United States
Environmental Protection
Agency
Municipal bnvironmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-062 Apr. 1984
Project Summary
Restoration of Failing On-Lot
Sewage Disposal Areas
Daniel D. Fritton, William E. Sharpe, Albert R. Jarrett,
Charles A. Cole, and Gary W. Petersen
Two techniques were evaluated for
rehabilitating failing septic tank/soil ab-
sorption systems water conservation
and absorption bed resting. These
techniques may offer less costly alter-
natives to complete replacement of the
soil absorption area.
Eleven homes with failing soil absorp-
tion areas were identified in the Centre
County, Pennsylvania, region. At each
home, the soil and site were character-
ized, and baseline data were collected
on household water flow and septic
tank effluent quality. Water conserva-
tion devices were then installed at one
of three levels of predicted water reduc-
tion capability maximum, moderate,
or minimum. At three of the minimum
water conservation homes, effluent was
also diverted to a specially designed
alternative trench for 10 months to per-
mit the main absorption area to rest.
After conservation measures were ap-
plied, water flow and effluent quality
were measured for periods comparable
with the baseline data collection period.
In addition, the soil absorption areas
were characterized by weekly measure-
ments of surface conditions and effluent
ponding levels for up to 2 years.
Median in-house water use reductions
were statistically significant and ranged
from 9.8% to 42.5%. The water use
reductions were in accord with the in-
creased concentrations of most effluent
quality parameters. Maximum levels of
water conservation generally succeeded
in restoring failing absorption beds, but
lower levels of conservation did not.
Absorption bed resting also restored
failing systems. None of the three rested
systems malfunctioned in the 16 months
after effluent was redirected to them.
However effluent was ponded in them,
and the level continues to rise, sug-
gesting that the effluent will have to be
directed to the alternative trench at
regular intervals.
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
This research project evaluated
rehabilitative techniques for failing septic
tank/soil absorption systems (ST-SAS) to
find a less costly alternative to constructing
a new drainfield. The subordinate objectives
were: (a) to determine the ability of existing
water conservation hardware to correct ST-
SAS malfunctions; (b) to rest the main drain-
field and restore its ability to absorb effluent,
and to evaluate the feasibility of small aux-
iliary soil absorption areas for that purpose;
(c) to document how water conservation
hardware reduces wastewater and affects its
quality, and to determine how the home-
owner accepts these devices; and (d) to
determine whether or not water conserva-
tion or absorption bed resting or both
restored the failing system.
Site Selection and
Characteristics
Solicitation of homeowners with failing
onsite systems was initiated through
newspaper advertisements. Responding
homeowners were subsequently visited, and
12 homes in Centre County, Pennsylvania,
were ultimately selected for this study. Most
systems were new to moderately old (2 to
13 years), and most of the failures were
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relatively persistent in that homeowners had
been having problems for more than a year.
Eleven of 12 sites were identified as malfunc-
tioning by surfacing of septic tank effluent
in the yard. The severity of surface symp-
toms was not an adequate indicator of
systems that could be corrected by water
conservation, however, since soil permeabil-
ity and age of malfunction were also impor-
tant parameters.
A comprehensive characterization of the
soil was performed at each site, and the
detailed results are contained in the final
report. Background data were also gathered
on water table depth and soil permeability.
Soils ranged from sandy loam to clay. Per-
colation rates varied from 7 to 1217 sec/mm.
All systems were concluded to be failing
either because the effluent/soil interface was
clogged or otherwise compacted and
smeared, or because the overall soil per-
meability was too low for the existing
hydraulic loading.
Water Conservation Devices
The water conservation devices selected
for installation at 11 of the sites are described
in Table 1. The mean in-house water use
before and after conservation device installa-
tion is summarized in Table 2. As expected,
the three sites with maximum conservation
devices reduced the peak hydraulic loads and
produced the greatest mean water use
reduction. These sites used 27.3% to 42.8%
less water than for the comparable period the
previous year. Moderate conservation sites
showed mean water use reductions of
14.7% to 36.7%, and the reductions in
minimum conservation sites ranged from
10.0% to 33.1%.
Impacts of Water Conservation
The maximum water conservation devices
improved the existing malfunctions at the
sites receiving this treatment. Only one of
the moderate-level conservation sites
showed a similar improvement, and none of
the minimal-level sites showed any improve-
ment. Even at the maximum conservation
level, some intermittent problems still existed
at two of the three sites (though in all cases
there was considerable improvement over
the continual problems that existed before
water conservation).
Equipment costs for water conservation
devices were substantial for the maximum
conservation levels, with installed costs
around $1000 (not counting $540 for
automatic front-loading washers). Equip-
ment and installation costs are shown in
Table 3. The cost of water conservation refit
was generally less than replacing the entire
soil absorption area or constructing a small
alternative soil absorption area.
Table 1. Conservation Devices Installed at the 11 Sites Used in the Study
Site Aerators Shower Heads' Toilets*
Maximum^ Level:
2> Bath 1-5.7 Ipm Bath 1 - Lovo Bath 1
Kitchen - none Microphor
4" Bath 1,2 - 1.9 Ipm Bath 1 - Navy Bath 1,2
Kitchen - 9.5 Ipm Bath 2 - Lovo Microphor
7 Bath 1,2 - 1.9 Ipm Bath 1,2 - Nova Bath 1,2
Kitchen - 9.5 Ipm Microphor
Moderate1: Level:
1 Bath 1,2 - 1.9 Ipm Bath 1,2 - Lovo Bath 1,2
Kitchen - none pressure
5 Bath 1,2,3 - 1.9 Ipm Bath 1 - Nova Bath 1,2,3
Kitchen - 1.9 Ipm pressure
8 Bath 1,2,3 - 1.9 Ipm Bath 1,2 - Nova Bath 1,2,3
Kitchen - 9.5 Ipm pressure
Minimum1 Level:
3 Bath 1,2,3 - 1.9 Ipm Bath 1,2 - Lovo Bath 1,2,3
Kitchen -9.5 Ipm low flush
6 Bath 1,2,3 - 1.9 Ipm Bath 1,2 - Lovo Bath 1,2,3
Kitchen - 9.5 Ipm low flush
9 Bath 1 - 1.9 Ipm Bath 1 - Lovo Bath 1
Kitchen - 9.5 Ipm Dams
10 Bath 1,2 - 1.9 Ipm Bath 1,2 - Nova Bath 1,2
Kitchen - 9.5 Ipm Dams
12 Bath 1 - 1.9 Ipm Bath 1 - Lovo Bath 1
Kitchen - 9.5 Ipm Dams
'All shower heads produce 7. 6 Ipm (liters per minute) maximum at 345 kPa except the Navy (1.9 Ipm).
>>Pressure toilet (3.8 to 5.7 liters per flush), microphor 11.9 liters per flush), and low flush (13.3 liters
per flush).
c Designed levels of conservation were 40+ % for maximum, 20% for moderate, and 10% for minimum.
"White-Westinghouse front loading automatic washing machine installed April 1981 and removed July
1981.
Table 2. Mean In-House Water Use Before and After Installation of Water Conservation Devices'
Water Consumption llpcd) Probability
Before11 After11 % "before = "after
Site x 95%CI x 95%CI Reduction (a = .05)
Maximum Con-
servation Level:
2° 197 ±19 118 ±13 40.0 .0000
4° 131 ±14 95 ±10 27.3 .0000
7 191 ±19 109 ±22 42.8 .0000
Moderate Con-
servation Level:
1 97 ±17 83 ±15 14.7 .0964
5 239 ±33 154 ±28 35.6 .0001
8 248 ±64 157 ±36 36.7 .0072
Minimum Con-
servation Level:
3 273 ±41 245 ±55 10.0 .2043
6 254 ±53 204 ±34 19.5 .0560
9 259 ±48 218 ±47 16.0 .1030
10 207 ±55 167 ±36 19.3 .1103
12 199 ±39 133 ±23 33.1 .0024
'In-house use (liters per capita per day) was determined by subtracting outside hose bibb use from total
site use for each site except 4 and 6. Additional outside bibb use occurred at sites 4 and 6, therefore
total in-house water use was determined by summing toilet, shower, and laundry water use.
''Meters were read before devices were installed during the spring and summer 1980 (April 9, 1980, to
May 9, 1980, for sites 1,2,3,4,6 and 9; and June 3, 1980, to July 3, 1980, for sites 5,7,8,10 and 12).
After conservation devices were installed, monitoring was done in spring 1981 (May 19, 1981, to June
19, 1981, for all sites).
'Sites 2 and 4 also had front-loading washers from April 1981 to July 1981.
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All water conservation devices were well
received by individual homeowners except
for the faucet aerator-flow controls and the
Navy showers. Homeowner opinion tended
to be negative on faucet aerator-flow con-
trols, with seven reporting the device to be
either poor or fair and five reporting it to be
excellent or good. The Navy shower was re-
jected in two homes during a brief pretest
period and conditionally accepted in a third
home where it was little used during the
study. Responses to all the other devices
were mostly excellent or good, with air-
assisted toilets drawing excellent ratings
from all three homeowners using that device.
Maintenance problems were minimal on all
devices except the water pressure toilets.
The mean septic tank effluent quality
before installation of the conservation
devices is summarized in Table 4. As ex-
pected, the concentrations of most septic
tank effluent parameters increased
significantly at sites after installation of water
conservation equipment, with the maximum
water conservation sites having the most
significant increases.
Though this study has clearly demon-
strated that the installation of waste-flow
reduction hardware will result in higher con-
centrations of pollutants in septic tank ef-
fluent, mass loading should remain constant
or be reduced somewhat by virtue of im-
proved septic tank treatment. Moreover, any
increase in pollutant concentration should be
more than offset by the significant decrease
in hydraulic load on the septic tank/soil ab-
sorption system.
Two of the study systems used ion ex-
change water softeners to mollify the effects
of hardness in the domestic water supply.
These systems had septic tank effluent
chloride concentrations that were more than
10 times those of homes without ion ex-
change water softeners.
Alternative Trench Systems
Alternative onsite trench systems were
constructed at three sites, and effluent was
diverted from the original failing soil absorp-
tion area. Trenches contained 100 mm of
limestone sand on the trench bottom. The
sand was covered with 150 mm of 2B-lime-
stone gravel, with the distribution lateral
placed above the gravel. A layer of untreated
building paper separated the gravel and
lateral from the trench backfill. The ST ef-
fluent was pumped to each alternative trench
by a 0.25-kW pump located in a 2.2-m3 dose
tank positioned after the septic tank. Each
pumped dose was 400 to 500 liters. Effluent
flow was distributed to the alternative tren-
ches for 283 to 325 days at the three sites.
Following the ST flow diversion, the oil
soil systems naturally drained and returned
Table 3. Water Conservation Equipment and Installation Costs in 1980 Dollars
Site
Maximum Con-
servation Level:
2
4
7
Moderate Con-
servation Level:
1
5
8
Minimum Con-
servation Level:
3
6
9
10
12
Labor
Cost
$104
154
181
56
76
121
76
76
0
0
0
Equipment
Cost-
$1,248<$708P
1,4741934)
984
642
967
1,004
295
295
19
42
19
Total
Cost
$1,352($812)
1,72811,088)
1,165
698
1,125
1,125
371
371
19
42
19
Costs of individual items in 1980 dollars were: Pressure toilet, $309.37; microphor toilet, $661.79 (in-
cludes toilet at $301.30, compressor at $195.50, installation kit at $44.99, air filter at $65.55, and pressure-
reducing valve at $54.45); conventional water-saving toilet. $98.22, toilet dams, $5.00; Nova showerhead,
$8.25; Lovo 1 showerhead, $5.50; 1.9-lpm Chicago Faucet faucet-flow control, $3.85; 9.5-lpm American
Std. faucet-flow control, $3.11; faucet aerator adaptor, $1.85.
''Costs without automatic front loading washer machine t$540).
Table 4. Septic Tank Effluent Quality Comparison
Parameter
COD (mg/L)
TOC (mg/L)
Nonfilterable residue (mg/L)
TKN (mg/L)
Ammonia-N (mg/L)
Total P (mg/L)
Ortho P (mg/L)
Chloride (mg/L)
pH
Total Coliform (MPN/ml)
Fecal Coliform (MPN/ml)
'Arithmetic means except where noted.
''From Otis and Boyle (1976).
"From Salvato (1972) (median values).
"Geometric means.
Study Homes'
(before device installation)
485
174
108
77
52
18
13
45
6.9
62,000'
1,100*
Literature'
360*
54"
55"
3*
/5»
12*
80=
7.4*
1, 100,000°
4,21O>
to aerobic conditions. After approximately
10 months of flow diversion to the alternative
trenches, flow to the previously failed SAS
was resumed. Ponding was observed within
a few months in all of the systems, but they
continued to function satisfactorily for more
than 16 months (the end of the study). The
data (see Figure 1 for an example) indicated
complex and almost unpredictable responses
in the effluent ponding levels at each of the
three sites. Each ponding level is affected by
septic tank flow rates, precipitation, subsur-
face drainage, evapotranspiration, and in-
filtration and it can be explained only if each
of these facators can be quantified. The data
indicate that resting has restored the absorp-
tion area capability, but it also suggests that
periodic resting will probably be needed in
the future as well. These results indicate that
an old system should not necessarily be
abandoned, because at least part of its func-
tion can be restored after a period of resting.
The full report was submitted in fulfillment
of Cooperative Agreement CR807115-01 by
the Pennsylvania State University under the
sponsorship of the U.S. Environmental Pro-
tection Agency.
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"
1980
Sept Oct Nov
Date of Observation
1981 1982
Dec Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
o
5
I I
Semiweekly
T^^ I
Weekly
Lnn
T
iUh
i rruir, r,
30
40
I
c 50
01
Uj
2 60
c
70
Effluent Diverted
to Alternate Trench
Nov. 1980 to Aug. 1981
"Top of Gravel Bed (Effluent Discharges at
9 cm Level Through Vent)
_L
Bottom of Observation Tube
A \ \ _1 1
Figure 1. Effluent ponding levels in the soil absorption area and semiweekly or weekly precipitation for Site 9.
Daniel D. Fritton, William E. Sharpe, Albert R. Jarrett, Charles A. Cole, and Gary
W. Peter sen are with Pennsylvania State University, University Park, PA 16802.
James A. Heidman is the EPA Project Officer (see below).
The complete report, entitled "Restoration of Failing On-Lot Sewage Disposal
Areas," (Order No. PB 84-168 970; Cost: $14.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
U S GOVERNMENT PRINTING OFFICE; 1984 759-015/7676
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE 8. FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
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