United States
                    Environmental Protection
                    Agency
 Municipal Environmental Research »
 Laboratory
 Cincinnati OH 45268
                   Research and Development
EPA-600/S2-83-063  Sept. 1983
SEPA         Project  Summary
                    Evaluation  of  Alternative
                   Wastewater  Collection  and
                   Treatment  Methods for  Three
                    Small  Kansas Communities

                    Kenneth C. Wiswall, Alice L Lenthe, and Robert P. G. Bowker
                     Alternative wastewater management
                   systems were evaluated for the three
                   small communities of Corning, Furley,
                   and Havana, Kansas.  All three com-
                   munities are rural, agriculturally-or-
                   iented settlements with populations of
                   less than  200. Numerous failures of
                   onsite systems have been reported. Soil
                   conditions are such  that individual
                   wastewater systems  such as septic
                   tank/soil absorption alternatives are
                   not feasible on a widespread basis. The
                   wastewater collection alternatives
                   considered included conventional grav-
                   ity sewers, small diameter gravity
                   sewers (conveying septic tank effluent),
                   and pressure and vacuum sewers; the
                   treatment alternatives included package
                   plants, spray irrigation, and continuously
                   discharging lagoons.
                     For Corning and Havana, wastewater
                   collection by pressure sewers using
                   individual and clustered  septic tank
                   effluent pumps and  treatment via
                   continuously discharging lagoons were
                   found  to be the most cost-effective
                   wastewater management solutions.
                   Although the pressure sewer collection
                   alternative was also found to be most
                   cost effective for Furley at the projected
                   future population, the cost effectiveness
                   of pressure versus gravity sewers was
                   found  to  be  sensitive to projected
                   growth. It was thus recommended that
                   population projections for Furley be
                   reassessed, which may affect choice of
                   alternatives. Overall, wastewater col-
                   lection via small diameter pressure
                   conveyance of septic tank effluent was
                   found to be the least costly collection
                   alternative for the three  small com-
munities investigated. Compared with
various pressure sewer configurations
as well as with small diameter gravity
sewers, conventional gravity sewers
had the highest  total  present worth
cost.
  This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory. Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).

Introduction
  The Clean Water Act of 1977 (PL 95-
217) requires that alternatives to conven-
tional wastewater treatment be consid-
ered—alternatives that potentially may
reduce capital and operation/main-
tenance costs  or reduce energy con-
sumption. For communities with popula-
tions of less than 3500, both alternative
collection and treatment systems may
qualify for increased  Federal grant
assistance of up to 85% of the eligible
project costs. Before 1977, the plans for
many facilities did not adequately evalu-
ate alternative wastewater technologies,
many of which are particularly applicable
to small communities.

Methodology
  The original facility plans for the three
communities, prepared in 1977, were
analyzed in detail. Site visits were made
to the communities to review the validity
of cost assumptions used in the plans and
to document existing conditions at each
location.

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  Present and projected populations for
the Kansas communities are shown in
Table 1.
  Soil  conditions in  the area, as con-
firmed by district geologists, local sani-
tarians, and  observations during field
visits, are described as "slowly permeable
and unsuitable for septic tank systems."
Soils in the area are  predominately silty
clay underlain by clays with moderate-to-
high shrink/swell potential. Bedrock and
groundwater are deep and do not present
a problem with sewer  construction  or
maintenance  of  adequate  separation
distance between subsurface disposal
systems  and bedrock or groundwater.
Soil  permeability, however, precludes
virtually all  onsite treatment/disposal
alternatives throughout most  of the
planning areas.  Near each community,
land is available that could be used for
siting treatment facilities (e.g., package
plants  or lagoons) or  land  application
systems.
  Because of unsuitable soil conditions
throughout most of the  planning areas,
further  analysis focused on alternative
collection and treatment systems. Treat-
ment alternatives evaluated for each
community included package plants,
lagoons with  spray irrigation of effluent,
and  conventional discharging lagoons.
For Corning, collection systems analyzed
were:
(1)  Septic Tank Effluent Pump  (STEP)
pressure  sewers; (2)  small diameter
gravity  sewers  conveying septic tank
effluent; and (3) conventional gravity
sewers. For  Furley:  (1) STEP  pressure
sewers  (one STEP  unit per user);  (2)
clustered  STEP pressure sewers (more
than one user per STEP unit); and (3)
conventional gravity sewers. For Havana:
(1) clustered  STEP pressure  sewers; (2)
partial sewering (approximately one half
the planning area) with STEP pressure
sewers, with the remainder of the homes
served by upgraded onsite systems; and
(3) conventional gravity sewers.
  A  present  worth  cost analysis was
performed for the various alternatives for
each community based on future popula-
tions. Assumptions used for the analysis
are listed below:

  •  Planning period  = 20 years
  •  Interest rate = 7%
  •  Service life = 20  years for STEP unit
     components
  •  Salvage  value = value at end of
     planning period
  •  User costs = calculation based on an
     EPA grant:
         85% of eligible costs for alterna-
        tive collection and treatment
        systems, and 75% for conven-
        tional collection and treatment
        systems
  Unit cost  assumptions for collection
alternatives were critical for performing
an accurate  cost-effective analysis. The
unit cost assumptions used in the
evaluations are summarized (Table 2).
Results
  Treatment  alternatives were first
evaluated to determine which system(s)
provided reasonable service at the least
cost and with low operation and main-
tenance requirements consistent with
the financial and technical capabilities of
the communities. Table 3 represents a
preliminary cost-effective analysis of the
package  plant, spray irrigation, and
continuously discharging  lagoon  alter-
natives. Lagoons were selected based on
low capital cost and the lack of need for
substantial operation  and maintenance
requirements,  such as  highly  skilled
operators, maintenance  of mechanical
and electrical equipment, and energy
utilization. In addition, the State of Kansas
considers lagoons to be acceptable, low-
cost alternatives that are particularly
applicable to small communities. Thus,
continuously discharging lagoons were
selected as  the most  viable treatment

Table 1.   Population Data
alternatives for all  three  Kansas com-
munities. It should be noted thatthe costs
presented in Table 3 are based on
treatment of raw sewage. During the final
cost-effective analysis, these costs were
revised to reflect changes in organic
loading that would result from pretreat-
ment  by  septic  tanks for the STEP
pressure  sewer  and small diameter
gravity "effluent" sewers.
  Various alternative collection systems
including small diameter gravity, grinder
pump and STEP pressure, vacuum, and
conventional  gravity sewers were first
subjected  to preliminary screening.
Further detailed analyses were limited to
the small diameter,  STEP pressure, and
conventional  gravity sewer alternatives.
In addition, consideration  was given to
the "clustered" STEP collection system,
whereby each pumping unit serves two
or more homes.
  The results of the overall cost-effective
analysis are  presented in Table  4.  For
Corning,  the  most cost-effective alter-
native was collection via STEP pressure
sewers and treatment using a continu-
ously discharging lagoon.  For  Furley,  a
"clustered" STEP pressure collection and
lagoon treatment system had the  lowest
present worth cost. For Havana,  partial
sewering via a STEP pressure sewer with
lagoon treatment  and upgrading of the
Community
Corning
Furley 1
Furley II*
Havana

No. Units
105
40
40
75
Present

Population

152
97
97
184
Future
No. Units
124
55
165
87
(20 yr)
Population
208
140
500
220
 *An additional future population projection was considered to illustrate the impact of potential
growth.


 Table 2.    Summary of Unit Cost Assumptions for Wastewater Collection Alternatives
Item
4-in. gravity sewer
8-in. gravity sewer
4-in. gravity service connection
1-1 /4-in. PVC pressure sewer
1-1/2-in. PVC pressure sewer
2-in. PVC pressure sewer
2-1 /2-in. PVC pressure sewer
3-in. PVC pressure sewer
4-in. PVC pressure sewer
Conventional septic tank/soil
absorption system (installed)
STEP system (installed, with septic
tank)
STEP pump
Grinder pump
Pump station
Total Installed
Unit Cost ($)
$15.00/ft \
20.00 /ft \
5.00/ft ]
3.00/ft \
3.75 /ft I
4.00/ft \
4.25/ft [
4.7 5 /ft 1
5. 50 /ft. '

3,000.

1,300.
400.
1.750.
—
O&M
<$/yr)

$500/mile



100 /mile




15

45*

75
800
*For each system, not including tank pumping.

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remainder  of  onsite systems had a
slightly lower present worth cost than the
completely sewered STEP pressure
option.  However,  because of the  pre-
dominance of adverse soil conditions in
the area, the totally sewered alternative
was recommended.
  Table 5 summarizes the estimated user
charges for each community.  The  re-
commended alternatives had associated
user costs ranging from $145 to $276 per
household per year. With the exception of
Corning, user  charges are considered
within acceptable ranges (as percent of
median income)  based  on EPA recom-
mendations outlined in Program Require-
ments Memorandum 79-8. Other funding
sources (HUD), which  will  reduce the
local share of capital costs and thus user
charges, have been secured for Corning.
Conclusions
  Alternatives to  conventional gravity
collection may be more cost-effective for
small communities or low-density fringe
areas surrounding larger municipalities.
Many factors affect the relative costs of
collection  systems,  including  housing
densities, topography, and soil character-
istics.  Pressure  sewers often  have
 Table 5.    Summary of Estimated User Costs for Wastewater Collection and Treatment*
 Alternative
     Median Household
       Income, $/yr
      User Cost,
        $/yr
                                                                      %of
                                                                  Median Income
 Corning                          $4,509
  STEP pressure sewer
  Small diameter gravity sewer
  Conventional gravity sewer
 Furley                           77,700
  STEP pressure sewer
  "Clustered" STEP sewer
  Conventional gravity sewer
 Havana                          74.335
  STEP pressure sewer
  Partial STEP with onsite
    systems
  Conventional gravity sewer
                            $145
                              195
                             295

                             325
                             276
                             337

                              155

                              140
                             270
                          3.2%
                           4.3
                           6.5

                           1.9
                           1.7
                           2.0

                           1.1

                           1.0
                           1.9
 * Treatment via continuously discharging lagoons.
economic  advantages for low-density
areas, hilly topography,  and restrictive
soil profiles. The last two conditions may
substantially increase the costs of gravity
sewer installation because of the require-
ment for deep  cuts and/or lift stations
(hilly topography) and the need to provide
shoring and trench dewatering (high
groundwater) and/or blasting (thin soils
over bedrock). Because of their inherent
characteristics, pressure  sewers  can
generally be installed at a uniform depth
below ground following  the  natural
topography.
Table 3. Summary
Treatment
Corning
Package plant
Spray irrigation
Discharging lagoon
Furley
Package plant
Spray irrigation
Discharging lagoon
Havana
Package plant
Spray irrigation
Discharging lagoon
of Costs of Treatment Alternatives (1979 $)
Capital Cost, $ O&M Costs. $/yr

$30,000
98,600
53,749

27,000
98,175
71.845

33,000
72.700
39,997

$6.800
5,000
1.500

4.760
3,000
2,000

7.480
3,000
1.500
Total Present
Worth, $

$102.039
151,570
69,640

77,427
129,957
93,033

1 12,243
104.482
55,888
                   In some cases, feasibility of pressure
                 sewers should not be based sotely on a
                 cost-effective analysis. Two  other im-
                 portant factors are the  ability to the
                 community to ensure proper day-to-day
                 operation and maintenance of the system
                 and the  impact of prolonged power
                 outages. The latter factor was considered
                 to be a valid consideration for these study
                 areas owing to experiences with extended
                 power outages.
                   The full report  was submitted in
                 fulfillment of Contract No. 68-03-2775
                 by  Roy  F. Weston,  Inc., under the
                 sponsorship  of the U.S. Environmental
                 Protection Agency.
 Table 4.   Summary of Cost-Effective Analysis (1979 $)
           (Includes cost of treatment by discharging lagoon)

                                       Construction, $
Alternative                           find, land & salvage)
                          Operation and Maintenance
                     Annual, S/yr
                 Present Worth, $
                    Total Present
                       Worth. $
Corning
  STEP pressure sewer
  Small diameter gravity sewer
  Conventional gravity sewer
Furley
  STEP pressure sewer
  "Clustered" STEP sewer
  Conventional gravity sewer
Havana
  STEP pressure sewer
  Partial STEP with onsite
    system upgrading
  Conventional gravity sewer
$271,978
 455,533
 505,339

 163.550
 144,310
 226.000

 192,785

 206.820
 315,387
$7.625
 6,870
 5,010

 4,935
 4,125
 2,190

 6.185

 4,770
 3,405
$80,780
 72,780
 53,075

 52,280
 43,700
 23.200

 65.520

 50.535
 36,070
$353,000
 528,000
 558,000

 216.000
 188,000
 249.000

 258.000

 257.000
 351,000

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      Kenneth  C. Wiswall and Alice L,  Lenthe are with Roy F.  Weston, Inc.,  West
        Chester, PA 19380; and Robert P. G. Bowker is with the U.S. Environmental
        Protection Agency, Cincinnati, OH 45268.
      Robert P. G. Bowker is the EPA Project Officer (see below).
      The complete report, entitled "Evaluation of Alternative  Wastewater Collection
        and Treatment Methods for Three Small Kansas Communities," (Order No. PB
        83-247 197; Cost: $10.00, subject to change) will be available only from:
             National Technical Information Service
             5285 Port Royal Road
             Springfield, VA 22161
              Telephone: 703-487-4650
      The EPA Project Officer can be contacted at:
             Municipal Environmental Research Laboratory
             U.S. Environmental Protection Agency
             Cincinnati, OH 45268
                                                   *US GOVERNMENT PRINTING OFFICE 1983-659-017/7190
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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