City Council Agenda Packet 03-11-1994Ro
AGENDA FOR THE SPECIAL MEETING OF THE CITY COUNCIL
Friday, March 11, 1894 - 2:30 p.m.
Mayor: Ken Maus
Council Members: Shirley Anderson, Clint Herbst., Brad Fyle, Patty Olsen
Call to order.
2. Discussion of Wasterwater Treatment Plant facilities expansion plan.
3. Adjournment.
CITY OF MONTICELLO
FACILITIES PLAN
WORK SESSION
SERIES 100 - FLOWS AND LOADS
SERIES 200 - DISCHARGE REQUIREMENTS
MARCH 11, 1994
DEFINITIONS
BIOCHEMICAL OXYGEN DEMAND (BOD.)
OXYGEN DEMAND OF BIODEGRADABLE ORGANIC
MATTER
TOTAL SUSPENDED SOLIDS (TSS)
FILTERABLE SOLIDS IN WASTESTREAM
INFILTRATION
WATER SEEPAGE THROUGH THE SEWER SYSTEM
PIPES AND VAULTS
INFLOW
SURFACE AND SUBSURFACE STORMWATER
ENTERING THE SEWER SYSTEM
DOMESTIC SOURCES
ALL RESIDENTIAL, COMMERCIAL, AND
INSTITUTIONAL SOURCES (EXCLUDES INDUSTRIAL
SOURCES)
CURRENT WASTEWATER TREATMENT PLANT,
FLOWS AND LOADINGS
Percent
Design' of
Parameter Present ( 2000) Design
Wastewater Treatment Plant Influent
Flow, mgd
0.66
0.91
72
Biochemical oxygen demand
(BOD,), ppd
2,250
6,270
35
Total suspended solids (TSS), ppd
1,550
3220
50
Domestic Sources
Flow, mgd
0.57
0.77
74
BOD,, ppd
1,150
1,600
72
TSS, ppd
1,100
1,470
75
Industrial Sources (Sunny Fresh Foods)
Flow, mgd
0.09
0.14
64
BOD,, ppd
1,100
4,670
23
TSS, ppd
450
1,750
28
' Design loadings for the year 2000 are
taken from the Facilities
Plannine Resort for the Citv of Monticello, Minnesota, January,
1977, by OSM.
PRELIMINARY ASSESSMENT OF
INFLOWANFILTRATION (I/Dl
REGULATORY GUIDELINES - DOMES'T'IC PLUS III
EPA- INFILTRATION < 3000 GPDANCH/MILE
MPCA - INFILTRATION < 120 GPCD
MPCA - INFLOW < 275 GPCD
CITY OF MONTICELLO - DOMESTIC PLUS 1/I
EPA
7 DAY CONSECUTIVE FLOW = 792 GPD/INCH/MILE
MPCA - INFILTRATION
YEAR
FLOW RATE
1991
115 GPCD
1992
114 GPCD
1993
118 GPCD
MPCA - INFLOW
PEAK INFLOW 154 GPCD
WASTEWATER TREATMENT PLANT EFFLUENT LIMITATIONS.
ll PARAMETER I EXISTING NPDES PERMIT PROJECTED NPDES PERMIT' �l
CARBONACEOUS
BIOCHEMICAL OXYGEN 25 mg/L I
25 mg/L**
DEMAND (cBODS)
TOTAL SUSPENDED SOLIDS 30 mg/L
30 mg/L**
(TSS)
FECAL COLIFORM 200/ 100 mL
200/ 100 mL
TOTAL CHLORINE RESIDUAL I
0.038 mg/L
PHOSPHORUS -P I
Monitor
TOTAL KJELDAHL I
Monitor
NITROGEN
AMMONIA -NITROGEN I
I Monitor
1. BASED UPON MPCA PROJECTIONS
2. AMMONIA LIMITATIONS WILL BE IMPOSED IF DISCHARGE IS NOT TO MISSISSIPPI RIVER
** TOTAL MASS OF POLLUTANT DISCHARGED TO
REMAIN AT EXISTING LEVELS
I
PAST, PRESENT, AND PROJECTED CITY OF MONTICELLO POPULATION
16.000
14.000 'o
12,000
10.000
l�' •
e,000 ...
a 6.000
4,070
2.000
0
1970 1990 1990 2000 2010 2020
Year
Census Bureau 25 Home Starts —•— 50 Home Starts
Data
—v 75 Home Starts 100 Homo Starts
INDUSTRIAL GROWTH
CASE 1 - EXPANDED SUNNYFRESH FOODS
CASE 2 - EXPANDED SUNNYFRESH FOODS WITH
ADDITIONAL WET INDUSTRY
CASE 3 - EXPANDED SUNNYFRESH FOODS WITH
ADDITIONAL DRY INDUSTRY
CASE 4 - EXPANDED SUNNYFRESH FOODS WITH
ADDITIONAL WET AND DRY INDUSTRY
50M
45M
4000
3500
� 3000
2500
2000
1500
1000
500
0
PROJECTED INDUSTRIAL ORGANIC LOADINGS
Monticello WWTP Industrial Blochemicaf Oxygen Demand loads for Year
2020.
Average Max Month Max Week Max day
I
X -Y - 00Home ttarh/yr - IndustrIal Growth Case (Y)
N Present tnausttial Load 0 Expanded Sonnyftosh Load 1:1 Unidentified Industry Load I
CURRENT AVERAGE INDUSTRIAL BOD LOAD = 1100 POUNDS PER DAY
Monticello WWTP Industrial Total Suspended Solids Loads for Year 2020.
A,u,age Max month Max wcsok Max (joy
3000
2500
2"
IbW
500
X -Y o M HOMO stafttroar - Industrial Growth Casa (Y)
1 0 Pfesont InaustrIal Load 0 E 900ndod Sunnyllosh Load 0 Undontiflod Industrkil Load I
CURRENT AVERAGE INDUSTRIAL TSS LOAD - 450 POUNDS PER DAY
PROJECTED DESIGN ORGANIC LOADINGS
Monticello WWTP Design Biochemical Oxygen Demand loads for Year
2020.
Average Mac month Max week Maw day
120DO
10000
g 8000 -- ---- -- - - -
q 6000 - - -- -- - - - - - -
4000 -� - - - - - - - -
-
p
X -Y = (X) Home StarWyear - Induslrka Growth Case (Y)
0 Domestic Load ❑ Industrlal Lootl
CURRENT AVERAGE BOD LOAD = 2250 POUNDS PER DAY
O
Monticello WWTP Design Total Suspended Solids Loads for Year 2020.
Average Mai month _Max week Mar' day-
120M
ay
00
120
10000
O 8000 t �'
6000
I
X -y a Oq Homo Starts/your - Industrial Growth Case (y)
0 Domestic Load C3 Indusl6ol Load
CURRENT AVERAGE TSS LOAD = 1550 POUNDS PER DAY
PRESENT AND PROJECTED INDUSTRIAL FLOWS
Scenario Flow. mgd
Present Industrial Design Flow 0.16
;Projected Industrial Flows
50 home starts/yeor
Industrial Growth Case 2
0.35
Industrial Growth Case 3
0.30
75 home starts/year
Industrial Growth Case 2
0.42
Industrial Growth Case 3
0.35
Monticello WWTP Design Flows for Year 2D20
ADWF AW WF 1dt4WF i44wwf P;WWF
p ._
5
4
E 3
2
z•Y . txt Hwe rtanUyear . IndusMal Grown caw M
CURRENT FLOW = 0.66 MGD
PRELIMINARY COST COMPARISON
RELATIVE
GROWTH SCENARIO CAPITAL COST
50 HOME STARTS PER YEAR
INDUSTRIAL GROWTH CASE 2
+ 10%
INDUSTRIAL GROWTH CASE 3
BASE CASE
75 HOME STARTS PER YEAR
INDUSTRIAL GROWTH CASE 2
+ 35 %
INDUSTRIAL GROWTH CASE 3
+ 15
COST COMPARISON ASSUMES 50 HOME STARTS PER
YEAR - INDUSTRIAL GROWTH CASE 3 WILL HAVE
THE LOWEST CAPITAL COST.
ALL OTHER CAPITAL COSTS REFLECT AN
ESTIMATED PERCENT INCREASE ABOVE THE BASE
CASE CAPITAL COST.
Id"iT
TECHNICAL MEMORANDUM I
DATE: MARCH 8, 1994
TO: JOHN SIMOLA, CITY OF MONTICELLO
FROM: JON PETERSON, OSM
SUBJECT: MONTICELLO FACILITIES PLAN
SERIES 100 - FLOWS AND LOADS
OSM COMM NO. 5216.00
Introduction
This technical memorandum presents projections of the City of Monticello's population and
wastewater flows and loads through the year 2020. A review of existing wastewater
treatment plant operating data is also presented to assess infiltration and inflow (1/1) in the
City's sewer system and determine current organic loadings from domestic (residential,
commercial, institutional) and industrial sources.
To develop future wastewater flows and loads, several evaluation steps were necessary. The
first step was to review the current service area and associated wastewater flows and loads,
including 1/1, using historical records. The second step involved estimating future
residential, commercial, institutional and industrial growth. The third step utilized the
information developed in the first two steps, along with accepted standards for designing
wastewater treatment plants to project wastewater flows and loads to the year 2020.
Service Area
Figure 1-1 shows the City of Monticello's current sewer system service area. At this time
approximately 4,920 of the City's 5,200 persons arc served by the municipal sewer system.
The remaining 280 persons use on-site sewage disposal systems and are expected to be
connected to the sewer system within 5 to 10 years. An additional 500 persons utilize on-
site sewage disposal facilities which arc not currently within City limits, but will be
connected to the system within 5 to 10 years.
Current Flows and Organic Loads 1D�T
i
During the past 15 years, the influent sewage characteristics at the Monticello wastewater
treatment plant (WWTP) have changed considerably with changes in population and
industrial activities.
Table I-1 provides a summary of the existing Monticello WWTP rated design capacity based
upon the 1979 upgraded treatment plant. To evaluate design conditions for the next 20
years, current flows and organic loads were evaluated using monthly operating reports from
January, 1991 through December, 1993.
Flows
Figure 1.2 presents reported monthly average influent flows at the Monticello W WTP during
1991 through 1993.
The influent flow during the past three years has averaged 0.66 million gallons per day
(mgd). Sunnyfresh Foods, the major industrial user, discharged an average of 0.09 mgd of
sewage during this period. Bondhus Industries, the City's other industrial user, discharges
low volumes of flow and organic loadings and is considered typical of a commercial source.
Current influent flows to the Monticello WWTP are roughly 75 percent of the rated design
capacity.
The wastewater flow conditions used in designing WWTP are average dry weather (ADW),
average wet weather (AWW), maximum wet weather (MWW), peak hourly wet weather
(PHWW) and peak instantaneous wet weather (PIWW) flow. Table 1-2 provides an
explanation for developing these flows and their use in W WTP design.
The average dry weather (ADW) flow averaged 0.61 over the three-year period with a slight
increase from 0.58 mgd in 1991 to 0.62 mgd in 1993. ADW condition assumes normal
groundwater with no runoff (inflow) into the sewerage system and average industrial flows
from Sunnyfresh Foods of 0.09 mgd. ADW conditions occurred in November or December
of each year.
The average wet weather (AWW) flow from 1991 through 1993 average 0.73 mgd. The 1993
AWW flow of 0.78 mgd was the greatest in the three-year period due to the high rainfall.
AWW conditions occur during the early summer months of Jay or June. AWW condition
are the wettest 30 -day average and high groundwater with inflow. The existing AWW flows
also include an average industrial flow of 0.09 mgd.
A summary of existing flows and rainfall records for the past three years is provided in
Table 1.3.
Infiltration and Inflow
A preliminary assessment of infiltration and inflow (1/1) in the Monticello sewer system was
prepared by reviewing rainfall event records, including amount of precipitation and duration
of event, along with flow records at the Monticello WWTP. Based on this data, a
determination of whether the City's sewer system has excessive 1/1 per capita according to
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Mr. John Simola
City of Monticello
March 7, 1994
Page I-3
the Minnesota Pollution Control Agency (MPCA) and the Environmental Protection Agency
(EPA) guidelines was made.
The definition of EXCESSIVE infiltration has changed during the past 10 years. The
original definition by the EPA states that infiltration is MM excessive if it falls within the
following limits:
Length of Sewer in Citv
1. Greater than 100,000 ft
2. 10,000 to 100,000 ft
3. Less than 10,000 ft
Maximum 7 -day Average
Nonexcessive Infiltration Rate
less than to 3,000 gpd/in./mile
3,000 to 6,000 gpd/in./mile
6,000 to 10,000 gpd/in./milt
With the expiration of the federal grant program, the State of Minnesota established
regulation Chapter 7077 which covers infiltration and inflow for State Grant or Loan funded
projects. Chapter 7077 defines infiltration and inflow as follows:
Subp. 12. Excessive infiitration. "Excessive infiltration" means the quantity
of flow which is more than 120 gallons per capita per day (domestic base
flow and infiltration) or the quantity of infiltration which can be economically
and effectively eliminated from a sewer system as determined through cost
effectiveness analysis.
Subp. 13. Excessive inflow. "Excessive inflow" means the maximum total
flow rate during storm events that results in chronic operational problems
related to hydraulic overloading of the treatment facility or that results in a
total flow of more than 275 gallons per capita per day (domestic base flow
plus infiltration plus inflow). Chronic operational problems may include
surcharging, backups, bypasses, and overflows.
Chapter 7077 does not identify the time period of storm event in which the flow must occur.
For purposes of this study, an assessment of the infiltration will be made using both criteria.
Table 1.4 shows that Monticello's sewer system is 274,000 feet long and, therefore, falls
within category 1.
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Mr. John Simola
City of Monticello
March 7, 1994
Page 1-4
During the past three years, the maximum seven consecutive day flow received at the
wastewater treatment plant occurred from July 5, 1993 through July 11, 1993. An average
flow during this period was 0.802 mgd.
During this period an average of 0.765 mgd was pumped from the city wells to the city as
a whole. However, not all of this water gained access to the sanitary sewer. The Water
Department performs an accounting of water usage within the city. Table 1-5 entitled Water
and Sewer Use Worksheet is a summary of data for 1993. This table shows that the volume
discharged into the sewer (total sewer consumption) is less than pumped from the wells.
Table 1-5 shows the estimated residential sewer consumption based upon residential water
usage during winter months. Total public/institutional and commercial sewer consumption
is based upon water meter readings. Industrial sewer consumption is the combined sewage
flows from Sunnyfresh Foods and Bondhus. Three reductions are shown. The first
reduction is for known water losses or spills. The second reduction is the difference
between the volume pumped into the watermains (total water used from well) and the
volume sold to the customers by the Water Department (total water consumption), based
upon individual water meter readings. This difference is sometimes identified as water
system loss. The third reduction is the difference between water sold to the customer and
that volume which the customers discharge the sewer.
Table I-5 shows that during the third quarter, 1992 the water system loss was about
10,630,000 gallons or 14.0 percent of the total water usage. Table 1-5 also shows that the
difference between water sold to customers (total water consumption), and the estimated
volume of wastewater discharge to the sewer was about 16,035,000 gallons.
The City Water Department does not read the water meters daily so water consumption
billing information is not available for the period from July 5 through July 11, 1993. An
estimation of the loss was made as follows.
During the third quarter, 1993, 14.0 percent of the water pumped from the city wells did not
reach the customers. For this 1/1 study, it is assumed that 14.0 percent of the water pumped
from the city wells did not reach the sewer front July 5 through July 11, similar to the third
quarter 1993. Also, it is assumed that the entire "known loss' occurred during the July 5
through July 11 period. In reality the "known loss" likely did not all occur within the study
period so this assumption will over estimate the infiltration. However, if the infiltration to
the system is shown to be non -excessive using this conservative assumption then no further
analyses will be required to further focus in on a more accurate value.
Table 1-5 shows a third difference between water consumption and total sewer consumption.
The table does not identify the basis for this difference. Nevertheless during the third
quarter of 1993 the difference was 16,035,000 or 24.8 percent of the total water consumption
records. Assuming this signifies a further reduction of the wastewater discharged j= the
system, this percentage of water must be reduced from the water "sales" records to
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Mr. John Simola
City of Monticello
March 7, 1994
Page 1-5
determine wastewater contributed to the sewer. For the July 5 through July 11 seven day
period being evaluated for this infiltration study, the wastewater contribution to the sewer
is 208,000 gallons per day less than the water sold. The calculated infiltration for the peak
seven consecutive day flow then is the difference between the wastewater volume received
at the Monticello WWTP and the volume contributed to the sewer by the customers or
0.311 mgd.
Table I-4 shows that 392.20 -inch diameter miles exist in Monticello, so the system -wide
infiltration equals 792.96 gpd/inch/mile. This is significantly less than the MPGA guideline
of 3000 gpd/inch/mile. Thus the Monticello Sanitary Sewer System is not subject to
excessive infiltration according to the EPA guidelines.
To calculate infiltration according to Minnesota Regulations Chapter 7077 wastewater flow
records were reviewed for year 1991, 1992 and 1993. The annual average domestic plus 1/1
flow was 0.569, 0.563 and 0.584 mgd for years 1991, 1992 and 1993 respectively. At a
sewered population of 4,922, the per capita now for each respective year was 115 gpcd, 114
gpcd and 118 gpcd, which is less than the 120 gpcd requirements.
For three months (May, June, July 1993) the Monticello system experienced flows in excess
of 120 gpcd. Thcsc were 122 gpcd, 136 gpcd and 125 gpcd respectively. According to the
definitions in 7077, the Monticello system would be experiencing possible excessive
infiltration during those three months, and a cost effectiveness analysis would be required
to make the final determination of whether the infiltration is excessive.
Minnesota Rules define excessive inflow as tha
domestic plus 1/1 flow recorded during the past
on June 21, 1993, following a 0.57 inch rainfall.
less than that defined by Minnesota Rules.
t which exceeds 275 gpcd. The maximum
three years was 0.758 mgd which occurred
The per capita flow was 154 gpcd which is
Figure 1-3 shows the hourly variation in ADW, ADW with high groundwater and storm
event conditions.
Figure 1.3 shows the peak infiltration due to high groundwater is 0.23 mgd. The peak
hourly inflow from a 0.4 inch one-hour rainfall event was 0.25 mgd occurring at 4:00 P.M.
Adjusting the peak hourly inflow for a 0.4 inch rainfall event to the five-year one-hour and
25 -year one-hour rainfall events used in calculating the peak hourly and peak
instantaneously wet weather flow (PHWWF and PIWWF) results in 1.06 and 1.43 mgd of
inflow for the PHWWF and PIWWF, respectively.
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Mr. John Simola
City of Monticello
March 7, 1994
Page 1-6
Peak infiltration and peak inflow will be used in estimating PHWW and PIWW flows.
Sewer Billines
Evaluation of the 1992 and 1993 sewer billings suggests roughly 43 percent of the influent
wastewater is from residential sources, 20 percent is from 1/1, or approximately 0.13 mgd,
16 percent is from commercial sources, 14 percent is from industrial, and 7 percent from
institutional sources.
With a scwcrcd population of 4922 persons and neglecting the industrial flows of 0.09 mgd,
the existing domestic hydraulic loading averages 115 gallons per day per capita (gpd/cap).
Domestic hydraulic loading includes all residential, commercial, institutional and 1/1
contributions, but excludes industrial flows. This is slightly greater than the 10 State
Standards and MPCA recommended design criteria of 100 gpd/cap for future domestic flow
contributions.
Influent 5 -day total biochemical oxygen demand (BODS) and total suspended solids (TSS)
mass loadings were evaluated to estimate current organic loadings to the Monticello WWTP.
Figures 1.4 and 1-5 show influent BODS and TSS loadings from January 1991 through
December 1993, respectively.
Figures 14 and 1-5 show several extreme organic loading fluctuations in the influent waste
stream. These fluctuation arc primarily attributable to changes in organic discharges from
Sunnyfresh Foods.
Tablc 1-6 provides a summary of the Monticello W WI -P influent organic loadings. Present
average influent BODS and TSS concentrations and loadings arc significantly less than the
design parameters used in 1979. Average influent BODS concentrations of 400 milligrams
per liter (mg/L) arc less than one-half the original design of 825 mg/L. Due to the large
decrease in BODS waste strength, the influent BODS load is only 35 percent of the influent
design load. Similarly, influent TSS concentrations of 275 mg/L arc roughly 65 percent of
the design TSS strength and current TSS mass loads arc 50 percent of the design TSS load.
The large difference between the current and rated organic loadings is primarily due to
changes in Sunnyfresh Foods organic loadings. Table 1-7 provides a breakdown of current
and design organic loadings in the W WTP influent broken down by domestic and industrial
contributions.
The Monticello WWTP is now in year 15 of a 20 -year design life. Projections of domestic
flows and loads developed for the design of the W WTP arc in close agreement with present
flows and organic loadings. However, present industrial contributions arc significantly less
than previously projected. The lower industrial loadings arc the result of Sunnyfresh Foods
Mr. John Simola
City of Monticello
March 7, 1994
Page 1-7
changing from an egg processing facility to specialty products manufacturing. In addition,
the implementation of a pretreatment program regulating industrial waste discharges has
affected organic loadings to the Monticello WWTP.
On average, Sunnyfresh Foods supplies approximately 50 and 30 percent of the reported
influent BODS and TSS loads, respectively. Alternatively, assuming 0.25 pounds per day
BODS per capita (ppcd), Sunnyfresh Foods discharges an average BODS load equivalent to
4,400 persons. Assuming 0.25 ppcd TSS, Sunnyfresh Foods discharges an equivalent TSS
load as 1,800 persons. As described previously, Bondhus discharges less than one percent
of the influent BODS and TSS loadings to the WWTP.
The average Sunnyfresh BODS and TSS concentrations over the past 3 years were 1,300 and
400 mg/L, respectively.
Table 1-8 presents the organic loading per capita in terms of BODS and TSS for average and
maximum month conditions. Domestic organic loadings represent the average loading from
residential, commercial, and institutional sources. Organic loads from Sunnyfresh Foods are
not included. Average BODS and TSS loadings of 0.25 and 0.24 ppd/cap are representative
sewer systems with low 1/1 and households utilizing garbage disposal. Tcn-state standards
recommend design loadings of 0.22 and 0.25 ppcd for BODS and TSS, respectively.
Growth Projections
Future wastewater flows and organic loads can be estimated using population and industrial
growth projections within and near the City limits. Utilizing this information, flows and
loading trends, design flows and loads for future years can be projected.
During the last 2 decades, the City of Monticello has experienced rapid population growth.
The City has grown from 1,636 persons in 1970 to approximately 5,200 in 1994;a 4.9 percent
annual growth rate.
In January 1994, Northwest Associated Consultants, Inc., the City's planner, projected
population growth for Monticello using the State Demographers population projections for
Sherburne and Wright Counties and past population trends for Monticello, Big Lake and
Becker Townships. Northwest Planning assumed that commercial and institutional growth
rates would be in proportion to the existing mixture of commercial and institutional land use
to residential population. Industrial growth is discussed later in this memorandum. Figure
1.6 presents the population forecasts for the City of Monticello based upon slow and fast
growth scenarios labeled 25 and 50 Home Starts per year, respectively. The faster growth
rate scenarios of 75 and 100 House Starts per Year based upon current housing trends in
Mr. John Simola
City of Monticello
March 7. 1994
Page 1-8
Monticello were estimated by city staff. Annual growth rates for each population projection
scenario is also given in Figure 1-6.
As seen in Figure 1-5, the planning period population projection ranges between 8,400 and
15,045 people. However, the 50 and 75 home starts per year arc believed to be more
representative of future growth trends because they are based upon past and current housing
start rates. Therefore, flows and loads based upon 50 and 75 home starts per year will be
developed.
Table 1-9 provides a summary of the present and projected domestic design flows and loads
for each viable population projection.
Design flows are based upon existing flow rates and projected population and industrial
growth estimates. The 1991 through 1993 data served as basis of the design flows. Future
design flows were estimated assuming domestic sewage flows increase by 115 gpd/cap for
future population increases. The domestic flow increase of 115 gpd/cap is greater than the
MPCA recommended domestic design flow of 100 gpd/cap.
Future domestic organic loadings were assumed to increase at the organic loading rates
previously presented: BOD., of 0.25 ppcd and 0.37 ppcd for average and maximum month,
respectively and TSS of 0.25 ppcd and 0.35 ppcd for average and maximum months,
respectively. The average TSS loading factor of 0.25 ppcd was selected based upon 106state
standards for new construction rather than average TSS loadings during the past three years.
It was assumed that future maximum week and maximum day organic loadings will occur
during the maximum month and will likewise increase at the maximum month loadings.
The City of Monticello currently has two industrial users: Sunnyfresh Foods and Bondhus
Corp. Sunnyfresh Food is a major industrial user whose discharges currently account for 15,
50, and 30 percent of the flow, BOD, and TSS influent loadings to the Monticello WWTP,
respectively. Bondhus discharges account for less than one percent of the flow, BOD, and
TSS influent loadings and is therefore, considered a minor industrial user. Predicting
industrial growth is difficult since the type of future industry is not readily identifiable and
industrial growth is not tied to a specific location.
Four growth scenarios were used for evaluating industrial growth. The first two cases assume
growth in wct industry (industrial facilities utilizing water in the processing of goods). Case
1 assumes Sunnyfresh Foods wastewater flows and loads will increase by 25 and 50 percent,
respectively, by the year 2020. This is based upon planned expansion provided by
Sunnyfresh Foods. Table 1-10 provides a summary of the flows and loads for expanding
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Mr. John Simola
City of Monticello
March 7, 1994
Page 1-9
Sunnyfresh Foods. Since expansion of Sunnyfresh Foods without additional industrial
growth is highly unlikely, three additional alternatives were investigated assuming an
expanded Sunnyfresh Foods and additional wet industry, dry industry or a combination
thereof.
Case 2 assumes expansion of Sunnyfresh Foods as described in Case 1 plus growth of
additional wet industry similar to Sunnyfresh Foods. The additional wet industry was
assumed to grow in proportion to population such that if the existing ratio of industrial
loading to domestic loading is 1:1, this ratio, using the expanded Sunnyfresh Foods loads
plus the unidentified wet industry loads, will remain constant in the future.
Case 3 assumes the planned expansion of Sunnyfresh Foods in Case 1 plus growth in dry
industry. Dry industry growth was predicted by estimating the current industrial building
square footage per capita (150 square feet per person) and assuming this ratio will remain
constant with population increases. Based upon 150 s.f./person, Case 3 projects 56 and 78
acres of new dry industry growth for the next 20 years for population at year 2020 of 10,637
and 12,841; respectively. Dry industry sewage flow are assumed to be typical of current
commercial facilities water usage of 160 gpd/1,000 s.f. with 80 percent of water usage is
discharged to the sewer and typical domestic waste organic loadings. Commercial industries
typically assume 100 gpd/1,000 s.f. versus the 128 gpd/1,000 s.f. assumed. Organic loadings
are typical of domestic sewage.
Case 4 is a combination of Cases 2 and 3. Case 4 assumes Sunnyfresh Foods will expand
as planned in Case 1, dry industry will increase as in Case 3 and unidentified wet industry
will increase by 30 percent of the existing Sunnyfresh Foods loads. Under this scenario, the
flows and loads developed for Case 4 were essentially identical to Case 2, and, therefore,
are considered equal.
A comparison of the projected flows and organic loads generated from Cases 2 and 3 for
50 and 75 house starts per year is presented below in Table 1-11.
Mr. John Simola
City of Monticello
March 7, 1994
Page I-10
DST
Another factor to consider when developing flow and load projections is the contribution
out -of town students and workers and seasonal residents have on wastewater flows and
loads. Currently, the contribution from out of town workers is negligible and is not
expected to increase significantly within the planning period. The contribution of current
out-of-town students is accounted for in institutional land use. As such, institutional growth
discussed previously accounts for any increase in out -of town students. Current and future
seasonal resident contributions are considered negligible in Monticello.
Design Flows and Loads
Using existing flow and organic loading data and projected growth for Monticello, we can
estimate the design flows and organic loadings. Wastewater flows and loadings to the
Monticello WWfP change with the time of day and season. Developing design conditions
for every flow or loading condition is not economically prudent or time efficient. As such,
the 5 previously described now conditions and four design organic conditions were defined
for use in the liquid and solids stream alternative evaluation. Thcse conditions are average
annual, maximum month, maximum week, and maximum day conditions.
Average annual loadings are typical of loading during both average dry and wet weather
conditions.
The maximum month and maximum week conditions are representative of the highest
organic loading expected for a calendar month/week and the maximum day predicts
sustained short-term loading conditions.
Maximum month and week conditions are imperative the in design of the treatment facilities
since the City's existing and future National Pollutant Discharge Elimination System
(NPDES) permit contains weekly and monthly discharge limitations.
Table 1-12 provides a summary of the design flows and loads for each growth scenario.
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Mr. John Simola
City of Monticello
March 7, 1994
Page 1-14
Figure 1-1
Figure 1-1 City of Monticello Existing Service Area
Mr. John Simola
City of Monticello
March 7, 1994
Page 1-15
Table 1-1. City of Monticello Fsisting Wastewater Treatment Plant Rated Design Capacity.
Parameter Value
Flow, mgd
Average
0.91
Sustained peak
1.40
Biochemical oxygen demand
milligrams per liter
826
pounds per day
6370
Total suspended solids
milligrams per liter
425
pounds per day
3225
Total kJeldahl nitrogen
milligrams per liter 45
pounds per day 340
1 W I�m17�'6lV �tD�R Im1YY
Figure 1-2. Monticello Wastewater Treatment Plant Flows 0991-
1993).
1
0.9 I 1
0.8 ,
E 0.7— -
0.6
0.4
W z
Month
—+— 1991 1942 - 1993
Pope r- 1 (/
Mr. John Simola
City of Monticello
March 7, 1994
Page 1-17
Table I.2. Wastewater Flow Design Conditions.
Item
Description
Purpose
ADW
Average dry weather flow assumes
Determine if flow equalization
normal groundwater, no runoff.
should be evaluated and to meet
average permit limitations.
AWW
Average wet weatehr flow (wettest
Facility design to meet average
30 -day average for mechanical plant
permit limitations and to
and wettest 180 -day average of
detemrine if flow equalization
controlled discharge pond systems).
should be evaluated.
Assume high groundwater iwth
inflow.
MWW
Maximum wet weather flow received
For facility design to meet
during a seven-day period divided by
maximum permit limitations.
seven. Assumes high groundwater
with inflow.
PHWW
Peak hourly wet weather flow.
Clarifier and disinfection sizing
Assumes high groundwater with
and to determine if flow
inflow due to a five-year one-hour
equalization should be evaluated.
storm event.
PIWW
Peak instantaneous wet weather flow.
Hydraulic design and to determine
Assumes high groundwater with
flow at which bypassing of plant
inflow due to twenty-five year one-
may be allowed.
hour storm event.
Mr. John Simola
City of Monticello
March 7, 1994
Page I-18
Table 1-3. Summary of Monticello Wastewater Treatment Plant Influent Flows. (1991-1993)
im�►mavacvuavuaimm
Year
Item 1991
1992 1993 Average
Flow, mgd
0.66
0.65 0.66 0.66
0.62
0.62 0.63 0.63
Average annual 0.72
0.68 0.78 0.73
Average dry weather
Average wet weather
Annual rainfall, inches
im�►mavacvuavuaimm
Mr. John Simla
City of Monticello
March 7, 1994
Page I-19
Table 14. Sanitary Sewer Inventory for Monticello, Minnesota
Total Length
Sanitary Sewer Diameter
Feet
Miles
Inch -Diameter Miles
4 -inch Services
120,000
22.7272
90.91
6 -inch
4,380
0.8295
4.98
8 -inch
76,470
14.4829
115.86
10 -inch
36,300
6.8750
68.75
12 -inch
9,520
1.8030
21.64
15 -inch
14,150
2.6799
40.20
18 -inch
7,560
1.4318
25.77
21 -inch
2,560
0.4848
10.18
24 -inch
3,060
0.5795
13.91
TOTAL
274,000
51.89
392.20
Notes:
I. Infiltration is the difference between that flow received at the wastewater
treatment plant and that which is discharged into the sewer from
residential, commercial, institutional and industrial sources. The
maximum seven-day average infiltration is determined by comparing the
flow received at the wastewater treatment plant for the highest recorded
seven consecutive days, and subtracting the wastewater that the customers
contributed to the sewer during the same period. Water pumping records
are usually the basis for determining the water contributed from the
custiners.
nu momc VR .O`4=M-IM
TA, 61, Z - S'
TOW WATER TON' KNOWN TOTAL
YEAR USED WATER LOSSES WATER
FROM WELLS v SPILLS C.S.I t'0n
(0-4 (01) (L•q
(WAY., Do3t) (W.- o0vt) NIJ OannL7
Janw,y (
19,673 000
O'1'w1
. «erwry
17,773 000
NM.mb.+
Marti 1
_ 19 537 Ow
DK.mb.r
Ar 5„brolal
Sd 993 6dJ')
AvrO
COM1SumPirM
19.4]9.000 1
M•Y
�
71,177,000
(DAO
_Jun.
(Uw DamO}
7],493,000
(U:8 066170}
I
a1 :wblola! 1
,'.::.�....,
Gs ;69.0m 1
(I JN7 75 7SG OW
( Auquil 7d,0,a,000
ru.nm., _ 73.r,e.00e 1ii
ar 5ubl0i•I _ �n -ee nas I
,00000 I
150000 1
WATER AND SE.'/CR USC WORKS11CR
1
Toil WASTEWATER
O'1'w1
T.:tt REStO
».ce7.0061
NM.mb.+
Toil INDUSTRIA{,
19.951.004
DK.mb.r
SEWER
7p,5a 7.000
�•'�9+.1
COM1SumPirM
w,17a 000
TOTALS
�
101 O7G,0OO1
,00000 I
150000 1
WATER AND SE.'/CR USC WORKS11CR
1
Toil WASTEWATER
SEWER
T.:tt REStO
TWAT PUOUCJINST
Tv.1 COMMCRCIAL
Toil INDUSTRIA{,
SEV/ER
5Cw"rR
SEWER
5E1YER
co,,,. —
COM1SumPirM
cials—ptl0,1
c-s—o-
(9A7
(0aq
(DAO
(.1
(Uw DamO}
(via Odtnq)
(U:8 066170}
(U.a O.6w,9
,'.::.�....,
:,' .,
374.500 ...
...... ,
iI
, :r.
. . • '"f
TOTAL
1
Toil WASTEWATER
SEWER
TREATMENT PLANT
coli—o—
FLOW
l0aq
(0aO
(t21. DIibnO)
(PuPir WOrai}
19.101.000
?100.0001
.'
' I 10.000,0001
1500.0
51.7!5 Ole
75.99. 117 ( a,r04,d12 (
tl.a]T,a,3 f!!
S?2t,r09 ( a),e0] 6i7 (
58.870000
••,
!,
?100.0001
.'
,'•• :1'•`•':�.: ,'),
11.
...
�'::,.. ,
r)
1s.a90.oao1
��
,'.::.�....,
:,' .,
374.500 ...
...... ,
iI
, :r.
. . • '"f
75.Jaa.000
86 500
I F''
'L_ I
_
--
V•
^4
..
7.5x3 000)
5- O8, <70
tG,+er.w:a ( 777,37.
a 777,414 I
4 700 G75�—_
.8.047 ars I
4],710000
34500
"
r. I, '... ,'}''.., :It.
,.5- ..
. .. ..'•��.i
.. 1
1,.r07000.
1
•�1.'1•
,1
3G 500
.. •• i.
:.i
,.L .,,
i', I
7f.ae0.00o
__..—.._
�
�
." , •
�
I
!� ,''.N'1'
19.650.000
73 000 1
44,703.11.8 1
26.3100.. 1 ..07.00
9 017.CO4 (
0 979..90
(^
-0,/.8.57p�.
62-12000
1
!
'i'.
�!"
- "(t4 '.4
��
7,100.000
�.. .�5..
:+
_ .•
n.al,000
.J
-
10,1 X1.000
75,000_
.`• ,yf
t,., �
•
_—
1175.0001
53592/511
76,391 937,
.•1 TT,7391
11,790.511
a.85.377 50192,97.
50,60.,000
..571,000)
77, 771187
10',050578 ( Y7,d91,075
'0.83,0&4 (
}9,905,}61 ( 192,947.070
239,141.000
RC5IDSCWCR(aC1usq 00- 25.073.70 013 • 37,724,312 0:,4 - 76,781.041
5-zd
Figure 1-3 Monticello WWTP (low patterns during varying flow
regimes.
1.2
1
E 0.6 -� �7 / '� lr - •-•
D.
0.4 l
0.2 "•
of
Time, hours
Pop'r-ii
—•— ADWF (1 / 1 /93)
—+— ADWF with high
groundwater
—•— Wet weather (7/5/93)
NIPMCl +A}HOW, jLJJAe4
Figure 1-4. Monticello Wastewater Treatment Plant Influent
Biochemical Oxygen Demand (BOD) Loadings(1991-1993).
3500
3000 I
2500 y
2000.
1500 1
1000 I A
500� (L � g o
Month
—•— 1991 —ti— 1992 '— 1993 1
PCQe t- it
Figure 1-5. Monticello Wastewater Treatment Plant Influent Total
Suspended Solids (TSS) Loadings (1991-1993)
3500
3000
v 2500
2000
1500
1000 I i
%0 I
z CL
Month
—6— 1991 1992 - 1993
Pogo I = Z I
Mr. John Simola
City of Monticello
March 7, 1994
Page 1-24
Table 1-6. Summary of Monticello WWTP Influent Organic Loadings
Parameter
1991
1992
1993
Average
Biochemical oxygen demand (BODS)
Average, mg/L
450
395
365
400
Average, ppd
2470
2150
2002
2210
Max month, mg/L
585
530
490
535
Max month, ppd
3310
2790
2685
2930
Max day, ppd
3945
3850
3665
3820
Total suspended solids(TSS)
Average, mg/L
285
290
250
275
Average, ppd
1575
1570
1380
1510
Max month, mg/L
555
410
315
425
Max month, ppd
3125
2155
1970
2415
Max day, ppd
5510
4645
6260
5470
�w umiova�ooi�ennawo,wr
Mr. John Simola
City of Monticello
March 7, 1994
Page I-25
Table 1-7 Present and Design Organic Loadings for the Monticello WWTP Influent, Domestic
and Industrial Sources.
1 W Na01OVR1LLRaO�MNlaalmY
Design'
Percent of
Item
Present
( 2000)
Design
Wastewater Treatment Plant Influent
Flow, mgd
0.66
0.91
72
Biochemical oxygen demand (BOD,), ppd
2,210
6.270
35
Total suspended solids (TSS), ppd
1,510
3220
50
Domestic Sources
Flow, mgd
0.57
0.77
74
Biochemical oxygen demand (BOD,), ppd
I,I50
1,600
72
Total suspended solids (PSS), ppd
1,100
1,470
75
Industrial Sources (Sunny Fresh Foods)
Flow, mgd
0.09
0.14
64
Biochemical oxygen demand (BOD,), ppd
1.100
4,670
23
Total suspended solids (PSS), ppd
450
1,750
28
' Design loadings for the year 2000 aro taken from the Facilities Planning
Retort for the
City of
Monticello. Minnesota, January, 1977, by OSM.
1 W Na01OVR1LLRaO�MNlaalmY
Mr. John Simola
City of Monticello
March 7, 1994
Page I-26
Table 1-8. City of Monticello Calculated Domestic Organic Loadings per Capita
Parameter
1991
1992
1993
BODS, pound/day/capita
Average
0.26
0.27
0.23
Maximum month
0.33
0.38
0.39
Month occurrence
Sept.
March
TSS, pounds/day/capita
0.23
0.26
0.22
Average
0.36
0.37
0.32
Maximum month
Month occurrence
Sept.
March
�wumovuxoa�aaumm
Average
0.25
0.37
0.24
0.35
Figure 1-6. POO. Present and Projected City of Monticello Population.
16.000
14,000
12000
14000
O.00D
4000
4.160
2000 ✓
I
0 1 1 1 1
1970 1900 1990 1000 7010 2010
Y"
—•— c4 —•— 25160 —•— mlwno
Doom Stam Stath
Data
—a— 75m —•— Im w—a
Stam Stam
I
Po7x4at1on Prdoatbn
Ua Corwn I
Ilam Stam por Y—
Y—B.—,
25
to 75
100
1970
1.636
1900
2&70
1790
5015
1994
5100
5.200
4100 5.200
4100
1000
5070
6.660 7.327
7.995
1010
7.110
WO 14015
11.570
?070
7 Mual
9140
10,637 12941
15.06.5
Compondod
C,r..nh k0o
4.76
18%
78% 3.5%
4.79E
16.000
14,000
12000
14000
O.00D
4000
4.160
2000 ✓
I
0 1 1 1 1
1970 1900 1990 1000 7010 2010
Y"
—•— c4 —•— 25160 —•— mlwno
Doom Stam Stath
Data
—a— 75m —•— Im w—a
Stam Stam
Mr. John Simola
City of Monticello
March 7, 1994
Page 1-28
Table 1.9. Present and Projected Domestic Design Flows and Organic Loadings
2,600
3,100
Projected Domestic
Maximum month
3,800
Contributions
1,700
Maximum week
for Year 2020
Present Domestic
2,000
Maximum day
Contribution
7.800
House Starts Per Year
Parameter
50 75
Flow, mgd--
Average dry weather
1.28 1.47
0.53
Average wet weather
1.38 1.63
0.69
_Biochemical oxygen demand, Ibald_ - - ----
- _ _ -- _ _ _ _' - — _
_ _ -- -
Average
2,700 3,300
1.200
Maximum month
4,000 4,900
1,800
Maximum week
4,200 5,000
2,000
Maximum day
4,800 5,600
2,600
Total suspended solids Ibs/d
Average
2,600
3,100
1,100
Maximum month
3,800
4,600
1,700
Maximum week
4,100
4,900
2,000
Maximum day
7.000
7.800
4.900
I VINmOVLL1LOaaOhlraRlp)lmtl
Mr. John Simola
City of Monticello
March 7, 1994
Page I-29
Table 1.10.
Present and Future Industrfal Loadings for an Expended Sunn)iresh
Foods (Case 1)
Current Industry
Present Design
Projected Ddgn
Parameter
Contribution
Contribution
Contribution
Flow, mgd
0.09
0.16
0.20
BOD, -
Average
1100
1100
1650
Maximum Month
1400
1400
2100
Maximum Week
1900
1900111,
2850
Maximum Day
2600
2000151
3000
TSS
Average 450 500 750
Maximum Month 815 815 1200
Maximum Week 955 10001°' 1500
Maximum Day 1000 1100 1650
mes:
' Current industry maximum month flow and load is the average of the maximum month flow and load in
1991. 1992, and 1993.
r Current industry maximum week flow and load is the average of the maximum week flow and load in
1991, 1992. and 1993.
s Current industry maximum day flow and load is the average of the maximum day flow and lad in
1991, 1992, and 1993.
° Present design flow baud upon maximum day flow in agreement between Sunnyfmsh Foods and City
of Monticello.
' Resent design maximum week and maximum day BOD, loads based upon agreement between
Sunnyfresh Foods and City of Monticello. Maximum week loads have been adjusted for a 5 day
discharges versus 7 days.
Resent design maximum day and maximum day TSS loads based upon agreement between Sunnyfresh
Foods and City of Monticello. Maximum week lads have been adjusted for a 5 day discharges versus
7 days.
IW I►miL7�LLINaaOlQaatmKY
Table 1-11. Present and Future Industrial Loadines for Wei and Dry Industry Alternatives
Industrial Contributions Design Flows and Loads In Year 2020
Oeslrn Loads /Year 2020
fleuse Start Per Year
0 '7S
Current Alternative 2 Altemadve 3 Alternative 2 Alternative
Industry Present apand Wet Expand Dry Expand vv.'a Expand Dry
Parameter Contribution Design Industry Industry Industry Industry
Flow. mad 0.09 0.161" 0.32 0.30 0.36 035
Biochemical Oxygen Demand
i
Average 1100 Ileo 2400 1900 2900 2000
Maximum Month 1400 1400 3000 2400 37W 25W
Maximum Week 1900 19W" 3800 3000 4600 3100 .
Maximum Day 2600 2000'') 4000 3200 4800 3400
TOW Susoended Solids ,
Average 450 500 IOW 900 1300 1000
Maximum Month 815 815 I8W1400 7100 1500
Maximum Week 955 1000'•) 2000 1700 2400 1800
Maximum Day IOW I100'" 2200 1900 2500 2000
Notes:
' Current industry maximum month flow and load is the average of the maximum month flow and load in 1991, 1992, and
1993.
2 Current industry maximum week flow and load is the average of the maximum week flow and load in 1991, 1992, and
1993.
s Current industry maximum day flow and load is the average of the maximum day flow and load in 1991, 1992, and
1993.
4 Present design now based upon maximum day flow in agreement between Sunnyfresh Foods and City of Monticello.
' Resent design maximum week and maximum day BOD, loads hated upon agreement between Sunnyliesh Foods and City
of Monticello. Maximum week loads have been adjusted for a 5 day discharges versus 7 days.
• Resent design maximum week and maximum day ISS loads based upon agreement between Sunnyfresh Foods and City
of Monticello. Maximum week loads have been adjusted for a 5 day discharges versus 7 days.
Mr. John Simola
City of Monticello
March 7, 1994
Page I-31
Table 1-12. Summary of Design Flows and Loads for Each Population Project and Industrial
Growth Scenario
BOD. PPD
Averate
50 House Starts Per Year
75 House Starts Per Year
6100
Alternative 2
Alternative
Alternative 2
Alternative 3
8600
Expand Wet
3
Expand Wet
Expand Dry
Parameter
Industry
Expand
Industry
Industry
10.400
9000
Dry
Industry
3600
3500
Flow. mad
4100
Maximum Month
5600
—
Averaee Dry Weather
1.57
1.52
1.89 -.
1.82
Avemee Wet Weather
1.73
1.68
2.05
1.98
Maximum Wet Weather
2.02
1.98
2.35
2.27
Peak Hourlv Wet Weather
4.19
4.14
4.89
4.82
Peak Instantaneous Wet
4.57
4.52
5.24
5.19
BOD. PPD
Averate
5100
4600
6100
5200 I
Maximum Month
7000
6400
8600
7400
Maximum Week
8000
7200
9600
8100
Maximum Dav
8800
8000
10.400
9000
TSS. PPD
Averare
3600
3500
4400
4100
Maximum Month
5600
5200
6700
6100
Maximum Week
6100
5800
7300
6700
LM..,,- ,,..
ovn
anm
to am
mm G
I V7uaxCIW.1L011t0liv�n na �6Y
j_,;
TECHNICAL MEMORANDUM II
DATE: MARCH 8, 1994
TO: JOHN SIMOLA, CITY OF MONTICELLO
FROM: JON PETERSON, OSM
SUBJECT: MONTICELLO FACILITIES PLAN
SERIES 200 - DISCHARGE REQUIREMENT'S
OSM COMM NO. 5216.00
This technical memorandum summarizes the City of Monticello's wastewater treatment
plants (WWTP) existing and projected future National Pollutant Discharge Elimination
System (NPDES) permit requirements for continued discharge into the Mississippi River
and possible future discharge to an alternative receiving stream. The projected future
discharge standards are based upon discussions with Minnesota Pollution Control Agency
(MPCA) staff.
Existing NPDES Permit
The MPCA reissued the Monticello WWTP's NPDES permit (MN 0020567) on
December 31, 1989. This permit authorizes the Monticello WWTP to continuously
discharge treated wastewater through its existing outfall (outfall 010) to the Mississippi
River through December 31, 1994. The effluent limitations defined in the permit are
shown in Table 2.1.
The WWTP is currently rated to treat 0.91 million gallons per day (mgd) of wastewater.
A WWTP is considered a minor discharger and is subject to reduced monitoring
requirements, if its capacity is less than 1.0 mgd.
The permit also requires the Monticello WWTP to submit dechlorination facility plans
and specifications to the MPCA for approval and to initiate dechlorination facility
operation by December 31, 1994. The City of Monticello has received approval of said
plans and specifications and is in the process of completing construction of the
dechlorination facilities.
1.W1"0%r 1ACnQW3\TMQMrU
Mr. John Simola
City of Monticello
March 7. 1994
Page 11-2
Table 2-1. Monticello Wastewater Treatment Plant Existing Elfluent Limitations
Concentration I.imitations mg/L Mass Loading Limitations kg/d
Parameter Monthly Average Weekly Average Monthly Average Weekly Average
5 -Day carhonaceous
biochemical oxygen
25 40
demand
Total suspended solids
30 45
Fecal Coliform
200/100mL
(March 1 - October 31)
p11,
6.0-9.0
Chlorine residual=
0.1 mg/L
' Daily Limitations.
= Daily maximum applicable upon completion of dechlorination facilities
J,VUI& nciwac0RRMT QULw
86.1 138
103 155
d
Mr. John Simola ' : z \
Citv of Monticello
LFT
March 7, 1994
Page 11-3
Future NPDES Permits
The facility's plan will investigate two alternatives for increasing the wastewater
treatment capacity. The first alternative assumes the existing WWTP is expanded and
continues to discharge treated wastewater through Outfall 010 to the Mississippi River.
The second altemative assumes additional treatment facilities are constructed at a site
remote from the existing WWTP and treated wastewater is discharged to the Mississippi
River or to a nearby small receiving stream such as Otter Creek. This alternative is
based upon the Facilities Planning Report for the Citv olLMonticello. Januarv, 1978,
recommendation for expanding the existing WWTP at a remote site. These two
alternatives were discussed with MPCA staff concerning future effluent requirements for
Monticello's wastewater treatment facilities.
The Monticello WWTP currently discharges to a specially protected reach of the
Mississippi River which is classified as a 1C, 2Dd, and 3D Outstanding Resource Value
Water (ORVW).
The Class 1C designation requires that Mississippi River water meet drinking water
standards after treatment consisting only of solids removal and chlorination. Class 213d
waters are protected as a source of drinking water, shall be suitable for aquatic
recreation and full body contact, and shall permit the propagation and maintenance of
commercial fishes and their habitats. The Class 3f3 industrial consumption designation
requires the water to he suitable for general industrial purposes(except food
consumption) with only moderate treatment.
However, the major impact of the current Mississippi River classification to the City of
Monticello is that Minnesota regulations require that "No person may cause or allow a
new or expanded discharge of any sewage, industrial waste, or other waste to any ORVW
unless there is no prudent and feasible alternative". This is commonly referred to as
non -degradation of an ORVW, for practical purposes, and prohibits any increase in the
quantity or "mass" of certain pollutants discharged from a WNVT*P, regardless of increases
in the volume of wastewater treated. A March 1, 1994 letter from the MPCA confirms
that it will he very difficult to justify increases of the mass loadings from an expanded
Monticello WWrP.
A similar circumstance recently occurred when the City of Elk River, which also
discharges wastewater to the Mississippi River, completed a "prudent and feasibility
analysis" for increasing the mass of pollutants discharged from its WWTP. The analysis
identified additional costs for maintaining mass loadings at current levels, as compared to
increasing mass loadings in proportion to projected flow increases at $1.6 million. The
analysis also estimated the effects of the additional mass loadings on the Mississippi
)AIII-DO\c611 kr 915\nnuwm
Mr. John Simola
City of Monticello
March 7, 1994
Page 11-4
River water quality. Those effects were negligible in terms of three toxic water
parameters evaluated: ammonia, dissolved oxygen, and suspended solids. The costs
were deemed reasonable by the MPCA and the pollutant mass loadings were not
permitted to increase over current levels.
As such, Minnesota regulations make it extremely difficult for a WWTP or discharger to
increase the mass loading of pollutants over current levels. At this time, given the
MPCA's stated position and difficulties experienced by Elk River, it is unlikely the
permitted mass of pollutants discharged will be increased. Although unlikely, later parts
of this study may justify increases in mass loadings.
However, the City of Monticello can increase the volume of wastewater flow, if the mass
of pollutants discharged does not exceed the present limitations defined in its NPDES
permit. Table 2-2 summarizes the MPCA's projected effluent limitations for the
expanded Monticello WWTP. It shows effluent concentration limitations and mass
loadings for carbonaceous biochemical oxygen demand (cBODs) and total suspended
solids (TSS) will remain as defined in the existing NPDES permit. As such, the
expanded WWTP could comply with the concentration limitations, but violate the mass
loading limitations, thus resulting in a discharge violation. Accordingly, for new designs,
as flows increase, pollutant (BODS & TSS) concentrations in the effluent must decrease.
Ultimately, as concentration discharge requirements are lowered, advanced treatment
processes such as filtration will be required. We estimate that advanced treatment will
most likely be required at a flow of about 1.4 mgd, depending upon final clarifier
performance. Filtration of the entire waste stream is not necessary initially, as a fraction
of the waste stream may be filtered and blended with non -filtered treated wastewater to
meet effluent limitations.
The new permit may also limit total residual chlorine discharges to 0.038 mg/L and
require additional monitoring for phosphorus and nitrogen compounds. Since the
average projected wet weather flow will be greater than 1.0 mgd, the Monticello WWTP
will he classified as a major discharger and will be required to complete effluent toxicity
testing. Projected toxicity testing requirements have not yet been established but
generally involve
�.\uum\crvn.\rnuarsm7u.wi y
Mr. John Simola
City of Monticello
March 7, 1994
Page 11-5
Table 2.2. Projected Discharge Requirements for the Monticello Wastewater Treatment Plant Discharging to the
Mississippi River.
Concentration Umilations mg/L
Mass Loading Limitations kg/d
Parameter Monthly Average Weekly Average
Monthly Average Weekly Average
5 -Day carbonaceous
biochemical oxygen 25 40
86.1 138
demand
Total suspended solids 30 45
103 155 l
Fecal Coliform (3/1- 200/100ml-
10/31)
Total Chlorine Residual 0.038 mg/Lt
pill 6.0-9.0
Total Phosphorus as P Monitor I/wk
Ortho -Phosphate as P Monitor 1/mo
Kjeldahl Nitrogen as N Monitor 1/mo
Ammonia Nitrogen as N Monitor I/mo
Nitrate Nitrile as N Monitor I/mo
Daily Maximum Limitations.
)
= Daily Limitation.
WIC\SNL\('ORN��11CClILY01
Mr. John Simola
City of Monticello - (`
March 7, 1993
Page 11-6
Alternative 2 - New or Additional WWTP
Discharge requirements for additional wastewater treatment facilities at a site remote
from the existing WWTP were also investigated. If the City constructs a new treatment
facility at a remote site the mass loading limitations for cBODs and TSS established for
the existing WWTP will apply to the combined discharges of the existing and new
WWTP's regardless of whether the new treatment plant discharges to the Mississippi
River or a smaller receiving stream such as Otter Creek which leads to the Mississippi
River.
In addition, if the new WWTP discharges to Otter Creek, the WWT'P will be required to
meet seasonal ammonia effluent limitations, more stringent cBOD, limitations and
maintain a minimum dissolved oxygen concentration of 6.0 milligrams per liter (mg/L) in
all discharges. Table 2-3 provides a summary of MPCA's projected effluent limitations
for discharges to Otter Creek. Maximum ammonia and minimum dissolved oxygen
(D.O.) limitations are required for Otter Creek to permit the propagation and
maintenance of mol or warm habitats. Ammonia is toxic to fish and also depresses D.O.
in water, which is necessary for most aquatic species.
Since the projected wastewater expansion will increase the average wet weather flow
capacity by 0.2 mgd, an "economic and social development" analysis must be completed.
This analysis will evaluate the cost and benefit of the new discharges. Economic and
social development refers to jobs, taxes, recreational opportunities and other impacts on
the public resulting from the new discharge.
Conclusion
Based upon preliminary discussions with the MPCA, the City of Monticello will be
required to maintain the mass loading of pollutants discharged from its expanded
wastewater treatment facilities at levels equal to those established in its existing permit,
unless it can prove the cost for meeting the existing mass loadings are deemed
unreasonable by MPCA. The City will be required to begin additional monitoring of
ammonia and phosphorus compounds and limit the amount of residual chlorine in its
WWTP effluent.
Discharge of treated wastewater to Otter Creek or a similar low now receiving stream
will require additional capital and operation costs as nitrification facilities to convert
ammonia to a less toxic nitrogen form and will be required to maintain the existing mass
loading of pollutants discharged.
J Wl..WMIA\ R1S1n IIIlYIII
Mr. John Simola
City of Monticello
March 7, 1994
Page 11.7
Table 2.3. Projected Discharge Requirements for the Monticello Wastewater Treatment Plant Discharging to the Otter Creek.
Concentration Limitations mg/L Mass Loading Limitations kg/d
Parameter
Monthly Average Weekly Average Monthly Average Weekly Average
5 -Day carbonaceous biochemical oxygen demand
53 86.1 138
Total suspended solids
30 45 103 155
Fecal Coliform (3/1-10/31)
200/100mL
Total Chlorine Residual'
0.038 mg/L'
pill
6.0-9.0
Total Phosphorus as P
Monitor I/ wk
Ortho -Phosphate as P
Monitor 1/mo
Kjcldahl Nitrogen as N
Monitor 1/mo
t
Nitrate Nitrite as N
Monitor I/mo
Ammonia -Nitrogen
Summer (June -Sept)
1.1
Fall (Oct -Nov)
3.1
Winter (Dec -Mar)
10.2
Spring (Apr -May)
2.2
I Daily Maximum Limitations.
= Daily Limitation.
v If the discharge is within 1/2 mile of the creek's confluence with the Mississippi River, this increases to 25 mg/L.
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