EPA-908/3-77-004
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U. S. ENVIRONMENTAL PROTECTION AGENCY
ROCKY MOUNTAIN — PRAIRIE REGION
REGION VIII
REPORT
ON THE PLANT EVALUATION
AT OLD FAITHFUL WASTEWATER
TREATMENT
YELLOWSTONE NATIONAL PARK
OPERATION & MAINTENANCE SECTION
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AUGUST. 1977
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EPA-908/3-77-004
REPORT ON THE PLANT EVALUATION
AT
OLD FAITHFUL WASTEWATER TREATMENT PLANT
YELLOWSTONE NATIONAL PARK, WYOMING
AUGUST 1977
Owen K. Boe, Project Engineer
Leon Malloy, Engineering Technician
Control Technology Branch
Water Division
Region VIII
U.S. Environmental Protection Agency
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DISCLAIMER
This report has been reviewed by the Region VIII Office of
the Environmental Protection Agency, and approved for publication.
Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
i
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TABLE OF CONTENTS
Page No.
I. INTRODUCTION 1
II. SUMMARY AND RECOMMENDATIONS 1
III. DESCRIPTION OF PLANT 2
IV. OPERATION EVALUATIONS 6
FIGURES
FIGURE 1 - Flow Schematic at the Old Faithful WWTP 3
FIGURE 2 - Settled Effluent Turbidity at the Old Faithful
WWTP 9
TABLES
TABLE 1 - Principal Design Criteria of the Old Faithful
WWTP 4-5
11
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I. INTRODUCTION
The National Park Service (NPS) has recently constructed several
new wastewater treatment facilities at the Yellowstone National Park.
These facilities represent a major commitment by the Park Service to
ensure that the high quality of water 1n the Park is not degraded by
the presence of man.
To ensure that their new facilities perform as expected, the Super-
intendent of Yellowstone National Park requested assistance from the
EPA to train Park personnel 1n process control procedures and to provide
performance evaluations of treatment facilities. Specific technical
assistance was requested for the n1trificat1on-denitr1f1cation facility
located at Fishing Bridge. Limited additional assistance was provided
at the Old Faithful facility. Two weeks of troubleshooting on-site
technical assistance was conducted 1n August 1976 and extensive follow-up
through telephone calls continued for the remainder of the operating
season.
The intent of this report is to document these technical assistance
activities and to provide recommendations to the Park Service relating
to the problems that were encountered.
II. SUMMARY AND RECOMMENDATIONS
In response to a request from the Superintendent of Yellowstone
National Park, EPA provided assistance to the Park Service 1n August
1976. The assistance was primarily directed at the nitr1f1cat1on-
den1tr1f1cat1on facility at Fishing Bridge but some time was also
devoted to the Old Faithful wastewater treatment plant.
Observations and process control data obtained at the Old Faithful
facility strongly indicated that the high temperature of the waste-
water was a critical factor which influenced all phases of operation.
It 1s suspected that nitrification was occurring in the plant (primarily
due to the warm sewage) even though the facility was not designed to
nitrify. Settleometer tests revealed the formation of extensive gas
bubbles which caused excessive floating of sludge 1n both the settlometer
and the clarlfler. This gas was probably nitrogen gas, the end product
of den1tr1f1cat1on.
Operational changes were made in an attempt to both reduce the
degree of denltrlflcatlon in the clarlfler and the degree of nitrifica-
tion in the aeration tanks. These changes showed some promise of
improving plant performance but full evaluation of the problem was not
possible due to the short time spent at the plant and lack of available
data.
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The following recommendations are provided to aid the operations
staff 1n optimizing treatment performance.
1. Maximum operator attention is needed during the start-up period
to establish a carefully controlled sludge wasting program. The quantity
and frequency of sludge wasted may be higher than expected due to the
warm sewage temperature.
2. Due to relatively warm sewage temperatures the system may also
need to operate at less than design hydraulic detention times. This
can be accomplished by not using all of the aeration tanks.
3. The final clarlfler should be operated to minimize sludge
detention times 1n order to reduce denltrification.
4. Ammonia nitrogen data should be collected and correlated to
the rising sludge problems.
5. Maintain thorough process control tests and data analyses to
aid 1n further process control analyses.
6. Utilize one or more of the reaeratlon basins as a N2 stripping
basin. This may require some additional pumps, possibly a1r-Hft pumps
to redistribute return sludge to appropriate aeration basins.
III. DESCRIPTION OF PLANT
The Old Faithful treatment facility 1s a 0.51 mgd activated sludge
plant. The plant has the flexibility of operating 1n a conventional
or contact stabilization mode. Contact stabilization Is the primary mode
of operation. Figure 1 Is a schematic flow diagram of the facility and
Table I shows the various units with their physical dimensions.
The sewage enters the plant and passes through a communltor and
parshall flume prior to entering a wet well. The sewage 1s then pumped
from the wet well to the contact stabilization tank. Mixed liquor
from the contact tank flows to the secondary clarlfler. The sol Ids
which settle to the bottom of the clarlfler are returned to the reaeratlon
basin. Reaerated sludge then passes to the contact tank. Scum and
waste activated sludge are pumped to the aerobic digester. Secondary
effluent flows over the clarlfler weir to a chlorine contact tank and
then is pumped to the evaporation/percolation ponds.
2
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FIGURE I - Old Faithful WTP
3
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TABLE I - Principal Design Criteria of the Old Faithful WWTP
Design Population 5,500
Average Flow-MGD 0,51
Peak Flow-MGD 1.2
Biochemical Oxygen Demand-(5 Day)-lbs./day 1,378
Suspended Sol1ds-lbs./day 1,350
Emergency Storage (existing septic tank)-Gal. 48,000
Secondary Treatment Unit
Control Building Pumping Station 1 at 300
Number & Capacity of Pumps-GPM 2 at 900
Contact Aeration Section
Number of Tanks 2
Dententlon time at design flow-hours 1.5
A1r Supply-CFM 526
Volume, each tank - FTJ 4,356
Reaeratlon Section
Number of Tanks 4
Detention time at design flow hours 8.2
Air Supply-CFM 975
Volume, each Tank - FT3 5,953
Sludge Recirculation Pumps-GPM 2 at 400
Clar1f1er
Number 1
Overflow Rate-Gal. sq. ft./day
Design 400
Peak 950
Diameter - feet 40
Sldewater Depth - feet 9
Volume - FT* 11,309
Aerobic Digester
Diameter - feet 40
Sldewater Depth - feet 12
Volume - FT3 15,072
A1r Supply-CFM/min./lOOO cu. ft. volume 30
Chlorine Contact Unit
Type of Chlor1nat1on Gas
Detention time at design flow/hours 0.79
Volume - FT* 2,880
Chlorine feed rate-lbs./day max. 200
Effluent pumps-number & GPM 2 at 900
4
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Sludge Beds
Area - Sq. feet 10,500
Area/Population Equiv. - sq. feet 1.9
Aeration Blowers
Number & Capacities - CFM 1 at 1,500
1 at 750
1 at 450
1 at 220
Percolation - Evaporation Ponds
Total Area - Acres 3,77
Number of Cells 6
Number of Sealed Cells 1
Total Volume - 670,000
5
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IV. OPERATION EVALUATIONS
A. Prior to Technical Assistance:
On July 10, 1976, the plant was put Into operation. Data shows
that Initial start-up of the facility was quite rapid. The desired
amount of solids 1n the system was achieved 1n less than two weeks.
Normally, 1t takes more time for most plants to achieve full operating
status. This was believed to be the result of the high temperature
sewage which was received by the plant. Influent temperature ranged
from 23.5 to 25 degrees Centigrade. Considerably higher microorganism
activity would be expected at these temperatures.
During the start-up of the facility, the plant was operated in
the plug flow mode. Process control graphs showed that 1n approximately
a week and a half (July 10, 1976) the plant contained a good quality
sludge. However, during the latter part of July, sludge quality started
to deteriorate. The process control graphs showed that the sludge 1n
the settleometer would rise 1n less than sixty minutes, an Indicator
or poor quality sludge. Analyses of the available data revealed that
sol Ids wasting was deficient. By not wasting any sol ids, solids became
overoxldlzed and resulted 1n the problem of rising sludge. It was also
suspected that nitrification was occurring 1n the aeration tank and that
significant den1tr1f1cat1on was occurring 1n the final clarlfler resulting
1n rising sludge.
The mode of operation was then changed from plug flow to contact
stabilization. The long reaeration detention times, however, seemed
to compound the problem of overoxldlzed sludge. The reaeration time
was about 19 hours/day and contact time was approximately 3-4 hours/day.
B. Process Control Assistance:
1. Implementation of Process Control Procedures
The process control procedures implemented were developed
by A1 West and modified by Region VIII Operation and Maintenance Section
staff. The tests consisted of the centrifuge test, dissolved oxygen
test, depth of blanket settleometer test, and turbidity test. Following
1s a brief description of each test.
Centrifuge Test: Samples of the reaeration basin, contact
tanks, return sludge and waste sludge were analyzed for suspended sol Ids
by the centrifuge. Suspended sol Ids tests were also performed by the
analytical balance gooch crucible method to correlate MLSS to percent
solids by centrifuge.
6
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Depth of Blanket Test: The depth of blanket test was used
for determining the depth of sludge 1n the final clarifler.
Turbidity Tests: The turbidity test was used to evaluate
process performance and to indicate whether the process was improving
or deteriorating. Samples were taken from the clearest spot on the
final clarifler.
Dissolved Oxygen Tests: This test was used to determine
dissolved xoygen levels in the liquid at various places, (aeration basin,
return sludge, final clarifler effluent and influent).
Settleometer Tests: Samples were taken of the mixed liquor
1n the reaeratlon basin and the contact tank for settleometer tests. The
settleometer test was used to observe sludge settling characteristics.
All of these tests with the exception of the settleometer
test were performed four times/day. The settleometer test was performed
two times/day. The tests results along with other Information were used
in calculation to make up process control graphs and to make process
control adjustments.
2. Process Modification
Evaluation of the facilities during the week of August 4, 1976
revealed that some adjustment had to be made to achieve equal flow and
solids distribution 1n the two contact tanks. One contact tank was
receiving more sol Ids and more flow due to the location of the Influent
pipe and the flow splitter gates. The flow from the reaeratlon tanks
pass over weirs and enter a channel where 1t contacts the raw sewage. A
90 degree turn 1n the channel brings the mixture to the contact tank.
This condition resulted 1n most of the solids and the flow bypassing the
naearest aeration tank.
After discovering this condition, alterations were made so
the raw sewage and the reaeratlon tank effluent were well mixed before
approaching the contact tank. Gate valves were adjusted to build up the
head in the channel just before the mixed liquor and sewage entered the
contact tank. The flow split was then regulated by the uniform head
and similar orifices created by each gate valve.
3. Operational Assistance
Further evaluation of the facility confirmed that the system
contained an old sludge. From observation of the settleometer test
1t was felt that significant denltrlflcatlon was taking place In the
final clarifler. Sludge was floating to the top of the settleometer
within forty minutes after settling. The Initial action taken was to
establish a wasting program.
7
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Follow-up on Monday morning, August 9, 1976, indicated
that conditions had not Improved. The surface of the final clarlfier
was covered with scum. The solids 1n the settleometer, after settling,
rose to the surface 1n less than forty minutes. Effluent turbidity was
high due to cloudy watar and the solids which floated to the surface of
the clarlfier.
Wasting was again increased and two reaeratlon basins were
taken out of service to reduce sludge reaeratlon time. Raw sewage was
split so that a portion of the flow entered the remaining two reaeratlon
basins as well as the contact basins creating a step-feed operation. Flows
were adjusted periodically to maintain equal distribution of flows to
each basin. Flow meters were not available for each basin so a bucket
and stop watch were used for measuring flow. Approximately three days
later, process control tests revealed significant Improvements In sludge
quality. The sludge 1n the settleometer was beginning to stay on the
bottom of settleometer longer, burbldlty was Improving and the appearance
of the aeration basin and clarlfier was Improving. The process control
tests and graphs showed that the quality of operation was Improving along
with plant effluent quality. On Friday, August 13, 1976, the turbidity
was down to six JTU's and the trend charts indicated that the plant was
heading 1n the right direction. Figure II 1s a graph showing effluent
settled turbidity FTU and shows the best result, a 1.9 JTU on August 16,
1976.
Subsequently, however, the turbidity started to rise. On-
site assistance had ended but telephone communications was continued.
The operator reported that he believed the plant had been hit with some
type of toxic material which upset the process. Sludge started to rise
1n the clarlfier again and turbidity 1n the effluent started to rise.
The operator reported that at times the surface of the
clarlfier would be clear, but at other times the surface would be
covered with sludge. The operator also reported that he saw evidence
of an excessive amount of grease entering the treatment system. This
situation continued until the facility was shut down for the winter.
8
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i CwHNllrAL MtrUM I UMIM
1. REPORT NO. 2.
EPA-908/3-77-004
3. RECIPIENT'S ACCESSION NO.
4. title and subtitle Report on The
Plant Evaluation at Old Faithful Wastewater
Treatment Plant - Yellowstone National Park
5. REPORT DATE
Auaust. 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Owen Boe and Leon Malloy
8. PERFORMING ORGANIZATION REPORT NO.
B. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Protection Agency
1860 Lincoln Street
Denver, Colorado 80295
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The National Park Service (NPS) has recently constructed several new waste-
water treatment facilities at the Yellowstone National Park. These facilities
represent a major commitment by the Park Service to ensure that the high quality
of water 1n the Park 1s not degraded by the presence of man.
To ensure that their new facilities perform as expected, the Superintendent
of the Yellowstone National Park requested assistance from the EPA to train Park
personnel 1n process control procedures and to provide performance evaluations
of treatment facilities. Specific technical assistance was requested for the
n1tr1f1cat1on-denitr1f1cat1on facility located at Fishing Bridge. Limited
additional assistance was provided at the Old Faithful facility. Two weeks of
troubleshooting on-site technical assistance was conducted 1n August 1976 and
extensive follow-up through telephone calls continued for the remainder of the
operating season.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sewage Treatment
Activated Sludge
High Temperatures
Yellowstone National
Park
Old Faithful WWTP
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
21. NO. OF PAGES
in
20, SECURITY CLASS (Thispage)
22. PRICE
EPA Form 2220-1 (R«v. 4-77) previous edition is obsolete
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