Domestic Fact Sheet 7.0

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Domestic Fact Sheet 7.0 Powered By Docstoc
					                       PUBLIC NOTICE SHEET




Superior Metropolitan District #1. Richard Elliott, Director, 124 E. Coal
Creek Drive, Superior, CO 80027, PHONE: (303) 499-3675; PERMIT NO.: CO-
0043010; Boulder County.

Second Renewal

DRAFTER: Holly Brown

DISCHARGE: To Rock Creek.
                            COLORADO DISCHARGE PERMIT SYSTEM (CDPS)
                             FACT SHEET FOR PERMIT NUMBER CO-0043010

                               SUPERIOR METROPOLITAN DISTRICT #1
                                       BOULDER COUNTY

                                                      TABLE OF CONTENTS

                    I.        TYPE OF PERMIT ................................................................................ 1 
                    II.       FACILITY INFORMATION ................................................................ 1 
                    III.      RECEIVING STREAM ......................................................................... 2 
                    IV.       FACILITIES EVALUATION ............................................................ 2 
                    V.        PERFORMANCE HISTORY ............................................................. 3 
                    VI.       TERMS AND CONDITIONS OF PERMIT...................................... 5 
                    VII.      REFERENCES .................................................................................. 15 
                    VIII.     PUBLIC NOTICE COMMENTS ..................................................... 16 


I. TYPE OF PERMIT                   Domestic Major, POTW, 2nd Renewal, Surface Water

II. FACILITY INFORMATION

   A. Facility Type:       Domestic - Major Municipal, Mechanical Plant
      Fee Category:          Domestic Wastewater - Mechanical Plants, Category 21, Subcategory 6
      Category Flow Range:   Sewage from 1,000,000 up to 2,499,999 gpd
      Annual Fee:            $6090 effective July 1, 2007

   B. SIC Code:                4952 Sewerage Systems
      Facility Classification:    Class B per Section 100.5.2 of the Water and Wastewater Facility
                                  Operator Certification Requirements

   C. Legal Contact/Permittee:            Richard Elliott, Director
                                          124 E. Coal Creek Drive, Superior, CO 80027
                                          (303) 499-3675

      Facility Contact:                   Ron Weaver, Certified Operator Class A
                                          ECO Resources, Inc.
                                          6050 W. 54th Ave.
                                          Arvada, CO 80002
                                          (303) 307-3200

      Facility Location:                  2025 Honey Creek Lane, Superior, CO 80027, Latitude: 39° 56' N,
                                          Longitude: 105° 8' W

   D. Discharge Point:                    Outfall 001A, following disinfection and prior to mixing with the
                                          receiving stream.

   E. Facility Flows:                  2.2 MGD
ISSUED                               EFFECTIVE                                                        EXPIRATION
  F. Major Changes From Last Renewal:

         •   Outfall 002A discontinued - The facility has received a notice of authorization from the Division that
             covers the wastewater reuse of this discharge and therefore dual coverage under this individual
             permit is not necessary.
         •   Metals limits and/or monitoring (Cr+6, Cu, Fe, Hg, Ni, Se, Zn)
         •   New total ammonia standard
         •   Change from Fecal Coliform to E. coli


III. RECEIVING STREAM

  A. Waterbody Identification:       COSPBO08, Rock Creek

  B. Water Quality Assessment:

     An assessment of the stream standards, low flow data, and ambient stream data has been performed to
     determine the assimilative capacities for Rock Creek for potential pollutants of concern. This information,
     which is contained in Appendix A to this rationale, also includes an antidegradation review, where
     appropriate. The Division’s Permits Section has reviewed the assimilative capacities to determine the
     appropriate water quality-based effluent limitations as well as potential limits based on the antidegradation
     evaluation, where applicable. The limitations based on the assessment and other evaluations conducted as
     part of this rationale can be found in Part I.A of the permit.

     Outfall 001A will continue to be the authorized discharge point to the receiving stream

IV. FACILITIES EVALUATION

  A. Infiltration/Inflow (I/I)

     As per its permit application, the permittee currently serves a population of 11,300 persons. Based on a
     high 30-day average flow of 1.33 MGD as reported in its permit application, the flow per capita per day
     was computed to be 118 gallons per capita per day (gpcpd). This is less than the Division’s threshold of
     120 gallons per capita per day, thereby demonstrating that infiltration and inflow are not problematic in
     the service area.

  B. Lift Stations

     Table IV-1 summarizes the information provided in the renewal application for the lift stations in the
     service area.




         Table IV-1 – Lift Station Summary
                                                                                     % Capacity
              Station             Firm Pump
                                                         Peak Flows (gpd)            (based on
              Name/#             Capacity (gpm)
                                                                                     peak flow)
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 3, Permit No. CO-0043010

            Coal Creek Lift      2 pumps at 750                250,000                    12%
            Station              gpm each (1500
                                 total)

   C. Treatment Facility

       The facility consists of a mechanical bar screen, aerated grit chamber, grit classifier, two activated
       sludge aeration basins, two secondary clarifiers, and gas chlorine disinfection with dechlorination.
       Influent flow is measured via a 9-inch Parshall flume and the effluent flow is measured via an 8-inch
       ultrasonic meter; both are equipped with continuous electronic flow recorders. The permittee has not
       performed any construction at this facility that would change the hydraulic capacity of 2.2 MGD or the
       organic capacity of 6,000 lbs BOD5/day, which were specified in the rationale for the previous permit.
       That document should be referred to for this information. These capacities will continue in this permit.


   D. Biosolids Treatment and Disposal

       According to the permit application, biosolids are treated in a digester to Class B biosolids. The
       digested biosolids are further dewatered in a centrifuge and the resulting sludge cage is stored in a truck,
       which hauls sludge twice each week to a nearby landfill.

       1.   EPA General Permit

            EPA Region 8 issued a General Permit (effective October 19, 2007) for Colorado facilities whose
            operations generate, treat, and/or use/dispose of sewage sludge by means of land application,
            landfill, and surface disposal under the National Pollutant Discharge Elimination System. All
            Colorado facilities are required to apply for and to obtain coverage under the EPA General Permit.

       2. Biosolids Regulation (Regulation No. 64, Colorado Water Quality Control Commission)

            While the EPA is now the issuing agency for biosolids permits, Colorado facilities that land apply
            biosolids must comply with requirements of Regulation No. 64, such as the submission of annual
            reports as discussed later in this rationale.

V. PERFORMANCE HISTORY

   A. Monitoring Data

       1. Discharge Monitoring Reports - Table V-1 summarizes the effluent data reported on the monthly
          Discharge Monitoring Reports (DMRs) for the Superior Metropolitan District #1 WWTF from
          February 2007 through January 2009. In order to complete a reasonable potential analysis (discussed
          later in the fact sheet) the past five years of available DMR data was used.

Table V-1 – Summary of DMR Data
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 4, Permit No. CO-0043010


                                  # Samples                                                                   Number
                                                Reported Average       Reported Maximum          Previous
                                      or                                                                      of Limit
           Parameter                             Concentrations          Concentrations        Avg/Max/AD
                                  Reporting                                                                   Excursio
                                                 Avg/Min/Max             Avg/Min/Max           Permit Limit
                                   Periods                                                                       ns

Influent Flow (MGD)                  24             0.86/0.73/1              1/0.84/1.2      Report/Report
Effluent Flow (MGD)                  24            0.55/0.05/1.2           0.93/0.15/1.8       2.2/Report
pH (su)*                             24              6.8/6.5/7.2              8.1/7.4/9          6.5 - 9
Fecal Coliform (#/100 ml)**          24               2.2/2/3.6                2.9/2/17        2000/4000
TRC (mg/l)                           24              NA/NA/NA             0.16/0.05/0.45         NA/0.5
NH3, Tot (mg/l)                      24            0.87/0.03/12             2.1/0.03/23          NA/NA
NH3, Tot (mg/l) Jan                   2          0.065/0.04/0.09           0.16/0.12/0.2       6.3/Report
NH3, Tot (mg/l) Feb                   2             1.5/0.34/2.6              3.3/1.6/5        4.4/Report
NH3, Tot (mg/l) Mar                   2             5.8/0.09/12              12/0.32/23        4.4/Report         1
NH3, Tot (mg/l) Apr                   2            0.83/0.15/1.5            2.2/0.45/3.9       4.4/Report
NH3, Tot (mg/l) May                   2             0.54/0.05/1             3.3/0.16/6.5       6.3/Report
NH3, Tot (mg/l) Jun                   2           0.06/0.06/0.06          0.16/0.13/0.18       6.3/Report
NH3, Tot (mg/l) Jul                   2           0.17/0.12/0.21          0.55/0.37/0.72       6.3/Report
NH3, Tot (mg/l) Aug                   2           0.05/0.05/0.05          0.11/0.07/0.14       6.3/Report
NH3, Tot (mg/l) Sep                   2          0.055/0.03/0.08         0.085/0.03/0.14       6.3/Report
NH3, Tot (mg/l) Oct                   2          0.095/0.05/0.14           0.4/0.15/0.65       6.3/Report
NH3, Tot (mg/l) Nov                   2           0.07/0.03/0.11           0.12/0.03/0.2       6.3/Report
NH3, Tot (mg/l) Dec                   2             1.2/0.03/2.4            2.7/0.04/5.4       6.3/Report
BOD5 (mg/l)                          24               2.3/2/5.7                4.9/2/54         NA/NA/
BOD5, influent (mg/l)                24            319/211/427             398/233/602          NA/NA/
BOD5, influent (lbs/day)             24          2258/1636/2720          2815/1754/4124         NA/NA/
BOD5, effluent (mg/l)                24               2.3/2/5.7                4.9/2/54          30/45/           1
BOD5 (% removal)                     24              99/98/100               NA/NA/NA            85/NA/
TSS (mg/l)                           24                5.7/5/9                 7.9/5/20         NA/NA/
TSS, influent (mg/l)                 24           525/266/2268            891/281/7111          NA/NA/
TSS, effluent (mg/l)                 24                5.7/5/9                 7.9/5/20          30/45/
TSS (% removal)                      24              99/97/100               NA/NA/NA            85/NA/
Oil and Grease (mg/l)                24              NA/NA/NA                   0/0/0            NA/10/
As, TR (µg/l)                        12             0.54/<1/1.3             0.54/<1/1.3      Report/Report
Cd, Dis (µg/l)                       10           0.046/<0.1/0.1          0.046/<0.1/0.1     Report/Report
Cr, TR (µg/l)                        10              6/<0.1/50               6/<0.1/50       Report/Report
Cr+6, Dis (µg/l)                     12              9.2/<1/50                9.2/<1/50          NA/NA
Cu, Dis (µg/l)                       10              32/7.9/113              32/7.9/113      Report/Report
CN, Free (µg/l)                       4            13/<0.01/20              13/<0.01/20          NA/NA
Fe, Dis (µg/l)                       10               50/0/166                50/0/166       Report/Report
Pb, Dis (µg/l)                       10             0.7/<0.9/4.2            0.7/<0.9/4.2     Report/Report
Mn, Dis (µg/l)                       10                11/4/28                 11/4/28       Report/Report
Hg, Tot (µg/l)                       12            0.05/<0.2/0.2           0.05/<0.2/0.2     Report/Report
Ni, Dis (µg/l)                       10             5.4/<40/40               5.4/<40/40      Report/Report
Se, TR (µg/l)                        12              2.6/<0.2/8              2.6/<0.2/8      Report/Report
Ag, Dis (µg/l)                       10           0.027/<0.2/0.2          0.027/<0.2/0.2     Report/Report
Zn, Dis (µg/l)                       10              98/47/221               98/47/221       Report/Report
Wet, acute
         pimephales, LC50             8                   //               100/100/100
                                                                                               LC50>100
        ceriodaphnia LC50             8                   //               100/100/100
 *The pH data shows the minimum reported values in the "average" column, and the maximum reported values in the
"maximum column

** Geometric mean
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 5, Permit No. CO-0043010

NA means Not Applicable
NV means No Visible Sheen

       2. Additional Data – State sampling results for the Superior Metropolitan District #1 WWTF were
          collected in 2007, but were not available for use in this summary. However, according to the
          Division’s sampling staff, all results were well within the facility’s effluent limits.

   B. Compliance With Terms and Conditions of Previous Permit

       1. Effluent Limitations –The data shown in the preceding table(s) indicate apparent violations of the
          permit. One excursion for BOD5 and one for ammonia in the month of March.

            There was also a reported violation for pH, which appeared to be a misplaced decimal reporting 83
            instead of 8.3.

            The permittee has been in apparent compliance with all other numerical limitations of the permit.



VI. TERMS AND CONDITIONS OF PERMIT

   A. Discussion of Effluent Limitations

       1. Technology Based Limitations

            a.   Federal Effluent Limitation Guidelines – There are no existing Federal Effluent Limitation
                 Guidelines for domestic wastewater treatment facilities.

            b. Regulation 62: Regulations for Effluent Limitations – These Regulations include effluent
               limitations that apply to all discharges of wastewater to State waters. These regulations are
               applicable to the discharge from the Superior Metropolitan District #1 WWTF.

                 i.   BOD5 and TSS - The BOD5 and TSS concentrations are the most stringent effluent limits and
                      are therefore applied. The removal percentages for BOD5 and TSS also apply based on the
                      Regulations for Effluent Limitations. These limitations are the same as those contained in
                      the previous permit and are imposed effective immediately.

                 ii. Oil and Grease – The oil and grease limitations from the Regulations for Effluent Limitations
                     are applied as they are the most stringent limitations. These limitations are the same as those
                     contained in the previous permit and are imposed effective immediately.

                 iii. pH and Total Residual Chlorine - The pH and total residual chlorine concentrations specified
                      in the Regulations for Effluent Limitations are not the most stringent and thus are not used as
                      discussed below.

       2.   Water Quality Regulations and Guidance Documents

            a. Water Quality Assessment – The WQA in Appendix A contains the evaluation of pollutants
               limited by water quality standards. The mass balance equation shown in Section IV of Appendix
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 6, Permit No. CO-0043010

               A was used for most pollutants to calculate the maximum allowable effluent concentration, M2,
               that could be discharged without causing the water quality standard to be violated. For
               ammonia, the AMMTOX Model was used to determine the maximum assimilative capacity of
               the receiving stream. A detailed discussion of the calculations for the maximum allowable
               concentrations for E. coli, total residual chlorine, ammonia, and metals and cyanide is provided
               in Section IV of the water quality assessment contained in Appendix A.

               The maximum allowable effluent pollutant concentrations determined as part of these
               calculations represent the calculated effluent limits that would be protective of water quality.
               These are also known as the water quality-based effluent limits (WQBELs). Both acute and
               chronic WQBELs may be calculated based on acute and chronic standards, and these may be
               applied as daily maximum (acute) or 30-day average (chronic) limits

          b. Antidegradation - Since the receiving water is Use Protected an antidegradation review is not
             required pursuant to Section 31.8(2)(b) of The Basic Standards and Methodologies for Surface
             Water.

          c. Determination of Total Maximum Daily Loads (TMDLs) – This stream segment was previously
             on State’s 303(d) list for ammonia, and a TMDL was completed. However, the completed
             TMDL does not account for the change to the new total ammonia standard and is therefore, not
             implemented in this permit.

          d.    Colorado Mixing Zone Regulations – Pursuant to section 31.10 of The Basic Standards and
               Methodologies for Surface Water, a mixing zone determination is required for this permitting
               action. The Colorado Mixing Zone Implementation Guidance, dated April 2002, identifies the
               process for determining the meaningful limit on the area impacted by a discharge to surface
               water where standards may be exceeded (i.e., regulatory mixing zone). This guidance document
               provides for certain exclusions from further analysis under the regulation, based on site-specific
               conditions.

               The guidance document provides a mandatory, stepwise decision-making process for
               determining if the permit limits will not be affected by this regulation. Exclusion, based on
               Extreme Mixing Ratios, may be granted if the ratio of the design flow to the chronic low flow
               (30E3) is greater than 2:1. Since the discharge is to a zero low flow stream, the permittee is
               eligible for an exclusion from further analysis under the regulation.

          g. Reasonable Potential Analysis - Using the assimilative capacities contained in the WQA, an
             analysis must be performed to determine whether to include the calculated assimilative
             capacities as WQBELs in the permit. This reasonable potential (RP) analysis is based on the
             Determination of the Requirement to Include Water Quality Standards-Based Limits in CDPS
             Permits Based on Reasonable Potential, dated December, 2002. This guidance document utilizes
             both quantitative and qualitative approaches to establish RP depending on the amount of
             available data.

               A qualitative determination of RP may be made where ancillary and/or additional treatment
               technologies are employed to reduce the concentrations of certain pollutants. However, absent
               limitations, a facility may no longer continue such pollutant reductions and therefore the
               discharge would result in RP. For this reason, the Permits Section may make a qualitative
               determination that absent effluent limitations, there is RP for these pollutants to cause or
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 7, Permit No. CO-0043010

              contribute to exceedances of water quality standards. This may apply to E. coli, ammonia, total
              residual chlorine, nitrate, or total inorganic nitrogen.

              To conduct a quantitative RP analysis, a minimum of 10 effluent data points from the previous 5
              years, should be used. The equations set out in the guidance for normal and lognormal
              distribution, where applicable, are used to calculate the maximum estimated pollutant
              concentration (MEPC). For data sets with non-detect values, and where at least 30% of the data
              set was greater than the detection level, MDLWIN software is used consistent with Division
              guidance to generate the mean and standard deviation, which are then used to establish the
              multipliers used to calculate the MEPC. If the MDLWIN program cannot be used the Division’s
              guidance prescribes the use of best professional judgment.

              For some parameters, recent effluent data or an appropriate number of data points may not be
              available, or collected data may be in the wrong form (dissolved vs total) and therefore may not
              be available for use in conducting a RP analysis. Thus, consistent with Division procedures,
              monitoring will be required to collect samples to support a RP analysis and subsequent decisions
              for a numeric limit. Samples requirements will be listed at a MON outfall, and all results shall
              be reported on a DMR. A compliance schedule may be added to the permit for the request of a
              RP analysis once the appropriate data have been collected.
              For other parameters, effluent data may be available to conduct a quantitative analysis, and
              therefore a RP analysis will be conducted to determine if there is RP for the effluent discharge to
              cause or contribute to exceedances of ambient water quality standards. The guidance specifies
              that if the MEPC exceeds the maximum allowable pollutant concentration (MAPC), limits must
              be established and where the MEPC is greater than half the MAPC (but less than the MAPC),
              monitoring must be established. Table VI-1 contains the calculated MEPC compared to the
              corresponding MAPC, and the results of the reasonable potential evaluation, for those
              parameters that met the data requirements. The RP determination is discussed for each
              parameter in the text below.

          Table VI-1 – Reasonable Potential Analysis
                                                 30-Day Average               7-Day Ave or Daily Max
                     Parameter                    WQBEL Reasonable                 WQBEL Reasonable
                                         MEPC                             MEPC
                                                  (MAPC) Potential                 (MAPC) Potential
           As, TR (µg/l)                  1.3        50      No (Qual)      1.3       NA         NA
           Cd, Dis (µg/l)                 0.1       4.4      No (Qual)      0.1       12      No (Qual)
           Cr+3, Dis (µg/l)               NA        157        MON1         NA       1211       MON1
           Cr+6, Dis (µg/l)               50         11      Yes (Qual)     50        16      Yes (Qual)
           Cu, Dis (µg/l)                 236        20         Yes         236       32         Yes
           CN, Free (µg/l)                                                  20        NA         NA
           Fe, TR (µg/l)                  1005     1000         Yes
           Pb, Dis (µg/l)                  4.2      6.7      No (Qual)      4.2      173      No (Qual)
           Mn, Dis (µg/l)                  43      2241         No          43       4057        No
           Hg, Tot (µg/l)                  0.2     0.01      Yes (Qual)     0.2       NA         NA
           Ni, Dis (µg/l)                  554     113          Yes         554      1020      Monitor
           Se, Dis (µg/l)                   8       4.6      Yes (Qual)      8        18      Yes (Qual)
           Ag, Dis (µg/l)                  0.2      1.6      No (Qual)      0.2       9.9     No (Qual)
           Zn, Dis (µg/l)                  316     258          Yes         316      256         Yes
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 8, Permit No. CO-0043010

       3. Pollutants Limited by Water Quality Standards

          pH – This parameter is limited by the water quality standards of 6.5-9.0 s.u., as this range is
          more stringent than the range specified under the Regulations for Effluent Limitations. This
          limitation is the same as that contained in the previous permit and is imposed effective immediately.

          E. Coli –The limitation for E. Coli is based upon the WQBEL as described in Appendix A. A
          qualitative determination of RP has been made as the treatment facility has been designed to treat
          specifically for this parameter.

          The E. coli 30-day and 7-day geometric means calculated as proposed limits are more stringent than
          previous comparable permit limits (e.g., 0.32 times the fecal coliform limits). However, self-
          monitoring data previously summarized in Table V-1 show that these proposed limits can be met and
          thus they are imposed as permit limits effective immediately.

          Total Residual Chlorine - The limitation for total residual chlorine is based upon the WQBEL as
          described in Appendix A. A qualitative determination of RP has been made as the treatment facility
          uses TRC for disinfection.

          The calculated WQBELs for total residual chlorine are more stringent than the previous permit
          limits. An evaluation of the self-monitoring results previously summarized in Table V-1 for total
          residual chlorine indicates that the facility may not be able to consistently meet the WQBELs. For
          this reason, interim limitations will be established at the current permit limitations, and a compliance
          schedule as discussed later in this rationale, will be set forth to provide the facility with time to meet
          the WQBELs

          Ammonia - The limitation for ammonia is based upon the WQBEL as described in Appendix A. A
          qualitative determination of RP has been made as the treatment facility has been designed to treat
          specifically for this parameter.

          Previous monitoring as shown in Table V-1 show that this limitation can be met and is therefore
          effective immediately.

          Total Recoverable Arsenic – The RP analysis for total recoverable arsenic was based upon the
          WQBEL as calculated in Appendix A. With the available data the minimum requirements of the
          MDLWIN program were not met (30% above detect). However, the maximum of the few ‘hits’
          above detect was found to be considerably lower than the WQBEL, therefore, based on a qualitative
          analysis a determination of no RP was made.

          Dissolved Cadmium – The RP analysis for dissolved cadmium was based upon the WQBEL as
          calculated in Appendix A. With the available data the minimum requirements of the MDLWIN
          program were not met (30% above detect). However, the maximum of the few ‘hits’ above detect
          was found to be considerably lower than the WQBEL. Therefore, based on a qualitative analysis a
          determination of no RP was made.

          Dissolved Hexavalent Chromium – The RP analysis for dissolved hexavalent chromium was based
          upon the WQBEL as described in Appendix A. With the available data (note only ‘total’ chromium
          data were available) the minimum requirements of the MDLWIN program were not met (30% above
          detect) to determine the appropriate statistics to determine the MEPC. However, based on a
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 9, Permit No. CO-0043010

          qualitative approach and the maximum of the few ‘hits’ above detect was found to be significantly
          larger than the WQBEL and a determination of RP was made. Therefore, a limit (30-day average
          and daily maximum) has been added to the permit. Based upon previous monitoring, the permittee
          may not be able to consistently meet this limitation and a compliance schedule has been added to the
          permit to give the permittee time to meet this limitation.

          Dissolved Copper – The RP analysis for dissolved copper was based upon the WQBEL as described
          in Appendix A. With the available data log-normal distribution was used to determine the
          appropriate statistics to determine the MEPC. The MEPC was greater than the MAPC and therefore
          limitations are required. Therefore, a numeric limit (30-day average and daily maximum)
          requirement has been added to the permit. Based upon previous monitoring, the permittee may not
          be able to consistently meet this limitation and a compliance schedule has been added to the permit
          to give the permittee time to meet this limitation.

          Cyanide -The RP analysis for cyanide was based upon the WQBEL as described in Appendix A.
          There were not enough data to complete a quantitative analysis. However, a qualitative
          determination of RP was made based on the few available datums that were well above the MAPC.
          Therefore, a numeric limit (daily maximum) requirement has been added to the permit. Based upon
          previous monitoring, the permittee may not be able to consistently meet this limitation and a
          compliance schedule has been added to the permit to give the permittee time to meet this limitation.

          Total Recoverable Iron - The RP analysis for total recoverable iron was based upon the WQBEL as
          described in Appendix A. With the available data (note only dissolved iron data were available) the
          MDLWIN program was used to determine the appropriate statistics to determine the MEPC. The
          MEPC was greater than the MAPC and therefore limitations are required. Therefore, a numeric
          limit (30-day average and daily maximum) requirement has been added to the permit. Previous
          monitoring as shown in Table V-1 show that this limitation can be met and is therefore effective
          immediately.

          Dissolved Lead - The RP analysis for dissolved lead was based upon the WQBEL as calculated in
          Appendix A. With the available data the minimum requirements of the MDLWIN program were not
          met (30% above detect). However, the maximum of the few ‘hits’ above detect was found to be
          considerably lower than the WQBEL, therefore, based on a qualitative analysis a determination of
          no RP was made.

          Dissolved Manganese - The RP analysis for dissolved manganese was based upon the WQBEL as
          calculated in Appendix A. With the available data the log-normal distribution was used to determine
          the appropriate statistics to determine the MEPC. The MEPC was less than half of the MAPC and
          therefore limitations are not necessary at this time.

          Total Mercury - The RP analysis for total mercury was based upon the WQBEL as calculated in
          Appendix A. With the available data (note only dissolved mercury data were available) the
          minimum requirements of the MDLWIN program were not met (30% above detect). There were a
          couple of ‘hits’ at the MDL (0.2 ug/l, which greater than the WQBEL) and a qualitative
          determination of RP has been made. Therefore, a numeric limit (30-day average) requirement has
          been added to the permit.

          Dissolved Nickel - The RP analysis for dissolved nickel was based upon the WQBEL as described in
          Appendix A. With the available data the MDLWIN program was used to determine the appropriate
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 10, Permit No. CO-0043010

          statistics to determine the MEPC. The MEPC was greater than the MAPC and therefore limitations
          are required. Therefore, a numeric limit (30-day average and daily maximum) requirement has been
          added to the permit. Previous monitoring as shown in Table V-1 show that this limitation can be
          met and is therefore effective immediately.

          Dissolved Selenium - The RP analysis for dissolved selenium was based upon the WQBEL as
          calculated in Appendix A. With the available data (note this was ‘total’ selenium data) the minimum
          requirements of the MDLWIN program were not met (30% above detect). However, the maximum
          of the few ‘hits’ was found to be greater than the WQBEL and based on a qualitative analysis a
          determination of RP was made. Therefore, a numeric limit (30-day average and daily maximum)
          requirement has been added to the permit. Based upon previous monitoring, the permittee may not
          be able to consistently meet this limitation and a compliance schedule has been added to the permit
          to give the permittee time to meet this limitation.

          Dissolved Silver - The RP analysis for dissolved silver was based upon the WQBEL as calculated in
          Appendix A. With the available data the minimum requirements of the MDLWIN program were not
          met (30% above detect). However, the maximum of the few ‘hits’ that were above detect was found
          to be considerably lower than the WQBEL. Therefore, based on a qualitative analysis a
          determination of no RP was made.

          Dissolved Zinc - The RP analysis for dissolved zinc was based upon the WQBEL as described in
          Appendix A. With the available data the log-normal distribution was used to determine the
          appropriate statistics to determine the MEPC. The MEPC was greater than the MAPC and therefore
          limitations are required. Therefore a, numeric (30-day average and daily maximum) requirement has
          been added to the permit. Previous monitoring as shown in Table V-1 show that this limitation can
          be met and is therefore effective immediately.

          Temperature- New temperature standards have been approved and will be incorporated into each
          basin’s regulation as they come up for review. Interim temperature standards have already been
          incorporated into the South Platte River Basin, and are applied as a MWAT of 30 degrees C, with no
          daily maximum standard. The MWAT is the maximum weekly average temperature, as determined
          by a seven day rolling average, using at least 3 equally spaced temperature readings in a 24-hour day
          (at least every 8 hours for a total of at least 21 data points).

          The daily maximum is defined as the maximum 2 hour average, with a minimum of 12 equally
          spaced measurements throughout the day. However, the discharge is to effluent dependent waters
          and, therefore, in accordance with Regulation 31.14(14), no temperature limitations are required.

          Organics – The effluent is not expected or known to contain organic chemicals, and therefore,
          limitations for organic chemicals are not needed in this permit.

       4. Metal Speciation

          For standards based upon the total and total recoverable methods of analysis, the limitations are
          based upon the same method as the standard.

          For total recoverable arsenic, the analysis may be performed using a graphite furnace. This method
          may produce erroneous results and may not be available to the permittee. Therefore, the total
          method of analysis will be specified instead of the total recoverable method.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 11, Permit No. CO-0043010


          Until recently there has not been an effective method for monitoring low-level total mercury
          concentrations in either the receiving stream or the facility effluent. Monitoring for total mercury
          has been accomplished as part of past permit conditions and analytical results have all been found at
          less than detectable levels. However, detection levels only as low as 0.2 ug/l have been achieved,
          versus a total mercury limit of 0.011 ug/l. To ensure that adequate data are gathered to show
          compliance with the limitation and consistent with Division initiatives for mercury, quarterly
          effluent monitoring for total mercury at low-level detection methods will be required by the permit.

          For metals with aquatic life-based dissolved standards, effluent limits and monitoring requirements
          are typically based upon the potentially dissolved method of analysis, as required under Regulation
          31, Basic Standards and Methodologies for Surface Water. Thus, effluent limits and/or monitoring
          requirements for chromium, copper, lead, selenium and zinc will be prescribed as the “potentially
          dissolved” form.

          For cyanide, the acute standard is in the form of "free" cyanide concentrations. However, there is no
          analytical procedure for measuring the concentration of free cyanide in a complex effluent.
          Therefore, ASTM (American Society for Testing and Materials) analytical procedure D2036-81,
          Method C, will be used to measure weak acid dissociable cyanide in the effluent. This analytical
          procedure will detect free cyanide plus those forms of complex cyanide that are most readily
          converted to free cyanide.

          For total recoverable trivalent chromium, the regulations indicate that standard applies to the total of
          both the trivalent and hexavalent forms. Therefore, monitoring for total recoverable chromium will
          be required.

          For hexavalent chromium, samples must be unacidified. Accordingly, dissolved concentrations will
          be measured rather than potentially dissolved concentrations.


       5. Whole Effluent Toxicity (WET) Testing - For this facility, chronic WET testing is required. (See
          Part I.A.1. of the permit).

          a. Purpose of WET Testing – The Water Quality Control Division has established the use of WET
             testing as a method for identifying and controlling toxic discharges from wastewater treatment
             facilities. WET testing is being utilized as a means to ensure that there are no discharges of
             pollutants "in amounts, concentrations or combinations which are harmful to the beneficial uses
             or toxic to humans, animals, plants, or aquatic life" as required by Section 31.11 (1) of the Basic
             Standards and Methodologies for Surface Waters.

          b. In-Stream Waste Concentration (IWC) – Where monitoring or limitations for WET are deemed
             appropriate by the Division, chronic in-stream dilution as represented by the chronic IWC is
             critical in determining whether acute or chronic conditions shall apply. According to the
             Colorado Water Quality Control Division Biomonitoring Guidance Document, dated July 1,
             1993, for those discharges where the chronic IWC is greater than 9.1% and the receiving stream
             has a Class 1 Aquatic Life use or Class 2 Aquatic Life use with all of the appropriate aquatic life
             numeric standards, chronic conditions apply. Where the chronic IWC is less than or equal to 9.1,
             or the stream is not classified as described above, acute conditions apply. The chronic IWC is
             determined using the following equation:
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 12, Permit No. CO-0043010


              IWC = [Facility Flow (FF)/(Stream Chronic Low Flow (annual) + FF)] X 100%

              The flows and corresponding IWC for the appropriate discharge point are:

                                                                     Facility Design
                         Discharge        Chronic Low Flow,
                                                                          Flow,             IWC, (%)
                           Point             30E3, (cfs)
                                                                           (cfs)

                            001A                    0                      3.4                100%

              The IWC for this permit is 100 %, which represents a wastewater concentration of 100 %
              effluent to 0 % receiving stream.

              Chronic WET Limit –This facility is expected to discharge metals at concentrations that have
              been found to have toxic effects to fish and other aquatic life. Further, this facility discharges
              both chlorine and ammonia, both of which can cause toxicity at low concentrations. On this
              basis, the Division believes there is reasonable potential for the discharge to interfere with
              attainment of applicable water quality classifications or standards. Because of this condition, the
              chronic limit has been incorporated into the permit and becomes effective August 1, 2012. Prior
              to the chronic limit becoming effective, the permittee is required to conduct routine monitoring.
               The results of the testing are to be reported on Division approved forms. The permittee will be
              required to conduct two types of statistical derivations on the data, one looking for any
              statistically significant difference in toxicity between the control and the effluent concentrations
              and the second identifying the IC25, should one exist. Both sets of calculations will look at the
              full range of toxicity (lethality, growth and reproduction). If a level of chronic toxicity occurs,
              such that there is a statistically significant difference in the lethality (at the 95% confidence
              level) between the control and any effluent concentration less than or equal to the In-stream
              Waste Concentration (IWC) and if the lethality IC25 < the IWC, the permittee will be required to
              follow the automatic compliance schedule identified in Part I.A.7. of the permit, if the observed
              toxicity is due to organism lethality. Once the chronic lethality limitation becomes effective,
              only exceedance of the limitation specified in Part I.A.5. will trigger the requirement for
              conducting the automatic compliance schedule identified in Part I.A.7. of the permit. Prior to
              and after the limitation becomes effective, if the toxicity is due to differences in the growth of
              the fathead minnows or the reproduction of the Ceriodaphnia, no immediate action on the part of
              the permittee will be required. However, this incident, along with other WET data, will be
              evaluated by the Division and may form the basis for reopening the permit and including
              additional WET limits or other requirements.

          c. General Information – The permittee should read the WET testing section of Part I.A.5. of the
             permit carefully. The permit outlines the test requirements and the required follow-up actions
             the permittee must take to resolve a toxicity incident. The permittee should read, along with the
             documents listed in Part I.A.7. of the permit, the Colorado Water Quality Control Division
             Biomonitoring Guidance Document, dated July 1, 1993. This document outlines the criteria
             used by the Division in such areas as granting relief from WET testing, modifying test methods
             and changing test species. The permittee should be aware that some of the conditions outlined
             above may be subject to change if the facility experiences a change in discharge, as outlined in
             Part II.A.2. of the permit. Such changes shall be reported to the Division immediately.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 13, Permit No. CO-0043010


       7. Stormwater – Stormwater discharges from wastewater treatment facilities with a design flow of 1.0
          MGD or more, or that are required to have an approved pretreatment program, are required to be
          covered by a CDPS Stormwater Discharge Permit Associated with Light Industry Permit or a
          Stormwater No Exposure Certification in order to be discharged to Waters of the State.

          Division records indicate that Superior Metropolitan District No 1 applied for and obtained coverage
          under a general permit for stormwater discharges associated with light industries for the Superior
          Metropolitan District No. 1 WWTF. The CDPS certification number is COR-011159. Stormwater
          permitting issues for this facility will be handled separately by the Division’s Stormwater Unit.

       8. Economic Reasonableness Evaluation – Section 25-8-503(8) of the revised (June 1985) Colorado
          Water Quality Control Act required the Division to "determine whether or not any or all of the water
          quality standard based effluent limitations are reasonably related to the economic, environmental,
          public health and energy impacts to the public and affected persons, and are in furtherance of the
          policies set forth in sections 25-8-102 and 25-8-104."

          The Colorado Discharge Permit System Regulations, Regulation No. 61, further define this
          requirement under 61.11 and state: "Where economic, environmental, public health and energy
          impacts to the public and affected persons have been considered in the classifications and standards
          setting process, permits written to meet the standards may be presumed to have taken into
          consideration economic factors unless:

          a. A new permit is issued where the discharge was not in existence at the time of the classification
             and standards rulemaking, or

          b. In the case of a continuing discharge, additional information or factors have emerged that were
             not anticipated or considered at the time of the classification and standards rulemaking."

          The evaluation for this permit shows that the Water Quality Control Commission, during their
          proceedings to adopt the Classifications and Numeric Standards for South Platte River Basin,
          Laramie River Basin, Republican River Basin, Smoky Hill River Basin, considered economic
          reasonableness.

          Furthermore, this is not a new discharger and no new information has been presented regarding the
          classifications and standards. Therefore, the water quality standard-based effluent limitations of this
          permit are determined to be reasonably related to the economic, environmental, public health and
          energy impacts to the public and affected persons and are in furtherance of the policies set forth in
          Sections 25-8-102 and 104. If the permittee disagrees with this finding, pursuant to 61.11(b)(ii) of
          the Colorado Discharge Permit System Regulations, the permittee should submit all pertinent
          information to the Division during the public notice period.

   B. Monitoring

       1. Effluent Monitoring – Effluent monitoring will be required as shown in the permit document. Refer
          to the permit for locations of monitoring points. Monitoring requirements have been established in
          accordance with the frequencies and sample types set forth in the Baseline Monitoring Frequency,
          Sample Type, and Reduced Monitoring Frequency Policy for Industrial and Domestic Wastewater
          Treatment Facilities. This policy includes the methods for reduced monitoring frequencies based
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 14, Permit No. CO-0043010

          upon facility compliance as well as for considerations given in exchange for instream monitoring
          programs initiated by the permittee. Table VI-2 shows the results of the reduced monitoring
          frequency analysis for Outfall 001A, based upon compliance with the previous permit.

          Note that for those parameters with violations (shown in Table V-1), reducing monitoring frequency
          is not applicable, this is the case for BOD.

          The quarterly monitoring frequency for mercury is imposed consistent with the Divisions’ recent
          initiative to include quarterly monitoring for mercury because of the changes in analytical procedure
          that will allow total mercury to be quantified at much lower concentrations.

Table VI-2 – Monitoring Reduction Evaluation


          2. Pretreatment Program - The permittee is not required to maintain a formal pretreatment
          program. However, conditions for industrial waste management conditions will be included in the
          permit.

   C. Reporting

       1. Discharge Monitoring Report – The Superior Metropolitan District #1 must submit a Discharge
          Monitoring Report (DMR) on a monthly basis to the Division. These reports should contain the
          required summarization of the test results for all parameters and monitoring frequencies shown in
          Part I.B of the permit. See the permit, Part I.B, C and D for details on such submission.

       2. Annual Biosolids Report – The permittee will be required to submit an annual Biosolids Report
          which includes the results of all biosolids monitoring performed for the year and information on
          management practices, land application sites, site restrictions and certifications. The Annual
          Biosolids Report is due by February 19th of the following year. Refer to Part I, Section D.3 of the
          permit.

       3. Special Reports – Special reports are required in the event of an upset, bypass, or other
          noncompliance. Please refer to Part II.A. of the permit for reporting requirements. As above,
          submittal of these reports to the US Environmental Protection Agency Region VIII is no longer
          required.

   D. Additional Terms and Conditions

       1. Signatory Requirements – Signatory requirements for reports and submittals are discussed in Part I,
          Section D.1 of the permit.

       2. Compliance Schedules – The following compliance schedules are included in the permit. See Part
          I.A.8 of the permit for more information.

              a. Activities to Meet Total Residual Chlorine Final Limits

              b. Activities to Meet Dissolved Hexavalent Chromium, Potentially Dissolved Copper, Weak
                 Acid Dissociable Cyanide, Total Mercury and Potentially Dissolved Selenium, WET Chronic
                 Final Limits
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 15, Permit No. CO-0043010


           All information and written reports required by the following compliance schedules should be
           directed to the Permits Section for final review unless otherwise stated.

VII.    REFERENCES

   A. Colorado Department of Public Health and Environment, Water Quality Control Division Files.

   B. “Design Criteria Considered in the Review of Wastewater Treatment Facilities”, Policy 96-1, Colorado
        Department of Public Health and Environment, Water Quality Control Commission, April 2007.

   C. Basic Standards and Methodologies for Surface Water, Regulation No. 31, Colorado Department of
        Public Health and Environment, Water Quality Control Commission, effective May 31, 2008.

   D. Classifications and Numeric Standards for South Platte River Basin, Laramie River Basin, Republican
        River Basin, Smoky Hill River Basin, Regulation No. 38, Colorado Department of Public Health and
        Environment, Water Quality Control Commission, effective March 30, 2009.

   E. Colorado Discharge Permit System Regulations, Regulation No. 61, Colorado Department of Public
        Health and Environment, Water Quality Control Commission, effective April 30, 2008.

   F. Regulations for Effluent Limitations, Regulation No. 62, Colorado Department of Public Health and
        Environment, Water Quality Control Commission, effective March 30, 2008.

   G. Pretreatment Regulations, Regulation No. 63, Colorado Department of Public Health and Environment,
        Water Quality Control Commission, effective April 01, 2007.

   H. Biosolids Regulation, Regulation No. 64, Colorado Department of Public Health and Environment,
        Water Quality Control Commission, effective March 01, 2008.

   I.   Colorado River Salinity Standards, Regulation No. 39, Colorado Department of Public Health and
        Environment, Water Quality Control Commission, effective August 30, 1997.

  J.    Section 303(d) List of Water Quality Limited Segments Requiring TMDLs, Regulation No 93, Colorado
        Department of Public Health and Environment, Water Quality Control Commission, effective April 30,
        2008.

  K. Colorado’s Monitoring and Evaluation List, Regulation No 94, Colorado Department of Public Health
        and Environment, Water Quality Control Commission, effective April 30, 2008.

   L.   Antidegradation Significance Determination for New or Increased Water Quality Impacts, Procedural
        Guidance, Colorado Department of Public Health and Environment, Water Quality Control Division,
        effective December 2001.

   M. Memorandum Re: First Update to (Antidegradation) Guidance Version 1.0, Colorado Department of
        Public Health and Environment, Water Quality Control Division, effective April 23, 2002.
COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 16, Permit No. CO-0043010

   N. Determination of the Requirement to Include Water Quality Standards-Based Limits in CDPS Permits
       Based on Reasonable Potential, Colorado Department of Public Health and Environment, Water Quality
       Control Division, effective December2002.

   O. The Colorado Mixing Zone Implementation Guidance, Colorado Department of Public Health and
       Environment, Water Quality Control Division, effective April 2002.

  P.   Baseline Monitoring Frequency, Sample Type, and Reduced Monitoring Frequency Policy for Domestic
       and Industrial Wastewater Treatment Facilities, Water Quality Control Division Policy WQP-20, May 1,
       2007.

  Q. Implementing Narrative Standards in Discharge Permits for the Protection of Irrigated Crops, Water
       Quality Control Division Policy WQP-24, March 10, 2008.

   R. Procedural Regulations for Site Applications for Domestic Wastewater Treatment Works, Regulation
       No. 22, Colorado Department of Public Health and Environment, Water Quality Control Commission,
       effective June 30, 2004.

   S. Regulation Controlling discharges to Storm Sewers, Regulation No. 65, Colorado Department of Public
       Health and Environment, Water Quality Control Commission, effective May 30, 2008.

   T. Water and Wastewater Facility Operator Certification Requirements, Regulation No. 100, Colorado
       Department of Public Health and Environment, Water Quality Control Commission, effective April 30,
       2006.

                                                                                              Holly Brown
                                                                                             April 17, 2009

VIII. PUBLIC NOTICE COMMENTS