ALASKA SEWAGE LAGOONS
FEDERAL WATER QUALITY ADMINISTRATION
NORTHWEST REGION
ALASKA WATER LABORATORY
College, Alaska
-------
ALASKA SEWAGE LAGOONS
by
Sidney E. Clark
Harold J. Coutts
Robert L. Jackson
Presented at the
Second International Symposium
on Sewage Lagoons
Kansas City, Missouri (June, 1970)
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
ALASKA WATER LABORATORY
COLLEGE, ALASKA
Working Paper No. 8
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ALASKA SEWAGE LAG.OONS
by
Sidney E. Clark*
Harold J. Coutts**
Robert Jackson***
There are many isolated communities and governmental installations
in Alaska with populations of less than 1000 people. Most native -
villages are not sewered. A few of the government outposts are served
by extended aeration package plants, others have septic tanks, and the
rest have no treatment. Some of the septic tanks dump directly into
the ground.
An aerated lagoon with its ability to handle overloads and its simp-
licity of operation is attractive for remote installations. Faculatative
lagoons with their extreme simplicity are also attractive for remote site
application, especially areas where power is unavailable or extremely
expensive ($0.25 to $1.00 per kilowatt-hour).
In 1957 a small facultative lagoon was placed in operation north of the
Arctic Circle at Fort Yukon, A-laska. The system is a leaky lagoon
(no definite effluent line exists) that serves a school.
Late in 1967 the Alaska Air Command and the Alaska Vlater Laboratory
entered into an agreement to construct and operate a research field
facility that included an aerated lagoon pilot plant at Eielson Air
Force Base, 22 miles southeast of Fairbanks in Interior Alaska. Most
of the information in this report has been obtained from the Eielson
lagoon.
For presentation at the Second International Symposium For Waste Treat-
ment Lagoons, June 23-25, 1970, Kansas City, Missouri.
*Sidney E. Clark, Acting Chief, Cold Climate Research, Federal Water
Quality Administration, Alaska Water Laboratory, College, Alaska.
**Harold J. Coutts, Research Chemical Engineer, Cold Climate Research,
Federal Water Quality Administration, Alaska Water Laboratory,
College, Alaska.
***Robert Jackson, Research Chemist, Cold Climate Research, Federal
Water Quality Administration, Alaska Hater Laboratory, College, Alaska.
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COLD REGIONS LAGOON EXPERIENCE HISTORY
When considering lagoons for Alaska and Northern Canada application,
strong emphasis must be placed on cold weather impact.
Facultative Lagoons
The Northern Regions Sewage Lagoon Performance Statistics presented
in Table 1 indicate a number of factors of importance: 1. winter BOD
and solids removal efficiencies are not significantly improved by
longer detention times in a single cell, but are significantly im-.
proved when a system has several cells operated in series; 2. BOD
removal efficiencies are not affected by increases in lagoon depth;
3. bottom sludges will accumulate and their rate of accumulation
will, in general, increase as one travels north, and the rates vary
from 8.8 to 14.0 cu ft per 1000 people per day; and 4. although winter
efficiencies for the removal of total col ifonus are not well defined,
winter removals of 97.7 to 99.9 percent were reported at Inuvik and
-Yellowknife. Pathogenic organisms have been isolated from the sewage
"deposits of early expeditions and camps in the Arctic and Antarctic
many years after man's activities at the sites had ceased (2).
The actual lagoon size is directly proportional to the required system
detention and the system cost-is also directly proportional to the
length of detention; therefore, loading rates become a highly im-
portant factor. Svore (29) found that loading rates are the key to
odor control and states that "10 Ibs applied BOD per acre per day
usually eliminates Spring breakup odor problems; 20 Ibs applied BOD
per acre per day creates odor during Spring breakup of 1 to 2 weeks
duration; 25-30 Ibs applied BOD per acre per day creates odors of
3 to 4 weeks duration; and 50-60 Ibs applied BOD per acre per day
creates odors that persist for as long as 3 months". On the other
hand, Brisbin (6), Dawson (7,8,9), and Higo (13) have found that
odor control can be attained at much higher organic loading rates.
At Moose Jaw, Saskatchewan, odor problems became so serious with a
loading of 1080 Ibs applied BOD per acre per day and 7 day detention
.that the lagoons had to be bypassed. The Sutherland, Saskatchewan
laqoons operating at 1300 to 2600 Ibs applied BOD per acre per day
and detentions of 2.75 and 1.45 days seldom create odors detectable
at distances greater than 1000 feet with detectable odors generally
'limited to distances less than 100 to 300 feet. Dawson (7,9)
reports definite improvements at Yellowknife, Northwest Territories,
wnen a short detention anaerobic primary cell (0.6 day detention
and 8 ft depth) was added. Higo (13), after investigating a number
of lagoons in Alberta, Canada, concludes that the potential for odor
production can be minimized when designing short detention time
-------
TABIE I. NORTHERN REGIONS SEWAGE LAGOON PERFORMANCE STATISTICS
Latitude, °N
January Average A1r Temperature, °F
Lagoon Type
Lagoon Depth (ft.)
Detention Time (days)
Loadl ng— *BOD5/acre/day
~IBOD5/iooo ft.3/day
Ice Conditions — Duration Starting Month
to End Month
--Depth (ft.)
Sewage— Source
— Winter Temperature, "C
Lagoon Temperature— Summer , °C
—Winter, °C
Operation Efficiency
—BOD, Summer % Removed
—BOD, Winter % Removed
— Suspended Solids, Summer, % Removed
—Suspended Solids, Winter, % Removed
—Total Conforms, Suirmer, % Removed
— Total Conforms, Winter, % Removed
Odor Conditions Near Lagoons
Comments
Bottom Sludge Accumulation, ft.3/1000 capita/day
Information and Data Source
Reference
to
3
T
. oi
T-
|*
•— z
68°21 '
-28.2
(Febr. -34.1)
Facultative
1.9-3.4
73-136
8.9-9.6
0.082
October
May
To bottom ex-
cept at inlet
Raw Domestic
19°C
12.5-20°C
<1°C
73-89
41
92
85
99.7
99.9+
Noticeable at
700 ft.
Swamp area with
brush and trees
in lagoon
—
Dawson, 1967
§
S %
oJSS
^fci
II
S1- £
~±£
62°
-20.3
(Febr. -28.2)
Facultative
3.2
134
15
0.108
October
May
1-1/2
Raw Domestic
<6.5°C
14-20-C
re
70
41
—
„
—
Definite
Probl em
Nearly anaerobic
with some exposet
sludge banks
—
Dawson, 1967
(Compiled From Reports and Publications Referenced in Last Line)
Yellowknlfe, N.W. Territories
After Modification
Series Operation
Primary Cell Secondary Cell
62°
-20.3
Anaerobic
8.0
0.6
5170-6170
. 11.9-14.2
None
0
" Raw Domestic
"<6.5°C
14-20°C
36
36
—
"
73
80
None Reported
—
12.9
62°
-20.3
Facultative
3.2
99
18.8-19.4
0.136
October
May
T-l/2
Primary Effluent
<1.5°C
14-20°C
75* (61)**
59 (35.9)
-
~
99.99
None Reported
Natural lake
with construc-
tion deficiencies
— '
Dawson, 1967
3
2
f.
..
IS
52°
Edmonton
+1 7
Facultative
5.0
202
25.7
0.118
November
March
5.0
Raw Domestic
9-1 0°C
18°C
92.0
30.1
76
—
Low Level
—
—
Hi go, 1965
Drayton Valley, Alberta
(3550)
Series Operation
(Cell K out 12/20/61-4/11/62)
Cellfl Cell 12 Cell 03
52°
Edmonton
+3.7
Facultative
5.0
52
55.5
0.255
November
April
2.0
Raw Domestic
--
19-21°C
0.5-3°C
70.5
29.1
61.1
69.2
—
Low Level
„
-
52°
Edmonton
+3.7
Facultative
5.0
33
Summer/Winter
26.9/62.0
0.124/0.285
November
April
2.5
Primary Effluent
<1.0°C
19-23°C
0.5-3°C
86.0* (52.5)**
40.8 (16.5)
56.6 (-11.5)
71.7 (8.1)
"
Low Level
„
-
52°
Edmonton
+3.7
Facultative
4.0
36
Sunnier/Winter
9.2/ 38.6
0.05/0.222
November
April
2.5
Cell K
Effluent
<0.5°C
19-21 °C
0.5-3°C
92.5* (46.4)**
53.5 (21.4)
58.1 (3.4)
72.7 (3.5)
"
Low Level
..
-
Hi go, 1965
Stettler, Alberta
(3800)
Operated in Series
Primary Jl Primary J2 Secondary Jl Secondary §2
52°
Edmonton
..-+3.7
Anaerobic to
10
5.94
1433
3.29
December
February
Short durations
0.3
Raw Domestic +
Milk Process.
8-1 1°C
18-22°C
1.5-5°C
37.0
28.2
69.6
64.1
—
Moderate
Algae showed
in this pond from
April to fall
8.75
52°
Edmonton
+3.7
Facultative
5
6.20
Summer/Winter
488 / 429
2.24 / 1.97
December
March
0.2-1.0
Cell Jl
Effluent
1.5-5°C
17-21°C
0.5-3°C
63.6* (42.3)**
37.3 (12.7)
71.1 (4.9)
74.1 (27.9)
—
Moderate
—
52°
Edmonton
+3.7
Facultative
5
75.2
Summer/Winter
20.8 / 35.8
0.096 / 0.164
November
April
3.5
Cell K
Effluent
0.5-3°C
18-22°C
0.2-2°C
93.0* (80.7)**
51.1 (22.0) -
74.5 (11.8)
85.2 (42. 6J
—
Nil
Storage with
release spring
and fall
—
52°
Edmonton
+3.7
Facultative
5
87.4
Summer/Winter
3.49 / 24.2
0.016 / 0.11
November
April
3.5
Cell #3
Effluent
0.2-2°C
18-22°C
0.1-1°C
95.5* (35.7)**
73.0 (44.6)
87.1 (49)
87.1 (12.8)
—
Nil
Storage with
release spring
and fall
—
Hi go, 1965
2°
-
:acultative
-
-
SO-80
lovember
(pril
._
-
!5-98
36
tone
Reported
Two ponds
>perated alter-
lately
--
Sparling, 1961
o
3 •—
«-j(l
I. at 0
Arctic Circle
-12
Facultative
3.0
-
85 (winter only)
0.75
To bottom at
edges
School
20°C
<1.0°C
-
None
Noticed
No overflow
High ground-
water area
-
Anderegg, 1960
Lazy Mountain
Children's Home,
Palmer, Alaska
62°
+12
Facultative
2-5
2+
40
0.46
October
April
2
School
1.5°C
35-50
2 weeks in
Spring
—
-
Anderegg,
1959
Camrose, Alberta
(7708)
Series Operation
Long Long
Primary #1 Primary #2 Secondary #1 Secondary #2 Detention #1 Detention $2
52°
Edmonton
+3.7
Anaerobic
10.0
6.2
Summer/Winter
808/808
3.71/3.71
November
March
Nil-0.3
Raw Domestic +
Milk Process.
14-16°C
17-23°C
1-5°C
44.5
41.2
52.8
79.6
Moderate to
High
52°
Edmonton
+3.7
Facultative
10.0
5.75
Summer/Winter
488/514
2.24/2.36
November
March
N11-1.0
Primary 01
Effluent
1-5°C
17-23°C
1-4°C
55.1* (19.1)**
46.6 (9.2)
56.9 (8.7)
85.8 (30.4)
Moderate to
High
52°
Edmonton
+3.7
Facultative
5.0
3.45
Summer/Winter
697/754
3.20/3.46
November
March
2.5
Primary J2
Effluent
1-4°C
17-23°C
0.5-3°C
59.4* (9.6)**
52.4 (10.9)
73.8 (39)
87.1 (9.2)
Slight
52°
Edmonton
+3.7
Facultative
5.0
3.45
Summer/Winter
590/693
2.71/3.18
November
April
3.0
Secondary #1
Effluent
0.5-3°C
18-23°C
0.5-3°C
77.6* (44.7)**
52.8 (0.8)
79.0 (19.8)
91.0 (30.2)
Slight
52°
Edmonton
+3.7
Facultative
5.0
101
Summer/Winter
U5/23.4
0.062/0.107
November
April
3.0
Secondary #2
Effluent
0.5-3°C
19-23°C
0.1-2°C
96.3* (83.5)**
60.3 (15.9)
77.7 (-6.2)
91.8 (8.9)
Not Noticeable
52°
Edmonton
+3.7
Facultative
5.0
93
Summer/Winter
2.1/21.6
0.01/0.10
November
April
3.0
Long Det. £1
Effluent
0.1-2°C
19-23'C
0.1-3°C
49* (98.1)**
71.5 (28.2)
92.7 (67.3)
93.6 (21.8)
Not Noticeable
School Load Plus Milk Processing Plant.
Sludge— thick, black
Offensive odor to good draining fine dark
9.5-10.1
9.5-10.1
..
Higo, 1965
•X
CO "fl3
cl 1
if B!
"flj 0. l/> fO
••- X >>U_
LL| LLJ l/>- — •
64°
-10
Facultative
4.5
18
125
0.637
1 November
April
' <1.0
Air Base
Domestic
21 °C
19-21°C
1°C
73
51
87
87
None
Reported
Bottom sludge taken
in Jan: 8 Febr. had
50% volatiles
-
Rubel, 1965
-------
systems by provision of central submerged influents, depths of 10-20...
feet, detention of 2 to 4 days (not over 4 days at existing flows),
and BOD loading not to exceed 9 Ibs applied BOD per 1000 cu ft per -
day (4000 Ibs applied BOD per acre per day at 10 ft depths).
Dawson (7, 8, 9) and Grainge (12) have found that stabilization lagoons
operating under extreme winter conditions provide BOD and solids
removal rates that are approximately equivalent to primary waste
treatment.
Both North Dakota (31) and Minnesota (1, 11) are recommending that
stabilization lagoons be designed with sufficient volume to provide
for retention of all winter flows; thus limiting effluent discharge
to that period of the year when adequate treatment is obtained.
Aerated Lagoons
Aerated Lagoons have operated successfully in cold regions of the
contiguous United States and Canada for a number of years. The first
aerated lagoon in Alaska was located at the Eielson Air Force Base,
near Fairbanks, and operated by the Arctic Health Research Center.
The cost of construction of aerated lagoons is almost directly pro-
portional to detention requirements; therefore, reasonable performance
versus detention time prediction capabilities are necessary. Several
investigations have collected data for aerated lagoon operation per-
formance within the temperature range of 0°C to 10°C; selected sources
are shown in Figure 1. The curves demonstrate that there is a high
probability for obtaining BOD removal efficiencies greater than
80 percent at detentions less than 15 days with lagoons operating
at temperatures less than 5°C.
Another factor affecting sizing of aerated lagoons is a volume re-
quirement for bottom sludge accumulation. Reid (19) suggests that
approximately 1/2 inch of annual sludge accumulation can be expected
when a perforated tubing aeration system is utilized for aeration
and mixing.
Although several different submerged aeration systems appear com-
pletely feasible for Alaska application, some of which have been
used in Canada, only the performance of perforated plastic tubing
manufactured by Hinde Engineering, Inc. has been reported in the
literature. The results obtained by Reid (19), preliminary results
of current Alaska Water Laboratory investigations, and aeration design
approaches described by others (14, 16), indicate that air delivery and
placement are not nearly as critical for aerated lagoons as for ex-
tended aeration and activated sludge. Furthermore, system reliability
is more important than its actual configuration for air delivery.
-------
ioo_
90
80..
o 70.4.
60..
XGellman (10) Kraft Wastes
2°C
© Gellman (10) Kraft Wastes
10°C
O Sawyer (24) Textile Wastes
13°C
-{- Tov/nsend (30) Jomestic and
Seasonal ^ntie'ry V.'astes
5°C
O McKinney (15) Domestic '.'astes
. Reid (19) Domestic Wastes
0-1°C
50.
-1 —15
Detention Time (Days)
FIGURE 1
AERATED LAGOQMS
PERFORMANCE EFFICIENCIES
lo
15
-------
.Although Reid (19,20,21) presents a strong case for the utilization of
perforated tubing for aerated- lagoons in cold regions, it is feasible
to design other diffuser systems that will provide adequate mixing.
According to Van Heuvelen (31), "There are two waste treatment facilities
of the diffused air tube type which have gone through several winters.
The quality of effluent appeared to be satisfactory the first year, but
operation and maintenance problems increased and the quality of the
effluent decreased. The holes in the tubing were subject to clogging
and the recommended cleaning method did not open them up. The com-
pressors had to work under a higher pressure to overcome the additional
back pressure caused by the holes being plugged. The additional main-
tenance caused considerable, concern to the owners of these installations."
In regard to cleaning procedures for the perforated plastic tubing
diffuser systems, Stewart, City of Regina, Saskatchewan (28) states,
"The chief mechanical problem we have encountered is due to the small
holes in the aeration tubing becoming blocked. It has been necessary
to lower the water levels in the lagoons to clean the tubing holes,
either by cutting new holes or by deforming (bending between two
-toilers). It appears in our case that deforming the tubing gave more
lasting results".
Black (5) reported successful operation of a Welles floating aerator
at Hinton, Alberta and a Lightnin fixed unit at Prince George, British
Columbia in exposed temperatures of -29°C to -35°C,'
Solids separation devices located in short detention primary cells
(12 to 36 hour) followed by short detention aerated lagoon secondary
cells (3 to 5 days) show considerable promise. Rupke (23) considers
systems with the dividing wall being the solids separation system
to be feasible provided adequate mixing in the primary cell is provided.
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ALASKA WATER LABORATORY
EXPERIMENTAL AERATED LAGOON PERFORMANCE
The experience to be discussed in this section has been acquired
with a research pilot facility that was constructed jointly with the
Alaska Air Command-at Eielson Air Force Base (EAFB), 22 miles south-
east of Fairbanks, Alaska.
The climate at EAFB, located at 64 1/2°N latitude, is continental
including extreme temperatures of -80°F to +100°F with a mean annual
temperature of approximately 25°F.
The research pilot lagoon located at EAFB was constructed with vertical
walls to avoid an appropriate side-wall influence when scaling up to
actual system size. The EAFB lagoon is a 20 mil PVC-lined wood crib
structure, 14 feet deep, 15 feet wide, and 82 1/2 feet long. Operating
depth is 12 feet. The lagoon is divided into 6 cells in series. The
system has been operated with a total detention of 30 days (ice in-
fluence not recalculated) and accumulative detentions of: 1.8, 4.7,
8.3, 13.7, 21.0, and 30 days. Raw domestic sewage is utilized as feed.
Flow measurement is accomplished with a dump tank and a timer on the
feed pump and is checked by measuring effluent flow with a V-notch
weir. Periodic leak tests are conducted to further varify flow through
validity. In the lagoon, each cell in series is fed from the previous
cell through a 2 in. diameter, 10 ft. long hose. Commercial perforated
tubing was the first aeration device evaluated. It is 3/8 in. flexible
plastic tubing with 8 1/2 slits per foot. The tubing is supported on
wires 16 inches above the bottom. To alleviate sludge plugging, cell
1 has 14 tubes; cells 2 through 4 have 8 tubes; and cells 5 and 6 have
4 tubes. The second'aeration system now under investigation utilizes
open valve disc air diffusers. This diffuser is essentially a 2 1/2
in. diameter shrouded disc, which sits on the open end of a 1/8 in. NPS
pipe threaded into a header. The disc has a lift of 1/6 in. during
full open air flow and "seals" the 1/8 in. pipe opening when the air
is shut off.
The facility v/as placed in operation during the Winter of 1968-69.
System efficiencies for BOD reduction are presented in Figure 2.
During the winter, the temperature in the first 2 cells is a trans-
ition temperature from 20°C down to less than 5°C. The normal
winter operating temperature for an aerated lagoon in Alaska varies
from approximately 0° to 5°C. A close look at the family of curves
in Figure 2 indicates several things. 1. There is a decided lag
between winter removal curves and the summer removal curve. A small
portion of this lag can be attributed to the ice influence on actual
detention time, starting with cell 3. High among the potential
explanations for the remaining lag are a lag in bacterial population
build-up, created by low temperatures; depressed winter DO (0 a high
percentage of the time) in cells 1 and 2 (tube clogging); and lower
endogenous respiration rates at lower temperatures. 2. Summer BOD
-------
100-,-
r
i • • MAXIMUM. ICE THICKNESS
• Winter 1970
10 • - 15 20
Detention Time (Days)
25
1st v/inter
plastic tubing
2nd winter .
plastic tubing
Open eeratcr,
winter
Early summer'
plastic tubing'
J 5 ft
-1 4
-! ^
I 6
j 2
«
1
30
FIGURE 2
ALASKA .V.'-M:.R LAGQP.ATOP.Y
AERATED LAron::s
B'.O.D.
-------
removal efficiencies peak out between 15 and 20 days detention and drop
off beyond 20 days detention. This is believed to be due to the effects
of excessive algae growth. As the summer curve is for the first summer's
operation and very little sludge had an opportunity to settle out in
the last 3 cells, bottom influence is not believed to be significant
in explanation of the summer efficiency reduction at higher detention.
Algae were present in cells 2, 3, 4, 5, and 6 from mid-April to late
September. 3. The second winter's data show a consistent BOD re-
moval efficiency reduction of approximately 5 percent below the first
winter curve when perforated tubing provided the aeration and mixing.
4. The winter BOD removal efficiency curve for valve disc open aerators
shows a significant improvement over the second winter perforated tubing
system, and the valve disc open aerator curve is approximately the same
as the first winter perforated tubing curve. 5. Maximum ice thickness
of 4 1/2 feet to 5 feet may be expected near the effluent.
Preliminary results of tests with the system converted to a 4 cell
system of the same detention time indicate that removal efficiencies
for a 4 cell system are similar to those of a 6 cell system.
The total coliform removal efficiencies and effluent numbers are:
January-February 99.70% 3xl05/100 ml
March 99.97,% 2x10^/100 ml
Contamination from the extended aeration effluent backing up during
early January as a result of the common outfall, undoubtedly influenced
these values. Summer 1969 effluent measurements for fecal indicators
were:
July August
Total Coliforms • 5.5x10^ organisms/100 ml 1.2x10^ organisms/100 ml
Fecal Col if onus 440 " 700
Fecal Enterococci 126 : 64
At the EAFB aerated lagoon, with 10 1/2 feet submergence, 0°C, 2-10 mg/1
DO, and 80+% BOD removal, the tubing transfer efficiency calculates out
to approximately 1 to 2 percent. No credit has been assumed or provided
for surface transfer or BOD removal by primary sedimentation. (Ultimate
'BOD assumed to be 1.5 times the 5-day, 20°C BOD).
Current operating experience, using perforated tubing at the EAFB aerated
lagoon has required frequent repair and maintenance. There have been
considerable tubing clogging problems which have sent more than one
compressor to the graveyard. The first attempt at HC1 (gas) cleaning
was successful bt;l very s^-ortli ved ^as_the tubina reclpgged in less
-------
than two weeks. Before gas cleaning the perforated tubing, orifice
pressure drop was greater than 3 psi at an air capacity of 1.5 cu ft
per minute per 100 feet of tubing. After the first dose of gaseous
HC1, the air rate increased by 50% with no change in pressure drop.
The compressor discharge temperature was greater than 200°F at 9 psig
with ambient air temperatures of 10 to 40°F.
NORTHWAY, ALASKA AERATED LAGOON PERFORMANCE
Northway, Alaska is located in Interior Alaska near the Canadian border.
The coldest temperature in the United States has been recorded at North-
way, which is -82°F.
The Northway lagoon is a bentonite-lined wood crib structure 42 feet
by 54 feet by 7 1/2 feet operating depth. It has a longitudinal baffle,
splitting it in two cells, 21 feet wide. Operation started during
September 1965. Perforated plastic aeration tubing provides aeration
and mixing with the spacing being according to the manufacturer's
recommendations.
The Northway lagoon raw sewage averages approximately 240 mg/1 BOD.
Feed temperatures vary between 2°C and 25°C. The BOD removals at
Northway do not vary significantly for summer or winter figures, with
an average removal of 77% in the first cell and a total of 85% removal.
According to the Site Manager (26), tube clogging has been a major
problem, and the use of HC1 (aqueous) has not been very effective. The
Northway lagoon started out as a 30 day detention system but a decreasing
population has reduced the load to the present 60 to 70 day detention
system.
In June 1967 sludge core samples were examined and appeared to be
preserved exactly as deposited. However, in August 1967 and May 1968,
bottom samples had a definite black appearance and the physical
characteristics of partially digested sludge. Significant methane
production occurred during the summer of 1967. The maximum depth
of bottom sludge did not increase, but its location shifted between
the August 1967 and May 1968 sample dates. This shifting.seems to
.indicate that gas production resuspends bottom sludge and thus
assists in providing aerobic and anaerobic digestion.
The mixing action of aerated lagoons allows the sludge zone temper-
ature to rise above 12°C during the months of June, July, and August
and part of September in Interior Alaska. Maximum bottom temperatures
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recorded at Northway were 19°C. Samples taken during March 1970 at
Northway indicate a sludge.accumulation of approximately 6 inches in
-the first cell and approximately 3 inches in the second cell. For
4 1/2 years, this indicates an accumulation rate of 1 inch per year,
or approximately 9 cu ft per 1000 people per day. This is less than
observed rates for most stabilization ponds. It is difficult to pre-
dict what the long range accumulation and comparison will be. However,
since the system is essentially a eutrophic lake, one would expect
continued and accelerated bottom deposit build-up.
A Northway bottom sludge core sample taken in March 1970 from the
first cell was sectioned and analyzed for fecal indicator bacteria.
The 9 in. core was cut in three sections as follows: 0-3 inches
bottom; 3-8 inches mid; and 8-9 inches top layer.
Organism Density
MPN counts on a per wet gram basis
No. of organisms x 10'
Presumptive Total Coliform
Confirmed Total Col i form
Fecal Col iform
Presumptive Enterococci
Confirmed Enterococci
Top Mid Bottom
4,
3.
2.
13
13
49
13
4.
221
221
22.
13
3.
172
172
1
It appears that the sludge located deeper in the core has a more
favorable environment for preservation of fecal organisms. These
bottom cores represent a stable bottom uninfluenced by resuspension
dating from mid-September 1969 or 7 months of low temperature. The
sludge temperature was less than 1°C and only one of four cores from
the first cell at Northway had a pH less than 7.0.
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GENERAL ALASKA
AERATED LAGOON EXPERIENCE
Aerated lagoons started in Alaska with the successful operation of a
small unit at Eielson Air Force Base specifically placed in operation
for research purposes in 1964. Reid (19,20) studied the small lagoon
located at EAFB and reported BOD removal efficiencies of 68-90% and
solids removal efficiencies of 67-68% for winter operation, with
primary settled sewage loadings of 68-200 IDS of BOD per acre per
day (0.4 to 3.1 Ibs applied BOD per 1000 cu ft per day). He found
that loading rates between-0.4 and 2.4 Ibs applied BOD per 1000 cu
ft per day gave efficiencies of 60-80% BOD removal. The system was
initially a single cell system with a depth of 4.4 feet and a surface
area of 0.13 acres; later this was changed to a two cell system.
If we assume that the data presented by Reid (19,20) are for treatment
of raw sewage, expected winter efficiencies should range between 58%
at 6 days and 78% at 37 days.
There are 17 aerated lagoons in Alaska at the moment. All but one
.use the perforated tubing for aeration .and mixing. Their locations
are shown on Figure 3 and listed below.
No. on Map • Location Operating Agency
1 Amchitka AEC
2 Annette Island FAA
• 3 Bethel . FAA
4 N. Kenai • .Big Bear Oil Refinery
5 Cold Bay • FAA
6 Cordova FAA
7 Security Squad (Elmendorf AFB) AAC
8 Eielsbn AFB AAC-FWQA
9 Fire Island (Anchorage) FAA
10 Fort Greely U.S. Army
11 King Salmon AAC
12 ' McGrath • FAA
13 Northway . FAA
14 Prudhoe Bay Private Construction
15 Scenic Park (Anchorage) Public
16 Wildwood (Kenai) . AAC
17 . Yakutat FAA
The Alaska Water Laboratory has obtained information for seven of the
aerated lagoons, which serve mainly military and FAA sites, located
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FIGURE 3 ..
LOCATIONS OF ALASKA
AERATED LAGOONS
-20
S\tT$
<£/t>^0
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at Northway, McGrath, Cold Bay, Bethel, Fort Greely, Eielson Research
Facility, and Fire Island. Perforated tubing was used in all cases.
Performance data to establish the efficiency of these lagoons are
very limited, but basically they have shown good results in the first
year or so of operation.
Methods and materials of construction related to frost-heave and ice
action have presented problems (26,17). Construction in permafrost '
should be given special consideration. The Bethel lagoon was constructed
in permafrost and melted a large ice lens under one of the retaining
embankments (17). The Northv/ay lagoon was constructed with vertical •
3 inch wood plank walls in a permafrost area. Frost action has started
to jack the long walls out of the ground and system failure is eminent
(26). Its bentonitre lining has proven satisfactory.
A PVC lining was used to seal the Fire Island lagoon. Its upper half
has been protected by layers of hand laid rocks. No problems have
been reported (18) . .
The Fort Greely lagoon had vertical wood partitions which were jacked
up during filling in freezing weather (25). This action also destroyed
the integrity of the plastic membrane liner on the bottom. An earthen
embankment should also be considered an area of trouble unless there
is proper selection of materials.
The clogging of perforated tube diffuser systems with resultant com-
pressor problems seems to be a general problem (26,18,17). As clogging
progresses, efficiency reduction occurs.
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FORT YUKON
FACULTATIVE LAGOON PERFORMANCE
Fort Yukon, Alaska is located North of the Arctic Circle and has a
continental climate. Although the recorded extremes do not match
Northway for low or Fairbanks for high, the average annual temperature
is lower than either Fairbanks or Northway and the probability of
extended cold periods is greater.
The Fort Yukon facultative lagoon came into existence in 1957 under •
an experimental classification. Although it has an experimental
classification, very little actual operating data have been collected.
The Alaska Water Laboratory has initiated a study to obtain perform-
ance data for an annual cycle of operation. Results from the first
field trip are presented in Figure 4 and Table 2.
The contributing population equivalent of 63 people provides a loading
of 124 people per acre and is calculated as follows:
Fraction day No.of people Fraction yr Pop. Eg.
Student
Population 1/2 200 180/365 = 50
Adult/Winter 1 15 270/365 = 11
Adult/Summer 1 • - 6 95/365 = J^
63 total
people
Average annual sludge accumulation = 15,900 cu ft = 18 cu ft
63 people person
14 years year
Lagoon size: 125'xl25'x8' deep; 3:1 slopes
Winter surface loading: (125+24)(125+24) = 22, 200 sq ft
22,200 =0.51 acres
43,500
Winter loading: 63 = 124 people; say 100-150
0.51 acre
£_
The lagoon at Fort Yukon had an operating water depth of 8 feet in
March 1970. Conversations with maintenance people at the school
indicate that the lagoon depth decreases through the summer when there
is no loading. The lagoon does not have an effluent, so performance
figures have little meaning. The approach taken with this "leaky"
lagoon has worked ,?t-Fort Yukon, as evidenced by tHe_1ack of concern
by Fort Yukon residents about the lagoo'ri existing within tneir community'.
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Shi.
No.
COD
BOD
{
Solids
V'ol.
-iQ u'\cl
87
198
7.03
L
571
7.13
7.7,3
17
IskTj
7. JO
L
/oo
35 ^
12. "
7.02.
7.09
FIGURE 4
BOTTOM SLUDGE DEPTH PROFILE (in incSv
FORT YUKON LAGOON
., 1970
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TABLE 2
ENTERIC INDICATOR BACTERIA IN SLUDGE
FORT YUKON SEWAGE STABILIZATION POND
Counts obtained per gram of sludge by MPN method
Sample Location (See Figure 4)
1 2 4
Presumptive Total Coliforms* 1,300,000/gm 22,100/gm 7,900/gm
Confirmed Total Coliforms* 490,000 10,900 7,900
-Fecal Coliforms* 130,000 1,720 4,900
Presumptive Enterococci* 700. 240 240
Confirmed Enterococci* 310 33 49
Clostridia** . _ 5.3xl05 4.5xl04 6.3xl04
No Salmonella found in the samples**.
*Dr. R. Gordon, Research Microbiologist, Alaska Water Laboratory,
provided these analytical results.
**Mr. L. Miller, Chief, Bacteriology Section, Arctic Health Research
Center, provided these analytical results.
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CONCLUSIONS
Aerated Lagoons
Aerated lagoons, when, properly designed, are simple, reasonably efficient
waste treatment systems suitable for small communities. Aerated Lagoons,
unlike facultative lagoons, do not require large surface areas, have
odor problems, or have a high level of bottom sludge accumulation.
Experienced operators are not required, as a properly designed system
is extremely simple to operate.
With large exposed areas, ice will form to depths of greater than 4 feet
on aerated lagoons. Spring thermal expansion of ice layers may create
considerable strain on embankments, especially vertical walls.
Utilizing gross bubble air diffuser systems, BOD removals of 80% to
greater than 90% are feasible during the winter, depending on the
number of system cells in series, individual cell detention time, and
total system detention time. With perforated tubing (restricted)
diffusers, BOD removals of 70 to 85% are to be expected depending on
system configuration, detention time, and age of the aeration system.
BOD removals greater than 86 to 88% are not feasible during the summer
because of the algae load. When a restricted (partially clogged)
aerator was used, the BOD removal efficiency was observed to drop as
the lagoons age. The maintenance and clogging problems encountered
with the restricted aeration system have not been found with the open
type.
Provision of a system with a treatment efficiency (BOD removal) greater
than 80% greatly increases the project's first cost (construction) but
does not significantly increase operating costs.
Two lobe, positive displacement compressors will provide satisfactory
performance without being enclosed in a heated building. High
operating pressures greatly increase compressor maintenance problems.
At 9 to 13 psig (clogged aeration system), discharge temperatures are
over 200°F; at 5 to 6 psig, discharge temperatures are less than 90°F
when outdoor ambient temperatures are 10-40°F.
Aerated lagoons are not efficient nutrient removal systems. On an
annual basis, phosphates are removed during the summer and released
during the winter, causing an apparent winter increase, but the
annual net removal is essentially zero. Total nitrogen removals v/ere
approximately 30 % in the summer and 0% in the winter.
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Facultative Lagoons
There are four important considerations .in the design and use of
anaerobic and facultative lagoons for v/aste treatment.
Public Health Implications: Anaerobic and facultative lagoons are
a definite improvement over disposal to the street, back yards, •
or an outdoor privy. The application of these systems to waste
disposal in remote villages, where a source of reasonably priced
power supply is unavailable, should be given serious consideration.
Bottom sludge definitely accumulates faster than it is stabilized,
so the system will have to eventually be abandoned. The question
then becomes one of "how much public health hazard does an abandoned
sewage lagoon create?" Deep, lightly loaded lagoons will have many
years of service. Information on the degree of winter removal of
coliforms is extremely scarce; however, there does appear to be a
significant reduction. Pathogenic organisms have been isolated from
early expeditions and camps in the Antarctic and Arctic, indicating
long survival under refrigerated conditions.
Nuisance Potential: Anaerobic and facultative lagoons should always
be located downwind (prevailing) and at least 1/4 mile from the nearest
inhabitants. An obvious and reasonably reliable means for minimizing
odor production is the utilization of a design loading of 20 Ibs BOD
per acre per day or less. However, Alberta and the Northwest Terri-
tories have had reasonable success in minimizing odor production
through utilization of deep primary cells loaded at high rates (1 to
4 day detention), followed by long detention time cells in series.
The reasons why a short detention primary cell usually will not pro-
duce large amounts of odor are not clear. It is undoubtedly a
combination of factors, two of which may be high flow rates in the
overlying liquids and the concentration of potential odor production
in a small area.
System Loading and Process Efficiency Requirements: The evidence for
utilizing anaerobic and facultative lagoon design loads of less than
50 Ibs BOD per day per acre is overwhelming. However, the favorable
experience with several cells in series and utilization of a short
detention time (1 to 4 days) deep primary cell is reasonably well
documented, and should not be overlooked. Winter BOD removal rates
of 80-90%"are not feasible; therefore, serious consideration must be
given to winter storage with summer treatment in a shallow lagoon,
where a two cell system is feasible.
System Configuration and Construction: The influence of ice cover,
frost-heave, and depth must be carefully considered in the physical
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design of lagoons for an extremely cold climate. Influent, cross-over,
and effluent lines should be submerged, with the influent line centrally
located. Canadian experience indicates that deep lagoons are prefer-
able; however, the question exists, "what influence does the increase
in depth have in the formation of a strong thermocline?" Extreme
care must be exercised in application of lagoons in permafrost areas,
where ice-rich soil may exist.
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REFERENCES
1. Anonymous, "Sewage Stabilization Ponds in Mi=nesota", Minnesota
Department of Health, Division of Environmental Sanitation,
Section of Water Pollution Control (March 1963).
/
2. Alter, Amos J., "Sewerage and sewage Disposal in Cold Regions",
DA Project IT062112A130, Corps of Engineers, U.S. Army Cold
Regions Research and Engineering Laboratory, Cold Regions Science
and Engineering Monograph 111-056 (October 1969).~
3. Anderegg, J.A., C.F. Walters, D. Milliard, and H.F. Myers,
"Eskimo Algae Make Lagoons Work at the Arctic Circle", reprint
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Science Conference of the Alaska Division, American Association
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t>
9. Dawson, R.N., "Sewage Lagoon Treatment, Yellowknife, Northwest
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Quality Improvement, University of Texas Press.
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11. Ginner, Gary F., Section! of Sewage Works, Pollution Control
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,. Department of Health, Education, and Welfare, College, Alaska
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in Arctic Alaska", presented.at the 18th Annual Convention of the
Western Canada Water and Sewage Conference, Regina, Saskatchewan
(September 15, 1966).
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22. Rubal , John and Danny R. Gray, "Stabilization Pond Operation",
unpublished report, Eielson Air Force Base, Alaska (1965).
23. Rupke, J.W.G. , "Report on the Application of Aerohydraulic Guns
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Ontario", Division of Research, Ontario Water Resources
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Operation", Advances in Hater Quality Improvement, Water Resources
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25. Scarborough, Thomas, Corps of Engineers, Fairbanks, Alaska,
personal communications (April 1970).
26. Schultz, Patrick, Site Manager, Northway Federal Aviation Station,
personal communications (March 1970).
—27-,- Sparling, A.B., "Winter Operation of Sewage Lagoons in Manitoba",
Department of Health, Section of Environmental Sanitation.
28. Stewart, E., Plant Engineer, Public Works and Engineering Depart-
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United States", Advances in Water Quality Improvement, Water
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;30. Townsend, Allan R., Sebree Unsal, and Boris L. Boyko, "Aerated
i. Lagoon Design Methods: An Evaluation Based on Ontario Field Data",
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31. Van Heuvelen, W., Chief, Environmental Health and Engineering
Services, State Department of Health, Bismarck, North Dakota,
personal communications (February 6, 1969).
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