United States
Environmental Protection
Agency
Office of Water
Program Operations
Washington DC 20460
May 1984
sxEPA
Is Your Proposed
Waste water Project
Too Costly?
Options for
Small Communities
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Wastewater
Facilities
For Small
Communities
A Tall Order
and a healthier.environment.
Mostsma.l communitiesfind itdifficu.tto afford conventional^^^^^^^
r^nt* qince 1972 the U S Environmental Protection Agency (EPA) has paia /o/° OT m*L
'
at need new or improved wastewater treatment facilities?
burden without reducing the quality of treatment?
The Small
Community
Dilemma
Relative Cost Of Sewering By Size Of Community
Harder to Raise Capital. In addition to higher costs smalle r communities have more difficulty j ;j
financing their facilities. Some common financial problems include. ,,, ^
. Lower Income - In general, annual incomes of rural households are about $3,000 less
than urban househoids.
'
greater share of the tax burden. - ._ , | '-
; often have difficulty qualifying forthe bond ;
iw bond rating. Further, a small communityjis
f .m I I ^ „. .» .HA *» i i vs * r\f -I-V^O nOrtn
pay ° MghJr interest rate because of the smaller amount of the bond.
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Choose
Appropriate
Technologies
Has Your
Community
Selected A Project
With Reasonable
Costs?
Management Problems. Most small towns have the resources and expertise to
mTn° 'ewastetwater sVstems- TheY ^Idom can get the skilled persSnne^SSdS^rp
management, construction supervision, billing, accounting, budgeting, opefaS and
maintenance necessary for a sophisticated treatment plant.
As you can see, selecting a wastewater treatment option, finding the best financial
eCe
and
How do you solve this dilemma? First, it's vital to keep cists down The most imnortant «,«,
-«
_ , . . " , •—o--.- - M-" (->vov> <_M iiuooyotem isto help your
problems at an early stage when they can be more easily resolved.
Part A-Proiect Capital Costs And Si7inr|
Indicator
Capital Cost of Sewers
Capital Cost of Treatment
Total Project Capital Cost
Allowance for Future Flow
Suggested Criteria
$4000 per household
$ Spergallon per day of capacity
$.6000 per household
50% of initial flow
Part B-Cost to the Residential
Indicator
Customer
Annual Operations and Maintenance Cost
Annual Household Cost
$ 10C
1.5%
Suggested Criteria
per household
of median household income
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What To Do If
Sewers Or
Reduce Project Scope. If the projectyou are planning istoo costly, it may be possible to reduce
te she. Take a hard look at the population projections and flow estimates Be raal.stic about
estimates of future growth and wastewater treatment needs and reevaluate the extent of
Treatment Facilities sewering you propose. Can some pipes be eliminated by using onsite or cluster systems m
ArP Too Exoensive outlying areas? A water conservation program may reduce wastewater flow and the size of
Are TOO Expensive out.yng |ant .|ta,somay allow continued use of onsite systems. Another idea
for communities expecting high growth is to construct the facilities in stages to spread out
your town's investment over a longer time period.
Simplify Design. Often there are ways to simplify the design of facilities to cut costs and make
operationeasier.Makesurethelayoutoftheplantisasefficientasposs.bleandehmmateall
nbn-essentialfeaturessuchasbrickveneerwallsonbuildingsandpavedroadsw.thcurbsand
gutters. Perhaps laboratory or otherfacilities, and even plant operators, could be shared with
a neighboring town.
Improve Financing. Sometimes the cost to finance a project can be reduced Be ce.rtairi that
all potential funding sources for the project have been considered Some Federal and State
agencies have low interest loans. To reduce interest rates, some States have bond banks o.
win guarantee local bonds. In some cases, extending the bond life can reduce annual costs.
Your State water quality officials or Regional EPA staff may know of some innovative financing
methods that could save you money.
Have You Chosen
An Appropriate
Technology?
Astandardwastewatertreatmentfacility may not be the best solution foryoursmall community
situation. A combination of approaches may be needed to solve different wastewater problems
within the community. One or more of the technologies described below may be the most
appropriate foryour community. All are proven technologies currently being used successfully
across the country.
Onsite Systems
Some communities have avoided sewers altogether by using systems that treat the wastewater
at each homesite. Properly installed and maintained onsite systems will operate satisfactorily
for twenty years or more in areas where site conditions are suitable. A management district
can be set up to oversee operations.
Septic Systems. The most common onsite system is the septic tank, soil absorption system.
This simple method settles out solids in a buried tank, which is cleaned every 3 to 5 years
Liquid flows from the tankto a drainage bed or trench and filters into the soil through perforated
pipes.
Alternative Onsite Systems. Several different types of onsite systems have been developed
to operate in situations not suitable for conventional septic systems such as steep slopes, rocky
or tight soils and high groundwater.
Aerobic System.This variation uses an aerobictank instead of a septictankto mix airwith
the wastewater for additional treatment before disposal.
Dosing. Some systems-use a leaching bed ortrench but pumpthe wastewater in measured
doses to allow a more even flow over the entire distribution area.
Alternating Beds. If space is available, two alternating absorption fields can be used so one
can have time to recover its ability to absorb wastes.
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Mounds. Where soils are rocky ortight or the watertable is high, a mound can be created
with fill material. The wastewater from a septic.or aeirobic'tank is allowed to seep through
the soil in the mound, which provides the treatment.
Septic tank
E-T Beds. An evapo-transpiration (E-T) bed is similar 1o a mound but relies more on the
evaporation of the wastewater through the bed and pjlant cover.
Sand Filters. Still another system which uses a septic or aerobic tank is a sand filter. A two
to three foot bed of sand installed in the ground filters the wastewater from the tank. The
filtered wastewater can be disposed through the soil or discharged to a stream. Some States
require disinfection before stream discharge.
Stream discharge
Alternative Sewers
Since conventional sewers are usually by far the majorcapital cost item of a wastewater system,
alternative sewers should be carefully considered. Alternative sewers are smaller in size and
are installed at shallow depths. Since they have no manhole's and fewer joints, much less rain
and ground water gets into alternative sewers so treatment plants can be smaller. One or more
of the following alternative sewers are generally better suited for small communities than
conventional sewers. i
Smal! Diameter Gravity Sewers. Small diameter gravity sewers carry septic tank effluent. The
pipes, which are usually plastic, can be small (4 inches iri diameter) and placed at less slope
than a conventional sewer. Operation and maintenance requirements are low.
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Pressure Sewers. Pressure sewer systems use a small pump at each house to movewastewate*
under pressure through small diameter plastic pipes to a treatment facility or a larger interceptor
sewer. The pumps are of two types. Grinder pumps are housed in basement or underground
tanks and grind the raw sewage while pumping it. The other type is the septic tank effluent
pumping system, called STEP. STEP systems have less expensive pumps and have fewer
problems with grease buildup than grinder pump systems.
Pressure Sewer System
Septic tank with effluent pump
Vacuum Sewers. In a vacuum sewer system, wastewater from each home is drawn through
small collector pipes to a central collection station by vacuum. The vacuum collection station
houses a pump which deliversthewastewatertothetreatmentfacilityoraninterceptorsewer.
Wastewater entry into the system is controlled by vacuum valves at each home or at groups
of homes. Because of their limited ability to lift wastewater, vacuum sewers are best suited to
flat areas where gravity sewers would be too expensive.
Cluster Systems
Where conditions are not suitable for onsite systems, cluster systems can be used. The most
common form uses alternative sewers to transport either septic tank effluent from several
houses to a common drainfield, or raw wastewater from several houses to a common septic
tank followed by disposal. Treatment can also be provided by a pond, sand filter, mound or
land application. Typically each cluster system serves a group of two or more homes but less
than an entire community.
Cluster System
Drainfield
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Low Cost Centralized Treatment
Some simple and reliable centralized treatment systems 1that are well suited to small community
situations are ponds, lagoons, trickling filters, oxidatioiii ditches and overland flow land
treatment. All are well established methods for providing
In general, they cost less to build and run than the commc n method of treatment called activated
sludge. They also use less energy and are easier to operate and maintain^
standard levels of treatment or better.
Trickling Filter
If your community is starting to plan a wastewater project, make sure the engineer you choose
has experience with these small community technologies. If your ongoing project does not
consider these technologies, a reevaluation of alternatives may be in order.
i.
Putting in a wastewater system that effectively and reliably does the job, yet doesn't financially
strap the community, is a challenge. This challenge can be met by making careful choices to
keep down the cost of construction, operation, mainterance and financing.
MORE INFORMATION FROM
• EPA National Small Wastewater Hows
Clearinghouse
West Virginia University; Morgantown, WV
26506; 800-624-8301
« Center for Environmental Research
Information
26 W. St. Clair; Cincinnati, OH 45268;
513-684-7391
o EPA publications (call 202-382-7373)
—Small Wastewater Systems-Al-
ternative Systems for Small
Communities and Rural Areas,
FRD-10
—Emerging Technology series of
foldouts
—Less Costly Wastewater Treatment
Your Town
—Financial Capability Summary
Foldout—A Simplified Approach
Your EPA Regional Office
1. Boston
(CT, ME, MA, NH, PI, VT); JFK Federal Bldg.;
Boston, MA 02203; 617-223-7210
2. New York
(NJ, NY, PR, VI); 26 Federal Plaza; New York,
NY 10007; 212-264-2525
3. Philadelphia
IDE, MD., PA, VA, WV, DC,l;6th & Walnut Sts.;
Philadelphia, PA 19108; 215-597-9814.
4. Atlanta
(AL, GA, FL, MS, NC, SC, TN, KY); 345 Courtland
St., N.E.; Atlanta, GA 30308;' 404-881-4727
5. Chicago
(Ml, Wl, MN, IL, IN, OH); 230 S. Dearborn St.;
Chicago, IL 60604; 312-353-2000
6. Dallas
(TX, OK, AR, LA, NM);
1201 Elm St.; Dallas, TX 75270; 214-767-2600
7. Kansas City
IKS, NE, IA, MO); 324 E. 11th St.; Kansas City,
MO 64108; 816-374-5493
8. Denver
(CO, MT, WY, UT, ND, SD); 1860 Lincoln St.;
Denver, CO 80203; 303-837-3895.
9. San Francisco
(CA, AZ, NV, HI, GU, American Samoa, Trust
[Territories of the Pacific); 215 Fremont St.; San
Francisco, CA 94105; 415-974-8088
10. Seattle
(WA, OR, ID, AK); 1200-6th Ave.; Seattle, WA
38101; 206-442-5810.
I EPA does not endorse, approve, or "
ij disapprove any system described here.
f Not all systems shown are approved by
j all jurisdictions. To get EPA funds, a
l[ project must meet Federal, State, and
3' local standards.
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