION INOINIIMS
p...,
-------
r"
EL
UJ
Q
• 5 •
•10-
•15 •
-
-
u
co
SM
SP
/^/^
SOIL DESCRIPTION
Surface Elevation' — ^ ™
Medium dense, moist, brown, silty,
fine SAND.
Very dense, moist to dry, grayish -brown
SAND. (Weathered Rock)
Top of Rock 9.0 ft.
Soft to moderately hard, gray
SANDSTONE. [~
Bottom of hole at 11.5 ft.
SAMPLES
II
DEPTH.feel
v
L
SIANIMHU
PENETRATION RESISTANCE
(140 Ib. weight, 3O"drop)
A Blows per foot
0 25 50
1/15/74
•
•
49/6"^
50/1" A
i rrckin 0 25 50
LEGEND • % Water content
-H 2.0"O.D. split ipoon sample # Impervious seal
H 3.o" O.D. thin- wan sample £*- water level Cathcart Sanitary Landfill Site
•* Sample not recovered • Piezometer tip
LOG OF BORING NO R 7
Atterberg limits' P Sampler pushed l_WVJ wr DWRM^vj I1W. U- (
| — e>— -(-«•• Liquid limit USC Unified Soil W-1035-64
VV— . — .Natural water content Classification Q HI O Hi -A. B S. I JT C.
^V Plastic limit eoiL MSCMANICB » FOUNDATION fNaiNiine
210
Plate A-8
-------
I
x"
0.
UJ
Q
• 5 '
-10-
•15 •
•20
•
O
in
3
SM
SP
GM
SM
SP
/M
SOIL DESCRIPTION
Surface Elevation: - 265'
Msdium dpn
-------
W -1UJO -O-i
TABLE A
TEST PIT LOGS
CATHCART SITE, SNOHOMISH COUNTY
Depth - ft. Soil Classification
Test Pit No. 1
0.0-3.0 Medium dense, moist, tan, silty SAND.
3.0 - 5.0 Medium dense, gray, moist, silty, fine SAND and
sandy SILT.
5.0 - 6.5 Dense to very dense, gray, moist, gravelly, silty SAND.
(Till) No water.
Test Pit No. 2
0.0-0.5 Forest Duff and Topsoil.
0.5 - 4.0 Medium stiff, mottled brown and gray, fine, sandy SILT.
4.0 - 6. 0 Hard, mottled brown and gray, gravelly SILT.
(Weathered Till)
6.0-8.0 Medium dense, tan, moist SAND.
8. 0 - Hard, brown SANDSTONE.
(Water seeps at 2. 0 and 5. 0 feet.)
Test Pit No. 3
0.0-4.0 Medium dense, tan, moist to wet, silty, fine SAND.
4. 0 - 9.5 Medium dense, mottled brown and gray, wet, silty,
gravelly SAND.
9.5 - SANDSTONE.
(Strong water flow at 4. 0 feet.)
Test Pit No. 4
0.0-0.5 Forest Duff.
0.5 -2.5 Loose, reddish-brown, weathered, silty, fine to medium
SAND.
2.5 - 4.5 Medium dense, brown, slightly silty, fine to medium SAND
with fragments of SANDSTONE.
4.5 - 5.5 Medium dense, brown, clean, medium SAND.
5.5 - 7.5 Dense, brown, silty SAND with fragments of SANDSTONE.
7.5- Refusal in hard SANDSTONE.
(Water seeps at 7.5 feet.)
a- EC o i--A- B a. z XT c.
212
-------
W-I035-64
TEST PET LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 5
0.0 - 0.5 Forest Duff.
0.5 - 3.0 Loose, brown, clayey, silty, medium to coarse SAND.
3.0- 4.5 Loose, brown, clean, medium to coarse SAND.
4.5 - 8.0 Medium dense, brown to tan, clayey, silty SAND.
8.0 - 12.5 Very dense, brown and gray, silty, gravelly SAND. (Till)
(Seeps at 8.0 feet.)
Test Pit No. 6
0.0-2.5 Loose, black, organic Topsoil and Roots.
2.5 - 5.0 Medium dense to dense, tan to brown, clayey, silty, fine
to medium SAND. (Weathered Sandstone)
5.0- Refusal in hard, brown Sandstone. (Slow seep at 5. 0 feet.)
Test Pit No. 7
0. 0 - 1.0 Forest Duff and Topsoil.
1.0 - 2.5 Loose, reddish-brown, silty, fine SAND.
2.5 - 9.0 Dense to very dense, brown, silty, fine to medium SAND.
9.0-12.0 Very dense, blue-gray, silty, gravelly SAND. (Till)
(Seeps at 3. 0 and 9.0 feet.) (Slight caving at 8. 0 feet.)
Test Pit No. 8
0. 0 - 0.5 Forest Duff and Topsoil.
0.5 -2.5 Loose, brown, clayey, silty, medium to coarse SAND.
2.5 -6.0 Medium dense, brown, silty, fine to coarse SAND with
thin beds of clean SAND.
6.0-7.5 Very dense, brown, silty, pebbly SAND. (Till)
(Seeps at 6.0 feet.)
Test Pit No. 9
0.0-0.5 Forest Duff.
0.5 -2.0 Loose, reddish-brown, very silty, gravelly SAND.
2.0-4.5 Loose, brown, silty, gravelly SAND with cobbles.
4.5 - 8.5 Very dense, gray, silty, gravelly SAND. (Till)
(Seeps at 4.5 feet.)
a-H: o L-A-B e. iisra.
-------
W-1035-64
TEST PIT LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 10
0.0- 0.5 Forest Duff.
0.5 - 2.5 Loose, reddish-brown, very silty, fine to medium SAND.
2.5 - 8.0 Loose, brown, silty, fine to medium SAND with scattered
pebbles and gravel.
8.0-10.0 Very dense, gray, silty, gravelly SAND. (Till)
(No water.)
Test Pit No. 11
0. 0 - 0. 5 Forest Duff and Topsoil.
0.5 - 2.0 Loose, brown, slightly silty, gravelly SAND.
2.0 - 7.0 Dense, brown, silty, gravelly SAND. (Till)
7.0-9.0 Very dense, brown, silty, gravelly SAND.
(Seeps at 0.5 feet.)
Test Pit No. 12
0.0-0.5 Forest Duff and Topsoil.
0.5 - 8.0 Medium dense, brown, silty SAND. (Weathered Sandstone)
8.0-9.0 Dense, brown, gravelly SANDSTONE.
(Seeps at 7.5 and 8. 0 feet.)
Test Pit No. 13
0.0-0.5 Forest Duff.
0.5 - 3.0 Dense, brown, silty, fine to medium SAND with sandstone
fragments. (Weathered Sandstone)
3.0 - 4.5 Very dense, brown SANDSTONE. (No water.)
Test Pit No. 14
0.0- 9.0 Medium dense, brown, silty, gravelly SAND.
9.0-10.0 Very dense, gray, silty, gravelly SAND. (Till)
(Seeps at 9.0 feet.)
Test Pit No. 15
0.0-0.5 Forest Duff.
0.5 - 6.0 Medium dense, brown, silty, gravelly SAND.
(Weathered Till)
6.0-8.0 Very dense, gray, silty, gravelly SAND. (Till)
(Seeps at 6.0 feet.)
OBJ OLA. BS, iisrc.
214
-------
W-1U35-54
TEST PIT LOGS (CONT.)
Depth .- ft. Soil Classification
Test Pit No. 16
0.0-0.5 Forest Duff.
0.5 - 5.0 Medium dense, brown, silty, fine to medium SAND with
scattered gravel.
5.0 -7.0 Medium dense, brown, silty to clean, fine to medium SAND.
7.0-9.0 Very dense, gray, silty, gravelly SAND. (Till)
(Seeps at 7.0 feet.)
Test Pit No. 17
0.0-0.5 Forest Duff.
0.5 - 5.0 Medium dense, brown, silty, fine to medium SAND with
scattered gravel.
5.0-7.0 Medium dense, brown, silty to clean, fine to medium SAND.
7.0-9.0 Very dense, gray, silty, gravelly SAND. (Till)
(Top of till is at 7.5 feet.)
Test Pit No. 18
0.0-0.5 Forest Duff.
0.5 -2.5 Loose, brown, organic Topsoil.
2.5 - 5.5 Very stiff, brown, sandy CLAY.
5.5 - 7.5 Hard, blue, sandy SILT.
7.5 - 9.0 Dense, blue, silty, fine to medium SAND.
(Strong seeps at 7.5 to 9.0 feet.)
Test Pit No. 19
0.0-1.0 Loose, black, organic Topsoil.
1.0-5.0 Loose to medium dense, brown, sandy SILT.
5. 0 - 8. 0 Very stiff, brown SILT with thin beds of sandy SILT.
8.0-9.5 Dense, brown, silty SAND.
(Strong seep at 8. 5 feet.)
Test Pit No. 20
0.0-0.5 Grass and Topsoil.
0.5 - 3.0 Loose to medium dense, reddish-brown, silty, fine to
medium SAND.
3.0 - 5.5 Thin bedded, medium dense, brown, silty, fine to medium
SAND.
OH3OL-A.BQ. I1STC.
215
-------
W-1035-64
TEST PIT LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 20 (continued)
5.5 - 6.0 Medium dense, brown, clean, fine to medium SAND.
6.0-9.0 Hard, brown, friable SANDSTONE.
9.0-9.5 Very hard, blue, dry SANDSTONE.
(Seeps at 3. 0 to 8. 0 feet.)
Test Pit No. 21
0. 0 - 0.5 Forest Duff and Topsoil.
0.5 - 4.5 Medium stiff, yellow-brown, sandy SILT.
4.5 - 6.5 Loose to medium dense, gray, clean, medium to coarse,
pebbly SAND. (Water bearing)
6.5 - 8.5 Dense, gray, sandy GRAVEL.
(Water standing at 7. 0 feet.
Test Pit No. 22
0.0-0.5 Forest Duff and Topsoil.
0.5 - 3.5 Soft, brown, sandy, clayey SILT. (Weathered Rock)
3.5-8.5 Interbedded, hard, brown and gray, sandy SILT and
silty SAND. (Some sandstone fragments) (Weathered Rock)
8.5-8.9 Hard, blue, silty, micaceous SANDSTONE.
(Seeps at 8.5 feet.)
Test Pit No. 23
0. 0 - 0.5 Forest Duff and Topsoil.
0.5 -4.0 Soft, brown, sandy, clayey SILT. (Weathered Rock)
4.0-8.5 Stiff, brown, sandy SILT with rock fragments.
(Rock becomes harder with depth. (Weathered Rock)
8.5-8.6 Hard, brown SANDSTONE. (Dry. Impermeable.)
Test Pit No. 24
0. 0 - 0.5 Forest Duff and Topsoil.
0.5 - 1.0 Soft, reddish-brown, silty, sandy CLAY with roots.
1.0 - 4.0 Medium dense, gray and brown, silty, fine to coarse
SAND with thin beds of stiff silt.
4. 0 - 10. 0 Dense, brown, very silty, fine to medium SAND with
some gravel.
10.0 - 11.0 Dense, blue, silty, fine to medium SANDSTONE.
(Seeps at 2.5 feet and 9.5 feet.)
O-3EC O 3L..A.B 8. INC.
216
-------
W-1035-64
TEST PIT LOGS (CONT.)
Depth - ft. Soil Classification
Test Pit No. 25
0. 0 - 0.5 Forest Duff and Topsoil.
0.5 - 3.0 Soft, reddish brown, sandy SILT.
3.0- 6.0 Stiff, brown, sandy SILT.
6.0- 9.0 Medium dense, gray, clean SAND.
9.0 - 10.0 Hard, brown, silty CLAY.
10.0-11.0 Dense, blue SANDSTONE.
(Seeps at 3. 0 feet and 8. 0 - 9. 0 feet.)
GJ-El O L.-A.B S. INC.
217
-------
APPENDIX B
LABORATORY TEST RESULTS
ZG O X--A.B S. IXSTC.
218
-------
W-1035-64
NATURAL MOISTURE CONTENT
Boring Sample Natural Moisture
No. No. Content (%)
B-1A S-l 21.8
S-2 12.8
S-3 11.0
B-1B S-l 23.0
B-4 S-l 13.4
S-2 11.0
S-3 7.4
S-4 9.2
S-5 16.8
S-6 20.6
S-l 18.9
B-5 S-l 29.6
S-2 16.1
B-6 S-l 12.9
S-2 9.6
S-3 8.5
S-4 9.7
S-6 10.8
S-7 9.7
S-10 11.5
B-7 S-l 28.8
S-2 14.1
a- B: o L.-A-B a. i rrc. Plate B-l
219
-------
W-1035-64
RESULTS OF PERMEABILITY TESTS
Test No. Boring No. Sample No. Permeability (cm/sec)
1 B-3 S-l 6.42X1CT7
2 B-8 S-5 4.46xKT7
3 B-6 S-8 2.56xlO~5
4 B-8 S-2 9.12xlO"6
5 B-6 S-5 1.04xlO"5
a- H o L.A.B e. i rrc. Plate B-2
220
-------
BORING NO B-3, S-l
DEPTH 2.5' -4.0'
OB3OL-A.B e. ZXTC.
OCOI.OOY AMO BOIL.
W.Q. 1035-64
no
ro
PROJECT Cathcart Sanitary Landfill Site
CO
a:
LJ
UJ
o
Ul
a.
90
h-
5 80
LU
^ 70
60
0
3 0
20
I 0
0
1000
PLATE
B-3
US. STANDARD SIEVE SIZE
3in I.Sin. 3/4in 3/8in *4 10 20 40 60 100 200
i i ill i i i i i i
100
s;
10 1.0 O.I
GRAIN SIZE IN MILLIMETERS
HYDROMETER
0.01
0.001
COB BLE S
GRAVEL
COARSE | FINE
SAND
COARSE
MEDIUM
FINE
SILT
CLAY
-------
ro
ro
BORING NO
DEPTH
PROJECT
t n n
Q O
7^ 8 O
UJ
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OHJOL-A.B S. IX4TC.
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PLATE
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"1000 100 10 1.0 O.I
GRAIN SIZE IN MILLIMETERS
COB BLE S
GRAVEL
COARSE | FINE
SAND
COARS
• MEDIUM | FINE
B-4
0.01 0
SILT
CLAY
001
-------
ro
ro
CO
BORING NO B-6, S-5
DEPTH 22.5' -24.0'
OJEDOIL.JLB e. I ITC.
AMD •OIL.
PROJECT Cathcart Sanitary Landfill Site
W.Q. 1035-64
PLATE B-5
U.S. STANDARD SIEVE SIZE
3in I5in 3/4in 3/8in *4 10 20 40 60 100 200
III!
HYDROMETER
1 UU
9n
i-
?£ R n
LU
^ 7 n
( U
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m
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COARSE | FINE
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COARS^ MEDIUM
FINE
0
SILT
CLAY
001
-------
ro
ro
BORING NO
B-6. S-8
DEPTH 37.5' - 39.0'
PROJECT
i n n i •
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H
^ R n
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\
O HI OIL, -A. B S. I 1STO.
4MCOI.OOV AMD SOU. KMOINBKHINa
Cathcart Sanitary Landfill Site
U.S. STANDARD SIEVE SIZE
3in .5in 3/4in. 3/8in.*4 10 20 40 60 100 200
i i i i i i i i i i i
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^
•*«
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GRAIN SIZE IN MILLIMETERS
COB BLE S
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COARSE | FINE C
SAND
;OARSE| MEDIUM J FINE
V
N,
l^
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). 1035-64
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-------
BORING NO B-7, S-3
DEPTH
GXBOL..A.B e. I WC.
-------
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DEPTH
PROJECT
inn i
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PLATE
HYDROMETER
"1000 100 10 10 O.I
GRAIN SIZE IN MILLIMETERS
COB BLE S
GRAVEL
COARSE [ FINE C
SAND
OARS^MEDIUM | FINE
B-8
0.01 0.001
SILT
CLAY
-------
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-------
APPENDIX F
SUBSURFACE INVESTIGATION AND
PERCOLATION TESTING OF BEDROCK
LANDFILL SITE
CATHCART, WASHINGTON
W-1035 -66
228
-------
-WASHINGTON, Ino.
IPovindation and Soils Engineering, Oeology
\\, 12893 N.E. I5;/i PL - Bellevue, Washington 98005 ' (206) GL 5-2018
502 So. llth St. • Tacoma, Washington 98402 • (206)272-8363
Telex 32-9424 3416 Everett Avenue - Everett, Washington 98201 • (206) 259-0817
August 9, 1974 W-1035-66
Stevens, Thompson & Runyan, Inc.
700 Plaza 600
Seattle, Washington 98101
Attention: Mr. Dirk Van Woerden
Subject: Subsurface Investigation and Percolation Testing of Bedrock
Landfill Site
Cathcart, Washington
Gentlemen:
This report presents the results of our subsurface investigation and
permeability testing of the bedrock formation at the Cathcart landfill site.
The test location was selected considering estimated depth of bedrock and
close proximity to an existing surface drainage path. It is our opinion that
the selection of the test site is fairly representative of bedrock conditions
throughout the site. The purpose of this study was to investigate the integrity
and permeability of the bedrock formation which consists of massive to inter -
bedded Sandstone and Siltstone.
SUBSURFACE INVESTIGATION
The subsurface investigation consisted of drilling one boring to a
depth of 26 feet below the existing ground surface, which was approximately
Elevation 330 at the test location.
The overburden soils, consisting of sandy silts and gravelly sands,
were encountered to about 8 feet in depth. Casing was then installed in the
boring to a depth of 9 feet to seal off the sandstone from the overlying soils.
To insure the casing was seated in bedrock, a constant head test was run.
Water leakage was not observed and the casing was considered sealed. The
boring was then advanced using an NX diamond coring bit which allowed re-
covery of rock samples. After a core run of 5 to 6 feet, permeability tests
were conducted to determine water loss in the bedrock formation. The hole
was sealed off and water pumped in under pressure. Water pressure was
BRANCH OFFICES IN MOST PRINCIPAL CITIES
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Stevens, Thompson & Runyan, Inc. W-1035-66
August 9, 1974 Page Two
increased in increments of 5 psi, and maintained for a certain time interval.
Any water loss was noted and recorded for each pressure increment. (An
increase of 1 psi is equivalent to a rise in head of 2.31 feet.) This process
continued until 15 psi had been attained, then pressure was reduced in 5 psi
increments down to the initial starting pressure, recording water loss for
each increment. Two other core runs were made to a depth of 18 feet into
bedrock and tested in the same manner as the first section. After completion
of drilling and water testing the last section, the entire length of sealed hole
in bedrock was pressure tested in increments. The maximum pressure used
for this test was 20 psi.
The location of the test boring is presented on the Site Plan, Plate I,
and water test data and boring log in the Appendix.
SUBSURFACE CONDITIONS
Our boring indicated very soft, wet, dark brown, sandy silt to 3.5
feet, underlain to a depth of 8 feet with medium dense, moist, yellow-brown,
gravelly, medium sand. These overlying sandy silts and sands represent
post glacial deposits resting on older Oligocene sandstone. These deposits
have been discussed in more detail in our earlier report (Geolabs Report,
W-1035-64, dated February 1974).
The bedrock formation was encountered at a depth of 8 feet below
the existing ground surface. Bedrock consists of thin to medium interbedded
siltstone and sandstone. The sandstone varies from medium to coarse
grained. The bedrock is moderately hard to hard, unweathered, and mod-
erately fractured. The bedrock surface shows a moderate degree of weather-
ing and fracturing that lessens with depth. The Rock Quality Designation
(RQD) was used as an indication of discontinuities and a more massive and
solid structure.
DISCUSSION AND RECOMMENDATIONS
General
The boring and permeability test performed for this additional inves-
tigation has confirmed our contention in our original report that the bedrock
is relatively impermeable. The existence of fractures near the rock surface
could easily be located after the overburden soils are excavated and sealed.
The integrity of the bedrock, without considering the joints and fractures,
is sound and impermeable, thus sealing of these minor openings will give an
impermeable barrier for leachate control. It is our opinion that the joints
and fractures in the rock are responsible for the minor water losses
sustained in our tests.
a-H: o IL..A-B e. lire.
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Stevens, Thompson & Runyan, Inc. W-1035-66
August 9, 1974 Page Three
Interpretation of Test Results
Test No. 1, run from 9.1 to 15.3 feet, showed a minor loss at 15 psi
and no loss of water at lower pressures. The permeability at 15 psi is about
13 cubic feet per square foot per year. This minor loss may be due to hair-
line fractures in the upper weathered bedrock.
The second test from 15 to 21.3 feet showed no loss of water which is
indicative of a sound impermeable bedrock.
The third test from 21 to 26 feet indicated a loss at 10 and 15 psi up
to 1.3 gallons per minute (gpm) at 15 psi, with 0.4 and 0.1 gpm at 10 psi.
The permeability at 15 psi was 166 cubic feet/square foot/year. No loss
was observed at 5 psi. This may be due to a joint or contact plane between
bedded siltstone and sandstone found at about 24 feet.
The fourth test, which was performed on the entire section of bed-
rock, showed lesser water loss than the third test, which may be an indication
of sealing the fracture. The permeability rate for this test varied from 64
to 36 cubic feet per square foot per year. The drop reduction may be due to
a partial sealing of the joint network.
Sealing of Joints
In our opinion, the losses sustained in our tests can be considered
minor and could be reduced or eliminated by sealing joints or fractures
encountered at the bedrock surface after the overburden has been removed.
The exposed bedrock surface should be inspected by an experienced
engineering geologist or Soils Engineer to locate areas that will require
sealing. The method of sealing should be left to the contractor's discretion,
and in such a manner as to assure proper sealing of the opening. It is our
opinion that a pressure grouting method should be used to obtain sufficient
penetration of the grout into the joint. Sealing of the surface joints and
fractures should be sufficient to obtain a relatively impervious bedrock
foundation.
We appreciate the opportunity to be of service to you on this project.
If you have any questions or require clarification of any point in this report,
please feel free to contact us.
a- H: o LA Be. i
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Stevens, Thompson & Runyan, Inc.
August 9, 1974
W-1035-66
Page Four
report:
The following Plate and Appendix are included and complete this
Plate 1
Appendix
Site Plan
Test Data
RSL/mh
%«»V**H«
\ ^\;;^!rr>V.«- _^.-V
^L.^
Ct^^^-
Respectfully submitted,
GEOLABS-WASHINGTON, INC.
/ / s /. ' •''
Roberts. Levinson, P.E
Chief Engineer
a- B: o 1L--A.B s. lire.
232
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H
LEGEND
ROAD
PROPERTY LINE
CONTOUR LINE-5' INTERVAL
PREVIOUS BORING
PREVIOUS TEST PIT
PRESENT BORING
BORING LOCATION MAP
C3-H: O L-A.B Q. INC.
OKOLOOV AMO «OIC KMaiMBBKIM*
OATI
SCAll
PLATE |
233
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D.
UJ
Q
Q
DESCRIPTION
SURFACE ELEVATION: 330 ft.
00
t-
CO
PERCENT RECOVERY
-5-
-15-
-20-
-25-
-30^
Very soft, dark brown, wet, sandy SILT.
Medium dense, yellow-brown, moist,
gravelly, medium SAND.
Gray to gray-green, medium hard to hard,
fine to medium grained SANDSTONE and
SILTSTONE in lenses to 6 inches thick.
Coarse grained SANDSTONE lens.
Soft, medium grained SANDSTONE lens.
Joint
Boring terminated at 26' on 7/22/74
7/19/74
Core Run 1
% recovered =63.6
RQD =0
Core Run 2
% recovered =92.1
RQD =28.6%
Core Run 3
% recovered =100
RQD =0
Core Run 4
% recovered =100
RQD = 40%
Core Run 5
% recovered = 97.8
RQD = 97.8%
LEGEND
1 Water Pressure Test Location
—L- and Number
_SL Water Level
RQD Rock Quality Designator
Snohomish County Sanitary Landfill
Cathcart Site
LOG OF BORING NO. B-9
W-10-35-66
£3. i 20-0.
•Oil. MICHAHICB ft rOUHDATION lNaiHII*»
Plats
234
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WATER PRESSURE TEST RESULTS
Pressure
(psl)
5
10
15
10
Pressure
(psi)
5
10
15
10
5
Test No. 1
Time of Test
(minutes)
3
3
7
3
3
Test No. 2
Time of Test
(minutes)
3
3
3
3
3
(Dspth 9.1' - 15.3')
Water Loss
(gpm)
0
0
.086
0
0
(Depth 15' - 21.3')
Water Loss
(gpm)
0
0
0
0
0
Permeability Rate
(foot3 /foot2 /year)
0
0
12.99
0
0
Permeability Rate
(foot3 /foot2 /year)
0
0
0
0
0
a-H: o L..A.B e.
235
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Test No. 3 (Depth 21' - 26')
Pressure
(psi)
5
10
15
10
5
Time of Test
(minutes)
3
3
3
3
3
Water Loss
(gpm)
0
.37
1.33
.1
0
Permeability Rate
(foot3/foot2/year)
0
56.08
166.12
Test No. 4 (Depth 10' - 26')
Pressure
(psi)
5
10
15
20
15
10
5
Time of Test
(minutes)
3
3
3
3
3
3
3
Water Loss
fepm)
.03
.93
.67
,93
0
0
0
Perm eabi lit
(foot3 /foot2,
2.66
62.77
36.54
42.54
e. IKTC.
236
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