PB85-197044
Investigations of Existing
Pressure Sewer Systems
Rezek, Henry, Meisenheimer and Gende, Inc.
Libertyville, IL
Prepared for
Environmental Protection Agency, Cincinnati, OH
Apr 85
V
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PBd5-197(m
EPA/600/2-85/051
April 1985
INVESTIGATIONS OF EXISTING
PRESSURE SEWER SYSTEMS
by
Joseph W. Rezek
Ivan A. Cooper
Rezek, Heary, Meisenheimer and Gende, Inc.
Libertyville, Illinois 60048
Contract Number 68-03-2600
Project Officer
James F. Kreissl
Wastewater Research Division
Water Engineering Research Laboratory
Cincinnati, Ohio 45268
WATER ENGINEERING RESEARCH,LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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1. REPORT NO. 2.
EPA/600/2-85/051
3. RECIPIENT'S ACCESSIOI^NO.
Wo5 19 70 44/AS
4. TITLE ANO SUBTITLE
Investigations of Existing Pressure Sewer Systems
8. REPORT DATE
April 1985
B. PERFORMING ORGANIZATION CODE
7. AUTHORIS)
Joseph W. Rezek and Ivan A. Cooper
a, PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME ANO AOORESS
Rezek, Henry, Meisenheimer, and Gende, Inc.
Llbertyville, Illinois 60048
10. PROGRAM ELEMENT NO.
11 tfwYr a^; W.NM-t)3- 2600
12. SPONSORING AGENCY NAME ANO AQORSSS
Water Engineering Research Laboratory - Cin., OH
Office of Research & Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
1WWW^IOP COVERED
14. SPONSORING AGENCY CODE
EPA/600/14
IS. SUPPLEMENTARY NOTES
Project Officer: James F. Kreissl (513)684-7614
TECHNICAL REPORT DATA
I wo areas previuuaijr unuus-uirem-cu m ~ — 77 - - , .
tenance history and septic tank effluent treatability. Nine sites were visited to higp
light these considerations, especially their relationship to overall system cost-
effectiveness.
Pressure sewer systems require numerous specialized components, each of which demand
varying degrees of operation and maintenance. This report considers operations and
maintenance for the following; on-lot, mainline, and treatment facilities,.
On-lot maintenance tasks differ for the two major types of systems'- grinder pump (GP;
and septic tank effluent pumping (STEP). Both preventive maintenance and breakdown
maintenance duties were investigated. Operation and maintenance (OSM) task frequence
for the nine investigated systems and differences between O&M tasks and frequencies ft
continuous occupancy homes versus vacation homes are presented.
17.
KEY WOROS AND DOCUMENT ANALYSIS
descriptors
b.IDENTIFIERS/OPEN ENDED TERMS C, COSATI Field/Croup
13. SiSTRlBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report!
UNCLASSIFIED
21. NO. OF PAGES
134 -
20. SECURITY CLASS (This pate)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 («•»)
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DISCLAIMER
The information in this document has been funded wholly or in part
by the United States Environmental Protection Agency under Contract No.
68-03-2600 to Joseph W. Rezek and Ivan A. Cooper. It has been subject
to the Agency's peer and administrative review, and it has been approved
for publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with
protecting the Nation's land, air, and water systems. Under a mandate of
national environmental laws, the agency strives to formulate and implement
actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. The Clean Water Act,
the Safe Drinking Water Act, and the Toxics Substances Control Act are three
of the major congressional laws that provide the framework for restoring and
maintaining the integrity of our Nation's water, for preserving and enhancing
the water we drink, and for protecting the environment from toxic substances.
These laws direct the EPA to perform research to define our environmental
problems, measure the impacts, and search for solutions.
The Water Engineering Research Laboratory is that component of EPA'S
Research and Development program concerned with preventing, treating, and
managing municipal and industrial wastewater discharges; establishing
practices to control and remove contaminants from drinking water and to
prevent its deterioration during storage and distribution; and assessing the
nature and controllability of releases of toxic substances to the air, water,
and land from manufacturing processes and subsequent product uses. This
publication is one of the products of that research and provides a vital
communication link between the researcher and the user community.
It is the expressed purpose of this report to describe and analyze
actual case histories of typical installations of pressure sewer systems in
the United States. The majority of this information was collected prior to
and during 1977. As additional data have become available, these histories
have been updated.
Francis T. Mayo, Director
Water Engineering Research Laboratory
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ABSTRACT
Two areas previously undocumented in pressure sewer evalua-
tions are operation and maintenance history and septic tank ef-
fluent treatability. Nine sites were visited under a U. S. EPA
contract to highlight these considerations, especially their re-
lationship to overall system cost-effectiveness.
Pressure sewer systems require numerous specialized com-
ponents, each of which demand varying degrees of operation and
maintenance. This report considers operations and maintenance
for the following; on-lot, mainline, and treatment facilities.
On-lot maintenance tasks differ for the two major types of
systems - grinder pump (GP) and septic tank effluent pumping
(STEP). Both preventive maintenance and breakdown maintenance
duties were investigated. Operation and maintenance (0 & M)
task frequencies for the nine investigated systems and dif-
ferences between 0 & M tasks and frequencies for continuous oc-
cupancy homes versus vacation homes are presented.
Mainline 0 & M tasks include periodic cleaning, repairing of
leaks, and maintaining system control and air release valves.
Some systems require periodic flushing of mains, particularly GP
systems with low velocities. Systems with existing loads signi-
ficantly less than design flows tend to have excessive grease
build-ups in mains, thus reducing capacity. Operating experi-
ence with grease build-ups are reported. 0 & M tasks for peri-
odic manual operation of air release valves depend on the designer's
choice of manual or automatic air release valves. Other infor-
mation gathered is presented similar to that for on-lot 0 & M.
Other areas included, but not previously reported in detail,
are 0 & M tasks for treatment systems receiving predominantly
pressure sewage, startup problems for either GP or STEP systems,
and how startup procedures relate to initial system and treat-
ment 0 & M. Odor control needs and examples of odor abatement
techniques are included, as well as considerations for corrosion
prevention.
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Treatability of pressure collected sewage from both GF and
STEP systems is no more exotic than treatment of conventional
gravity collected sewage. Secondary treatment standards can be
met with conventional aerobic treatment of either type of pres-
sure collected sewage. Treatment plant considerations include
deletion of comminutors in total pressure systems, and an in-
crease in STEP plant treatment efficiency due to substantially
reduced pollutant loadings.
A discussion of management practices, procedures, recurrent
problems, and public relations policies is included. This is
especially important when two or more users share a common on-
lot pumping facility.
This report was submitted in fulfillment of Contract Number
68-03-2600 by Rezek, Henry, Meisenheimer and Gende, Inc. under
the sponsorship of the U. S. Environmental Protection Agency.
This report covers the neriod from September 1, 1977 to June,
1978.
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CONTENTS
Foreword . iii
Abstract . . iv
Figures viii
Tables x
Abbreviations xii
Acknowledgments xiii
1. Introduction 1
2. Conclusions 3
3. Recommendations 6
4. Case Histories 8
5. Design of On-Lot Facilities 35
6. Design of Off-Lot Facilities 60
7. Construction Requirements 71
8. Operation and Maintenance 73
9. Treatments 89
10. Costs 97
11. Management Implications 105
References 109
Appendix 113
vi i
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FIGURES
Number Page
1 Gravity sewer construction may not be cost-
effective in certain areas 9
2 Phoenixville, PA pressure sewer system 9
3 Typical lakefront pressure sewer loop at Apple
Valley, OH 12
4 Grandview Lake, IN pressure sewer system
prior to expansion 13
5 Typical Hydr-O-Matic slide rail pressure
sewer pump installation at Grandview Lake, IN ... 13
6 Moses treatment plant using scippus and phragmite
reeds, Port Charlotte, FL 18
7 Gulf Cove pressure sewer area, Port Charlotte, FL . 19
8 Floating septic tanks 21
9 Houseboat pumping unit 23
10 Flexible pipeline connector in Klaus system,
Portland, OR 24
11 Domestic sewer system, Kalispell Bay Water &
3ewer District 26
12 Weatherby Lake, MO pressure sewer system
pump chamber 28
13 Access to Environment/One pump chamber 28
14 Inside home installation, Country Knolls
Subdivision, Clifton Park, NY 29
15 Details of Sausalito, CA's pressure sewer
pump installation 31
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FIGURES (continued)
Number Page
16 Hydr-O-Matic pump equipment mounted below
residence 33
17 Typical grinder pump on-lot facilities 36
18 Typical STEP system on-lot facilities 36
19 Septic tanks used in Glide-IdleyId, OR system 38
20 Typical effluent pump guide rail type system 39
21 Typical effluent pump union type system 39
22 Typical pump chamber In G1ide-Idleyld, OR
system 40
23 Pneumatic ejector for use in pressure sewer
system 41
24 Comparison of characteristics of a semi-positive
displacement grinder pump (Environment/One)
vs a centrifugal gr inder pump (Hydr-o-Matic) .... 46
25 Pump control cabinet for Glide-IdleyId , OR 52
26 Cut away Of Env ironment/One pump showing
pressure sensing bell on lower left with
1ines running to pressure switches at top
center of pump casing 53
27 Pipe sizing procedure 62
28 Automatic air release valve schematic 65
29 Valve box and cleanout at Har rison, ID 66
30 Terminal cleanout 67
31 Boot failure modes 78
32 Percent suspended solids removal vs overflow rate . 91
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TABLES
Number Page
1 General Development Properties, FL 17
2 Port St. Lucie Suburbanaer System 20
3 Houseboat Pressure Sewer Systems Near
Portlsnd, OR .*.«........a....................... 22
4 Comparison of Grinder Pump Auxiliary Equipment .... 43
5 Comparison of Grinder Pumps 48
6 Characteristics of Common Sewer Gases 58
7 Service Calls at Port St. Lucie, FL 76
8 Summary of Effluent Pump Maintenance Records 76
9 Distribution of Service Calls 80
10 Types of Service Calls - Weatherby Lake, MO 81
11 Semi-Positive Displacement Pump System Repair
Labor and Costs 82
12 Centrifugal Grinder Pump Repair Local Labor
and Cost Estimates 83
13 Piping System Preventive Maintenance 87
14 Mean Time Between Service Calls for all Types of
Pressure Sewer Systems 88
15 Municipal Household Characteristics, Albany, NY ... 91
16 Grinder and Solids Handling Pump Sewage
Characteristics 92
17 STEP System Sewage Characteristics 93
18 Typical Installation Cost of Simplex Pump Unit 99
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TABLES (continued)
Number Page
19 On-lot Facility Construction Costs 100
20 Piping System Construction Costs 101
21 Pump Overhaul Costs 102
22 Typical Annual Power Consumption Operating Co3ts .. 103
xi
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ABBREVIATIONS
MGD
million gallons per day
GP
grinder pump
STEP
septic tank effluent pump
0 & M
operation and maintenance
BODc
5
biochemical oxygen demand, 5 days
SS
suspended solids
FRP
fiberglass reinforced pipe
NEMA
National Electrical Manufacturer's Association
PVC
polyvinyl chloride
MUD
municipal utility district
NPT
National Pipe Thread
GPM
gallons per minute
MTBSC
mean time between service calls
H-O-A
hand-off-automatic
EPA
Environmental Protection Agency
STP
sewage treatment plant
S & L
Smith & Loveless
DWV
—- drain waste vent
CATV
community antenna television
C factor
Hazen-Williams coefficient
NFPA
National Fire Protection Association
NEC
National Electric Code
ABS
aerylonitrile-butadicue-styrene
kw
kilowatt
hp
horsepower
kPa
kilopascal
psi
pounds per square inch
If
linear foot
ft
feet, foot
in
inch
RPM
revolutions per minute
ISF
—— intermittent sand filter
RSF
recirculating sand filter
xii
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ACKNOWLEDGMENTS
Joseph W. Rezek served is Project Director for this study
with Ivan A. Cooper acting as Project Manager. William C. Bowne
of the Douglas County, OR Engineer's office served as the Pro-
ject Consultant, and C. Joseph Touhill of Touhill, Shuckrow and
Associates, Pittsburg, PA, functioned as Manuscript Preparation
Consultant. Professional assistance was provided by R. J.
Devery and S. M. Lacy. The excellent technical assistance pro-
vided by F. J. Bradke, N. G. Brown, G. E. Wilson and R. W.
Magnuson is especially appreciated. The secretarial and techni-
cal typing efforts of Cynth ia Mick ley Harris are gratefully ap-
preciated .
Special thanks to to various members of the staff of the
EPA's Water Engineering Research Laboratory in Cincinnati,
OH, particularly James F. Kreissl, Project Officer, who pro-
vided helpful guidance throughout the program.
We gratefully wish to thank all the system operators, con-
sultants, and state and local officials who participated in this
study, sharing their time and effort to bring this survey docu-
ment to the user community.
xiii
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SECT1UN 1
INTRODUCTION
In view of the need to provide smaller communities with low
cost solutions for collection and treatment of wastewater, there
is a need to provide more definitive information on methodolo-
gies for evaluating the potential of pressure sewage collection
systems. Likewise, regulatory agencies and consulting engineers
need to define bases for evaluating and designing cost-effective
alternatives. There are many advantages for a community to in-
stall a pressure sewage collection system. Among these are the
lower costs associated with a less expensive piping infrastruc-
ture. Pressure sewer piping material is less expensive than a
conventional gravity sewer system, and excavation, dewatering
and shoring costs are generally substantially less. Areas with
considerable rock close to the surface also will experience sig-
nificantly lower costs. Developer advantages also exist, since
the homesite pumping unit need only be added when a homeowner
decides to build on a purchased lot. Although there is poten-
tial for infiltration and inflow between the house connection
and the pumping unit, most of the pressure sewer system consists
of sealed piping which greatly diminishes this possibility.
Certain disadvantages also may be experienced with a pres-
sure sewer system compared to a gravity collection system. The
chief disadvantage is that the pressure sewer is more highly
mechanized. Therefore, more maintenance is involved for the in-
dividual home pumping unit and its associated on-lot facilities,
as well as piping system components such as inline control
valves, air release valves, flushing mechanisms anfl control of
odor.
There also are treatment considerations in pressure sewer
collection systems that may be different from conventional
gravity systems. In a STEP system there is a potential for
greatly reduced organic loading to the treatment facility at the
equivalent flow of a gravity collection system. This lower
organic loading may translate into a higher treatment plant flow
capacity with same unit sizing. Grinder pump collection sys-
tems, however, usually have a higher unit organic loading than
the gravity system, because all of the wastes from a homesite
will be conveyed to the treatment facility at a reduced flow
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volume compared to the gravity system which often would have the
transported wastes diluted with infiltration and inflow. If the
treatment facility receives solely pressure collected sewage,
whether it be from a GP or a STEP system, a comminutor is un-
necessary. The areas of operation and maintenance (0 & M) his-
tory and treatability of wastewater, have been relatively unex-
plored in other published works on pressure collection systems.
This report intends to fill the gap in information transfer
and offers positive examples of effective and economical collec-
tion facilities in low density areas, areas with construction
problems, and second home development situations.
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SECTION 2
CONCLUSIONS
The following are major conclusions reached based upon de-
tailed analysis of field investigations.
ON-LOT FACILITIES
Both GP and STEP pump units showed acceptable maintenance re-
sults. STEP pumping units showed a particularly high reliabi-
lity. This was only for the Hydr-O-Matic sump pump type of
units. Other effluent pumps, such as Peabody Barnes, do not
have a long enough service history to yield accurate results.
GP reliability also has been acceptable with the highest relia-
bility shown by the Hydr-O-Matic Hydrogr ind units followed in
descending order by Environment/One, and Peabody Barnes. Units
such as Toran, F. E. Meyers, and others either do not have suf-
ficient units in service or their products are too new to eval-
uate. Solids handling type pumps, such as the Peabody Barnes
5.1 cm (2 in) sewage ejector pumps, used in several marina type
installations, have an acceptable reliability.
Pumps should not use pressure switches as the primary on - off
control device. Mercury floats are better suited for this type
of installation.
Alarm systems should be provided to alert the homeowner that a
malfunction has occurred.
PIPING SYSTEMS
All inline shutoff control valves and air release valves should
be inspected and manually operated at least twice per year.
Systems that have mainline piping sized for a significant number
of future users have problems„ The problems are more severe
with GP systems since they carry significant volumes of grease.
Slow velocities create conditions suitable for grease and de-
tergent deposition.
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In STEP systems, increased residence time and slower velocities
increase the chances of gas and odor formation.
CORROSION
Corrosion is a problem in STEP systems. Connection bands and
valves for on-lot facilities should be stainless steel and
bronze. Plastic piping is superior to galvanized. Grey iron
and admiralty brass are not recommended. Brass will lose zinc,
leaving the copper susceptible to corrosion.
ODORS
Odors can be a problem in both the Gp and STEP pumping systems.
Odors in STEP systems have shown up mainly at intermediate lift
stations and not in the on-site facilities or at the STP. There
have been examples of GP systems that have had intermittent odor
problems. One means of controlling odor is by the addition of
hydrogen peroxide.
TREATMENT
GP sewage has a higher organic loading than conventional gravity-
collected sewage because there is no infiltration or inflow to
dilute HP sewage. STEP system sewage is considerably lower in
BODr and SS than gravity sewage because substantial portions of
the organic solids and ROD,, are removed in the sentic tank. Roth
BP and STEP sewage are amenable to conventional aerobic treatment.
OPERATION AND MAINTENANCE
Systems having yearly or semi-annual inspection of pumps and
piping system components are less likely to need emergency
breakdown maintenance.
Pump weight is a factor in servicing. Effluent pumps typically
are light enough for an individual to lift with one hand.
Grinder pumps, such as the Hydr-O-Matic, Toran, and Meyers, are
light enough for one individual to lift. Others, such as the
Peabody Barnes and Environment/One, usually require two indivi-
duals . However, several systems have used one individual to
service these heavier units.
Significant operator time is involved with construction coordi-
nation, particularly in continually developing communities.
Plans should be made to take these factors and costs into consi-
deration when preparing 0 & M budgets.
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COSTS
Existing STEP systems have an on-lot construction cost of be-
tween $1,000 to $2,000 per unit. GP units have a slightly
higher installed cost, from about $1,300 to $2,500 per unit.
SYSTEM MANAGEMENT
Systems with formal maintenance organizations had fewer customer
complaints and less system problems. Moreover, customers showed
more interest and were kept better informed about system opera-
tion than systems that lacked these types of organizations.
Where homeowners lacked formal assistance, many expressed an in-
terest in securing help from a formal, centralized entity.
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SECTION 3
RECOMMENDATIONS
The following recommendations are made to alleviate problems
in systems under design or planned. Implementation of these
recommendations plus the results of future investigations should
provide more highly reliable, easier to operate, and less ex-
pensive systems.
On-lot facilities should have a well thought out alarm sys-
tem to advise the homeowner when problems exist in his on-lot
pressure sewer components. Investigations should be made on use
of plastic and other non-corrosive components, particularly in
STEP systems, to improve longevity and cost-effectiveness of
valves and other piping components. Plastics also should be in-
vestigated for use in pumping units to lighten the weight for
ease of removal for service.
New excavation techniques and smaller diameter piping should
be investigated to reduce excavation and construction costs in
pressure sewer systems. Automatic release valves of sufficient
number should be used because manual air release valves result
in extraordinarily high 0 & M costs. Future systems should use
pipe locaters to help maintenance personnel during fault finding
procedures,or to aid other utility constructors when they are in-
stalling electrical, telephone, or water lines. Also, systems
should use color-coded pipe to prevent cross-connections.
Although pressure collected sewage is easily treatable, re-
search should be directed toward treatment optimization. For
systems that discharge less than 10% pressure collected sewage
into a gravity-fed plant, no difference from conventional treat-
ment should be noticed.
Pressure sewer systems should be used only if the design en-
gineer determines there is clear and significant cost-effective-
ness over a conventional gravity sewer system. A slight capital
cost advantage should not be justification for the use of a
pressure sewer in areas where conventional systems can be in-
stalled for a slightly higher initial capital cost, since a con-
ventional system may result in significantly less operation and
maintenance throughout its lifetime.
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All systems using pressure collected sewage should investi-
gate alternative management techniques to determine which is
most suitable for their particular situation. Existing regula-
tions, codes, and standards should be revised to reflect the use
of pressure sewer systems where economical and cost-effective.
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SECTION 4
CASE HISTORIES
BACKGROUND
According to the 1970 U. S. Census, 71.18% of U. S. housing
units are sewered, 24.52% are served by septic tank systems, and
4.30% use other methods (1). Numerous smaller communities and
rural areas fall in the unsewered category (2). EPA notes that
providing centralized collection and treatment systems is often
very expensive for smaller communities, sometimes exceeding
$10,000 per home (3). Walton, NY's centralized collection and
treatment system, for example, cost 43% of the town's assessed
valuation (4) . Collection systems may be a substantial portion
of these high costs. The EPA suggests generally over 80% (3),
while Bowne reports 91% in the Glide-Idelyde, OR area (5). Con-
struction of a gravity sewer system may also be a distruptive
element in community life (Figure 1).
As a result of high construction costs associated with con-
ventional collection systems, lower cost alternatives have been
investigated. Gordon Maskew Fair proposed a "sewer within a
sewer" concept for separating combined sewerage facilities in
larger municipalities (6) . These systems were found to be im-
practical, but the pressure sewer concept was determined to have
considerable merit in a study by the American Society of Civil
Engineers (6) . One of the earliest systems, now abandoned, was
designed by Clift in Kentucky in the 1960's (7). The EPA has
sponsored full scale experimental research of pressure sewer
systems in Albany,. NY; Phoenixville, PA (Figure 2); Grandview
Lake, IN; and Bend, OR (8, 9, 10, 11). The studv reported on
here has identified overr 60 existing pressure sewer systems with
approximately an equal number under construction or in some phase
of design, as shown in the Annendix.
GENERAL
Case histories of several
are included in this section,
project team members traveled
investigate in detail several
existing pressure sewer systems
As a condition of this contract,
to nine pressure sewer systems to
aspects, including design para-
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Figure 1. Gravity sewer construction may not be
cost-effective in certain areas.
• Location of pump storage grinders
Sing!# home
Existing
gravity
2 apartment!
7 apartments
Single home
Route 113
3 apartments
Existing manhole
Road surface
ui 140
Pressure
30-inch burial
500 1,000 1,500 2.000 2,500 3,000
Figure 2. Phoenixville, PA pressure sewer system.
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meters, construction, treatment, operation and maintenance,
costs, and management considerations. Other pressure sewer
systems which were near the selected systems were visited on
side trips to gain additional background information.
Along with interviewing the system operator, discussions
were held with contractors, state regulatory officials, pump
company repair personnel, and representatives of the major manu-
facturers of pressure sewer system pumps. Much of the substan-
tiating information was obtained from Environment/One, Inc.
(Paul Farrell); Peabody Barnes Pump Company (Robert Langford),
and Hydromatic Pump Company (Robert Holdeman).
A generalized history of each system is presented in this
section. More specific data relating to system components can
be found in the technical sections.
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CASE HISTORIES
Apple Valley, OH
This development is located a few miles east of Mount Ver-
non, OH, and is sometimes referred to as the "Little Jelloway"
system. The system is operated by the Knox County Sewer and
Water Department (Malcolm Bone, Supt.). In general, operator
and resident comments regarding the system have been favorable.
The Apple Valley facility is primarily a gravity sewer sys-
tem with various areas on the lakefront property served by small
localized pressure sewer systems emptying into the gravity sewer
(Figure 3). There are 425 homes, a school, laundromat, camp-
ground area, two beach houses and restaurants on the Apple Val-
ley system, a development owned by American Central Corporation.
Presently, 50 homes are served in pressurized lakefront loops,
with 225 homes ultimately to be served by pressure sewers out of
the 670 total planned connections. Therefore, this system has
characteristics of both pressure and gravity collection systems.
Operators have been pleased with the reliability and performance
of the Hydromatic 1.1 kw (1.5 hp) simplex grinder pumps, located
in canisters outdoors. Typically, two homes are connected to
one grinder pump installation. The first home on-line supplies
the electric power and receives a small monthly credit for the
electric power it provides.
The system was financed by borrowing money on the open mar-
ket. Per lot cost is obtained by dividing the capital costs by
the total number of lots. When a homeowner buys property he
must pay his share within thirty days. If the homeowners elects
not pay this amount within the thirty day per iod, the Knox
County Sewer and Water District then charges the individual for
twenty years a set amount on his tax bill. Each lot owner is
charged $14.00 per year, billed semi-annually, whether his lot
is connected to the sewer system or not. There is a usage
charge of $12.00 per quarter when connected.
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Figure 3. Typical lakefront pressure sewer loop
at Apple Valley, OH.
Grandview Lake, IN
The Grandview Lake pressure sewer system, east o£ Columbus,
IN, was designed during 1968 to 1970 by Seico, Inc. of Columbus,
IN (Figure 4) . The system was intensively monitored and re-
ported as a demonstration project, funded through a joint EPA-
FHA grant-loan agreement. The system, as reported to EPA, has
changed considerably, (3) and now 150 connections are served by
125 Envi ronment/One and 25 Hydr-O-Matic SP150 gr inder pumps
(Figure 5). About 20 of these units pump septic tank effluent.
These units show signs of corrosion. Other units that pump di-
rectly from the house use the septic tank as an overflow device.
Check valves are cast iron for Hydr-O-Matic and PVC for Envin n-
ment/One pumps. Cast iron valves, for ease of removal, are
recommended to be located horizontally, and PVC vertically to
prevent solids deposition from interfering with flap seating.
Brass gate valves are used for shutoff. Environment/One uses a
2.5 cm (1 in) service line, while Hydr-O-Matic uses 3.2 cm
(1.25 in).
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'11
¦Irrigated uiol
——— PVC pipe ln/e a$ shown)
HI lagocmeeHj
3M $ct€ lOlit
i
Figure 4. Grandview Lake, IN pressure sewer
system prior to expansion.
Figure 5. Typical Hydr-O-Matic slide rail pressure sewer
pump installation at Grandview Lake, IN.
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The treatment system receives only pressure sewage from
Grandview Lake. It consists of two lagoons, 39.6 m x 36.6 m
(130 ft x 120 ft) each flowing into a common clar if ier and
chlorinator unit, then to a metering chamber with a V-notch
weir. Some dilution water is added from the lake to the efflu-
ent , but dry weather sewage flow is estimated to be 38 - 57
m3/day (10„000-15,000 GPD) . Design capacity for the Hinde
aeration lagoons is 228 m3/day (60,000 GPD).
Effluent limits are 30 mg/1 BOD 5 and 30 mg/1 SS. Efflu-
ent sampling showed the lagoon was able to meet these limits,
BOD5 and SS removals are within effluent limits, and ammonia
nitrogen effluent concentrations, during the period that data
are available, show excellent results. Effluent temperatures
ranged from a high of 24.9° C down to a low of 11.3° C.
The system has no central operation and maintenance force;
all service calls are performed by local pump representatives.
Preventive maintenance is not performed on the pumping units or
the ni ping system. Maintenance on the pump units is nerformed by
an Environment/One representative in Indianapolis (nreviously Ralnh
Conn in CI arksvilie, IN), and Hvdr-O-Matic pumps are maintained by
nick Sherwood in Greenwood, IN.
The Lake Association charges $65.00 per year to each lot
owner, plus $7.00 per month as a user fee for occupied lots.
New connections must install a pump unit themselves, at a cost
of $1,800 to $2,000 complete, plus pay a $125 tap-on fee.
-14-
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Horseshoe Bay, TX
The Horseshoe Bay pressure sewer system near Marble Falls,
TX, was designed by Coulson and Associates, Houston, TX. The
system is in an expensive development on Lake Lyndon Baines
Johnson, an impoundment of the Lower Colorado River. The system
was installed in late 1971.
The Lower Colorado River Water Authority has specific re-
quirements for septic tank installations bordering the Lower
Colorado River. Between 0 to 61 m (0 to 200 ft) from the river,
septic tank installation requirements are extremely severe, es-
sentially prohibiting their use. The requirements are somewhat
less restr ictive, but still severe for the next 610 m (2,000
ft). Beyond 671 m (2,200 ft) , conventional requirements apply.
The Phase 1 pressure system includes 607 ha (1,500 ac) with
a potential of 4,500 dwelling units. A 1,093 ha (2,700 ac)
ranch nearby has been acquired for future development. Design
criteria assume a population for Phase 1 of 6,000, and a flow
rate of 0.38 m3 (100 gal) per capita per day. About 410 con-
nections on the pressure sewer system have been installed. Ap-
proximately 19,800 lineal meters (65,000 If) of 10.2, 15.2,
20.3, 25.4, and 30.5 cm (4, 6, 8, 10 and 12 in) pressure sewer
main have been installed with about 3,050 m (10,000 ft) present-
ly under construction in a mobile home area. Pressure sewer
pipe is rated at 1,110 kPa (160 psi) with a working system pres-
sure of 243 kPa (35 psi) . The pipe is buried at a depth of 76
cm (30 in) with cleanouts at the ends of pipes. Special flush-
ing devices are located throughout the system, and are operated
by an electronic timer. There are about 125 Environment/One
grinder sewer pumps and about 60 Hydr-O-Matic Hydrogrind pumps
installed.
Horseshoe Bay clubhouse and 60 original condominium units
were served by four exper imental General Electr ic grinder pump
units until 1974. They caused continual maintenance problems
for the system operator. In 1974, the four General Electric
units were removed and three 1.1 KW (1.5 hp) Hydr-O-Matic Hydro-
grind pumps were installed. In 3 1/2 years of operation, there
have been no problem". Recently, these pumps were refurbished
on a scheduled basis. Dual cutters in the clubhouse Hydrogrind
units are still sharp enough to be workable; however, impellers
have shown severe pitting and corrosion due to impact of alumi-
num foil from baking potatoes as well as other wastes from the
kitchen area.
Although many areas of the pressure sewer system at Horse-
shoe Bay are uphill from the treatment facility, the pressure
system was used throughout the entire development, except for
the septic tank area, which is well back from the lake. Two
reasons the pressure sewer system was used in an area that po-
-15-
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tentially coiild be served by gravity were: 1) rock was close
to the surface which required dynamiting trenches for installa-
tions of both sewer and water lines within the same trench (at a
maximum possible separation) and 2) the landscape planner wanted
to save as many existing trees in the area as possible. In a
conventional gravity sewer system, installed in straight lines
between manholes, many trees would have to be removed. With the
pressure sewer system, however, tree removal was reduced to a
minimum.
Three 30.5 cm (12 in) and one 25.4 cm (10 in) pressure sewer
lines deliver sewage to the treatment plant. The treatment
plant is a 379 m3./day (100,000 GPD) Neptune Microfloc package
facility. Discharge standards are 5 mg/l bod^, 5 mg/1 ss.
and 1 mg/1 phosphorous. Treated effluent is discharged to a
holding pond and then pumped to a golf course holding pond. At
the golf course holding pond the effluent is diluted by lake
water on the order of ten to one. The water is used to irrigate
the golf course.
There is a 1,893 m3/day (500,000 GPD) Neptune Microfloc
unit completed and ready for use, This plant will begin opera-
tion as plant flows exceed the design capacity of the original
379 m3/day (100,000 GPD) plant.
-16-
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Port Charlotte, FL
The General Development Company, a subsidiary of GDVr Inc.,
has developed over 95,000 ha (235,000 ac) on the Atlantic and
Gulf coasts, and the south central lake country of Florida.
Nearly 60,000 people live in seven General Development Company
properties. Table 1 shows areas and populations for these
properties.
TABLE 1. GENERAL DEVELOPMENT PROPERTIES, FL
Area
Location (hectares) (acres) Population
Port Charlotte 40,000 100,000 35,580
and North Port
Port St. Lucie 19,600 48,500 10,295
Port Malabar 17,500 43,200 7,685
Port Labelle 12,700 31,500 115
Port St. John 2,200 5,500 1,725
Sebastian 2,000 5 ,000 685
Highlands
Vero Shores and 650 1,600 835
Vero Beach
Highlands
Utility construction and service to these communities are
provided by a subsidiary division, General Development Utili-
ties, Inc. General Development Utilities is a regulated utility
company with over 1,480 km (925 mi) of utility lines, 15 oper-
ating facilities and 5 gas plants, representing an investment of
nearly $40,000,000. Active in research and development, General
Development Utilities has been instrumental in the evolution of
a pressure sewer system designed to relieve wastewater disposal
problems and rising costs of conventional systems. The new sys-
tem, called "Suburbanaer", has received conditional approval
from the State of Florida and a demonstration project has been
constructed at Port Charlotte. Testing continues at Port Char-
lotte and Port St. Lucie.
-17-
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In conjunction with Suburbanaer, the utility subsidiary has
an extended aeration facility for treating septic tank effluent
and has been conducting tests on a demonstration "Bullrush" area
of reed-like water plants for possible use as a virtually
energy-free treatment process {Figure 6).
Figure 6."Moses" treatment plant using scirtms
(bullrush) phragmite (reeds), Port Charlotte, FI.
General Development Utilities' President, Harold Schmidt,
was interviewed in connection with this project. He described
the system in general, a state monitoring program for the next
230 interceptor tank/pumping units to be installed, and system
performance and operation. However, he declined to be specific
on design details, operation requirements, maintenance history,
economics, or treatability.
There are two areas in Port Charlotte with pressure sewers,
Section 54 {the older original area with its own treatment
plant, also called Gulf Cove Area shown in Figure 7) and Sec-
tion 18. Other areas are planned, and are being designed using
a computer program.
-18-
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treatment plant
LIFT STATIOJ
Figure 7. Gulf Cove pressure sewer area,
Port Charlotte, FL.
Homes in Port Charlotte originally had no warning system.
All newly installed units have alarm systems and all old units
have or will have battery-operated remote control warning sys-
tems retrofitted.
Or iginal pumping equipment at Port Charlotte was Hydr-O-
matic SP-33 sump pumps, but rapid failures were experienced.
Presently, oil filled OSP-33 Hydr-O-Matic pumps are used. A
new type of mercury float with a delayed off switch will be
tested for potential replacement of the troublesome pressure
switch, and a new type of high level alarm transmitter (in
prototype) also will be evaluated.
The Gulf Cove area has six streets, all with 7.6 cm (3 in)
push-tite Johns-Manville pipe, flowing to a pump station where
chlorine or ozone could be injected, but is not, according to
the operator. Odors were not noticeable anywhere at the site,
including the conventional treatment facilities and the Bull-
rush "Moses" plant.
-19-
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'P°Et St, Lucie, fl
Port St. Lucie also is part of the General Development Com-
pany properties, and likewise is serviced by General Development
Utilities, Inc. Much of the information on this system was ob-
tained from Paul Kloser, General Development Utilities engineer.
He works on both the Port St. Lucie and Port Charlotte pressure
sewer systems, spending three days per week at Port St. Lucie.
Mr. Kloser is assisted by a maintenance man at each location and
part of their time is spent on installation supervision.
The Port St. Lucie Suburbanaer system became operational
August 1, 1973, and presently serves 191 homes, each having an
interceptor tank/pumping unit. Table 2 lists the year and
number of units installed each year.
TABLE 2. PORT ST. LUCIE SUBURBANAER SYSTEM
Year
Number Units Installed
1973
1974
1975
1976
1977
1978*
Total
12
60
38
29
46
_6
191
* Through February, 1978.
-20-
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Klaus System, Portland, OR
Portland, OR is located at the confluence of the Willamette
and Columbia Rivers. Numerous residents reside in houseboats
and originally disposed of their wastes directly into these
rivers. In 1967 , the Oregon Department of Environmental Quality
required all houseboats to eliminate raw sewage discharges.
Several homeowner organizations had pressure collection systems
designed and installed in the approximately 25 moorages in the
Portland area (Table 3) . Various modes of treatment exist:
pumping to gravity sewers, septic tanks and drainfields; small
package sewage treatment plants, floating package plants, and
floating or land-based septic tanks (Figure 8) . Table 3 also
shows many of the moorage sizes and types of treatment used.
Each houseboat uses a Peabody Barnes solids handling pump,
capable of passing 5.1 cm (2 in) solids. Pumps are housed in
galvanized steel basins, with newer units in fiberglass basins
(Figure 9) . A 3.8 cm (1.5 in) flexible hose carries the pumped
waste to a mainline pressure sewer. The 0.2 n»3 (50 gal)
basins are suspended from the houseboats. Pumps operate over a
25.4 cm (10 in) differential pressure, pumping 0.04 to 0.06
m3 (10 to 15 gal) per operation. Power is supplied either
with a conventional plug in an outdoor receptacle or through an
NEMA 3 cabinet. Pump discharges have swing check valves con-
structed of both bronze and brass mounted horizontally and ver-
tically .
Figure 8. Floating septic tanks.
-21-
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TABLE 3. HOUSEBOAT PRESSURE SEWER SYSTEMS NEAR
PORTLAND, OR
Number of
Houseboats
250 - 300
80
100
32
40
10
60
50
20
125
50
20
35
25
28
50
60
25
60
30
River
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Columbia
Willamette
Willamette
Willamette
Willamette
Willamette
Willamette
Willamette
Willamette
Willamette
Willamette
Location
Hayden Island
East of airport -
3 close together
3 moorages at
185th - 190th
4 moorages just
east of airport
13 moorages just
west of I 5
South side of
Tomahawk Island
North side of
Tomahawk Island
1 205
2 moorages east
side just south
of downtown
East side of
downtown
West side of
downtown
U. S. 30 and
Sauvies Island
Sauvies island
West of Sauvies
Island
West of Sauvies
Island
West of Sauvies
Island
West of Sauvies
Island
Treatment
To secondary
STP
Pump to sewer
Floating septic
tank
To sewer
To sewer
To sewer
Septic tank
on land
To sewer
1 to sewage
lagoon
4 to septic
tank
Floating S & L
STP
To floating STP
To lagoon
Septic tank on
land
Small S & L STP
-22-
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Figure 9. Houseboat pumping unit.
Pump operation is controlled by pressure switches, but due
to problems, mercury floats are now being installed. Pump mal-
function is noticed by the homeowner when a toilet backs up or
acts sluggishly.
Pipe material is ABS solvent welded with some PVC solvent
welded Schedule 40. Pipe rated at 694 kPa (100 psi) PVC was
considered too thin. Pipe jointing is by solvent welding with
rubber expansion and flex joints between some sections to ac-
count for movement (Figure 10) . The suspended pipe under walk-
ways is ABS or PVC, with cast iron or ductile iron where under-
ground construction was necessary. Depth of burial was 0.9 to
1.2m (3 to 4 feet).
-23--
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Figure 10. Flexible pipeline connector in
Klaus system, Portland, OR.
-24-
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Coolin and Kalispell, ID
Information gathered on these two systems, both located on
Priest Lake, is based upon interviews and discussions with
Messrs. Chris Warren, head of maintenance; Ken Durtschi, system
designer, Couer D'Alene, ID; and Bert Kilbeck, head of the re-
pair department of Dickerson Pump and Irrigation Company,
Spokane, WA.
When the systems were originally installed, Coolin had 345
customer equivalents, and 11 more have been added, making a
total of 356, Kalispell had 218 original customer equivalents,
and has since added 14 new hookups for a total of 232 {Figure
11) .
Treatment data is non-existent, due to the complete lack of
testing. Because no effluent is discharged from this system,
testing is not required. The three cell lagoon system has a net
evaporation loss, but spray irrigation facilities are provided
to spray effluent on nearby forestland if an accumulation of
sewage above maximum lagoon liquid level were to take place.
-25-
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O -* *»5
8 4W BJM
Fsw BM
DISTRICT BOUNDARY
DOMESTIC SEWER SYSTEM
^ KALISPELL BAY WATER & SEWER DISTRICT
Figure 11. Domestic sewer system, Kalispell
Bay Water & Sewer District.
-------
Weatherby Lake, MO
The city of Weatherby Lake, 19 km (12 mi) northwest of
Kansas City, MO, had on-site disposal systems which were pollut-
ing Weatherby Lake so severely that Larkin and Associates were
hired in 1971 to devise a community collection system, A pres-
sure sewer system was chosen as the most cost-effective solu-
tion, and presently 362 Environment/One pumps serve the com-
munity {Figures 12 and 13).
The design engineer, Glen Gray of Larkin and Associates, re-
ported (11): "The final project design consisted of 309 grinder
pump units; 10,700 lm (35,000 If) of main pressure sewer located
in the street rights-of-way and varying in size from 5.7 cin to
15.2 cm (2 1/4 to 6 in); 11,300 lm (37,000 If) of 3.2 cm 1 1/4
in) pressure service lines from pumps to street mains; 42 air
release valves; 24 flushing and cleanout connections and 1,600
lm (5,300 If) of 20.3 cm (8 in) gravity sewer for connection to
existing Kansas City interceptor sewers. Electrical load cen-
ters in raintight enclosures are located on an outside wall of
each house for easy access by maintenance personnel. Located
with the load centers is a receiver tank high water level alarm
horn to alert not only the homeowner but neighbors in case of
pump failure. Recorders are to be installed at four selected
points to monitor the system pressure over a long period of
time. Hopefully, this will furnish data for refinement of
future designs and provide an indication of probable maintenance
requirements."
The low pressure sewer system is constructed of SDR-26
(1,112 kPa or 160 psi rated) PVC pressure pipe. Solvent welded
joints were specified because of favorable experience in achiev-
ing pressure-tight continuous lengths of pipe with built-in
thrust takeup. However, the contractor requested, and was per-
mitted to use, compression type gasketed joints, and added
thrust blocks where necessary to resist the possibility of axial
movement. Since the normal system pressure will be 243 kPa (35
psi) or less, a static pressure test 416 kPa (60 psi) for two
house was specified. In those portions of the system which were
laid through rock, a rock saw was used, and sand bedd ing and
backfill was placed around the pipe. Otherwise clean earth
backfill was used and no unusual precautions were required.
Treatment data is unavailable since the Weatherby Lake sys-
tem pumps to the Kansas City municipal system. The treatment
plant treating this waste receives approximately 99% gravity
collected sewage and 1% pressure sewage.
-2 7-
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Figure 12. Weatherby Lake, MO pressure sewer
system pump chamber.
Access to Environment/One pump chamber
-------
Clifton Park, NY
The Country Knolls South development, north of Albany, NY,
in the town of Clifton Park, is owned and operated by Robert Van
Patten. Country Knolls now has 355 homes with a projected ul-
timate development of 510 homes. Environment/One grinder pumps
are used (Figure 14). On the grounds that this is a privately
owned system, Mr. Van Patten declined to give installation and
O & M for the majority of the system. He also preferred not to
disclose treatment costs and performance data.
The system was started in 1972 and is located only a few
miles from the Environment/One manufacturing plant in Schenec-
tady. As a result, the system has been studied extensively by
the manufacturer.
The treatment facility originally was an Environment/One
plant. However, this plant was taken out of service recently
and the system is now served by a county interceptor sewer.
Figure 14. Inside home installation, Country Knolls
Subdivision, Clifton Park, NY.
-29-
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Kappas Marina, Sausalito, CA
Kappas Marina is 1'.'~ted at Gates 6 and 6 1/2 in Sausalito,
CA. There are 117 user* on the two systems. Residents on Gate
6 use a combination of a total of 82 grinder pumps manufactured
by Environment/One, Hydr-O-Matic, Peabody Barnes, and Toran,
while Gate 6 1/2 residents use Peabody Barnes solids handling
pumps, capable of passing a 5.1 cm (2 in) sphere.
All houseboat - mounted pumps discharge to 3.8 cm (1.5 in)
B. F. Goodrich radial flex piping which connects into an Andrews
bronze quick disconnect through a 90° elbow. Flow then
passes through a bronze T pattern flap check valve, cast iron
plug valve, and into the main through a DeSanno #87 bronze connec-
tion combined with a 7.6 cm x 7,6 cm x 5.1 cm (3 in x 3 in x 2 in)
•PVC tee with a threaded end (Figure 15). The two systems have
430 m (1,410 ft) of 7.6 cm (3 in) PVC collection main flowing to
a lift station, and 520 m (1,700 ft) of 15.2 cm (6 in) force
main. Gate 6 pumps are all grinder pumps, including 52 Environ-
ment/One, 23 Peabody Barnes, 5 Hydr-0~Matic and 2 Toran..
-30-
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ELECTRICAL SUPPLY
AND CONTROL
2"0 FLEXIBLE HOSE
MAIN W WYE
CONNECTOR
^MOORAGE WALKWAY
H.W.L.
SUMP PUMP
L.W. L.
18V x 30"SUMP
Figure 15. Details of Sausalito, CA's
pressure sewer pump installation.
-3 1-
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Lake Mohawk, OH
The Lake Mohawk development is located in Malvern, OH, ap-
proximately 32 km (20 mi) southeast of Canton. The development,
started in 1963, surrounds a 206 ha (508 ac) lake with approxi-
mately 1,660 lots. Currently, the pressure sewer system is
served by 225 Environment/One grinder pumps. Environment/One
has a multi-year O & M contract for both the pressure sewer sys-
tem and the treatment facilites for this private, second home
development lake area. John Robertson, the system operator, is
under contract with Environment/One. He also owns the central
water system.
Originally, on-lot waste disposal was planned and installed
on some lots using individual septic tank systems, but failures
due to unsuitable soil caused the concept to be abandoned. The
homeowners association then looked at various alternatives. The
gravity sewer estimate proved too costly, so, in 1974, engineers
investigated a pressure sewer system alternative which was
accepted. The contract was let with an individual lot assess-
ment of $640 which included all collection mains and the treat-
ment plant If an existing septic tank system fails, then an
outside pump installation is necessary. The original owner of
the 0 & M contract, the Ohio Environmental Service Corporation
(now defunct), sold their contract to the Environment/One Corp,
Robertson's responsibilities include installation of the
pumps in new houses or replacement of an existing failed septic
tank system with outside Environment/One units. He handled 80
service calls during 1977 on approximately 210 units. The
engineer for the system, Friedal and Harris, North Canton, OH,
designed the pressure sewer system into 3 zones, having six lift
stations, three on each side of the lake.
Two treatment plants operate side by side. One is an Envi-
ronment/One batch type physical-chemical-biological treatment
plant and the other is an extended aeration facility. The ex-
tended aeration plant is located outdoors and the Environment/
One plant is covered. Total plant design capacity is 758 m3/
day (200,000 GPD) . Each of the two plants account for half of
the design flow capacity. Effluent from both of these plants
flow into a Hydroclear tertiary filter unit.
-32-
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Seabrook, TX
The Seabrook, TXr pressure sewer system uses Hydr-O-Matie
Hydrogrind grinder pumps to deliver pressure collected sewage
from two streets and a boat docking area to gravity mains which
flow to a STP. Presently, there are three duplex units and 22
simplex units installed (Figure 16).
Seabrook is located on Galveston Bay, about 32 km (20 mi)
southeast of Houston, TX. Because of rapid population growth,
municipal wells withdrew water from the shore area of Seabrook
at a rate faster than fresh water could be replenished. Hence,
the ground structure subsided, lowering the local ground eleva-
tion. Large areas of Seabrook, including platted streets and
lots, are now under water. As a section or area of the gravity
sewer system became unusable due to its invert sinking below the
subsequent downhill invert, the section is replaced by pressure
sewer mains and pumps.
Ultimately, when all gravity sewers become unusable, the
pressure sewer system will deliver the total sewage flow under
pressure to the treatment plant. Ground is subsiding so fast
that a small lift station at the corner of 11th Street and Todd-
ville Road that was three feet above ground ten years ago is now
three feet below grade.
Figure 16. Hydr-O-Matic pump equipment mounted
below residence.
-------
Point Venture, TX
The Point Venture pressure sewer system is located approxi-
mately 32 km (20 mi) from Horseshoe Bay, across the Lower Colo-
rado River, 64 km (40 mi) northeast of Austin, TX. It is a rec-
reational development with 125 townhouses and 17 single family
homes. An additional 37 single family homes are expected to be
built. The system operator is Wilson McDougal. The system uses
37 Environment/One pumps, both simplex and duplex, to pressurize
sewage for transport in small diameter PVC mains to a wastewater
treatment facility. Townhouse units are served by duplex Envi-
ronment/One pump units; however, there was only one workable
pump in most duplex units. The other unit was out for repairs.
The pressure collected sewage flows to a contact stabiliza-
tion package treatment facility and then to a holding pond,
which takes the treated sewage plus 5 times as much lake water
to achieve a diluted mixture. It then flows to a polishing
pond. From the polishing pond the water is pumped intermittent-
ly to the golf course for spray irrigation.
-34-
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SECTION 5
DESIGN OP ON-LOT FACILITIES
SYSTEM COMPONENTS
General
On-lot. pumping components are the heart of the pressure
sewer system. These components must be thoroughly investigated
and designed to function as a coherent system for all components
to function effectively. STEP components normally include the
interceptor tank for removing as much grease and solids as pos-
sible; the pumping chamber, which houses the effluent pump; the
effluent pump itself; discharge piping including check and dis-
charge shutoff valves; control systems for turning the pumps on
and of f; high level alarms; over flow device; and service lines
(Figure 17). GP components include a holding basin with suffi-
cient volume to accumulate enough liquid for a 1 to 2 minute GP
cycle operation; grinder pump, with a combination grinding and
macerating unit attached to the bottom of the pump; discharge
piping including check and discharge shutoff valves; control
circuits and components for operating the units; an alarm system
to alert the homeowner that a high level is exceeded in the
storage tank; and on-lot piping between the pump tank unit and
the main in the street (Figure 18). Both the STEP and GP units
must have power supplied to the units either through a control
cabinet mounted nearby or through a conduit directly into the
chamber unit which also contains the controls. Service connec-
tions on both types of systems are the same.
Piping components and treatment systems applicable to pres-
sure collected sewage are covered in other sections. Engineer-
ing design of the types of units selected will be covered brief-
ly because they are well detailed in other publications. The
following sections deal primarily with descriptions of existing
types of units. It should be noted that most manufacturers
offer the above components as package units. However, some cost
savings may be realized by the engineer putting together his
own package components rather than relying on the manufacturer1s
selections.
-35-
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Overflow ttvii Mimof
Ofnaff !**~< «mtor
Figure 17. Typical grinder pump on-lot facilities.
Junction bo* «nd
high l«*«H
2-Uk*i pit* tic pipe for •l«ctrteity-p»
34-inch concrvu pip* with flow and Hd
1/3hp aimp pump
Figure 18. Typical STEP system on-lot facilities.
-36-
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STEP ON-LOT FACILITY
Interceptor Tank
The function of the interceptor tank is to remove as much
grease and solids as possible and may provide storage volume in
case of a power outage. Interceptor tanks are either con-
structed out of concrete, steel (usually coated "i th protective
bitumastic covering), fiberglass or polyethylene. In some sys-
tems, existing septic tanks which are found to function well and
in good structural condition are used for this purpose. In most
situations, the existing septic tank is unsuitable and a new
tank is required. If a concrete tank is used, it usually is
rectangular and has a separate pumping chamber. Its advantage
is that it may be obtained locally and usually is the lowest in
cost. Steel septic tanks are used in the Priest Lake, ID, sys-
tems at Coolin and Kalispell Bay. The tank size varies from 300
to 700 gallons, they are cylindr ically shaped and installed ver-
tically .
The major ity of newer septic tanks used in these systems are
fiberglass. Fiberglass is the material of choice in the Florida
General Development Utilities systems, and at Glide-Idleyld, OR
(Figure 19) . The f iberglass units usually are cylindr ically
shaped, installed hor izontally and contain between 3.4 m3 and
4.17 m3 (900 and 1,100 gal) . The pump chamber is integral
with these units. The major advantages are water-tightness and
corrosion resistant. They are constructed with a continuous
layer of resin over the f iberglass media. Construction is
simple and the tanks are significantly lighter. In Florida,
with a high groundwater table, the fiberglass tanks are placed
over a trenched out area, filled with water, and allowed to sink
into the hole.
The tanks are usually maintained with a high water level.
GP tanks, however, which usually have a variable working volume
might require a concrete anti-flotation collar. Working volumes
vary from 1.1 m3 (300 gal) at Priest Lake, ID to almost 3.8
m3 (1,000 gal) at Bend, OR.
Pump Chamber
The septic tank effluent pump chamber can either be an inte-
gral component of the septic tank or a separate chamber mounted
adjacent to the septic tank. The pump chamber usually contains
the effluent pump, on - off controls, a high level control,
discharge piping and valves and a means of quick disconnecting
the pump from the effluent piping. If the pump chamber is
separate from the septic tank, it usually is mild steel with a
bitumastic coating. Covers also are steel with a bitumastic
coating and are bolted down, but infrequently sealed. The
-37-
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Figure 19. Septic tanks used in Glide-Idleyld, OR system.
chamber usually has a 7.6 and 10.2 cm (3 or 4 in) inlet from the
septic tank and a 2.5 cm, 3.2 cm, or 3.8 cm (1 in, 1-1/4 in or
1-1/2 in) pump discharge pipe diameter. A maximum liquid depth
of 0.6 m (2 ft) is provided with pump operation usually commenc-
ing when the sewage level is approximately 0.5 m (1-1/2 ft).
The method of mounting the pump within the effluent chamber
varies with design. There is a suspended system where the dis-
charge piping is installed through the basin cover and the pip-
ing and the suspension rod locate the pump. Since this piping
is through the cover a manway must be added to extend the basin
cover to ground level. This depth depends on the local frost
line and the system is infrequently used. More typical is an
effluent pump system where the pump is self-supported in the
basin and the discharge piping is connected through the wall of
the pump basin. Disconnection between the pump and discharge
piping is made possible by either a slide rail type system with
a quick disconnect coupling (Figure 20), or a union (Figure 21),
or with a pump connected to the discharge pump piping with flex-
ible plastic hose. The union type system is used in General De-
velopment Utilities, Florida systems and Priest Lake, ID. The
flexible hose connection is used in Glide-Idleyld, OR (Figure
22) .
The experimental pressure sewer system at Bend, OR had a
fiberglass pump chamber. This system used guiderails for ease
-38-
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Figure 20. Typical effluent pump guiderail type system
Figure 21. Typical effluent pump union type system.
-39-
-------
Figure 22. Typical pump chamber in Glide-Idleyld, OR system.
of pump removal. The range of liquid accumulated in the pump
chamber to be discharged on each working operation varied from
0.11 - .27 m^ (30 - 70 gal) in the various systems studied.
Effluent Pumping Equipment
Two types of pressurization devices can transport septic
tank effluent to a treatment facility: submerged, non-clog cen-
trifugal sewage pumps manufactured typically by Hydr-O-Matic or
Peabody Barnes, and the pneumatic ejector (Figure 23) currently
being field tested in various systems by Franklin Research and
Clow Corporation. Submersible centrifugal non-clog pumps cur-
rently are used in Florida, Priest Lake, ID, and the Glide-
Idleyld, OR. The Florida and Priest Lake systems use Hydr-O-
Matic sump pumps with varying Hp requirements of 0.25, 0.3,
0.37, 0.75, and 1.5 kw (0.33, 0.4, 0.5, 1 and 2 Hp) with shut-
off heads varying from 7.3 to 31 m (24 to 120 ft) at capacities
of up to 0.8 mVminute (220 GPM) . Sizing of pumps depends on
the combination of friction and elevation losses to be overcome.
The Port Charlotte and Port St. Lucie Hydr-O-Matic pumps are
oil filled Model OSP-33A, usually operating at a discharge capa-
city between 0.08 and 0.19 mVminute (20 and 50 GPM) . The
-40-
-------
tank
F |t*clo<
Figure 23. Pneumatic ejector for use in
pressure sewer system.
Bend, OR system uses the Peabody Barnes 0.37 kw (1/2 Hp) ef-
fluent pump with a similar rating. These pumps presently are
manufactured with bronze impellers to reduce corrosion that was
evident when original pumps had cast iron impellers. Solids
handling capabilities of these pumps are normally 1.9 cm to 5.1
cm (3/4 to 2 in), but because they pump septic tank effluent,
1.3 to 1.9 cm (1/2 to 3/4 in) solids handling capability should
be more than sufficient.
The Flor ida system is evaluating the suitability of an above
ground Jabsco effluent pump with a foot valve in the septic tank
to maintain suction. This may be an ideal solution for ser-
vicing; however, noise reduction must be further investigated
because of homeowner complaints of pump operating noise.
Except for some higher head models, most effluent pumps have
shutof f heads in the range of under 19.8 m (65 ft) . Re-design
of these units to produce a higher head at lower flows, along
with more plastic components to reduce corrosion and weight, and
reduction of solids handling capabilities, may produce a pump
that is more suitable for an effluent type system.
-41-
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GRINDER PUMP ON-LOT FACILITY
Grinder Pump Chamber
All GP manufacturers offer a complete package consisting not
only of the pump, but also the pump basin, discharge piping,
valving, electrical controls and warning systems (Table 4).
Standard basins have the pumps installed by either one of two
methods. Either the pump is suspended from or attached to the
basin cover and servicing requires a dead lift of the pump cov-
er, or the pump is located on rails and lifted from the basin
via a chain. In the second system the discharge flange discon-
nects from the discharge piping through a slide away coupling.
The major disadvantage of the suspended type system is that the
top of the basin cover in northern climates must be below frost
level. This means an additional manway must be installed up to
1.5 m (5 ft) deep. At this depth, it becomes more difficult to
dead lift the pumping unit.
Various manufacturers offer basins as shown in Table 4.
Peabody Barnes offers simplex or duplex basins in either the
rail system or the suspended model. The simplex is offered in a
0.6 m (2 ft) FRP and the duplex in a suspended 0.9 m by 0.9 m (3
ft by 3 ft) FRP. The simplex rail system is 0.6 m by 1.5 m (2
ft by 5 ft) steel construction and the duplex rail system basin
is 0.9 m by 1.5 m (3 ft by 5 ft). Larger sizes are available
upon request. Covers are standard steel construction through
1.5 m (5 ft) diameter.
Hydr-O-Matic offers both the suspended and rail type system
with the simplex suspended basin 0.6 m by 0.9 m (2 ft by 3 ft)
FRP and the duplex suspended pump system in a 0.9 m by 0.9 m (3
ft by 3 ft) FRP manhole. The simplex rail system is offered in
a 0.6 m by 1.5 m (2 ft by 5 ft) steel basin and the duplex rail
system in a 0.9 m by 1.5 m (3 ft by 5 ft) steel basin. Larger
size steel basins are available upon request. Standard steel
basin covers are available up through 1.8 m (6 ft) diameter.
Environment/One Company has only a suspended type of basin
system. The simplex suspended basin is either a 0.6 m by 0.9 m
(2 ft by 3 ft) or 0.9 m by 0.9 m (3 ft by 3 ft) FRP basin. The
duplex is a 0.9 m by 0.9 m (3 ft by 3 ft) FRP manhole. Covers
are available only in FRP through 0.9 m (3 ft) diameter. Spe-
cial manways also are offered to bring the basin up to ground
surface.
Toran has both the simplex and duplex suspended and rail
type systems with the simplex suspended in a 0.6 m by 0.9 m (2
ft by 3 ft) FRP basin and the duplex suspended in a 0.76 m by
0.9 m (2.5 ft by 3 ft) FRP basin. Simplex rail system is a 0.9
m by 1.5 m (2 ft by 5 ft) FRP and the duplex system is a 0.9 m
by 1.5 m (3 ft by 5 ft) FRP. Covers are available through a 0.9
m (3 ft) diameter.
-42-
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T.*,«l.E 4, COMPARISON Of GRINDER PUMP AUXILIARY E0UIPM£KT
Description
Chock Valve
Type of Syate*
Avallabia
Control Panels
Laval Control
Switches
Pgjbody Barncu
Standard - Ball type
%»ith caet body
Ktandard - Steal thru
SO-in diaaetor
Standard - Simple*
aueptmdud 2-It by 3-
I'Rl'j tfuplux »u»iy S-ft
• tculi l*r»jor eltuit
available
Simplex auapended r
duplox auapundud)
duple* alida awuyj
aimplux aiidu awoy
Standard - Sircplux
N£MA 1, }, duplux 3ft
optional - NL.nA 4
overload protection
in panuli unl or duo
contra.
Murewry typei timplex
eytten: - 2 requirodi
duplux eyattfo - 5 lo-
quired
Hydr-Q-Hatlc
Standard - Hall type
with cant tody
Standard - Steel thru
?t-in diametor
Standard - Simplex
auupendud 2-It by J-
I'HI'i duplex suvpendod
3-ft by 1-ft fhPi
«i.n[>i^R rail 2-it by
S-ft aiaelj duple*
rail 3-ft by >-lt
• teal; ldtgn tiio*
available
Simple* euapendodi
duplex euependodj
duplex aiidu awayi
itinipluM alidw away
Standard - Simplex
li duplox N&HA
3 optional - KE.HA 12,
A over lad protection
in panulj unl control
only
Morcury typa> aimpie*
ayatum - 1 requirodj
duplex ay»tu» - 3 c«-
4UifeU
Envi ron^tf nt /One
Standard - Gravity
opurated, flapper
typu with PVC bodyi
• Wo, require*
ami-siphoning air
it-'ludiu valve;
Jl-ppct typu
Standard - FRP thru
36-m diasiatur
Simplex kuapcn^cd;
duplex auspendiii
Control irtteipral
part of pump coret
overload protec-
tion in notori uni
control only
Prcaaure type lo-
cated m control
houiing of pu»p
COtxi
IS£40
Standard - Ball
type with caet
iron body
Standard thru
36-in dianeter
Siopla* aua-
pendudt duplex
¦ impended i im-
plex rail; dup-
le* rail
Supply capaci-
tor in junction
box and starter
if rcqueatudi
do not furnith
cofltplvtQ con-
trol panalj uni
control only
Mercury typui
aittplex ayatea
- J XjquireJf
duplex ayatcn -
3 required
F, C. Key*ra
Standard - flapper
type
Standard - Steel
tftr-j 31-in
-------
Other manufacturers offering both grinder pumps and basins
are P. E. Meyers, and Enpo Cornell. Pneumatic ejector stations
are sold by Franklin Research and Clow Corp.; however, these
pump systems and basins generally were not used in the systems
investigated for this study.
In general, most pump basins are located outdoors. Only two
systems investigated, the Country Knolls South Subdivision in
upstate New York and Lake Mohawk, OH system had some pump basins
located indoors.
It has been recommended that a pump chamber be well sealed,
but a pump that uses a pressure switch as its on - off device
must have adequate venting of the pump chamber. If the pump
chamber is not adequately vented, then a false turn-on signal
can be sent to the pump pressure switch if a large inflow of
sewage occurs. This has been apparent at Weatherby Lake, MO
where failures of the Environment/One pump occurred due to ina-
dequate venting of the pump chamber back through the house
plumbing.
Most pump chambers are not installed with overflow devices
as some excess storage is provided in the pump chamber. During
a power outage water usage would be curtailed due to the ina-
bility of the homeowner to use modern convenience appliances.
Some systems, however, do utilize an existing septic tank as the
overflow device, as in Grandview Lake, IN.
Grinder Pumping Equipment
There are two major kinds of grinder pumps currently in-
stalled in existing systems. They are either the semi-positive
displacement type manufactured by Environment/One or centrifugal
grinder pumps manufactured by Hydr-O-Matic, Peabody Barnes and
Toran. Other entrants into the marketplace, such as P. E.
Meyers and others have a limited number of pumps in pressure
sewer systems.
-44-
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The Environment/One semi-positive displacement pump uses a
large diameter grinder with two removable teeth rotating inside
stator rings. Sewage is pumped through a Moyno type stainless
steel rotor and rubberized stator or boot. The discharge piping
includes the check valve and anti-siphon valve between the pump
and the top of the pump basin. The pump is self-contained with
a separate dry compartment housing the motor. The motor is pro-
tected against running overloads or locked rotor conditions
through an automatic reset thermal overload protector. A
mechanical seal separates the pumping liquid from the dry motor
compartment.
The pump curve of the Env ironment/One unit has the semi-
positive displacement characteristic shown in Figure 24. The
semi-positive displacement nature means that with relatively
large changes in total dynamic head there are small changes in
capacity pumped. The National Sanitation Foundation has deter-
mined that pressurization above the 25 m (81 ft) maximum design
limit is possible; however, conditions above that level occur-
ring frequently and for long periods can adversely affect the
pump. If this pump is used in a slowly growing development, and
if maximum design velocity will not be reached for a long period
of time, a scouring velocity (usually assumed at 2 ft/second)
will not occur until maximum density is reached.
The Hydr-O-Matic Hydrogr ind submersible centrifugal pump
uses a 1.1 kw or 1.5 kw (1.5 or 2 hp) motor with a capacitor
starter in an oil lubricated chamber. A control box is mounted
at a separate location outside the pump chamber. Two mechanical
seals separate the pumping chamber from the motor compartment.
The original cast iron impeller has been replaced by a bronze
impeller to reduce deterioration found in earlier models. The
grinding mechanism has two cutters. There is an axial cutter
followed by a radial cutter that tends to chop stringy materials
that passed through the first cutter. These components are all
stainless steel.
The Peabody Barnes submersible centrifugal pump is offered
in a 1.5 kw (2 hp) capac itor start, oil lubricated model with
various voltages available. There is a single mechanical seal
on this pump with an extrusion type seal in front of the mechan-
ical seal. The impellers are ductile iron. The grinding
mechanism includes a cutter bar followed by an abrader of sili-
con carbide. The abrader has shattered when trying to wear down
metal particles in the sewage. The abrader is being replaced by
a metal component.
One of the newer entries into the submersible centrifugal GP
market is the Toran pump which has been used at the Sausalito
houseboat system at Kappas Marina. This pump is virtually iden-
tical to the Hydr-O-Matic pump with the difference being in the
secondary cutter mounted perpendicular instead of angled as in
the Hydr-O-Matic unit.
-45-
-------
c
<
o
<
E.'Onf (mod'i Fmell 2JO)
>
c.
<
c
?0
30
40
CAPACITY. O.
Figure 24. Comparison of characteristics of a
semi-positive displacement grinder pump (Environment/One)
vs a centrifugal grinder pump (Hydr-O-Matic).
Another entry is the F. E. Meyers pump. One of the signi-
ficant advances in this pump construction is a seal leak de-
tector that senses moisture between the tandem mechanical seals.
When moisture is detected, the pump can be removed for servicing
which would include only replacement of the f irst seal, thus
preventing moisture contamination of the main pumping chamber.
This maintenance could prevent replacement of a motor costing
many times more than replacement of the first seal.
A major advantage of centrifugal grinder pumps is that they
have a significantly changing head capacity curve. The capacity
-46-
-------
increases dramatically with a concurrent decrease in system
head. This means that in systems with low densities or low
growth rates, scouring velocities would be more frequent than in
the flat output of the semi-positive displacement type pump
(Figure 24).
Another consideration of the semi-positive displacement vs
the centrifugal pump is that in a plugged line situation both
pumps would be driven to shutoff head. The maximum pressure
that can be developed by the Environment/One pump is signifi-
cantly greater than a centrifugal pump. This pressure greatly
reduces the life of the stator, although it may possibly clear
the plug from the pipe. The centrifugal pumps will rotate with-
out discharging and the heat generated would be transferred in-
to the sewage liquid. The Environment/One pump is supposed to
be protected against overload pressure by use of a thermal over-
load protector with automatic reset capabilities. The Environ-
ment/One pump may be more suited in conditions where air release
valves have been placed incorrectly or are inoperative, because
the higher pressure generated by the semi-positive displacement
pump may be more suited to pump water against an air entrapment
than a centrifugal pump with a limited discharge head. Table 5
prov ides a detailed compar ison of grinder pumps currently
offered in the market place.
-47-
-------
TABLt 5, COMPARISON OF GRINDER FUK7B
Dc«cr tPtlOfi
Puftp Typa
L'iuctrical
Voliagti/i'haa*
I»pellar
Crindar Hucharsiam
Motor InauUtion
Puisp Conatrwction
Kunning Mpi
210/1
Inlat Shroud
Opening Six*
Pump Porformanc*
Wott/Orte
Scmi-poait\v« dia-
placement (water
tight}
1 hp, 1,72$ rpcaj
capacitor atartj
thwrmjlly protuctad
Uvito *ir
cooled
2 30/1
Mwchanical typa
with a atationary
ceramic aual and
carbon rc-t«»tinq
•ualinq »afficu
Heycra
Bail bearing
Stator alaatonar/
rotor atamlaaa
a t tu l
Shrtdd«r ring -
chrom* and ataali
cutter bar* -
aiainlwNa atcai
Cor« houalng car-
tridge nad* of
PVCi 9rtt*dn of
ctit iror»( faa*
tsnara 11 I
atainlcaa ataai
11
Capacitiva to 44
CPM with h«a4«
10 tos-u
7i iba
1-H-in HPT
Sufcaarsibiw ccn-*
trifugal
2 hp, 3,45Q rpsi
capacitor atari;
oil lubricated
230/1, 230/3,
200/3, 440/3,
S7J/3
fandoa ¦•chanicai
aoala in oil
filiwd chdBsCtiri
auai l«i*K prob«
iacludtid
Uppar daybla ball
buarlng with
lowar alwvvu
baaring
Shruddar ring «•
atainlsat at«*«li
radial cuttar -
b*r» itainUn
»tval
Puap and a»tor
houaing *ada> oF
caat iron
Capaeitiaa to 40
CPH *uh tiaaJa
to 10S-U
70 iba
1-%-ln NPf
OTHER SITE COMPONENTS
Check Valves
sewer pumps
The Peabody
Almost all pump companies marketing pressure
offer standard check valves with the pumping units.
Barnes, Hydr-O-Matic and Toran companies offer a ball type check
valve with a cast iron body. Env ironment/One pumps use a
gravity operated flapper type check valve with a PVC body. In
order to prevent the Environment/One pump from losing its self-
priming capabilities, a flapper type anti-siphoning valve, which
acts as an air release valve for the pump, is also furnished.
Materials of construction for check valves in GP systems are not
as critical as those used in STEP systems. General Development
uses a plastic ball check valve as well as brass and plastic
flapper valves. Brass valves are favored due to their long term
-48-
-------
0 & M reliability. They have a metal to metal seating face and
do not use a resilient seating face.
The quality of check valves has varied considerably. For
example, the Klaus houseboat system in Portland, OR originally
used brass valves of domestic origin. Because of their lighter
weight and thinner hinging device, these valves have been un-
suitable for service. The newer type of valves in service are a
Red and White brand import valve that is of substantially
heavier quality weight and higher price than used previously,
but has shown better service history.
Some systems use a backup check valve either in the pumping
chamber discharge line or in the service 1 ine from the pump to
the main. Most system operators find no preference to the lo-
cation of the check valve in either the vertical or the hori-
zontal mounting. However, the operator at Grandview Lake, IN
prefers the ball type valves located in the horizontal position
for easier removal for service and the flapper valves located in
the vertical position to prevent solids from depositing on the
bottom of the seating face. Peabody Barnes, on the other hand,
usually recommends the flapper type being installed in the hori-
zontal position and the ball valve in either the hor i zontal or
ver tical position.
In addition to a double check valve on Env ironment/One's
pumps, they include an anti-siphon valve. This prevents vacuum
conditions on the pump by admitting atmospheric air into the
pump discharge line.
Shutoff Valves
Shutoff v alves used in the pumping chamber typically are
gate valves; however, some systems such as Apple Valley, OH use
plug valves. The usualy practice with GP is to utilize a cast
iron body shutoff valve. However, in cer tain conditions the
body as well as the turn off wheel have been shown to corrode.
Utilization of shutoff valves in STEP systems has precluded the
use of cast iron bodies. Bronze is the material of choice as
several operators have reported problems with the plastic valves
which tend to crack with age or use. Seating of the plastic
valves also tends to wear and develops a "set". Brass valves
have had a poor service history as well. Admiralty brass tends
to lose zinc or dealloy, leaving the copper susceptible to cor-
rosion . Many designers use two shutoff valves for the system:
one usually being located in the pumping chamber and the other
located between the pump chamber and the main line.
On-lot Piping
Serv ice connections between the on-lot pumping unit and
service main vary in size between 2.5 cm and 5.1 cm (1 and 2
-4 9-
-------
in). The most common size is 3.2 cm (1.25 in) inside diameter
plastic piping. There are two bases for the selection of this
size. Typically, some pumps have used 3.2 cm (1.25 in) size as
their standard discharge pipe. When Environment/One developed
their unit, they sized the 3.2 cm (1.25 in) pipe based on the
headloss and capacity conditions of the ir pump to deliver a
scouring velocity of approximately 0.6 m/second (2 ft/second).
For GP, obviously the smaller the size piping, the larger the
scouring velocity will be for maintaining a clean pipe, but this
will result in a higher friction loss. STEP systems would not
be limited by a flush ing or scour ing requirement, therefore,
typically larger service lines would result in a lower friction
loss.
Most of the GP installations at Grandview Lake use one inch
piping, while in the Horseshoe Bay development 3.2 cm to 5.2 cm
(1.25 to 2 in) piping is used. Many of the STEP systems or
houseboat solids handling pump systems have 3.8 cm (1.5 in)
flexible hose. Examples of some STEP systems are: 3.8 cm (1.5
in) service lines at Priest Lake, ID; 3.2 to 3.8 cm (1.25 to 1.5
in) piping at the General Development Utilities systems in
Florida; and the Bend, OR system uses 3.2 cm (1.25 in) piping.
Most systems seen have standard 3.2 cm (1.25 in) service lines,
using PVC piping (Schedule 40 or SDR 26 lines).
Several systems have been experimenting with the use of
polyethylene service lines. For example, the Grandv iew Lake
system has SDR 21 and SDR 13.5 polypropylene and polybutylene
service connections. The SDR 13.5 is considered superior. It
is more difficult to utilize PVC service lines with brass fit-
tings than service lines with plastic fittings. Harbor Springs,
MI where GP are utilized has polyethylene services lines as well
as polyethylene mains.
Service taps typically are made under pressure. Common wet
tap procedures are used. Cock tapping saddle connections are
used with a curb shutoff valve; however, other types of tapping
can be used. In the General Development Utilities system in
Florida, the wet tap is made wi th a special tapping saddle wh ich
retains the bored out section of main line piping. Saddles and
tapping tools for PVC are common to most contractors familiar
with PVC underground piping.
Power Supply Requirements
Most effluent pumps are available in 120 volt, single phase;
230 volt, single phase or 230 volt, three phase. Grinder pumps
are available in only 230 volt, single phase, or three phase,
except for the Environment/One pump which is limited to 230
volt, single phase. Power supply connections are made at the
home master electrical panel or just after the meter. A sepa-
rate disconnect, such as a circuit breaker, is required at the
-50-
-------
homesite connection. All GP except the Environment/One come
with either a NEMA 1 or NEMA 3 cabinet which have their own cir-
cuit breaker or a hand-off-automatic (HOA) operating switch.
Overload protectors are usually available in the panels. The
Environment/One pump is not provided with a panel because the
controls are integral with the pump core. The Toran pump has
the capacitor supplied in a junction box, if requested. Use of
an automatic switch and a nearby control panel greatly simpli-
fies pump servicing since testing is simplified.
Effluent pumps are wired directly from the pump through the
control panel. In the General Development Utilities system, a
control panel is not used, so the electric feeder line just has
a plug-in connection to a home outlet. The plug-in connection
is the pump local disconnect. Typically, there is one home on a
single effluent or GP, simplifying power supply requirements.
Power is supplied from the control panel at a single residence.
When a pump unit is shared between residences, other arrange-
ments must be made. In Apple Valley, OH, the first residence on
a shared unit supplies the power and a credit of fifty cents per
quarter applied to the first pump users bill. If the resident
supplying power has service disconnected, a secondary source of
power must be provided from the remaining residents on the pump.
This is a complicating factor in shared pumps, but this has not
been a significant problem.
When a unit must be removed for service, the electric ser-
vice line and discharge line must be disconnected. Several GP
have waterproof disconnects or waterproof junction boxex in the
pumping chamber to facilitate pump removal. If an Environment/
One pump must be removed for service, the electric service lines
must be de-energized and then manually cut. When a new pump is
installed in that unit, the electric service lines are recon-
nected with the use of wire nuts or wire nuts and tape. Sepa-
rate electr ic circuits for the pumps and for the controls is
recommended at the Glide-Idelyde, OR system to prevent failure
of one system from affecting the other (Figure 25).
Control Systems
Many pump manufacturers offer package control systems that
include level control switches for activating the pumping units.
Many systems also use a high water level sensing device which
transmits a signal to an alarm light or horn located either at a
nearby control panel, in the kitchen or basement of the resident
served.
There are two major types of controls presently being used
in pressure sewer pumping units. The earlier systems have a
pressure switch which was utilized in the Peabody Barnes GP in
a private system near Bend, OR, and is used in the Environment/
One GP (Figure 26) . Hydr-O-Matic effluent pumps still use a
-51-
-------
Figure 25. Pump control cabinet for Glide-IdleyId, OR.
pressure switch in the General Development Utilities systems;
however, they are changing to the mercury float device. Mercury
floats have been used in most pressure sewer systems and are re-
ported to be the most reliable pressure switch. The Environ-
ment/One unit utilizes a sensing bell which transmits pressure
to a pressure switch. When sufficient pressure forces the dia-
phragm up against the contact, the circuit is completed. The
pressure switch must be vented to allow for movement of the dia-
phragm. The point of venting usually is at the top of the elec-
trical plug in Hydr-O-Matic units, or through a special vent
control device with a water exclusion check valve located in the
manway of the Environment/One pump unit chamber.
The mercury float device is a capsule of mercury imbedded in
a polyurethane tear drop shaped bulb. When the liquid level
rises, the bulb floats and rotates allowing the mercury to com-
plete two electrical contacts. For on - off control, two mer-
cury floats are required; one for turn-on level and one for
turn-off. The high level alarm usually requires a third turn-
on level. Peabody Barnes is experimenting with a differential
mercury float switch which has an angled mercury-containing
glass tube inside a polyurethane float. This would permit only
-52-
-------
HIGH LEVEL PRESSURE SWITCH
TERMINAL BLOCK
mi
TfM60ELAYRELAY.
CHECK VALVE
Figure 26. Cut away of Environment/One pump showing
pressure sensing bell on lower left with lines running
to pressure switches at top center of pump casing.
one mercury float to control the pump on and off levels. Cur-
rently under development is a magnetic plastic float which has
plastic floats riding on a rod which raises a magnet into con-
tact with a switch case. Usually the switch will not come into
contact with the liquid and is found to be impervious to grease
accumulation. This type of dev ice is not in cur rent usage in
any system investigated, but is planned for usage in the Glide-
Idleyld and in the Manila, CA systems. By far the most reliable
-53-
-------
system utilized is the mercury float system which usually is
attached to the discharge pipe or suspended from the top of the
pump basin.
The original reason for using the pressure switch was one of
economics. Recently the mercury float switch system has been
lowered in price to where it is competitive with the pressure
switch. Due to the number of service calls required for the
pressure switch turn-on device, future systems, with the excep-
tion of the Environment/One unit, are being installed with mer-
cury float switches. Special considerations are involved in any
system installed in California which has an requirement for ex-
plosion proof equipment inside a pressure sewer system manhole
or pump basin. Prom the experience of systems throughout the
country, there has been no evidence of the pump basin exploding
through the ignition of inflammable gases or gasoline spilled
into the pump chamber. This requirement in California has re-
sulted in the planning of intrinsically safe, highly sophisti-
cated , and expensive control circuits in the experimental sys-
tem in Manila, CA.
Corrosion and Materials of Construction
Corrosion often suggests rusting, or other attack to metals.
This report descr ibes corrosion in a broader sense, i. e., any
attack from the environment, occuring chemically, biologically
or otherwise wh ich destroys a material or hampers its perform-
ance . Deterioration of concrete, plastics or metal is included.
Grinder pump and STEP vaults present a corrosive environment
from several sources. Inside surfaces are wet, with a part be-
ing submerged and the remainder heavy with condensation. Corro-
sion can occur from constituents in the water supply itself,
such as chlorides, as well as from matter in the wastewater. As
sewage remains in the vault between pumping cycles, oxygen is
depleted from the wastewater and anaerobic conditions develop.
Digestion may occur to some degree, first entering the "acid"
phase, dur ing wh ich pH declines, presenting corrosive cond i-
tions.
Hydrogen sulfide is formed as inorganic sulfur compounds are
reduced in the absence of oxygen. H2S is corrosive in it-
self and also reacts biologically with thiobacillus bacteria on
moist surfaces to form sulfur ic acid, H2SO4, Corrosion
from this can be extreme.
Within the pressure sewer vault, corrosion may attack the
pump or the tank itself, whether concrete, fiberglass or some
other material. Special attention must be given to mechanical
parts and small parts where even slight deterioration can cause
failure. Consideration also should be given to equipment ex-
posed to general atmospheric cond i tions, such as electrical con-
trol panels located outside.
-54-
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Normal means of coping with corrosion problems within
pressure sewer vaults are by minimizing conditions conducive to
corrosion, and by selecting materials sufficiently resistant to
corrosion. Galvanic couples are avoided, and where dissimilar
metals are used, they are insulated from each other.
When vaults are well ventilated, the concentration of H2S
is greatly reduced. Designs are preferred where turbulence in
the pump vault is minimized, thus releasing less gas. Where
possible, flow should enter the vault without falling and be-
coming aerated. Serious corrosion occurs when sulfide and oxy-
gen and are present simultaneously.
Concern for corrosion may be greatest when an engineer
undertakes a custom component design, but the assumption that
corrosion matters have been contemplated in package units can
sometimes be disappointing. It is best to know the possibili-
ties of corrosion in a given environment and insure that materi-
als selected are suited for the application.
Concern for corrosion is frequently dealt with by a combina-
tion of methods, but selection of materials plays a major role.
Few materials are completely corrosion resistant, so cost and
degree of resistance is weighed against the time required for
failure to occur and the significance of the failure. The type
." corrosion to be expected also is of importance, whether it is
4 Form, deep pitting, or crevicing.
~>ump casings and impellers normally are made of grey cast
iron, a carbon and silicon alloy of iron. In pressure sewer
application, iron sometimes becomes plated with ferrous sulfide,
iron oxide, and organic matter all cemented together. Normally
this is of little significance in the pump's operation; however
when a pump remains in the wastewater for some time without
operating, such as when the home served is unoccupied, the im-
peller may become fixed to the volute. Then, when the pump
again runs, it may not exert enough starting torque to break
loose. Either the fuse or breaker, or the built in thermal
overload protects the motor, but a service call is needed. This
is an infrequent problem, and one that favors plastics insofar
as corrosion is concerned.
Common carbon steel has been used in pressure sewer vaults,
and is normally coated or plated. Usually, coated steel has not
performed acceptably. Forty steel septic tanks in service were
reported on in a study by the Public Health Service (12). The
study reported that 70% had holes through the steel, and an
average useful life of 7 years was suggested.
-55-
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Galvanizing (zinc) or cadmium plating often is applied to
steel. As with coatings, protection relies on perfect covering,
though zinc will cathodically cover small blemishes. Too often,
the plating is only cosmetic, as opposed to thicker plating of
industrial practice. Generally, plating has not performed well
in pressure sewer vaults, but has been satisfactory for items
exposed to the atmosphere.
Wh^n the properties of steel are required and conditions are
quite corrosive, stainless steel may be used. There are many
types of stainless steel, generally grouped as martensitic, fer-
ritic, austenitic, or precipitation hardened. Martensitic and
ferritic steels are also known as 400 series, and are identified
by being magnetic. Type 416 often is used successfully for
pump shafts. More delicate parts are best made of austenitic
stainless steel, usually 300 series. These are either non-mag-
netic or slightly magnetic. In a sewage environment, type 316
is favored; it is made more corrosion resistant by the addition
of molybdenum. Type 304 also is an excellent material and wide-
ly used, though not as corrosion resistant as 316.
Copper alloys are in common use as brass or bronze. Brass
is an alloy of copper and zinc, while bronze is copper and tin.
Brass is subject to dealloying; the zinc leaches out of the
material leaving soft copper. While many bronze alloys are
available, a typical one is 85-5-5-5 (copper - zinc - lead -
tin), and generally is acceptable for most use. A color may de-
velop on bronze, usually black, silver or green, but is more
tarnish than a matter or concern.
Plastics generally have proven to be superb. Some 8 years
of experience with plastics in pressure sewer vaults has shown
no deteriorating effect on PVC. Some products, however, are hy-
groscopic and may swell. This can cause mechanical parts to
fail. Fiberglass reinforced plastic (FRP) commonly is used to
make pressure sewer vaults. Wicking is possible should glass
fibers become exposed to moisture. To avoid this, a resin or
gel coat is applied to surfaces.
It is well known that sulfuric acid attacks concrete and
numerous cases have been cited where the crown or water surface
levels of concrete pipes have deteriorated to the point of
collapse. Experience with concrete septic tanks has been quite
good, however. Some jurisdictions require coating of the
soffit of tanks. A study by the Public Health Service was made
on concrete septic tanks in field use, ranging in age from
one-half to 39 years (12). Of the 150 tanks inspected, 91%
were judged to be in good or excellent conditions so far as the
concrete was concerned, with some showing spelling at and above
the water line.
-Sfi-
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Gases and Odors
Gases are produced in conventional sewers, force mains, and
pressure sewer on-lot facilities. Concern in piping systems is
mostly for hydrogen sulfide, owing to its corrosive, odorous and
toxic characteristics. The time period required for oxygen to
be depleted and production of H2S to start in force mains
usually is about 15 to 30 minutes. Production continues for
perhaps 24 hours, or until the sulfate is reduced. Pomeroy (13)
has shown that the rate of production is accelerated greatly by
anaerobic slimes which coat pipe walls. The same slime would be
present in pressure sewer on-lot facilities of both GP and STEP
design.
Table 6 outlines characteristics of gases which are of con-
cern in sewage systems. Both methane and hydrogen sulfide are
shown to be flammable and may be explosive. Hydrogen sulfide is
also very corrosive and oxidizes to form H2SO4, sulfuric
acid. Hydrogen sulfide is highly odorous and toxic.
When properly vented the tank atmosphere differs insigni-
ficantly from normal air. Danger of fire or explosion would be
greatest with just the right degree of imperfect ventilation.
Pressure sewer vaults must breathe. As flow from the home fills
the tank from pump "off" to pump "on" level, gases in the tank
atmosphere must be displaced. Air is then drawn in as the
liquid level drops while the pump runs.
There are differences among conventional sewer, septic tank
systems and pressure sewer systems. In a septic tank drain
field installation the liquid level in the tank increases very
slightly with flow and it is possible that some gases are
drafted to the drain field. These conditions do not exist in
pressure sewer design. While a scum mat may exist over septic
tank liquids, the authors have never noted any in the vault por-
tion of interceptor tanks used in STEP applications. While
conditions are relatively quiescent in septic tanks, some tur-
bulence is caused by pressure sewer pump liberating more gas.
Such differences as these should be considered in pressure sewer
design.
-57-
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TABIC C. CllAhACTLMSTlCS Uf COW*)!* tr-L* CASKS
V«jKit D«. r:» i ty
£iJ £ta:SLl££U^-lSi2l£ JM£_i_Xl Cl>»l
Kethanc CI* C.5»5 Asphyxiant
Carton Dioxide CO_
1.51 Asphyxiant
Cow-n
P?9, "iri.' «Lt
Coloi
udorless.
Colorlt-sft,
odor]tss.
tiStfltSS,
V.hen
» i < i h«'d
jr. i.uge
v u.int
rjy i.
t'hy&iclovit-"*!
11-y.Cl
Act* rtthuni-
10 derive
Citut of
o*y9wf.. :jGc»
r.ct i.ppoct
life.
Ccxifjoi t>e
tn^jred at
101 t ixe ihan
a t i. w - ; r.uies
ev-tr, if
j*-rt is »t
»i,st r LL
ProU.LtJy ».o
l:mt. pro-
vided oxygen
icfficjent
/or li!«.
(t by Vo I u«.o
3 1- hi c |
J-owi-r Uppci
1.1 r 11 1 i fr 11
5.0
15.0
it
4.0 lO fe.S
Hydrogen 5uMi.de R_S
1.19 Toxic
Rotten «?9o»ure for
3 to 15
ri r.ates *\
Q.01% j«-
pairx kvfi»o
of >r-c!l.
Odpf not
tviCi-ri! ol
high corv-
c»*r,'.f otior.g,
Color'.cfci.
Ccriu»ivc.
t&ry f.i-rvcfc,
1~5-j:11- fcc-nsc 0.02 to 0.03
Oi '.'ell
r •>p jd Iy aa
conci.'.:r*tjc.n
Dtaih i.i few
r n.'jiti at
o.n. C*-
pc«urc to
0.C7 to 0.1%
t «i-td iy
ci-u-s aeat«
poiuonng.
Par )l-3 iti
ttory
J»hyMOlo9i-
c e i Sy i:icri.
Color K-i»,
odor 1 »•»»,
tmiflrn.
£u|'i-oru
cc.- buit ton.
Noiir.al air
cunt jj n»
3 Q- VJl of
0,, Kun can
tolcrate
dvvr. to 1?*.
KiMir.ua i«:tQ«-roua
lO hfv. hv-
5©w 5 to 1*
probably
(otal.
Undesirable sewer gases may be controlled by a wide variety
of means. Either the sewage itself or the gases may be treated.
Chlorine (CI2), hydrogen peroxide (H2O2), ozone (O3),
oxygen (O2), ph adjustment and other chemicals have been used
for controlling gas emisssions.
When treatment of gases is required, a practical method
is use of a soil filter bed. Typically, this resembles a septic
tank drainfield, but is much smaller. Gases are conducted to a
perforated pipe bedded in gravel and covered with loam or a mix-
ture of soil and peat moss. Ventilation from the vault to the
soil bed has been accomplished mechanically or by the natural
-58-
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escape of gases. For detailed information, reference is made to
a paper by Carlson (14) and another by Stone (15).
For homes having an existing drainfield, gases might be
vented there. Another option is that a filter bed could be con-
structed in the same trench as used for the pump discharge or
service line. Both of these methods are being used experimen-
tally in the Glide-Idelyld, OR pressure sewer system. Where
groundwater is high, such a system cannot be expected to func-
tion properly and can be a source of infiltration to the sewer.
Mounded construction may be advantageous.
Imperfect ventilation which may allow gases to reach com-
bustible concentrations should be avoided.
While H2S is highly odorous in small quantities and is
heavier than air, this gas is usually dispersed sufficiently
when exhausted through the house vent. Complaints of H2S
odors are regularly reported when the vault covers are not
sealed. A slight odor is typical when vault covers are lifted
from either GP or STEP vaults.
There have been no known fires or explosions, though
numerous installations do not use explosion proof electrical
equipment. To render installations sufficiently explosion proof
at reasonable cost, some designers place the pump "off" level
above the top of the pump, keeping it submerged. In some cases,
two "off" level controls are used to insure that the pump re-
mains entirely below the liquid, and explosion proof controls
are sometimes used. When wiring is placed in a conduit between
the pump vault and electrical control panel, a conduit seal is
necessary.
Workmen normally need not enter pressure sewer vaults, so
poisoning or suffociation is not likely. Some dizziness has
been reported when a workman breathes the gases by lowering his
head into the vault. Designs are preferred where such action
is neither necessary nor possible.
-59-
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SECTION 6
DESIGN OF OFF-LOT FACILITIES
GENERAL
This section presents a compendium of various engineer's
designs and operator's modifications as they relate to pressure
sewer system design. Piping hardware selection is detailed as
well as engineering design considerations for applying the hard-
ware to a functioning system.
After a preliminary analysis of the number of homes and
character of the community, the system is layed out with
branches having the shortest runs and fewest changes in direc-
tion. Langford and others (3, 5, 16) suggest attempting to keep
a positive head on all pumps. Positive head will prevent: 1)
air plating of grease and solids on the lining of the pipe, 2)
large air accumulations at high points and 3) siphoning of
pumps. Langford also suggests that precise topographical sur-
veys of an area to be served are not as critical in a pressure
sewer system compared to a grav ity system.
Var ious methods exist to layout pressure sewers. For
example, Ken Durtschi designed the Priest Lake, ID system by de-
termining the elevation of each pumping unit and assigned a
suitable pump with a substantial safety factor to each loca-
tion. Basically, he discounted velocity as an important design
consideration within his system. Pipe sizes were determined by
an estimate of the number of homes pumping at any one time. The
Weatherby Lake, MO grinder pump system used data from rural
water systems according to the equation:
x , y0.515
where X = number of customers drawing water at any one time
Y = total number of customers connected to the system.
This analysis assumes all water used would be transported to the
waste system. Grandview Lake,. IN used a similar peak water de-
mand curve and returned 80% of that peak to the sewer with a C
-60-
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factor of 130. On the basis of that system, they presently are
designing new systems using 70% of the peak water demand with a
new minimum velocity of 0.61 m (2 ft) per second rather than the
previous veloc ity of 0.3 m (1 ft) per second.
Environment/One suggests designing the system for the maxi-
mum number of pumps operating at any one segment based on pre-
vious research work done by the firm (18) . Pumps at any one
segment are assumed to pump at 0.69 liters/second (11 GPM). The
friction headloss is determined in any one segment based on the
veloc ity of sewage in that segment when the maximum statistical
number of pumps are operating. Static elevation is then added
to the line segment and is accounted for by the greatest dif-
ference in elevation between that pump segment and the discharge
elevation.
There are several computer programs used for designing a
pressure sewer system. General Development Utilities in Florida
has a computer analysis that included pump curves in the com-
puter program and simulated development levels which translate
into population density and velocities (19, 20). One Hydr-O-
Matic representative in the Houston, TX area has developed an
analysis for sizing pressure sewer lines which tend to downsize
mains in order to increase veloc ity to a point consistent with
maximum scouring conditions and total head delivered by the
pump.
Bowne (21) has designed STEP systems with centrifugal pump-
ing units. His analysis incudes a determination of the number
of homes to be served and the peak flow from those homes. Then
the profile of the system is analyzed with hydraulic grade lines
of various sizes that are estimated to be suitable for the sys-
tem. The graphical analysis shows by inspection the correct
pipe size (Figure 27). Positive pressure throughout the system
is maintained by a pressure sustaining valve. Th is pressure
sustaining valve adds additional head and changes the hydraulic
grade line as shown. Individual pumping units are then selected
at each individual location consistent with head to be pumped
against and desired flow rate into the system.
PIPE
Var ious types of pipe material have been used in existing
pressure sewer systems including various ratings of PVC, poly-
ethylene and galvanized. Most systems use PVC piping exclusive-
ly . For example, pressure sewer mains in Albany, NY utilized
PVC Type 1 Schedule 40 pipe with PVC DWV fittings (3). Grand-
view Lake uses SDR-26 pipe as do those of General Development,
Priest Lake and Weatherby Lake pressure sewer systems. In th is
investigation PVC SDR-26 pipe was observed to be the most fre-
quently used piping component. Schedule 40 pipe is the most
expensive PVC pipe. Its pressure rating for 5.1 cm (2 in) pipe
-61-
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With pressure
sustaining valve
200
180
Without pressure
sustaining valve
6 inches
" 140
Ui
120
100
PIPELINE DISTANCE FROM DISCHARGE POINT, thousands of feet
Figure 27. Pipe sizing procedure.
1,920 kPta (277 psi) and for 7.6 cm (3 in) pipe is 1,820 kPa (263
psi). Schedule 40 pipe is unusual in that its pressure rating
varies with size. SDR 26 pipe has a pressure rating of 1,041
kPa (150 psi), whereas SDR 21 is 1,388 kPa (200 psi). These
pressure ratings are valid up to a temperature of 22.8°C
(73°F) and at higher temperatures than this, the pressure
rating is substantially reduced. There usually la a safety
factor rating in the piping systems. For example, SDR-26 pipe
can withstand in excess of four times its nominal pressure
rating .
Slip jointing offers a potential expansion and contraction
area which solvent weld piping systems do not. Usually the slip
joint piping system results in a much tighter system with fewer
leaks. Mechanical jointing, which results in a compression fit,
-62-
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has experienced a sufficiently high degree of success in water
system construction.
There are several reasons why pipe locator systems are used
in pressure sewer systems. They serve to warn contractors work-
ing on other underground utilities that a pressure sewer system
is nearby, thus preventing a possible break in the pressure
sewer line. They also serve to help the utility company locate
a broken pressure line and speed repairs. Also, the locator
system serves to differentiate between water, gas or other
underground utilities so a tap will not be made into the wrong
line.
There are various types of pipe locator systems available.
One system used in Glide-Idelyde, OR and in Grandview Lake, IN
consists of physical sign posts announcing the presence of
underground pressure sewer lines. Another system, also in
Glide-Idelyde, uses a toning wire, which is sensitive to a metal
locator, placed above the pressure sewer line. A third method,
not currently in use in any pressure sewer systems but used in
sewage force mains and by over 1,200 electric, water, gas, tele-
phone and CATV companies and utilities, is the Terra Tape system
manufactured by Gr if folyn Co. of Houston, TX. 11 is an inert
bonded layer of plastic with a metallic foil core. The manu-
facturer claims the tape to be highly resistant to anything en-
countered in the soil. This tape, when buried approximately 0.3
to 0.46 m (1 to 1.5 ft) below the surface and parallel to the
pipe line, provides detection by all pipe locators. It provides
positive dig-in protection frem accidental discovery by other
utilities excavating. This system is available at a cost of
approximately $0.03 to $0.05 per meter ($0.01 to $0.015 per ft).
Often, locator pins are laid on top of valve structures to
locate the valves by a metal detector. These locator pins
usually are sections of reinforcing steel rods that are placed
0.3 to 0.6 m (1 to 2 ft) below the soil surface. Another system
used to locate pressure sewer lines is to color code the pipe to
identify whether it is a water or sewer line. Various pressure
sewer systems, including General Development Utilities in
Florida, Grandview Lake, IN and others use various colors such
as brown PVC, green PVC or red striped PVC to denote the line as
a sewer. The Pennsylvania Dept. of Environmental Resources re-
quires underground sewer coding by color.
Another method of pipe location is to have a very detailed
set of as-built plans so the operator can tell quickly where and
at what depth a pressure sewer line is located.
-63-
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AIR RELEASE VALVES
Air release valves should be located at high points on the
pressure sewer line. The function of the air release valve is
to permit accumulated air and gases produced to be released from
the piping system so pressure buildups at Hie high points can be
avoided. When an air release valve operates, allowing accumu-
lated air to be discharged, flow resistance and headloss de-
creases, If a pump has sufficient head c.nd capacity, it is
possible for the velocity of the liquid to carry accumulated air
from the high points down the piping system and eventually out
at the discharge point; however, this frequently is not possible
and a line may become air locked.
Two major types of air release valves are available. One is
an automatic air release valve which will automatically purge
the high point of air without an attendant operating the system
(Figure 28). This valve is located in a small manhole. The
second type is a manual air release valve. It is nothing more
than a valve located on a riser connected to the main line pip-
ing system. The manual air release valve is significantly less
expensive than an automatic one, but frequent operation may off-
set capital savings. The automatic air release valve, on the
other hand, does require some minimal maintenance to assure that
grease has not accumulated inside the mechanism preventing auto-
matic operation. Operators report typical cleaning schedules of
two times per year.
Pressure sewer system operators suggested the desirability
of using more air release valves than were included in their de-
signs. For example, in Texas at the Lake LBJ MUD, manual air
release valves are located at major high points in the line.
However, the operator suggested more air release valves are
needed because the veloc ity of sewage in the pr essure mains
changes the point at which the air accumulates. The higher the
veloc ity in the mains, the fur ther downstream from the high
point the air accumulates. The same observation was made at
Grandview Lake, IN. It is interesting to note that for manual
air release valves operated in Texas, the operator often finds
between twenty seconds and a minute of high pressure air is re-
leased during manual purging. At the General Development Utili-
ties , the operator often can disconnect the service and work on
it for several minutes with only air coming out from the connec-
tion . Large volumes of air msty be minimized if a pressure sus-
taining device is I'sed to keep liquid from draining out of the
lines. This is especially true for those portions susceptible
to gravity flow during low flow conditions when air may replace
the liquid volume.
-64-
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COVER
SEWAGE Aifl
RELEASE VALVE
SHUT OFF VALVE
2 INCH MINIMUM CLEARANCE
r>2r -- —
=»
'<* ¦ 0/)QO
Ss«?.§^L-. ,
e* © &**
C^5S>e=K
OPTIONAL BACK FLUSHING HOSE
1 INCH BLOW OFF VALVE
v GRANULAR MATERIAL
iSSS* 18 INCI' MINIMUM DEPTH)
THREADED TEE
TO SUIT INLET
PRESSURE SEWER MAIN
OH COLLECTOR
Figure 28. Automatic air release valve schematic.
IN-LINE SHUTOFF VALVES
A number of pressure sewer systems use in-line shutoff
valves in the mainline piping. There are various reasons for
including shutoff valves in the piping system. At the ends of
the lines, a shutoff valve is included prior to a cleanout to
allow for ease of cleanout access without causing sewage spills.
Valves are used in the Apple Valley system in order to route
the piping system from a loop to linear layout. These valves
usually are operated at intervals between six months and a year.
Valves also may be located at intermediate inline cleanout loca-
tions to provide both access and bypassing for a broken sewage
line segment. Fully ported valves used in these situations are
either gate valves, which are most typical,* or less frequently,
plug valves, as used at Apple Valley. These valves have cast
iron bodies even in STEP systems . Corrosion does not seem to
be a significant factor with inline valves in contrast to basins
where the corrosive atmosphere attacks the outside surface of
cast iron valves.
-65-
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CLEANOUTS
Virtually every pressure sewer system has cleanouts of one
type or another. Cleanouts allow blockages in the line to be
removed; provide access for flushing the lines; and provide
access for bypassing a segment of line that may be temporarily
out of service. There are various types of cleanouts. An in-
line cleanout is usually located at changes of direction or at
confluences of pipes. It is installed with a cleanout facing
in one or both directions (Figure 29). There is an end of line
cleanout (Figure 30) and there are service line cleanouts where
two or more service lines are connected together. Cleanout
facilities almost always are located in meter boxes or in small
manholes.
sedoing roa oipe
SUPPORT AMO LCaCMimG
OP GOOUMO WAT EH
IMFILTRATIOU. < a" MIM.;
Figure 29. Valve box cleanout at Harrison, ID.
The spacing of cleanout facilities never has achieved a con-
cord. Kreissl's (3) report recommends 122 m (400 ft) to 183 m
(600 ft) maximum separation. However, in actual systems this
spacing recommendation is uncommon. Cleanouts only are found on
the ends of lines, at confluences of major lines, and at changes
in pipe 1ine siting.
FULL
POSTED
valve
potcast cowcaeie
HAMMOte
CLEAMOUT
•cleanout
-66-
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Meter box
Ball or gate valve
Figure 30. Terminal cleanout.
An example of an unusual type of cleanout facility is lo-
cated in the Country Knolls South pressure sewer system at
Ballston Spa, NY. End of line cleanouts are brought to an above
grade position and finished with a cap sti ck ing out of the
ground, although construction plans called for a below grade
line cleanout. According to the system operator, the cap has
blown out several times, possibly due to freezing conditions. A
disadvantage is accessibility to vandalism. On the other hand,
the cleanout is easily located.
An anc illary design concept to a cleanout connection is a
flushing station. Flush ing stations are used at Grandview Lake,
IN and the Lake LBJ MUD at Horseshoe Bay, TX. The advantage of
a flushing station is that it can automatically pump large
volumes of water through mains in order to clean out accumulated
solids and grease. At the Grandview Lake system there are 3.8
m3 (1,000 gal) holding tanks with 0.56 kw (0.75 hp) centri-
fugal pumps, actuated by timers and stopped by low level float
switches, flushing the mains with septic tank effluent. Several
similar facilities were provided at Lake LBJ, although they used
potable water with an air gap. The relative advantage of the
Grandview Lake system was that it did not add additional water
to the treatment facility. The H-O-A switches and timers which
control the flushing station can be set to operate during low
flow per iods.
-67-
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VELOCITY
Liquid velocity in pressure sewers is inextricably tied to
overall system design: i.e., nominal pipe diameter, number of
homes, and number of contributing units. There are two major
concerns in determining overall velocity: scouring and grease
accumulation, providing the contributing pumping units have suf-
ficient head to overcome the friction loss developed.
Scouring velocity in mains has been presented both by Hobbs
(22) and by Flaniga, et. al. (23) for the minimum scouring velo-
city for 5.1 cm to 20.3 cm (2 in to 8 in) plastic lines.
Battelle considered transport of sand using the equation:
Vs = d2/2,
where Vs = the minimum scouring velocity in
feet per second
d = the minimum inside pipe diameter
in inches.
In that study, sewage that was tested had grease concentra-
tions ranging from 15 to 365 mg/1, which approximated conven-
tional sewage. However, these tests were performed without
lengthy periods of flow or no -flow which could radically affect
the sand transport capability if a grease sand matrix were found
adhering to the piping system.
Grease accumulations in pressure sewers have been noticed at
ends of lines and, in some systems, in service lines and
throughout the mains. Grease accumulat ion adds to friction
losses by two mechanisms. First, an increasingly rough surface
lowers the coefficient of fr ict ion. Second, a decrease in the
effective open area of the pipe occurs, thus increasing friction
loss for the same liquid flow rate. Grease accumulation prob-
lems are less of a concern in STEP systems than GP systems.
PRESSURE
Pressure developed in any force main is related directly to
elevation and friction loss requ irements. Friction loss will
vary with time, presence of air, amount of grease and sol ids
plating, and the type of pump in service (e.g. semi-positive
displacement or centrifugal.) If a semi-positive displacement
pump is used, then greater heads can be developed to overcome
friction loss. A centrifugal pump develops only its shutoff
head, while the semi-positive displacement pump continues to
develop substantial amounts of head over its design head.
_68-
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Pressures seen in GP and STEP systems depend on the static
lifts of the system. For example, General Development Utilities
systems in Florida, are in very flat terrain, typically operate
at heads less than 7.6 m (?5 ft). Some of the systems in more
mountainous terrain, such as in Priest Lake, ID, operate over
elevation ranges in excess of 60 m (200 ft). If elevations to
be overcome are greater than the capability of the pumping unit,
then intermediate lift stations are required. Pressures in
virtually every pressure sewer system have been less than 625
kPa {90 psi) and more than 69 kPa (10 psi). The 625 kPa (90
psi) figure was encountered dur ing abnormal pumping conditions
due to accumulations of air at high points with inoperative or
nonexistent air release valves.
FUTURE SYSTEM USAGE
Many existing pressure sewer systems have been installed
with a substantially lower number of initial users than their
ultimate full-flow capacity. In some second home developments,
in fact, such systems have been installed and operated with as
few as 5 or 10% of the ultimate number of connected homes.
Questions frequently encountered during the design phase in-
clude : Should the designer plan the piping system for the en-
tire ultimate development or phase piping sizing to account for
future development? A corollary question is; If an area has
sufficient capacity to sewer all potential customers within a
service area, how can additional inputs beyond the existing
sewer area best be handled?
There are many ways to account for growth. For example, the
Apple Valley sewers in Mount Vernon, OH are partially gravity
and pressure. Areas served by pressure are lakefront proper-
ties . These areas have looped pressure sewers and feed back
into a common gravity manhole. Dur ing the initial low density
contribution to the piping system, valves are operated such
that the entire flow of the pipe may be clockwise or counter-
clockwise. This will enable all contributing units to flow
through the same pipe segment, The system has valving so that
if a valve at the far end of the loop were shut then half of the
contributing units would flow to one segment of the loop and
half would flow down the rema ining segment thus doubling the
capacity of the line without significantly increasing the
initial capital cost.
Another alternative for future development is to install the
lines at their ultimate capacity, but to account for possible
grease buildup during low or inactive flow periods by installing
flushing stations at the ends of lines. This is accomplished at
Lake LBJ MUD at Horseshoe Bay, TX.
-6 9-
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Another alternative is to install parallel lines, with one
of a smaller size and one of slightly larger size. When ulti-
mate development occurs both lines would be used. The disad-
vantages are the significant increase in the construction cost
and identification of service connections to both lines.
Another alternative to accomodate future growth is to plan for
parallel lines, but construct the second line as the need
arises.
-70-
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SECTION 7
CONSTRUCTION REQUIREMENTS
ON-LOT
On-lot facilities consist of the service line, pumping unit
valves and main connection. Frequently, pump systems have de-
signs which permit low intensities of labor input for complete
construction. General Development Utilities have simplified on-
lot installation by using a fiberglass tank and an effluent pump
which draws power through a plastic conduit plugged into an out-
side receptacle.
Proper construction of on-lot facilities are important to
the overall system success. For example, loose joints between
the home and pumping unit often can account for significant in-
filtration into the pressure sewer system. Loose joints also
may allow sand and silt to enter the pumping unit. Frost depth
should be considered. In a shallow installation in a northern
climate, severe problems may develon from freezing. This situa-
tion was encountered at Weatherbv Lake and solved bv the instal-
lation of stvrofoam cutouts. The location of the pumping unit
on-lot is dependent on maintenance, power sut>olv and aesthetics
which must be addressed in any proposed installation.
OFF-LOT
Unlike gravity sewers, some latitude is permitted in laying
pressure sewer pipe, but good jointing techniques are essential.
Careful bedding is an essential requirement to the piping sys-
tem. Bedding with approved granular material usually is speci-
fied . Care also must be taken in backfilling to prevent sharp
rocks or crushed stone from scouring the pipe.
Normal depth of pipe installation is no less than water main
burial for the same location. Pipe has been buried as shallow
as 0.45 m (1.5 ft) in Florida installations. Usual practice is
to secure the pipe at every change in elevation or direction by
the use of thrust block ing.
Various systems have different requirements for pressure
testing of the pipe. Typically, air or water testing for a
-71-
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period of 30 minutes to 2 hours has been practiced. The leak
test usually is perfrrmed at approximately 1,041 kPa (150 psig);
however, other pressures such as 694 and 868 kPa (100 and 125
psig) has been used.
Although solvent weld piping has been in common practice in
water systems for numerous years, push-tight joints on PVC pip-
ing have become an acceptable practice due to ease of installa-
tion, low leakage, and provisions for expans ion and contraction.
Solvent welds must be performed on a dry, clean pipe surface and
not during wet or very humid conditions. Bedding and pressure
tests would be similar to the requirements for water main in-
stallations for the same kind and class of pipe.
-72-
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SECTION 8
OPERATION AND MAINTENANCE
GENERAL
As with any complex mechanical system, pressure sewer sys-
tems require rigorous 0 & M. Some tasks are required daily,
weekly, monthly, semi-annually, annually or at longer intervals
for continued proper operation. Effective preventive main-
tenance has been found desirable in reducing the frequency of
emergency breakdown maintenance in pressure sewer systems.
This section is divided into tasks relating to 0 & M for
each of the on-lot components and those dealing with require-
ments of the piping system components.
The relative reliability of each system can be inferred by
analyzing a parameter called the "Mean Time Between Service
Calls" (MTBSC). This parameter, measured in years, determines
the mean time interval each component can last without a service
call for either repair or replacement. For example, if a system
had 400 pumps and each year 100 pumps required breakdown main-
tenance, then 25% of the pumps required service in a one year
interval. The MTBSC then is the reciprocal of the fraction of
pumps requiring service, or an MTBSC of 4 years.
Similar data is presented for most of the systems investi-
gated, where either detailed records were available, or where
the operator exhibited significant recollection to estimate
these parameters.
One of the greatest demands on an operator' s time in a
pressure sewer system is his supervision and coordination of on-
lot facility installations. Operators from Horseshoe Bay, TXj
Weatherby Lake, MO; Apple Valley, OH; Florida systems; Idaho
systems and other reported that they spend between 10 and 33%
of their time on this activity.
Inspection trips to various pressure sewer installations re-
vealed that recordkeeping generally is deficient. Most opinions
of operators are subjective and are based upon limited data, in
many cases, information given during interviews is contradic-
-73-
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tory. For example, where operators are of the opinion that the
system is performing well, service calls are understated when
compared to what documentation is available. The reverse often
is true when the operators are dissatisfied with system per-
formance .
The problem of securing objective data is compounded for hy-
brid systems, or those with several different pump manufac-
turers. Frequently no distinction is made between the types of
systems or the kinds of pumps serviced.
In this report attempts were made, wherever possible, to
segregate 0 & M information into distinguishable components.
Although potentially biased, pump manufacturers tended to be
good sources of more detailed information.
PUMPING SYSTEMS
Effluent Pumps
STEP systems at Port Charlotte and Port St. Lucie, FL, and
at Coolin and Kalispell, ID, include over 841 pump installa-
tions. The Florida locations are important because of the dura-
tion of operation; one area has been in operation since 1970.
In Idaho, the more than 588 pumps represent a sizable system.
Experience at these locations has been good and is expected to
improve because many early problems have been identified and
corrected. For example, at the Florida locations most pump
service calls were for pumps installed in the first three years.
Specifically, 11 out of 15 calls at Port St. Lucie were for
pumps installed in the first two years. Initially, Hydr-0-
Matic SP33, 1/4 hp pumps were used. Subsequently, it was shown
that pumps with oil-filled motor cavities (Hydr-O-Matic OSP-33a)
performed more reliably. Since 1974, at Port Charlotte, only 6
pump-related service calls have been reported for the 62 in-
stalled systems.
The oil-filled motor cavities caused problems at Idaho be-
cause leakage resulted in failures of the capacitor-relay
starter switch. Such problems were categorized as non-pump re-
lated and accounted for over 7 5% of operational problems. Leak-
age problems have been corrected.
Installation problems can account for a significant per-
centage of system failures. Twenty percent of the service calls
for pumps are ascribed to faulty installation at Port St. Lucie.
Likewise, in Idaho, poor wiring discovered at installation or
shortly thereafter was significant. As effluent pump installa-
tions become more numerous, it is reasonable to expect that
installation reliability will increase.
_74_
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The Florida systems originally used pressure switches for
level controls. Nearly 20% of service calls at Port St. Lucie
were related to pressure switch failures. Even though these
switches have an average life of 4 years and cost approximately
$15.00 to replace, some are being replaced by the more reliable
mercury float level switches.
A difficulty encountered in assessing STEP system reliabi-
lity is inherent in the manner in which service records are
kept. Problems with pumps are not necessarily reflective of the
total scope of system problems. For example, of the 191 units
installed at Port St, Lucie, maintenance records are fully
available for only 87. These records indicated 58 service calls
during a 5 year period; however, maintenance personnel report
about 5 to 8 service calls per month. Hence, assuming an
average of 6 service calls per month for the 5 year period (360
calls), roughly 16% were judged to be pump related. This figure
compares well with data from the Idaho systems where 12% (30 out
of 250 service calls in a 2 year period) of calls were due to
pumps.
Table 7 shows an approximate distribution of typ^s of 0 & M
problems at Port St. Lucie, along with potential remedies. At
all locations, a service call is made when the alarm light is on
and/or the toilets flush slowly.
The Idaho installations problems could be observed at other
systems located in rural areas. Frequently low voltages are en-
countered leading to increased pump currents and thence pump
overheating. Overheating in turn causes the two, 220 v fuses to
blow out and a failure signal occurs. Although the remedy is
simple - fuse replacement, the process is time consuming and
over a long term could conceivably be damaging to the pumps.
Pumps can become air bound when the pump vent hole becomes
plugged. The electrical cords and air vent 1ines are bundled in
Florida. In the event of a kink in the vent 1ine, repair is not
possible, and the entire bundle must be replaced. This is an
arduous task. Li kewi se, the bu idles cannot be extended, but
rather must be totally replaced.
Preventive maintenance plays a major role in reducing system
difficulties. Orig inally, the Florida systems scheduled pre-
ventive maintenance calls every three years. These are now per-
formed annually. Reduced service calls are attributed, in part,
to more frequent preventive maintenance. The Idaho system also
schedules one preventive maintenance call per year, at which
time the pumps and chambers are hosed to remove buildup of oils,
greases and scale.
Table 8 summarizes some of the important 0 & M characteris-
tics for the Florida and Idaho STEP systems. Parameters in-
-75-
-------
TABtiii ¦/, SERVICE CA_LL,S AT PORT ST. LUCIE, FL
Approximate % of
Total Service Calls
20
10
10
10
20
Problem
Installation;
a) Couplings blow off
b) Mercury float switch im-
properly adjusted
c) Inadequate electrical in-
stallation
Nothing wrong
House plumbing, pipes clogged
Frozen impeller - when part-
time residents leave and pump
is not in use scale builds up
on bridges from impeller to
pump body
Pressure switch
Remedy
a) Reattachment
b) Readjustment
c) Rewiring
Usually a plumber's
snake is sufficient
Manual rotation of
impeller to break
scale
Replace with mercury
float switch, new
pressure switch of
relieve kink in
breather tube
10
10
10
Electrical system
Pump clogged, can also be
caused by scale
Air lock (because of gas ac-
cumulation or air entrapment)
Call electrician
Refurbish pump
Retap pump vent hole
TAIlt.l; B. :;UMMAUY OI-' HFFI.UCNT PUMP MAINTKNANCt; HFCOKDS
Loc.it ion
Port St, Lucie
Iort Charlotte
Suction 18
Section
Cool in
K.i 1 ispo 11
Number of
I nst ii 1 lax. ions
101
25
33
356
232
Years of
Qperation
Number of
^rvica Calls
5 8
IS
IS
30
30
Me tin Time Between
Sc-rvice Calls
3.6 y r
6.3 y r
7.7 yr
37,4 yr3
37.4 yr3
*Jictst»d upon records for 8? pumps,
^iHimp related nervice calla.
'Hasud upon past two ye
-------
eluded are: number of installations, years of operation, number
of service calls and MTBSC. While these figures are estimates,
based upon records available, they do give an indication of
overall system reliability.
-77-
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Grinder Pumps (Semi-Positive Displacement)
Of the almost 100 pressure sewer installations in the
country, GP systems clearly predominate. As descri bed in
earlier sections, GP are either semi-positive displacement or
centrifugal types. Various operational and maintenance problems
are associated with each type of pumps; however, one general
class of problem with the semi-positive displacement pump has
been reported at every system visited. Moreover, this problem
comprised a very significant proportion of all system
failures. Hence, this problem - boot failure - will be dis-
cussed in some detail.
Figure 31 shows the five basic modes of boot failure, causes
of which are explained below. Tearing of the rubber skirt can
occur during short and periodic dry running of the pump stator.
This can be caused by failure of the pressure switch to shut
down pump operation after the chamber has been evacuated. I f
the pump runs continuously when dry, then the boot core can burn
out.
WEARING
OUT
SUTTIf
'—WEARING
BURNING OUT CORE
WEARING OUT NOSE
•TCARING OF SKIRT
Figure 31. Boot failure mode
-78-
-------
Another common failure mode occurs when the boot core is
worn out. This occurs when abrasives such as sand, plaster or
egg shells routinely enter the pump chamber. This problem can
be minimized by reducing the presence of abrasives through in-
struction of householders, installation of grit traps, or im-
proving the durability of the boot.
Core splitting can occur when over pressures of up to 694
kPa (100 psi) aro repeated for long periods. In most cases,
th.ic, J ess frequently observed problem can be minimized by care-
ful attention to overall system design and prevention of grease
buildup in service lines and mains. Finally, the wearing out of
the core nose is indicative of the end of boot useful life.
This problem is not regarded as normal and should not occur
for many years.
In its own evaluation of failure rates, the manufacturer of
the semi-positive displacement pumps has shown that inadequate
level switches caused boot failure at a rate three times that of
other pumps. Where chey corrected the level switch problems,
boot failures dropped drastically.
Typically at Horseshoe Bay, with about 50 service calls per
year, 75% of problems are ascribed to pressure switches with
another 10% attributed to booh failures from unknown causes.
The Lake Mohawk system also reports a high percentage of
service calls due to boot problems. Over 56% (98 of 174) of
service calls have been so categorized. During 1977, 85% of 80
service calls were for boot failures. 11 takes two hours for
one man to replace a boot, unless it is too deep for one man to
pull the pump; then two men are needed.
Country Knoll': South, one of the fitol semi-positive dis-
placement pump installations, reports 13,224 pump-months of ser-
vice. For this period, 391 pump repairs were reported. Boot
problems account for 64% of repair calls. Boot replacement
taKes from 1 to 1.5 manhours* Environment/One tested 20
selected pumps at this site by recording Doot:, failures before
and after raising the turn off level and readjusting the time
delay relays. These 20 pumps originally had the highest rate of
boot failures in the development. After modifications, no
failures were reported for the 13 month period to date.
The Sausalit.o, Kappas Gate 6 facility has 50 to 55 semi-
positive displacement pumps. The local pump representative re-
ported only 5 boot failures in two years. Replacement takes
about one manhour. Boot replacement at Weatherby Lake also is
reported to take one manhour. These problems represent about 39%
of all service calls. There was significant improvement in per-
formance of the semi-positive displacement pumps at Weatherby
Lake when the manufacturer replaced the time delay relay. In
-79-
-------
the older configuration the time delay relay switched on at 30
cm (12 in) and off at 14 cm (5.5 in). In the new edition, the
switch is on at 43 cm (17 in) and off at 30 (12 in) which is
similar to modifications made in the Country Knolls South test.
Clearly, this should be helpful in protecting the boot because
if the pump continues to run, the boot will remain immersed,
thus eliminating the dry running problems.
The manner in which maintenance records are kept can lead to
misinterpretation and erroneous diagnosis of problems. For
example, prev ious sections have shown that boot failures can re-
sult from several primary causes. At Lake Mohawk it was claimed
that 8 5% of service calls were boot failures. Only 5% are
attr i buted to pressure swi tch or time delay relays, when in fact
these may be the primary cause of boot failures.
Table 9 shows a distribution of service calls for two large
semi-positive displacement pump locations, i.e. Country Knolls
South (355 units) and Weatherby Lake (362 units), as reported
by Env ironment/One Corporation.
YMM.E 9. DISTRIBUTION OF SERVICES CAULS1
Country Knolls South
Problem Percentage
Boot failure 64
Time delay relays 1
Sensing ball plugged with 7
grease
Bearings 3
Centrifugal awitch 3
Unknown 16
100
Weatherby Lake
Problem Percent-age
Boot failure 39
Boot replacement, unknown 10
caui.e
Frozen discharge line 11
Pressure switch:
Failure 7
Overflow 8
Stuck 1
Circuit breaker off 6
Discharge check valve 6
leak
Jammed grinder 3
Unknown ()
100
•Now obsolete
'From data reported by Bnvironment/One Corp,
-80-
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Weatherby Lake service personnel have constructed a pump
test center for troubleshooting their semi-positive displacement
pumps. A breakdown of the types of service calls the system
experienced is included in Table 10.
TAULE 10. TYPES OF SERVICE CALLS - WEATHEttUV LAKE, HO
Install at ion
Pump and Piping Jnatallation
Elect riea 1
Circuit Breaker
Wiring
Horn Switch
Tot a 1
1'j.ibj)
Core Replaced - Damaged or Unknown Noise
Core Unplaced
JuMmsed Grinder
Motor Failure
Pressure Switch
Mechanical Seal
Shalt Seized
St .nor
Time Delay Relay
Cracked llousiny
Vibration
Repaired for Unspecified Heaaon
Total
I'ipin'l
llousio Service Line Broken or Blocked
Check Valve Leaked
Frozen Discharge Line
Total .
O t he r
Pump Tank Frozen
Lock on Tank I.id
Corroi; ion
Ho tiling Wrong
Vent Tank
Tot. 11
Total Service Calls
Pump Montha of Service
MTIJSC Total
Number
Calls
% of
Total MTDSC for
% of Service Category
Category Cal ) s (vearal
355
7,124
100
0.9
190
22
It
J! II
SB
37,9
27.6
3-1. 5
15.9
10.2
19
2
1
3
12
I
7
104
1
1
')
156
12.2
1 . 3
0.0
1.9
6t>
0
0.6
1 . 3
1 .9
5.4
0.6
0.3
0.9
~.4
0.3
2,0
29. 3
~. 3
0.3
0.6
0.9
44.3
3.8
11
7
JJ
37
29.7
18.9
51 .4
3. 1
2.0
_ 5 ,_4
10.b
16.0
2
1
1
10
_87
101
2.0
1 . 0
1 . 0
. 9
86. 1
0.6
0. 3
0.3
2.8
2tl . 'j
5.9
1.7
81-
-------
Table 11 shows a comparison of repair labor and costs for
several semi-positive displacement systems.
TAB Mi 11. SEMI-POSITIVE DISPLACEMENT PUMP SYSTEM REPAID I.ABOR AND COSTS
Location
Country Knolls South
Kappas Gate 6
Weatherby Laku
Lake Mohawk
Point Venture
Repair or Service
Control system
Boot replacement
Motor
Sea 1
Capacitor
Rotor
Bear ings
boot replacement
Boot replacement
f'resijuru switch
Time delay relay
Vi-nt kit
Clean stopped line from house to
pump
Klt'Ctrical
Pump overhaul parts:
Mutur
Uwitch
Time delay relay
i> e a 1 a
Boot.
.Small seals, bolts, nuts, etc.
Labor - M hrsl
Total
Boot Replacement
Hoot Replacement
Labor
(manhours)
2
1.5
1
1
0.7
1
0.3
0.2
0.3 - I
Cost
ill
50
J 92
1 20
B
30
2 U
•J
25
217
Grinder Pumps (Centrifugal)
One of the most commonly observed problems for centrifugal
grinder pumps is air binding and locking. Such problems have
been documented at Seabrook, TX; Apple Valley, OH; and Grand-
view, IN. Typical of the mode of repair is the procedure under-
taken at Apple Valley. The pumps are removed, shook and then
replaced. Such problems are most often seen at new pump
installations.
At Horseshoe Bay 3 centrifugal grinder pumps served 60 con-
dominiums, a clubhouse and restaurant. After 3 1/2 years of
use, there were no failures. Sixty centrifugal pumps have been
operating for a year at Horseshoe Bay. Only one service call is
reported and this was related to poor pump installation. Manu-
-82-
-------
factoring problems observed within two days after installation
were evident at Seabrook. Two of 16 pumps needed motor service.
Seabrook reports the following types of problems:
1. Two electrical control panel malfunctions, re-
paired by an electrician within 30 minutes.
2. One capacitor burn out.
3. One pump burn out.
4. One outage of unspecified cause.
At Apple Valley 55 service calls have been reported for the
centrifugal grinder pumps since October, 1974. Currently, there
are 51 pump installations. The operator claims that all but 4
or 5 service calls have been caused by grease on the fixed arm
float switches. Other service calls were related to skinning of
electrical wiring during installation causing a short circuit;
lightning; and defective wiring. The pressure sewers discharge
into a gravity system. The estimated division of operation and
maintenance between the pressure and gravity systems is 15 and
85%, respectively.
Table 12 shows labor and cost estimates for repair of cen-
trifugal grinder pumps.
TABLE 12. CENTRIFUGAL GRINDER PUMP RLUAiR LOCAL LABOR AND COST ESTIMATES
Hopair
Abrader Failure
Seal failure
2
Other repairs
Mew unit*1
Parts
Abrader
Impeller
Cutter
Seal
Motor
Pump refurbishing
Storage tank cleaning
Motor (2 hp)
Starter and control
panel
Part Cost
ILL
43
75
19
19
33?
741
175
Labor
shut).
3-4
0.3
1
Labor
ill
16 - 18
48 - 72
'Discounts: 25* for contractors
254 + 20% for wholesalers
*t'eabody Barnes, Sauaalito System (Uay Area, CA, May, 1978 costs)
^llydr-O-Matie, Seabrook System
-83-
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Valves
The most serious problem with valves is corrosion. At both
of the Florida installations inspected, Port Charlotte and Port
St. Lucie, the cast iron and brass valves corroded quickly. Ex-
perience has shown that bronze valves, now used at both Florida
systems, provide satisfactory results.
Every system using cast iron valves has noted corrosion
problems. Some other systems also have had trouble with brass
check valves. For example, the Klaus system in Portland has
replaced all of the original brass check valves with heavy duty
bronze valves.
Although several facilities reported no valve difficulties,
larger and older systems had some of the following types of
problems: grease plugs in-service line check valves; frozen
check valves; leaking check valves; and leaking air release
valves. Periodic flushing should prevent the formation of
grease plugs. In general, proper gasket and valve installation
can overcome most leakage problems.
ODOR ABATEMENT
Odor problems have been documented at several locations.
The most commonly observed location for odor problems is at lift
stations. Several novel methods have been used to overcome the
odor problems. For example, odors from the lift stations at
Kalispell are vented to a drainfield for soil scrubbing. At the
Klaus system when odors are found, the remedy involves resetting
the levels or timers on the pumps for more frequent intervals.
For the Klaus system, odors are a presumptive indicator of pump
difficulties, Weatherby Lake adds hydroara peroxide at three
lift station locations. About 0.06 ru^/day (15 gal/day) of
351 hydrogen peroxide is used for odot control.
Port Charlotte has the capability to add chemicals for odor
control, e.g. ozone or chlorine can be added at the pump station
before the treatment plant. However, odor abatement is rarely
used. In fact, the sister system, Port St. Lucie, has no odor
control capabilities.
At the Apple Valley system, pressure sewers discharge to a
gravity collection system. Odors have been noted near one man-
hole in particular; however, there is no conclusive evidence
that the odor results from the pressure sewers.
-84-
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CORROSION
Corrosion problems appear to be most severe in Florida in-
stallations. Difficulties with valves have been cited pre-
viously. in addition, steel clamps on pipes in pump chambers
corrode quickly. This problem has been cured by using all
stainless steel ba.
-------
Port Charlotte and Port St. Lucie, FL
In certain locations, nylon screens have been used between the
septic tanks and pumps as an experiment to determine if screens
can prevent wedging of large objects between impellers and the
pump housing. Screens clog because of large flctable objects
(presumably grease globules) and especially because of cigarette
filters. There is a serious questions of whether the screens
caused more problem than they were designed to overcome.
Klaus System, Portland, OR
One of the biggest problems in this system is misuse by home-
owners. Maintenance personnel have found garbage in the pump
chambers, and have removed sponges, shorts, sanitary napkins,
toys and balls from jammed pumps. Additionally, build up in
service lines require flushing about every six months.
Weatherby Lake, MO
This system has had poor exper ience with its alarm system.
Eleven horn or switch problems were reported in 1977. The
system has both light and horn alarms.
PIPING SYSTEMS
Preventive Maintenance
In general, the systems investigated had the canabilitv to
flush pressure sewer lines, hut most systems were flushed daily
only after a line was clogged. It may be presumed that such is
the case because system operators either believed that such
maintenance is unnecessary or because of lack of information on
preventive maintenance.
Table 13 summarizes information on piping system preventive
maintenance functions.
Breakdown maintenance, however, may not be the most cost-
effective solution for piping system maintenance. Many in-
stances of impaired hydraulic capacity due to grease buildup in
lines have been documented. Hence, running to failure could
lead to more expenditures than would be encountered if pre-
ventive maintenance were utilized.
The automatic flushing stations at Point Venture involve
submersible pumps in a water chamber controlled by an electronic
timer. At Apple Valley, flushing connections are available at
various locations. Some systems flush through cleanouts.
-86-
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TABLE 13. PIPING SYSTEM PREVENTIVE MAINTENANCE
Location
Maintained By
Flushing Frequency
Other Maintenance
Horseshoe Bay
Municipal Utility
District
Two weeks/year; also
automatic flushing
stations
Point Venture
Development operator
Four automatic
flushing stations
Apple Valley
Cour.ty
Annually
Quarterly installation
checks
Country Knolls
Development operator
At breakdown
Port Charlotte
Development operator
At breakdown
Septic tank pumping
Port St. Lucie
Development operator
At breakdown
Septic tank pumping
Kalispell
Development operator
At breakdown
Septic tank pumping
Klaus
Homeowner
As needed
Kappas
Homeowner
None
Grandview Lake
Homeowner
At breakdown
Septic tank pumping
Examples ot preventive maintenance utilized in several
systems include:
1) Apple Valley - In-line shutoff valves are manually
operated once or twice a year and direction of flow is
changed at about the same frequency for looped service
lines and mains.
2) Klaus System - Pipe flushing uses river water. For
example, it takes about two hours to flush about 1,200
feet of pipe. Lift stations are inspected every two
weeks with routine ma intenance occur ring monthly.
3) Grandview Lake - For installations where a septic tank
is involved, homeowners ptomp septic tanks about every
3 to 4 years.
MaIf unctions/Other Problems
A
Most piping system problems can be categorized as construc-
tion and installation related, leaks and breaks, and frozen
lines. In the first instance, problems occur when lines are not
installed at the proper depth and structural damage results when
there is poor pipe bedding; and when dirt or other foreign ob-
jects enter the lines during installation.
Leaks and breaks appear to be more frequent for dockside and
houseboat systems, which should be expected. This happens when
there is insufficient compensation to overcome shifting from
wakes and tides. At the Kappas system, six breaks were reported
for 35 installations over a two year period. Repairs took 10 to
15 minutes. Twice main dock lines came apart because of shi ft-
-87-
-------
ing and no hub fittings on the ABS pipe. Also, problems on the
connections between flexible hoses and rigid pipes have been
eliminated by installing a 90° elbow with a quick disconnect
f itting.
Other difficulties include clogging of lines because of air
and solids buildup, and solids accumulation at line ends. In
the latter case, the solids are soft and appear to be saponified
grease.
SYSTEM COMPARISONS
An estimator of the total operation and maintenance efforts
involved in the STEP, GP and solids handling pump systems is
presented in Table 14. The majority of the information avail-
able is in pump reliability, expressed as the MTBSC. Estimates
of overall system performance were obtained for only one of each
type of system, and may not provide a true indicator of system
reliability, including piping problems such as leaks, freezing
or air locks. Pump maintenance requirements are thought to be
over estimated, with actual operating pumps now yielding a
longer MTBSC than presented. This reflects the effect of vari-
ous and continual modifications made by pump manufacturers to
their units.
TAiLE 14. MtAN TIMfc UtTWCLN SlNVICt CklL'i *OK Al t TVI't-S Or PIO.S5.Ufci; SCHtK itSTLHS
Syatuw Y-.'.if
Si.jrl.ui
Pdrt Charlotta, PL ftti- j *?u
SictlOn 5*
foil €h*rlOtt«, PL STEP 1970
Section II
Port St. Luclw, I'L STLP I H ? J
Prlaat L*ke, iO STLF 1974
A»pl« VtlUy, OH CP 19?J
Saabrook, TX CP 1IH
SauaaHto, CA Houm- GP
boats
Point V«niur«, TX CP lt?J
Waath«rby L»k*, MO CP tt?5
Schanactady, Hf CP 1173
C&npball Avanu*
CmlUr, HO GP mt
Horataho* Sty. TX CP 197?
Country Knolia, w* CP H7J
Like Kohaw*, OH CP 111*
Ulil of tbm Pin.a, P* CP ISH
0u*k«r L±»ua, PA CP 1914
Portland, OR Hew§«- Solida 1941
boat* Handling
¦auaal 110, CA Houao- SnUdi
ba*ta HindiIn?
OVKJI )
!,2 •»!.<.,
I.J
),«
?. 5
t (
I,ft
2.1
1.0
1.5
i.4
Hyde -O-H ¦_
7.?
ft. 3
1,4
19.4
I ,5
5,4
10.0
Tor«>
5.1
1.0
-88-
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SECTION 9
TREATMENT
GENERAL
Characterization and treatability of pressure sewer waste-
water typically has been one of the most neglected aspects of
the entire pressure system concept. One of the most notable
benefits of a pressure sewage collection system is the veritable
absence of infiltration and inflow within the closed piping
system. However, there is the possibility of some infiltration
and inflow if there are leaky or poorly inspected joints between
the house and pumping unit, or if water enter* the pumping unit
basin or septic tank through cracks or misfitted joints.
Approximately half of the pressure sewer systems transport
sewage to their own treatment facility. Many of the systems
have treatment facilities that combine the pressure collected
sewage with sewage from other areas served by gravity. Of the
sites visited in this study, Country Knolls South, Horseshoe
Bay, par t of Port Charlotte, Grandview Lake, Coolin and Kalis-
pell, Lake Mohawk, and the Glide-Idelyde have their own treat-
ment facilities fully dedicated to treating 100% pressure
collected wastewater.
The major difference between GP and STEP system wastewater
is that GP system sewage has more concentrated BOD, SS and other
characteristics than gravity collected sewage; whereas STEP sys-
tem wastewater has lower concentrations compared to gravity
collected sewage. However, there may be some individual para-
meters that do not adhere to this generalization. Also, in STEP
systems, septage must be pumped out on a regular basis and the
treatment and disposal of this material must be taken into
account. For a further discussion of the treatability and state
of the art concerning this material, see reference (32).
-89-
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WASTE CHARACTERISTICS
Grinder Pump Sewage
Grinder pump sewage contains from moderate to strong waste-
water when compared to conventional gravity sewage. It is typi-
cally 25 to 50% stronger than in domestic gravity collected
sewage. Grinder pump sewage also produces more finely divided
solids (smaller particles) than a communitor in a conventional
treatment facility. Kreissl's (3) report indicates potential
for large variations in flows at a sewage treatment plant serv-
ing a community that only has pressure sewers. This large vari-
ation in flow has not been seen in any sewage treatment plant
visited during the course of this report.
The appearance of very fine particulate matter in GP sewage
is a consequence of the effective grinder mechanism in the
pumps. A disadvantage associated with this very finely ground
sewage may be that the solids tend to settle out more slowly
than they do in conventional gravity sewage. Figure 32 compares
the South Pearl Street GP sewage collected in the Albany
pressure sewer system study with gravity collected sewage in
tests at the Battelle Laboratories' pilot plant. Better re-
movals for comminuted gravity collected sewage compared to
pressure collected sewage from a GP system are shown at various
overflow rates.
Grinder pump sewage exhibits consistently higher organic
loadings than gravity collected sewage. The average influent
BOD5 of typical municipal wastewater is reported to be about
200 mg/1 by General Development Utilities in Table 15, while the
systems in Table 16 repor t a mean BOD 5 of 255 mg/1 with a
range of 93 mg/1 to 690 mg/1. Similarly, General Development
utilities reports typical municipal wastewater contains 200 mg/1
3S, while the systems in Table 16 report a mean SS of 264 mg/1,
with a range from 60 mg/1 to 1,080 mg/1.
3TEP System Sewage
STEP system sewage also has little or no infiltration or in-
flow as a result of the tight piping system. Removal character-
istics of the septic tank result in lower average concentrations
¦>£ organic loading than conventional gravity sewer systems. A
recent EPA report lists typical septic tank effluent as 100 -
L80 mg/1 BOD5, SS removal of 70 - 90% and grease removal of 70
- 90% in septic tanks. While these numbers reflect excellent
removals, many similar systems show significantly lower removals
:or all these parameters. It has been observed and reported
:hat there is some conversion of solid BOD5 into soluble BOD
.n the septic tank (5) . This liquification is reported to be
ntermittent and may be accompanied by gas production.
-90-
-------
60 -
50 -
Of 40 -
Q
3
o 30
w
a
w „„
o 20 -
UJ
a.
m
3
tn
10 -
1080
BATTELLE NORTHWEST (GRAVITY)
SOUTH PEARL
(pressure)
i
.15
1520
OVERFLOW
i
.20
2ieo
RATE
i
.25 (M/min)
3240 (spd/tl2)
Figure 32. Percent suspended solids removal vs overflow rate.
TABLE 15. MUNICIPAL HOUSEHOLD SEWAGE CHARACTERISTICS, ALBANY, NY
Parameter
mail
BOD.
ss
Total Solids
COD
Aromonia N
TKN mg, N/1
Total P mg, P/l
Ortho P0,
4
Alkalinity
Grease
Albany Project
L8J
180
200
700
400
11
31
11
40
Typical Municipal Waste
<3Si
210
200
600
350
12
33
24
14
[361
143
16.1
18.3
22.8
122
HZ1
200
200
700
500
25
40
100
100
Household Wastes
With Grinder Without Grinder
16)
490
480
910
81
105
57
89
i£L
435
380
710
64
84
61
65
-91-
-------
TABLE 1*. GtJMOC* AWO SOL2OS HANDLING PUHP SCW*CE CHARACTERISTICS
Crandvirv lake, XN
ti^7t - itm
Far^rtec
ss
Total Solid*
COO
Anmonfc* N
M02 4 NOj, »? "/i
TJCH
Total f
Grtho kj(
Alkalinity
Crcas*
pK
Ke#n
*30t
211
4}.*
7.21
lUngc
2(4 - 371
111 - 398
(2.1 - 45.3
14.1 - U.«
(J - t.«
Ward Sytta
Iwflutnt
Hcan
234 135 - 315
22* 12* - 34?
Lake Koh«»»i.
Kalvgrft, Oft
Mean
m
102
Hangc
93 - 119
(0 - lit
He«n
330
318
;n
*55
Si
0.1
14
15.f
».7
HI
• 1
kibmny. KY
jwflw«Bt
Hangc
21® - 504
131 - HI
S26 - f21
57© - 1,450
34 - (I
41 . 244
2.3 - 4t.l
1.3 - 11.9
ItS - 20*
Fhotnlmvil1c. >A
Inglwcnt
He»w
14*
211
SI
ll.S
2
241
J1
7.1
149
*.7
»*nq«»
104 - 191
101 - 514
311 - 524
36.5 „ 74.1
S.» - 1»
7.2 - t.3
Gr«ndv>e» L«X». in
Inf)uewt
W«an Wanqc
3*0 It© - 470
41? 145 - l.CtO
«
I
551 410 - 707
35 17 - 70
t.l 1-7
31 23 - 37
•HOj only
-------
Influent concentrations for various parameters are shown on
Table 17 (24). Only the Gulf Cove plant in the Port Charlotte
area treats exclusively STEP sewage. Limited data is available
in many systems as frequently only grab samples are taken. Com-
posite sampling techniques and recorded flow information is
generally not available.
TABLE 17. STEP SYSTEM SEWAGE CHARACTERISTICS*
Parameter (mq/1)
BOD-
!>
SS
Total Solids
COD
Ammonia N
N02 + N03, mg N/1
TKN
Total P
Ortho PO,
4
Alkalinity
Grease
PH
Dissolved Oxygen
Sulfide
Port Charlotte
Lakeshore
Circle Effluent
Itoldiryj Chambers
135
97
537
7,2
Port St. Lucie
Suburbanaer
Project
206
44
600
320
42
0.01
51
29
335
Port St. Lucie
Septic
Tank Effluent
92.5
107
706
31.7
14.7
7.5
Port Charlotte Gulf
Gulf Cove stp
Through 1975
Influent
123
102
834
0.01
5.55
7.83
7.2
Effluent
6.9
14.3
583
0.79
1.00
1.08
7.26
•Reference 24.
GRINDER PUMP TREATMENT PLANT DESIGN AND PERFORMANCE
As prev iously noted, the f inely ground solids associated
with GP sewage have been known to reduce the efficiency of
primary clarifiers in various systems. If primary settling
tanks are used, possibly more settling time and surface area
should be allocated to systems treating only GP sewage in order
to achieve the same removal of settleable materials as with
gravity sewage. However, treatment facilities such as the Lake
LBJ MUD at Horseshoe Bay and Lake Mohawk system, both of wh ich
have their own sewage treatment plants, find no difficulty in
removing SS even with a design based on conventional influent
characteristics.
-93-
-------
With a higher organic loading per unit volume in GP sewage
treatment systems, treatment kinetics may dictate a higher mixed
liquor SS concentration is needed to achieve the same removals
as would be observed in ?i system treating gravity sewage.
No treatment plant operator, either verbally or in reports,
mentioned any problems with variation in flows at the treatment
plant in pressure sewer systems. Sewage from a GP system also
has been noticed to be anaerobic when entering the treatment
facility.
Systems to date have not exhibited any difference in treata-
bility where loading characteristics did not differ between GP
vs gravity sewage. Effective treatment was found at conven-
tional treatment facilities at Horseshoe Bay, at the Ward system
in Bend, OR, and at the Lake Mohawk, OH tertiary plant utilizing
Hydroclear sand filter units which exhibited excellent and con-
sistent removals. It can be concluded that GP waste offers no
barriers to conventional biological treatment and any biological
treatment facility can, with minor modifications, accomodate
pressure sewage loadings.
STEP SYSTEM TREATMENT PLANTS
Due to the limited use of STEP systems throughout the
country, only one STP exclusively treats STEP system wastewater.
This is an extended aeration plant located in the Port Charlotte
area called Gulf Cove. Influent concentrations at this facility
typically are slightly lower than conventional gravity collected
sewage. However, wide variations have been observed. Lower
concentrations than the mean are due to recirculation of ef-
fluent into an influent pipe line. Significantly higher concen-
trations , of at least an order of magnitude have been observed,
but their causes are undocumented.
Since septic tanks remove a large portion of the SS and a
significant portion of the BOD5, plants may exhibit a lack of
adequate solids for treatment. In the case of the Gulf Cove
plant, sludge is frequently trucked in from other facilities in
order to supply enough biomass for continual treatment.
TREATMENT FACILITY 0 & M CONSIDERATIONS
General
Most treatment facilities treating either GP or STEP system
wastewaters have 0 & M considerations or requirements in direct
relationship to the sophistication and type of facility. Small
treatment systems generally have infrequent operator attention
similar to serv ing a conventional gravity sewered area. Typical
-94-
-------
maintenance tasks include: wasting of sludge; oiling and
greasing equipment! and recording plant information. Lagoon
systems are typically less labor intensive than a mechanical
system. More sophisticated treatment facilities, which may in-
clude chemical addition or tertiary treatment as well as larger
systems which accept pressure sewer waste, require significantly
more operator attention and management to insure continuously
effective treatment.
Maintenance requirements are low for small communities
having treatment plants in a pressure sewered area. At Horse-
shoe Bay, TX, the operator estimated 20 hours per week are spent
in operation. The operator reports approximately half of his
time is spent maintaining the aeration equipment at the aera-
tion tanks and the other half spent on the tertiary facilities
at this 379 m^/day (0.1 MGD) facility. Operational problems
include odors (present only during high humidity and temperature
conditions) and some corrosion at the lift stations and in the
chlorine contact tanks.
At Lake Mohawk, the operator reports approximately 55 hours
per month are spent on the treatment system, of which about 10
hours per month are spent at the lift station leading into the
plant, and the remaining 45 hours at the plant. This plant con-
sists of a 379 mVday (100,000 GPD) Env ir onment/One batch
type treatment unit and an additional 379 m3/day (100,000
GPD) activated sludge extended aeration type unit. Both units
feed into Hydroclear filters, then to a chlorine contact tank.
In this system, moat of the 45 hours per month of labor is
spent maintaining and operating the Environment/One batch type
unit.
Lagoons
Data is currently unavailable on STEP sewage treatment
lagoons. For example, the two systems at Kalispell Bay and
Coolin, ID accept pressure collected waste from STEP units.
These two cell aerated lagoons usually are operated in a facul-
tative mode without aeration during winter. Because the area
experiences a net evaporation, these basins act as non-overflow
containment lagoons. At some point in the future influent flows
will exceed the evaporative capacity and an existing spray irri-
gation system on nearby woodlands will be placed into use. At
this time there is no information on the effect or desirability
of spraying lagoon treated STEP sewage treatment.
Small Scale Treatment
In this report, most pressure sewer systems served 100 or
more homes. For cost-effective smaller treatment facilities,
consideration should be given to having several homes served by
a community disposal f ield or subsurface alternative. Where
-95-
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community facilities are employed a maintenance program may more
readily be instituted, A properly trained maintenance staff re-
sults in better system performance and relieves homeowners of
duties they may be ill-suited to accomplish.
A number of community alternatives exist, such as drainfield
disposal, sand mounds and sand filters. Mounds are used in
areas where a conventional soil absorption field is unsuitable
due to either slowly permeable soils, excessively permeable
soils, shallow soils over bedrock or seasonally high ground-
water . (26) The seepage system is built above natural ground in
a mound of sand which serves to distribute the effluent over a
large area. Dosing and pressure distribution principles are
used and laterals are small diameter perforated pipe. Properly
applied mound systems have proven very satisfactory.
Several designs of sand filters have been used to treat
septic tank effluent, most notably the intermittent sand fiIter
(ISF) and the recirculating sand filter (RSF). Effluent from
sand filters may be irrigated or disinfected and discharged to
receiving streams. The ISF is a sand bed of generally 0.61 to
1.0 m (2 to 3 ft) depth, receiving septic tank effluent with the
filtrate collected by underdrains. A typical size is based on
1.2 l/m2 (5 gal/day-ft2) and normally two are used to allow
a resting period. A common maintenance frequency of raking or
removing the top sand is at about six month intervals, though
this and effluent quality will vary depending on the sand size
used. Effluent BOD and SS normally are in the order of 10 mg/1
and 5 mg/1, respectively. Work by Sauer (27) and others (26)
contains more detailed information.
To reduce odors and extend the length of filter runs, Hines
and Favreau developed the RSF (28). This consists of a recircu-
lation tank and open filter of coarse sand. Effluent is dosed
onto the filter by a pump in the recirculation tank. The pump
is activated by a timer and provides about a 4:1 recirculation
rate. The sand bed is 1 m (3 ft) deep and is sized for 0.12
m3/day-m2 (3 gal/day-f'r.2). Both the recirculation rate
and sizing are based on the flow from the septic tank. Main-
tenance of the sand bed consists of removing the top 2.5 cm (1
in) of sand yearly. Hines reports BOD5 and TSS to average 5
mg/1 and 6 mg/1, respectively, following RSF treatment, (29)
and this has been buttressed by other experience. (30)
-96-
-------
SECTION 10
COSTS
CAPITAL COSTS
General
Use of pressure sewer systems has been promoted due to a
potential cost advantage in certain areas where gravity sewers
tend to be significantly more expensive. These areas include:
low density development areas that are unsuitable for on-site
disposal? hilly terrain where steep gravity sewer cuts or
numerous lift stations would be required; lakefront commun ity
developments where a gravity sewer serving lakefront lots would
have to be laid at an elevation below the lake level; areas with
rock close to the ground surface; areas with high groundwater
tables? areas where significant shoring and dewatering would be
required for installation of a gravity sewer system? and second
home or low growth developments where lots sales and home de-
velopment are slow and initial capital costs can be reduced.
Various communities either have estimated the cost of or
have installed pressure sewer systems for far less than a con-
ventional gravity alternative. In Central Chautanqua, NY, a
pressure sewer alternative would cost $1,200,000 vs $2,600,000
for gravity (4). The Grandview Lake estimate was $10,000 per
home for gravity sewers vs $2,000 per home for pressure sewer
systems. In Saratoga, NY, a small area was estimated to cost
$100,000 to sewer by gravity yet the area was served by GP for
only $20,000. In the Priest Lake, ID communities, approximately
$12,000,000 would have been spent for gravity sewers vs an
approximate installed cost for pressure sewers of $1,000,000 in-
cluding treatment. In the Glide-Idelyde system Bowne estimated
a present worth of $4,700,000 for the gravity alternative vs
$2,400,000 for the pressure sewer alternative. Golf View
Estates, IN estimated a gravity sewer system would cost $2,100
per lot vs a pressure sewer system cost of $1,550 per lot. In
the General Development Utilities, FL, one area of Port Char-
lotte serving 1,517 lots by gravity would cost $3,500,000 vs an
effluent pump system costing $1,200,000. Coincident with the
General Development Utilities savings in collection systems,
there was a concurrent savings {1977 dollars) of $ 164,910 .00 for
-97-
-------
the STP. The reason for this savings is the reduction in in-
filtration and inflow from a tight piping system, and a lower
wastewater strength due to the septic tanks removing a portion
of the organic loads.
Other alternatives are available besides a complete pressure
sewer system. For example, in Lake Lakengren, OH, a complete
gravity system was estimated to cost $3,810,000? however, a
combined gravity and pressure sewer system, where the pressure
sewers served only those areas that were difficult to be served
by gravity, would cost an estimated $3,117 ,000. Some other sys-
tems reported only the cost of the pressure sewer alternative.
Diamond Head development near Tulsa, OK is an estimated cost of
$1,500 per unit including collection lines and $2,300 per unit
including treatment. The Gulf Cove area in Port Charlotte was
estimated to cost $15,000 for 25 to 30 homes for collection.
Kreissl (3) reported seven unidentified municipalities with
reported savings from 34 to 83% over a gravity system. Per lot
costs averaged in the range of $2,000 to $3,000 with some rela-
tionship to the size of the development, that is, the more units
on the development, typically the greater the savings.
Kreissl*s analysis, however, did not take into account specific
regions of the country, labor rates, geological or hydrological
conditions.
On-lot Capital Costs
Kreissl reported on-lot equipment costs range from $700 to
$1,500 for GP pumping units alone, whereas GP packages cost fran
about $1,400 to $2,000 including the pump, basin, control panel
(where applicable), level controls, valves and piping (3). In-
stallation costs are an additional $300 to $700. Effluent pumps
frequently cost as much as $500. One manufacturer (33) esti-
mates the price of a union-type system as $841 and the rail-type
at $1,089. A fiberglass basin and pump cost approximately
$1,279, or $1,118 with a concrete basin. This includes the
basin, pump, controls, level controls, valves and piping. In-
stallation costs for the total system would be between $1,000
and $2,000 (33) Bowne estimates a STEP system price of $450
for the septic tank, $150 for the pump vault, $250 for the
effluent pump, $150 for electrical work, and $400 for installa-
tion, for a total cost of $1,325 (3) . Installed costs range
from $1,875 if the unit is located inside the house and $1,990
if the unit is installed outdoors. Typical installation costs
at Apple Valley after the pump package has been purchased, are
detailed in Table 18. A summary of on-lot facility construction
costs are shown in Table 19. A summary of piping system con-
struction costs, both estimated and actual, are shown in Table
20.
-98-
-------
TABLE 18. TYPICAL INSTALLATION COST OF SIMPLEX PUI4P UNIT
Backhoe
4
hours
e
$15.CO/hour
$ 60.00
shop Preparation
2
hours
«
6.00/hour
12.00
Man Hours Installation
IB
hours
e
6.00/hour
108.00
1%-inch Force Main (average)
150
feet
t
0.75/foot
112.50
3-12 electric wire (average!
75
feet
«
0.14/foot
10.50
•j-inch conduit (average)
17
feet
t
0.17/foot
2.89
*i-inch clamps
2
(
0.07/eaeh
0.14
30 amp Box
1
«
12.75/each
12.75
Breaker
I
«
8.40/each
8.40
Electric Fittings (box)
3
«
0.15/each
0. 45
Greenfield Fittings
2
t
1.90/each
3.80
ABS 4-inch Pipe
2
feet
t
1.25/each
2.50
Mater Plug
1
gallon
I
4.90/gallon
4.90
4 - 6-inch Rubber Seals
2
e
3.70/each
7.40
4-inch Plug (sewer)
1
!
2,40/each
2.40
Discharge 1%-inch Galvanized
1
*
1.13/each
1.13
Adapter Plastic to Steel
Stainless Steel Clamps
4
i
0.60/each
2.40
2>j-inch Saddle
1
e
7.80/each
7.80
1-ineh Corporation Stop
1
9
11.12/each
11.12
3-inch Brass Nipple
1
8
1.46 /each
1.46
H-inch Galvanized Coupling
1
t
1.35/each
1.35
l's-inch Galvanized Adapter
1
t
1 -13/each
1.13
Granular
8
tons
t
3.20/"ton
25.60
$ 400.62
This does not include the cost of
pump or controls.
~Hydr-O-Matic Simplex Pump unit at Apple Valley, OH,
Treatment Plant Costs
Construction costs for facilities treating pressure
collected sewage are not significantly different than those
facilities treating conventional gravity collected sewage. The
aerated lagoon system at Grandview Lake was constructed during
the 1974 to 1977 period at a total estimated cost of approxi-
mately $80,000 ($15,000 for excavation and earthwork and $65,000
for equipment). A Neptune Microfloc tertiary treatment facility
at Horseshoe Bay had an initial capital cost of $190,000 in 1973
to treat 3,000 m3/day (560 GPM). No plant design changes
were made to accomodate the pressure collected GP sewage. A
STEP treatment system at Priest Lake cost $65,000 in 1971. The
Harrison, ID treatment facility uses a lagoon system for treat-
ing effluent pumping system wastewater and cost approximately
$90,000.
-99-
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TMIX It. OW-LOT r*C3tSTY CONSTRUCTION COSTS
£. i « c i S c *
5 3 1 I I ! 8 | * 3 z a
! I 5 1 § £ 8. ° i I i | i ! i §
Is; 1 |
I 5 I I 3 t sit s I I s I a a
Tyf*
CP
a»
CP
CP
CP
STEP
STEP
STEP Solid.
STEP
CP CP
CP
STEP
CP
STEP
Tear
1S7I
1969
197S
1573
1935
19??
1975
197S 2971
1973
1973 1972
1974
1975
1974
1977
CCI
i.sbi
1.249
2,212
I.MS
2.212
2,577
2,212
2,212 2.493
1,195
1,195 1.753
3,020
2,212
2,401
2,577
Tot*i On-iot
2,050
1,582
2,000
72?
1,325
1,334 1,106
6?2 - m
1,3SC - 1,500
2,129
»2 - 992
1,300 - 1
.400
Crinder Pump
900
1,000 -
i.se©
1,1*2
1.200
1.8(1
3.150
9«7 - 1,19?
Effluent Pu^p
IU - 229
230 - 425
421 - 511
«0C -
500
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295-320
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6-31
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29
IS
12
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9
11
24
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7.4 c« f3 »nl clamp
Corporation Cock and 25
10.2 c» {« in> clawp
Corporation Cock *T>d SO
IS.2 cm (6 »nj cla»p
Wye lor Double Service 22-5
Pcmyre Service 2i0
Connection
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OPERATION AND MAINTENANCE COSTS
On-lot Facilities
Maintenance is required to keep pumps or their ancilliary
components in operating condition. Leekman {17) has estimated
$4 to $8 per month is necessary per GP for O & M. Dounoucos
(33) has estimated between 1.4 and 2% of the on-lot capital
costs should be allocated to annual 0 & M. Bowne (5) has re-
ported GP service contracts cost between $48 to $60 per year;
however, at Grandview Lake service contracts cost in excess of
$180 per year. A charge of $9 per lot is made for 0 & M at
Apple Valley. In addition, a $15 per quarter user fee is
charged to those lots connected to the system. This fee is
placed into a fund to repair on-lot and piping system com-
ponents. Golf View Estates has a $6 per month service charge.
0 & M costs of effluent pumps are estimated to cost sig-
nificantly less than GP, principally because there are fewer
moving parts. Bowne estimates nearly one half of the planned
$9.50 monthly charge will be allocated to maintenance of the
pumps and interceptor tanks (21). Of the $50 per year fee for
the effluent pump maintenance, approximately $20 per year is
allocated to a fund for pump replacement only and the remaining
$30 per year is for maintenance calls and pumping of the septic
tank at approximately ten year intervals. Typical pump overhaul
costs are presented in Table 21.
TABLE 21, PUMP OVERHAUL COSTS
Part
Cost
1.
Motor
$ 120.00
2.
Pressure Switch
B.00
3,
Time Delay Relay
30.00
4.
Seals
20.00
5.
Boot
9.00
6.
Small Seals, Nuts, Bolts
5.00
$ 192.00 plus four
hours labor
For a new installation, the total less cost of pump core is $200.00 material,
plus $800.00 labor.
-102-
-------
Electrical Costs
Pressure sewer systems use electrical energy to transport
wastewater to its point of disposal. For example, at the
Albany, NY and Phoenixville, PA experimental pressure sewer sys-
tems, EPA reports an electrical usage of 0.264 kw hours/m3 (1
watt hour/gal) to transport the collected sewage (3). This
equals $0.27/month/residence at $.043/kw hour (assuming each
residence has four persons each using 0.2 m3/day (50 gal) per
capita per day). Grinder pumps are less efficient in transport-
ing sewage than an effluent pumping system, since a GP will use
1.1 to 1.5 kw (1 1/2 to 2 hp), whereas an identical effluent
pump will use between 0.25 and 0.75 kw (1/3 and 1 hp) to produce
the same head and flows. This is due to the energy used to
drive the grinding mechar ism. Bowne estimates a 0.25 kw (0.33
hp) effluent pump unit can be operated at about $0.10/month in
his area of Oregon (21) . Another EPA report estimates both
grinder and effluent pump cost roughly $0.20/month for power
(3) .
At General Development Utilities, system operators estimate
the cost of operation at $1.33 unit/year ($ 0.05/kw hour). At
the Apple Valley system, if two or more homes share one GP, the
home supplying power receives a deduction of $1.50 per quarter.
The other home(s) on the line pays the full amount. Table 22
summarizes various typical annual power consumption and costs.
TABLE 22. TYPICAL ANNUAL POWER CONSUMPTION OPERATING COSTS
3
Estimated kwh
Appliance
Average Wattage
Consumed Annually
Cost t $0.044/kwh
Grinder Pump1
1,121
100
4.43
Effluent Pump2
247
27
1. 18
Oven - Microwave
1,450
190
8.42
Oven - Self Cleaning
4,800
1,146
50.77
Range with Self Cleaning Oven
12,200
1,205
53. 38
Refrigerator/Freezer (frostless 14 ft')
615
1,829
81.02
Washing Machine - Automatic
512
103
4.56
Water Heater - Standard
2,475
4,219
186.90
Air Conditioner - Room
1 ,566
3,445
152.61
Television - Solid State Color
200
440
19.49
Haste Disposer
445
30
1. 33
Trash Compactor
400
50
2.22
Coffee Maker
894
106
4.70
Energy Associates;, 1973.
-------
Piping Systems
Piping system 0 & M costs are by far overshadowed by the
maintenance efforts and costs associated with maintaining and
repairing on-site pumping units. As a comparison, gravity sewer
systems have been reported by the EPA to cost approximately
$0.23 to $0.26/m ($0.07 to $0.08/ft) per year which is equiva-
lent to .$248/km/year ($ 400/mile/year) (3). Bowne has estab-
lished some costs for maintaining rural water supply syst&ms
using small diameter PVC piping (21). (These costs are assumed
to be equivalent to those encountered in pressure sewer system
piping.) These costs are approximately $62 per km/year ($100
mile/year). This number reflects automatic air release valves
rather than manual air release valves, since manual valves re-
quire more operator attention. Grinder pump systems requ ire
more attention and therefore experience a higher 0 & M cost per
LF than effluent pumping systems due to grease buildup problems.
The Sausalito pressure sewer system, using GP to serve
houseboats, indicates the only problems are flex ible hoses
breaking and flexible connectors between rigid pipe lengths oc-
casionally cracking. These costs plus those associated with
maintaining lift stations are recovered by allocating $2.00/
month/user from the monthly moorage fee to an 0 & M account.
Other malfunctions with bur ied piping include: vehicles may
run off the shoulder of roads and run over shallowly buried PVC
piping, causing breaks; grease plugs; and infrequently reported
stoppages and leaks. Since these occurrences are sporatic and
highly variable with regard to the amount of time requ ired to
repair, costs are difficult to obtain and categori ze.
Treatment Plants
In Apple Valley, OH, the mechanically aerated treatment
plant with micro strainers treats mostly gravity collected
sewage and has an estimated charge of $83.32/lot/year. Country
Knolls South plant, using an Environment/One physical-biologi-
cal-chemical treatment plant, had a labor charge of $1,000/
month, a power bill of $800/month, and chemical usage of $800/
month. Customer charge was $40/year for treatment. The General
Development Utilities' Gulf Cove plants in Florida have an ex-
tended aeration facility serving 25 to 30 homes. The facility
initially cost $5,000 in 1972 with a plant operation cost of
$0.15/m3 ($0.56/1,000 gal). An additional treatment plant at
one of the General Development Utilities will service 1,517 lots
and treat 790 m3/day (208,500 GPD) less sewage using an ef-
fluent pump system compared to a gravity desi gned system. This
will save an estimated $42,635 in treatment costs. Of this
amount, $6,800 is directly associated with energy savings. The
lagoon system at Priest Lake, ID, had 0 & M costs of $8,600/year
in 1971.
-104-
-------
SECTION 11
MANAGEMENT IMPLICATIONS
GUIDANCE AND REGULATORY RESTRICTIONS
Existing or approved pressure sewer systems have been found
in at least 30 of the 50 states. Every state contacted indi-
cated a willingness to consider the installation of a pressur-
ized sewer system.
Requirements vary from state to state, such as California
which requires consultants to review options for providing an
"intrinsically safe" environment in the pumping chamber, in
accordance with the National Fire Protection Association (NFPA),
the National Electric Code (NEC) and California OSHA. One
California state official believed "intrinsically safe"
components will result in a 50% increase in on-site component
costs. This requirement is intended to reduce the risk of ex-
plosion from hazardous material spillage. Local codes not only
affect plumbing work, but also affect electrical work. Certain
areas have requirements for separate circuits for pumps as well
as controls and may also have requirements for approved wiring,
underground conduits, local disconnects and types of connec-
tions between the pump and household service.
Texas endorsed pressure sewer systems early in their history
and emphasized thirteen items in their design review: the number
of pumps on at any one time; scouring velocity; flush ing re-
quirements; cleanoutsj air release valves? bypassing of line
segments in the case of leaks or ruptures; alarms; quality power
being available in an area; holding tank capacity; reliability
of the pumping unit; backflow devices; the supplementation of
the gravity system as opposed to a complete pressurized sewer
system; and the encouragement of a good management system.
Several states have various levels of permits. For example,
in Virginia there is an experimental permit whereas in Texas
there are three permit levels: unconditional, conditional and
limited approval. Originally, pressure sewer systems were g iven
the limited approval classification. As systems prove relia-
bility, become more standardarized and regulatory officials be-
come familiar with their existence, pressurized sewer systems
-105-
-------
can be expected to gain an increased standing with regulatory
agencies.
SYSTEM ORGANIZATION MODELS
In the course of this study, system management models inves-
tigated fell into the three major categories. Under one model
the entire pressure sewer system, regardless of treatment, is
controlled by a unit of government. The controlling unit may
be a sewer district, municipal utility district, a city, a
county or other similar government organization. Under this
type of management, all variations of ownership may exist. For
example, in most instances, the entire facility, including the
on-lot pumping facilities and the transportation pipe network,
is owned by the governmental unit. Under some governmental unit
organizations, the pipeline is owned by the government unit,
but the homeowner owns the on-lot facilities, as in the Lake
LBJ MUD, Texas. At Lake LBJ MUD if the pump malfunctions it is
the responsibility of the homeowner to obtain service for the
unit.
Another option exists if the district owns the entire system
including on-lot facilities, and utility workers maintain the
on-lot facilities as well as the piping system. This type of
system is evident in Glide, OR; Apple Valley, OH; and Seabrook,
TX. A subcategory under this system, is Seabrook, where there
are both GP units and gravity served residences in the city.
Those on the pressure sewer system pay a higher monthly user
charge than those served by gravity. In Apple Valley the same
type of mixture occurs, but both gravity and pressure system
users pay identical monthly user fees. Another option under a
governmental unit organization model would be to have the dist-
rict contract for 0 & M labor. ""his is done in the Priest Lake
systems in Idaho, and Weatherby Lake, MO. At the Priest Lake
system, the operator places a bid for his services at the be-
ginning of the year, whereas in the Weatherby Lake system the
operator charges the district on a per service call basis, but
the operator is treated as a city employee.
A second major category of organization is to have a private
utility company own and operate the system. For example,
Country Knolls South near Albany, NY, owns and maintains the
pressure sewer system, but the individual users who have pur-
chased the pumping units pay the service company at the rate of
$11/service call. General Development Utilities Company, also
a private organization, owns the on-lot facilities and service
is included in the monthly user fee. Lake Mohawk, OH, operates
in the same manner, as Environment/One holding the service con-
tract , and a local independent repair organi zation charges Envi-
ronment/One on a per call basis. Environment/One accepts re-
sponsibility for maintaining the system on a per month user
-106-
-------
sponsibil ity for maintaining the system on a per month user
charge basis that is fixed for a five year period. At the
Country Knolls South development, a private utility owns the
piping system and the individual owns the pumping unit. Simi-
larly, the houseboat systems in Portland, OR and Sausalito, CA
an individual owns the mainline piping systems and the users own
their own pumps. When an individual needs pump maintenance, he
is free to contact anyone to repair his unit, but usually has
service performed by the local service representative. The
homeowner pays the repair charge directly to the service organi-
zation of his choice.
The third major category of organization model is where a
cooperative or homeowners' association maintains the piping sys-
tem with the individual owning and maintaining the pump units.
There is an elected homeowners association board which oversees
the system and deals with calls from the homeowners. When the
piping system needs repair, the homeowners call the association
who in turn call the local contractor. When the individual
needs repair on his pump unit, he is free to call the local ser-
vice organi zation for individualized service, or have the ser-
vice organization perform the needed repairs on a maintenance
contract. This management scheme is used at Grandview Lake, IN.
All system operators interviewed during the course of the
study suggest an overall comprehensive management system offer-
ing perpetual maintenance on the complete system with emergency
service charges built into the monthly user fee.
OTHER MANAGEMENT TASKS
Operators report preventive maintenance to be an important
task in pressure sewer systems. Management scheduling should
include preventive maintenance, although it occurs in less than
10% of existing pressure sewer systems. The most de-
tailed preventive maintenance programs occur in the Port Char-
lotte and Port St. Lucie systems and Apple Valley, OH. Pre-
ventive maintenance may require up to 30 minutes per unit twice
a year and include hosing down of the units and checking the
pump operation. It can of fer the advantage of reduction in
breakdown service calls and act as an excellent public relations
tool to the serviced community. In order to prevent carry-over
of solids from septic tanks, preventive maintenance is highly
desired in the STEP system where pumping of the septic tank is a
required maintenance item. The pumping interval varies from three
to ten years. Another preventive maintenance function is the
pulling and storing of pumps from homesites with temporary or
seasonal residence. This function would reduce "stuck pump"
problems of seasonal residents when they return to use their
units.
-107-
-------
There also is a need for continual education of the users of
a pressure sewer system, since the operators frequently have re-
ported pumping units clogged with extraneous material. Several
systems offer guidelines in regular newsletters sent out to
homeowners or placards designed to be located in the basement
of homes. These guidelines offer suggestions as to the use of
the system, including refraining from pouring grease into the
kitchen sink. Homeowners involved in an "unconventional" sewer
system have a desire to be kept continually informed as to the
sewer system's condition. At Weatherby Lake a periodic home-
owner's newsletter always includes some information about the
system operation, expenses, or other informative details. All
the operators interviewed under this project agreed that this
type of approach is beneficial in winning consumer acceptance
when coupled with an all inclusive maintenance organization.
-108-
-------
REFERENCES
1. Detailed Housing Characteristics (HC 1-B), 1970 Census
Bureau of the Census, U. S. Dept. of Commerce, Washington,
DC, 1972.
2. Cooper, I. k. and J. W. Rezek, "Septage Disposal In Waste-
water Treatment Facilities" in Individual Onsite Wastewater
Systems, N. McClelland, Ed., Ann Arbor Science Publishers,
Ann Arbor, MI, 1977,
3. Kreissl, J. F., "Alternatives For Small Wastewater Treat-
ment Systems - Status of Pressure Sewers Technology", U. S.
EPA, Technology Transfer EPA-625/4-77-011, Volume 7, Oct.
1977.
4. Wall Street Journal, Monday, July 26, 1976, Volume
CLXXXVIII No. 17, pp 1 and 10.
5. Bowne, W. C., "Sewerage Study for the Glide-Idley Id Park
Area, Douglas County, Oregon", Douglas County Dept. of
Public Works, Dec., 1975.
6. American Society of Civil Engineers, Combined Sewer Separa-
tion Using Pressure Sewers, U. S. DepFI of the In- terior,
Federal Water Pollution Control Administration, FWPCA
Report No. ORD-4, 1969.
7. Clift, M. A. "Experience With Pressure Sewerage," Journal
of Sanitary Engineering Division, American Society of
Civil Engineers, |4, 5, 849 - 865, 1968.
8. Carcich, I. G., L. J. Hetling, and R. P. Farrell, A
Prfessure Sewer Demonstration, U. S. EPA, Report No.
R2-72-091, 1972.
9. Mekosh, G. and D. Ramos, Pressure Sewer Demonstration at
the Borough of PhoenixvilleT Pennsylvania, uT IT EPA, Re-
port no. rS-73-270, Id73.
(continued)
-109-
-------
10
11
12
13
14
15
16
17
18
19
AO
REFERENCES (continued)
Hendricks, G. F. and S. M. Rees, Economical Residential
Pressure Sewage System with No Effluent, U. S. EPA, Tech-
nology Series, Report No. EPA-600/2-75-072, Dec., 197 5.
Gray, Glen C., "Environmental Constraints Challenge De-
signers Of Shoreline Community Near Kansas City, Missouri",
Professional Engineer, June, 1975, pp 42 - 44.
Weibel, S. R., Straub, C. P. and Thomas, J. R., "Studies
on Household Sewage Disposal Systems, Part 1", U. S. Public
Health Service, 1949.
Pomeroy, R. D., "Process Design Manual for Sulfide Control
in Sanitary Sewerage Systems", U. S. EPA, Technology Trans-
fer Publication, 19 74.
Carlson, D. A., and Leiser, C. P., "Soil Beds for the Con-
trol of Sewage Odors", Journal Water Pollution Control
Federation, 38, 829.
Stone, R., Newton, L. C. and Rowlands, J.r "Wastewater
Pumping Station Designed to Avoid Odor Problems", Journal
Public Works, Jan., 1975.
Langford, R. E., "Effluent Pressure Sewer Systems", pre-
sentee' at 1st WPCF Annual Conference, Philadelphia, PA,
Oct. 2-7, 1977.
Leckman, J., "Pressurized Sewer Collection Systems", pre-
pared for Illinois Institute of Env ironmental Quality,
1972.
Env ironment/One Corporation, "Design Handbook for Low
Pressure Sewer System", Third Edition, 1973, Schenectady,
NY, 20 pp.
Mendez, L. A., "South Gulf Cove Suburbanaer Sewage Collec-
tion System Hydraulic Analysis", General Development Utili-
ties Co., Miami, FL, Project No. 355-0944-72, April, 1977,
6 pp.
Mendez, L. A., "Appendices and Exhibits to Cuburbanaer
Sewerage Processing System", General Development Utilities
Co. , 1977, 58 pp.
(continued)
-110-
-------
REFERENCES (Continued)
21. Bowne, W. C., "Pressure Sewer Systems", prepared for
Douglas County, OR, 1974.
22. Hobbs, M. F., "Relationship of Sewage Characteristics to
Carrying Velocity", Report No. R-2598 to American Society
of Chemical Engineers, 19 67.
23. Flaniga, L. J. and R. A. Cudnik, "Review and Considerations
for the Design of Pressure Sewer Systems", performed by
Battelle's Columbus Laboratories for Hydr-O-Matic Pump
Division, Wylain, Inc., 19 74.
24. Kloser, P. C. and H. E. Schmidt, "The Suburbanaer Pressure
Sewer System Three Year History Gulf Cove Areas, Port Char-
lotte, Florida", General Development Utilities, Inc.,
Jan., 1976.
25. Bluem, R. A., and L. A. Mendez, "The Surburbanaer Sewerage
Processing System Compared with A Conventional Gravity
System in Plat Units 79 and 101 and a Portion of Unit 37,
Port Charlotte, Florida", prepared for General Development
Utilities, Inc., by General Development Eng ineering, Miami,
FL, 1977, 22 pp.
26. Otis, R. J., Boyle, W. C., et al, "Alternatives for Small
Wastewater Treatment Systems, On-Site Disposal", U. S. EPA
Technology Transfer, 19 77.
27. Sauer, D. K., "Intermittent Sand Filtration of Septic Tank
and Aerobic Unit Effluents under F ield Conditions",
master's thesis, Department of Civil and Environmental En-
gineering, University of Wisconsin, Madison , WI, 197 5.
28. Hines, M. and Favreau, R. E., "Recirculating Sand Filter:
An Alternative to Traditional Sewage Absorption Systems",
Proceedings of the National Home Sewage Disposal Symposium,
Proc. American Society of Agricultural Eng ineers, 17 5,
Dec., 1974.
29. Hines, M., "The Recirculating Sand Filter: A New Answer
For an Old Problem", Proceedings of the Illinois Private
Sewage Disposal Symposium, Champaign, IL, 1975.
(continued)
-111-
-------
REFERENCES (Continued)
30. Bowne, W. C., "Experience in Oregon with the Hines-Pavreau
Recirculating Sand Filter", Douglas County, OR, Engineer's
Office, Roseburg, OR, 1977.
31. Troyan, J. and D. P. Norris, "Alternatives for Small Waste-
water Treatment Systems - Cost Effectiveness Analysis",
U. S. EPA, Technology Transfer, EPA-625/4-77-011, Volume 3,
Oct., 1977.
32. Cooper, I. A. and J. w. Rezek, "Septage Management", U. S.
EPA, Technology Transfer EPA-625/ 4-77-011, Volume 2, Oct.,
1977.
33. Langford, R. E.# "Overview of Hardware for Pressure Sewer
Systems", Peabody Barnes Pump Co., Mansfield, OH, May 2,
1977, 27 pp.
34. Dounoucos, A., "Sanitary System Construction Costs Turn
Engineering Attention to Alternate Solutions",
Professional Engineer, 44, 8, 1974.
35. Benett, E. R., K. D. Linstedf and J. Felton, "Comparison
of Septic Tank and Aerobic Treatment Units", Paper pre-
sented at Rural Environmental Engineering Conference,
Warren, VT, 1973.
36. Metcalf and Eddy, Wastewater Engineering Collection Treat-
ment and Disposal, McGraw Hill, 1972, 231 pp.
37. Carcich, I. G., L. F. Hetling and R. P. Farrel, "Pressure
Sewer Demonstration" , Journal of Environmental Engineering,
Division A.S.C.E., 100, No. 1, pp. 25 - 40, 19 74.
38. Eblan, J. E. and L. K. Clark, "Pressure and Vacuum Sewer
Research and Development Project, City of Bend, Oregon",
U. S. EPA Grant No. 5803295,
-------
EXISTING RESIDENTIAL PRESSURE SEWER SYSTEMS.
SYSTEM
YEAR
SYSTEM
TYPE
MAMUTACTUP.ER(S)
CONKEC
PRESENT
TIONS
ULTIMATE
TREATMENT
X PRESSURE
AT TREATMENT
EKGIKEER
t. Apple Valley,
OH
1873
G.P.
Hydromatic
SI
225
Tertiary STP
10
M. M. Schlrtzlnger &
Assoc., Ltd.
Chllllcothe, OH
2. Diamond Head
Tulsa, CK
1972
G.P.
Hydromatic
IBS
188
Secondary STP
100
K.N. Cox & Assoc.,
Tulsa, CK
3, Chickasaw Pt.
Fair Play, SC
1974
G.P.
Hydromatic
Environment/One
SO
742
Lagoons - Spray
Irrigation
100 , -
Gary See
4, Souther Hills
Estates
Sellersbrug, IN
1973
G.P.
Hydromatic
Environment/One
23
225
Lagoon
100
Paul Moffat, KY •
S. Strongsvllle.CH
1974
G.P.
Hydromatic
18
20
Gravity Sewers
Very Small
Joe Molner
6, Thunderhead Lite
Unlonvllle, MC
1974
G.P.
Hydromatic
25
300
Lagoon
75
N. E. Isaacson,
Reedsburg, W1
7, Bogulusa. LA
1976
G.P.
Hydromatic
30
30
, Gravity Sewer
Very Snail
Dyer & Moody,
Baker, LA
8. Rome City, IN
1876
G.P.
Hydromatic
120
140
Tertiary
70
John R. Snell Engineer*,
Lansing, MI
i. Harbor Springs,
MI
1975
G.P.
Hydromatic
84
2,200
Gravity Sewer
Very Small
Williams & Work*.
Grand Rapids, MI
10. Lake Lakengren,
OH
1975
G.P.
Hydromatic
80
300
Secondary STP
IS
M. M. Schlrtzlnger 6
Assoc., Ltd,
Chllllcothe, OH
II. GrandviewLake,
IN
1970
G.P.
Environment/One
Hydromatic
ISO
3S0
Lagoon
100
Freese & Abplanalp,
Franklin, IN
12, Lake Meade.PA
1977
G.P.
Hydromatic
600
7S0
Secondary STP
80
Buchart-Horn,
Lewlsburg, PA
73
(0
t/1
H"
&.
0)
3
P>
i-i >
0)
w
"O
T3
U) M
C 25
H CJ
<0
c/j
CD
*.
CD
H
X
w
rt
n>
-------
I
SYSTEM
YEAR
SYSTEM
TYPE
MfC.'lTF.nC TL'P.ER i S!
CONKEC
PRESEXT
HONS
ULTIMATE
TREATMENT
% PRESSURE
AT TREATMENT
ENGINEER
13. Lake LBJ M.U.D.
Horseshoe Bay,
TX
1972
G.P.
Environment/One
Hydro matlc
200
4,000
Tertiary STP
100
Bennet Coulson
Engineers, Houston, TX
14. New Landings
of the Delta
Queen.
Dixon, IL
1973
G.P.
Envlro nment/One
12
2,200
Tertiary Batch
STP
100
Wlllard Hoffman
Engineers, Dixon, IL
IS. Rose Blanche.
New Foundland,
Canada
1977
G.P.
Environment/One
60
60
Secondary STP
Planned
20
James F. McLaren Ltd,
Toronto, Ontario,
Canada
IS. Cuyler, NY
197$
G.P.
Environment/One
43
60
Community
Septic System
100
John McNeil,
Homer, NY
17. Port Charlotte,
FL
1970
S.T.E.P.
Hydro matlc
62
1,600
Secondary STP
100
General Development
Utilities Engineers,
Miami, FL
18. Port St. Lucie,
FL
1972
S.T.E.P.
Hydromatlc
191
1.000*
Gravity Sewer
Very Small
General Development
Utilities Engineers,
Mlama, FL
19. Arrowhead
Estates, IX
1974
G.P.
Variety
(Detlectir
type)
Eco-Systems
10
100+
Secondary STP
Small"
Bldds & Mathews,
Wichita Falls, TX
20. GUde-Idleyld,
OR
1977
S.T.E.P.
Peabody Barnes
600
2,300
Secondary SIP
100
Parnmetrix, Inc.,
Eugene, OR
21. Bend, OR (EPA)
1976
S.T.E.P.
Peabody Barnes
11
11
Secondary STP
Very Small
C & G Engineers,
Salem, OR
22. Juniper Utilities,
Co., Bend, OR
1970
Solids
Handling
Peabody Barnes
400
1,800
Secondary STP
100
Parametrlx, Inc.,
Eugene, CR
-------
I
SY3TIM
YEAR
system
r/?E
r-A::v7AC tvp.er tsi
CONNEC
PRESENT
noNs
ULTIMATE
TREATMENT
% PRESSURE
AT TREATMENT
EXGIKEER
23. Portland, OR
Houseboat
Systems
1968
Solids
Handling
Peafcody Barnes
700
700
Varies
Varies
Klaus Pump & Equipment
Portland, OR
Also Others
24. Coolln, ID
1974
S.T.E.P.
Hydromatlc
356
3S6+
lagoon
100
K. A. Durtschl & Assoc.
Coeur D'Alene, ID
25. Kahspell Bay. ID
1974
S.T.E.P.
Hydro ma tic
232
232+
Lagoon.
100
S. A. Durtschl & Assoc.
Coeur D'Alene. ID
26. South Seas
Plantation,
Captlva, FL
1977
G.P.
Hydromatlc
33
60
Secondary STP
10
Johnson Engineers,
Fort Meyers, FL
27, Point Venture, TX
1972
G.P,
'Environment/One
37
175
Secondary STP
90
Assoc. Engineers,
Houston, TX
28, Weatherby Lake,
MO
19 75
G.P.
Envlronm«nt/One
362
900
Gravity Sewer
Very Small
Larkm & Assoc.,
Houston, TX
29, Saratoga, MY
1972
G.P,
Environment/One
10
10
Gravity Sewer
Very Small
City Engineer,
Saratoga Springs, NY
30. Country Knolls
South,
Clifton Park, NY
1973
G.P.
Environment/One
3SS
SOO
Gravity Sewer
Very Snail
Standard Engineering,
Albany, NY
31, Golfview Estates
;
1971
G.P.
Environment/One
SO
114
Gravity Sewer
Very Small
Environmental Control
Products,
Jeffersonvllle, IN
32. San Angelo, TX
1976
G.P.
Environment/One
160
1,250
Secondary STP
100
Water Dept., City of
San Angelo, TX
:33. Kappas Marina
! Gate 6 ,
j Sausallto, CA
1
1976
G.P.
Environment/One
Hydromatlc
Peabody Barnes
Toran
82
82+
Gravity Sewer
Very Small
E. Seattle, Sausallto.
CA
-------
SYSTSM j "-EAR
systim
TY?£
j,*^:;ufacti;?.er(s)
CONNECTIONS
PRESENT ULTIMATE
TREATMENT
% PRESSURE
AT TREATMENT
ENGINEER
ON
34.
I
Kappas Marina
Gate 6 i,
Sausalito. CA
I3S. Quaker Lake. FA
{36. Cavalier Lake,
j MS
i37. Black Butte, OR
l
138.
39.
40.
41.
42.
Wexford County,
MI
Lake Winona,PA
(Stony Hollow)
Mast Hope, PA
Bottle Bay, ID
Montgomery City
M.U.D. 6,
Woodlands, TX
43, Winter Green
Resort, Nelson
& Augusta
Cities, VA
1975
1976
1976
1976
1978
1976
1976
1977
1975
197S
Solids
Handling
G.P.
G.P.
S.T.E.P.
G.P.
G.P.
G.P.
S.T.E.P.
G.P.
G.P,
Peabody Barnes
Environment/One
Environment/One
Peabody Sarnes
Hydromatlc
Peabody Barnes
Peabody Barnes
Peabody Barnes
Envlronmtnt/One
Environment/One
35
110
SI
60
225
40
ISO
100
ZS
SO
35+
14S
450
225+
4,000
1,000+
200
2S
250
Gravity Sewer
Lagoon
45,000 GPD A.S.
Secondary
Treatment
Gravity Sewer
Extended Aeration
Extended Aeratlor
Lagoon
Gravity Sewer
Tertiary STP
Very Small
100
10
IS
100
100
100
Very Small
45
E. Baattte, Sausalito,
CA
Milnes Engineers,
Tunkhannock, PA
Reynolds Engineers, Inc
Jackson, MS
Century West Engineers
Bend. OR
John R. SnellEngineers,
Lansing, MI
Edward C. Hess &
Assoc., Stroudsburg, tt
Edward C. Hess &
Assoc., Stroudsburg, ®
K. A. Durtschl & Assoc.
Coeur D'Alene, ID
S & B Engineers,
Houston, TX
Htld Engineers,
Houston, TX
Willey & Wilson,
Lynchburg, VA
-------
SYSTEM
YEAR
SYSTEM
TYPE
MANUFACTURER (5!
CONNEC
PRESENT
TJONS
ULTIMATE
TREATMENT
% PRESSURE
AT TREATMENT
ENGINEER
44. Lake Monttcello,
Fluvanna City,
VA
1975
G.P.
Environment/One
60
200
Secondary STP
20
Gilbert Clifford &
Assoc,,
Fredericksburg, VA
45. Beaver Lake, Ot
1973
G.P.
Environment/One
70
1,800
Secondary STP
Hendrlck, Cox & Assoc.
Cleveland, OH
:
46. Lake Mohawk,
Malvern, OH
1974
G.P.
Environment/One
200
1,700
Tertiary STP
100
Frledl & Harris, Inc.,
North Canton. OH
47. Pewaukee Lake,
WI
1976
G.P.
Envlronment/Ona
50
Strand Assoc.,
Madison, WI
48. Lake of the
Woods,
Indianapolis, IN
1977
G.P.
Hydromatlc
20
120
49. Condo Project,
Indianapolis, IN
G.P.
Hy dramatic
30
100
SO. Campbell Ave.
System,
Schenectady, NY
1973
G.P.
Environment/One
23
23
Secondary STP
Very Small
City Engineers Office,
Schenectady, NY
SI. Limestone Hills
Sewer District.
Fayettevllle, NY
1973
... G.P.
Envlronment/Cne
12
12
Secondary STP
Very Small
Cato Cerlno & Spina,
Liverpool. NY
52. Hassenplug
Project, WV
G.P.
Environment/One
Hassenplug Assoc..
Pittsburg, PA
53. Elks Club,
Huntington, WV
G.P.
Environment/One
Hassenplug Assoc.,
Pittsburg, PA
54. Harrison, ID
1978
S.T.E.P.
Peabody Barnes
120
131
Lagoon
100
URS Engineers,
Spokane, WA
-------
YEAR
SYSTEM
CONNECTIONS
% PRESSURE
SYSTEM
TYPE
PRESENT
ULTIMATE
TREATMENT
AT TREATMENT
ENGINEER
SS. Cooper
1978
S.T.E.P.
Peabody Barnes
75
20.000
Extended Aeratlor
100
Blaylock, Threet &
Communities,
.
Assoc., Little Rock,
Bentonvllle, AR
AR
56. Busch
1975
G.P.
Envlronment/O ne
20
langley McDonald &
Properties,
Overman, Virginia
1 Williamsburg,
Beach, VA
VA
57. Seahrook, IX
1977
G.P,
Hydromatlc
10
115
Gravity Sewer
Very Small
Bay shore Engineers,
Secondary SIP
Deer Park, TX
SS. take of the
1976
G.P.
Environment/One
13
Pines, PA
59. Saw Creek, PA
G.P.
Environment/Cne
70
Edward C. Hess &
Assoc.,
Stroudsburg, PA
-------
OTHEK SYSTEMS
System
Vacation Village, Pennsylvania
Fairfield Glada, Tennessee
Glrard Homos, California
The Summit, Virginia
Alexandria Day, Minnesota
Orion Lake, Michigan
Fallen Leaf Lake, California
Toronto Island, Canada
Lake Mitchell, South Dakota
Wood Creek Resort, Texas
nose Mancha, New Foundland .
Canada
West Vancolver, Canada
Frlendswoods, Texas
North Rl»or Development,
Alabama
Ulster, Now York
Fairfield Day, Arkansas
Groton, Conno'ctlcut
DeGray Lake, Arkansas
Trails End, Goshen, Kentucky
Engineer
Cboco Assoclntof!, Ilagollon, PA
Thomas Swaffortl, Palrtleld Clado,
Tennessee
Sanders S Assoc,, Mountain View,
California
Cllbcrt Clifford .S Assoc. ,
Winchester, Virginia
McCombs - Knutson Assoc!,,
Minneapolis, Minnesota
tlubbel, Roth (. Clark, Bloam(ield
Illlls, Michigan
Clnlr Hill & Assoc., Reading,
California
James!*, Mncl.nron Ud, Wlllowdale,
Ontario, Canada
Schmachcr I'nglneerlnci, Mitchell,
South Dakota
Cnndlll, Rowlett & Scott, Houston,
Texas
fames T, Macl.nren, Wtllowdnlc,
Ontario, Canada
Greater Vancouver Sower & Drainage
District, Vancouver, Canada
engineering Science, Austin, Texas
Gllbreath, Foster £ Brooks, Inc.
J. Kenneth Frasler & Assoc.,
Ronssaloor, New York
Graver 5. Graver, Little Hock,
Arkansas
tlnyrien, Harding S Ouchnnan, Boston,
Massachusetts
U. S. Army Corpr. of Engineers,
Vlcksburg, Mississippi
Goshen Utilities, Goshen, Kentucky
119
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