EVALUATION OF WASTEWATER TREATMENT PLANT BIOSOLIDS STRATEGY by dgz16482

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									                                                                    EVALUATION OF
                                                            WASTEWATER TREATMENT
                                                          PLANT BIOSOLIDS STRATEGY
                                                                      ALTERNATIVES

1.        INTRODUCTION
The purpose of this memorandum is to present the BRMPAC with the detailed results from
the evaluation of the short-list of wastewater treatment plant strategy alternatives being
considered for the City of Toronto’s four wastewater treatment plants. The detailed
evaluation, using the decision-making model established for this project, provided a ranking
of the short-listed strategies for each plant.

2.        BACKGROUND AND METHODOLOGY

2.1       EVALUATION PROCESS
To summarize from previous documents provided to the BRMPAC, the decision-making
process to identify plant strategies that best met the criteria and represent the highest
value followed the following steps:

1. Identification of a long list of biosolids and residuals management options.

2. Screening of the long-list, to remove those options that are not feasible for the City.

3. Evaluation of each of the remaining management options using the decision-making
   model, to identify a short-list of management options.

4. Development of a long list of plant strategy alternatives for each of the City’s
   wastewater and water treatment plants, using the short-list of management options.

5. Evaluation of each plant strategy using the same decision-making model, to rank the
   strategies for each wastewater and water treatment plant and determine which
   strategy best meets the criteria. This document and attachments present the results of
   step 5 in the decision making process presented above for wastewater treatment
   plants.

Members of the KMK-B&V project team worked closely with City staff in developing scores
for each criterion. Scores were applied to reflect how well the strategies met the criteria,
relative to one another. A scoring system using 1 to 5 was used, where a score of 1
represents the most “risk” or “impact” and a score of 5 represents “best meets criteria”,
least “impact” or a potential benefit.

2.2       EVALUATION CRITERIA
The evaluation involved the development of technical information, costs and impacts for
each of the alternatives for criteria in eight categories, as follows:

     ♦   Technical performance considerations

     ♦   Biosolids management option considerations

     ♦   Operations considerations

     ♦   Construction considerations
Biosolids and Residuals Master Plan                                                      1
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                    EVALUATION OF
                                                            WASTEWATER TREATMENT
                                                          PLANT BIOSOLIDS STRATEGY
                                                                      ALTERNATIVES
    ♦   Community considerations

    ♦   Natural environment considerations

    ♦   Public health and safety considerations

    ♦   Financial considerations.

Each of the criteria categories and individual criteria were weighted in the evaluation
according to their importance. As presented in a previous memo, the final criteria and
weighting system were developed with input from the BRMPAC, public and City staff.

2.3       INTERPRETATION OF EVALUATION RESULTS
For each alternative, total weighted scores were calculated. The alternative receiving the
highest weighted score represented that which best met the evaluation criteria.

For some evaluations, there were more than one alternative with similar high weighted
scores, indicating that any of these would be “preferred”. To identify the most cost-
effective alternative, a “value” was calculated by excluding the cost portion from each
total score, and dividing the result by the 20-year life cycle cost. For alternatives that
score closely, this indicator was used to identify the alternative that provides the greatest
value (i.e., the most points per dollar).

2.4       SENSITIVITY ANALYSIS
A sensitivity analysis of the scores was completed to confirm the total score results. Two
different value weight scenarios were used for the sensitivity analysis, as follows:

    ♦   Technical and financial criteria category value weights were increased from
        approximately 50% of the total weight to 75% of the total weight, while
        environment/community/health category value weights were decreased from
        approximately 50% of the total weight to 25%; and,

    ♦   Environment/community/health criteria category value weights were increased from
        approximately 50% of the total weight to 75% of the total weight, while technical
        and financial category value weights were decreased from approximately 50% of
        the total weight to 25%.

The actual model weights and weights used in two scenarios for the sensitivity analysis
are presented in Table 2.1.




Biosolids and Residuals Master Plan                                                     2
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                       EVALUATION OF
                                                               WASTEWATER TREATMENT
                                                             PLANT BIOSOLIDS STRATEGY
                                                                         ALTERNATIVES
Table 2.1       Category Weights used in Sensitivity Analysis
                                           Model Weighting          Sensitivity Scenarios
            Criteria Category
                                                              Scenario 1             Scenario 2
 Technical Performance Considerations          12.6%           18.6%                   6.4%
 Considerations Related to Biosolids and
                                               11.4%           16.8%                   5.8%
 Residuals Management Option
 Operating Considerations                      10.3%           15.2%                   5.3%
 Construction Considerations                    7.6%           11.2%                   3.9%
 Community Consideration                       11.3%            5.8%                  17.0%
 Natural Environment Considerations            18.9%            9.7%                  28.4%
 Public Health Considerations                  18.9%            9.7%                  28.4%
 Financial Considerations                       8.8%            13%                     5%


2.5       DEVELOPMENT OF PLANT STRATEGY ALTERNATIVES
As described in earlier documents to the BRMPAC, the development of plant strategy
alternatives for each plant used one or more of the three short-listed biosolids management
options, and was based on the following:

     ♦   Strategy alternatives that take advantage of existing infrastructure (biosolids
         management processes) and use existing programs were considered;

     ♦   Strategy alternatives that replace existing infrastructure or programs were also
         considered;

     ♦   Any new or replacement facilities required to provide capacity for biosolids
         management will be provided by one or more of the three short-listed biosolids
         management options;

     ♦   All strategies must include a contingency management method, should one of the
         primary biosolids management methods become unavailable;

     ♦   Contingency would not involve using truck transfer of biosolids from one treatment
         plant to another within the City.; and,

     ♦   It is not considered reliable to provide contingency to landfilling by using an
         alternative landfill.

3.        ASHBRIDGES BAY TREATMENT PLANT

3.1       ALTERNATIVES EVALUATED
Table 3.1 summarizes plant strategy alternatives that were evaluated in detail.




Biosolids and Residuals Master Plan                                                           3
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                     EVALUATION OF
                                                                             WASTEWATER TREATMENT
                                                                           PLANT BIOSOLIDS STRATEGY
                                                                                       ALTERNATIVES
Table 3.1          ABTP Plant Strategy Alternatives
   ID                          Option                          Contingency                    Opportunities
   A1         Pelletization (at constructed capacity)    Fluidized bed               Beneficial use of cake on
                                                         incineration or landfill2   agricultural land (maximize
              Fluidized bed incineration (for
                                                                                     when available)1
              remaining capacity)                        Back-up incinerator
   A2         Pelletization (at constructed capacity)    Landfill2                   Beneficial use of cake on
                                                                 2                   agricultural land (maximize
              Raw material feed to industry (for         Landfill
                                                                                     when available)1
              remaining capacity)
   A3         Fluidized bed incineration for total       Back-up fluidized bed       Beneficial use of cake or pellets
              capacity                                   incinerator                 on agricultural land (maximize
                                                                                     when available)1
   A4         Raw material feed to industry (for total   Landfill2                   Beneficial use of cake or pellets
              capacity)                                                              on agricultural land (maximize
                                                                                     when available)1
Notes:
      1.   Using existing truck loading facility.
      2.   Landfill is based on long-term contract with municipal solid waste landfill.


3.2          PRESENTATION OF RESULTS
The attached tables present detailed information used in the evaluation and scoring of plant
strategy alternatives for Ashbridges Bay TP. The tables are organized as follows:

    ♦      The evaluation categories, criteria and value weights are listed on the left hand side
           of the table

    ♦      The plant strategy alternatives are shown across the top of the table

    ♦      Under each option, for each criterion, there is a comment that presents the rationale
           for the assigned score, and the assigned score (value from 1 to 5) is also presented

    ♦      The weighted total score for each criteria category is presented.

Table 3.2 presents a summary of the scoring for each alternative in each category as well
as total scores and comments indicating significant factors that helped to distinguish
among the alternatives. In addition, the “value” indicator for each alternative is presented.

A sensitivity analysis of the scores was completed to confirm the total score results. The
results of the sensitivity analysis are depicted in Figure 3.1 and indicate that regardless of
which set of weights is applied, Alternative A3 has the highest score.




Biosolids and Residuals Master Plan                                                                             4
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                          EVALUATION OF
                                                                                  WASTEWATER TREATMENT
                                                                                PLANT BIOSOLIDS STRATEGY
                                                                                            ALTERNATIVES

 Table 3.2           Summary of Plant Strategy Alternative Scoring for Ashbridges Bay TP
                                          Plant Strategy Alternative
                                  A1            A2           A3           A4
                Description Pelletization Pelletization Fluidized        Raw
                            and Fluidized and Raw           Bed        Material
                                 Bed         Material   Incineration    Feed to
                             Incineration     Feed to   Provided for   Industry
                               with Ash      Industry      100%
                            Management                    Capacity
               Contingency     Standby       Standby      Standby       Standby
                            fluidized bed    process fluidized bed      process
                             incineration equipment. incinerator       equipment
                             equipment.
Criteria Category Value                         Category Scores
                  Weight                                                                        Scoring Comments
Technical          12.6%        10.7          9.2          11.0           9.5      A3 best met criteria related to odour
Performance                                                                        emission potential and energy efficiency.
Considerations                                                                     Alternatives A1 and A2 that involve
(Biosolids                                                                         pelletization were scored lower based on
processing at                                                                      energy efficiency, since these use a large
plant)                                                                             quantity of fuel for drying.
Considerations     11.4%         9.9          7.7          10.6           5.8      A3 best met criteria related to reliability
Related to                                                                         due to year round availability and minimal
Biosolids Option                                                                   dependence on private sector contracts
Operating          10.3%         5.9          6.3           7.1           8.7      A4 best met criteria related to operations
Considerations                                                                     since it is the simplest operation (digestion
                                                                                   and dewatering only)
Construction       7.6%          4.9          5.1           5.1           5.8      A4 best met criteria related to construction
Considerations                                                                     because minimal construction is required.
                                                                                   A1 and A3 would . have long
                                                                                   implementation schedules.
Community          11.3%         9.4          7.5          10.7           7.1      A3 best met criteria related to the
Consideration                                                                      community since it has the lowest odour
                                                                                   potential and traffic.
Natural            18.9%        15.9          15.3         16.4          15.9      A3 best met criteria related to the natural
Environment                                                                        environment since it has low pollutant
Considerations                                                                     emissions and low supplemental fuel use.
Public Health      18.9%        14.5          15.1         13.9          15.1      A2 and A4 best met criteria related to
Considerations                                                                     public health and safety since raw material
                                                                                   feed to industry replace virgin materials
                                                                                   that would otherwise be used. Score for
                                                                                   A1 and A3 recognize community concern
                                                                                   related to incineration.
Financial          8.8%          5.8          6.2           6.6           4.6      A3 has the lowest operating and life cycle
Considerations                                                                     costs. A2 and A2 have low capital but
                                                                                   very high operating costs.
Total              100.0%        77            72           81            73
20 Year Life Cycle Cost         $245         $275          $245          $340
($ million)
Score (No Costs)                 71            66           75            68
Value Indicator                 0.29          0.24         0.31          0.20
Score/20 Year Cost)
(points per $million)




Biosolids and Residuals Master Plan                                                                                      5
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                                    EVALUATION OF
                                                                                            WASTEWATER TREATMENT
                                                                                          PLANT BIOSOLIDS STRATEGY
                                                                                                      ALTERNATIVES

                                                            Sensitivity Analysis
                                                                                                         Base Score
                   85                                                                                    Technical Emphasis
                                                                                                         Environment Emphasis
                   80

                   75
     Total Score




                   70

                   65

                   60

                   55

                   50
                                  A1                        A2                            A3                    A4
                                                                       Alternative



Figure 3.1                   Sensitivity Analysis Results for ABTP

4.                      HUMBER TREATMENT PLANT

4.1                     ALTERNATIVES EVALUATED
Table 4.1 summarizes the alternatives evaluated in detail.

Table 4.1                    HTP Plant Strategy Alternatives
     ID                                    Option                                    Contingency                 Opportunities
     H1                 Management at ABTP via Mid-Toronto                At ABTP                        -
                        Interceptor (MTI)
     H2                 Management at ABTP via new dedicated              At ABTP                        -
                        forcemain (direct to dewatering)
     H3                 On-site fluidized bed incineration for total      Back-up fluidized bed          -
                        capacity (with or without digestion)              incinerator at Humber TP, or
                                                                          at ABTP with liquid directed
                                                                          to MTI1
     H4                 Landfill for total capacity4,3                    At ABTP, with liquid sludge    Beneficial use on
                                                                          directed to MTI1               agricultural land (maximize
                                                                                                         when available)
     H5                 Raw material feed to industry (for total          MTI to ABTP1 or landfill2      Beneficial use on
                        capacity)                                                                        agricultural land (maximize
                                                                                                         when available)
Notes:
      1.            Biosolids processing and management capacity would need to be provided at the Ashbridges Bay TP.
      2.            Landfill is based on long-term contract with municipal solid waste landfill.
      3.            Potential for dedicated landfill can be considered.

Biosolids and Residuals Master Plan                                                                                           6
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                           EVALUATION OF
                                                                                   WASTEWATER TREATMENT
                                                                                 PLANT BIOSOLIDS STRATEGY
                                                                                             ALTERNATIVES
4.2         PRESENTATION OF RESULTS
The attached tables present detailed information used in the evaluation and scoring of
management options in the same manner as for ABTP, described in Section 3.2.

Table 4.2 presents a summary of the scoring for each alternative in each category as well
as total scores and comments indicating significant factors that helped to distinguish
among the alternatives. In addition, a “Value” indicator for each alternative is presented,
as described in Section 3.2.

Table 4.2            Summary of Plant Strategy Alternative Scoring for Humber TP
                                              Plant Strategy Alternative
                                 H1           H2           H3         H4          H5
                   Description Send to     Send to      New On-     Landfill     Raw
                               ABTP Via   ABTP via         site              Material to
                                 MTI         New        Fluidized             Industry
                                          Forcemain        Bed
                                                      Incineration
              Contingency Standby          Standby At ABTP via At ABTP At ABTP
                          process          process         MTI     via MTI     via MTI
                           equip.           equip.
Criteria Category   Value                          Category Scores
                   Weight                                                                             Scoring Comments
Technical            12.6%      10.4        11.0         11.4        9.8        10.1       H3 best met criteria related to odour
Performance                                                                                potential and impact on other plant
Considerations                                                                             processes.
(Biosolids
processing at
plant)
Considerations       11.4%      10.6        10.6         10.2        7.8        7.5        H1 and H2 best met criteria related to
Related to                                                                                 reliability and flexibility since ABTP is
Biosolids Option                                                                           available year-round and does not
                                                                                           require demolition of digesters for
                                                                                           construction.
Operating            10.3%       7.1         6.2          7.1        9.8        8.9        H4 is the simplest process to operate.
Considerations
Construction          7.6%       6.4         3.4          4.8        5.1        5.3        H1 does not require any on-site or off-
Considerations                                                                             site construction. Construction along
                                                                                           MTI route in H2 would have significant
                                                                                           impact.
Community            11.3%       9.5        10.4         10.1        7.6        7.3        H2 best met criteria related to odour
Consideration                                                                              potential, traffic and aesthetics
Natural              18.9%      16.4        16.4         16.4        11.9       15.1       H1, H2 and H3 best met criteria related
Environment                                                                                to air pollutant emissions and
Considerations                                                                             greenhouse gases.
Public Health        18.9%      13.9        13.9         13.9        15.1       12.6       H4 best met criteria related to public
Considerations                                                                             perception of risk and number of
                                                                                           potential exposure pathways
Financial             8.8%       7.8         7.0          4.6        4.6        3.8        H1 has lowest operating and life-cycle
Considerations                                                                             costs.
Total                100.0%      82          79           78          72         71
20 Year Life Cycle Cost         $73          $91        $155        $136       $261
($ million)
Score (No Costs)                 74          72           74          67         67
Value Indicator                 1.02        0.79         0.48        0.49       0.26
Score/20 Year Cost)
(points per $million)

Biosolids and Residuals Master Plan                                                                                           7
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                                     EVALUATION OF
                                                                                             WASTEWATER TREATMENT
                                                                                           PLANT BIOSOLIDS STRATEGY
                                                                                                       ALTERNATIVES

4.3                       SENSITIVITY ANALYSIS
The results of the sensitivity analysis are depicted in Figure 4.1 and indicate that
regardless which set of weights is applied, Alternative H1 has the highest scores.


                                                              Sensitivity Analysis
                   85

                                                                                                             Base Score
                   80
                                                                                                             Technical Emphasis
                                                                                                             Environment Emphasis
                   75
     Total Score




                   70


                   65


                   60


                   55


                   50
                                 H1                    H2                  H3                   H4                H5
                                                                      Alternative



Figure 4.1                       Sensitivity Analysis Results for HTP

5.                        HIGHLAND CREEK TREATMENT PLANT

5.1                       ALTERNATIVES EVALUATED
Table 5.1 summarizes the alternatives evaluated in detail.

Table 5.1                        HCTP Plant Strategy Alternatives
         ID                                   Option                                  Contingency              Opportunities
HC1                        On-site fluidized bed incineration for total   Back-up fluidized bed          -
                           capacity (with or without digestion)           incinerator
HC2                        Raw material feed to industry (for total       Landfill3                      Beneficial use on
                           capacity)                                                                     agricultural land
                                                                                                         (maximize when
                                                                                                         available)1
Notes:
             1.         Using existing truck loading facility built for raw material feed to industry.
             2.         Landfill is based on long-term contract with municipal solid waste landfill.


5.2                       PRESENTATION OF RESULTS
The attached tables present detailed information used in the evaluation and scoring of
management options in the same manner as for ABTP, described in Section 3.2.

Biosolids and Residuals Master Plan                                                                                           8
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                           EVALUATION OF
                                                                                   WASTEWATER TREATMENT
                                                                                 PLANT BIOSOLIDS STRATEGY
                                                                                             ALTERNATIVES
Table 5.2 presents a summary of the scoring for each alternative in each category as well
as total scores and comments indicating significant factors that helped to distinguish
among the alternatives. In addition, a “Value” indicator for each alternative is presented,
as described in Section 3.2.

Table 5.2           Summary of Plant Strategy Alternative Scoring for Highland Creek TP
                                                    Plant Strategy Alternative

                                                     HC1                     HC2

                             Description   Fluidized Bed Incineration    Raw Material
                                           (Replacement of Multiple     Feed to Industry
                                           Hearth with Fluidized Bed)

                            Contingency        Standby process              Landfill
                                                 equipment.

Criteria Category            Value                      Category Scores
                             Weight                                                                 Scoring Comments

Technical Performance        12.6%                   11.4                    10.1          HC1 best met criteria related to
Considerations (Biosolids                                                                  odour emission potential and energy
processing at plant)                                                                       efficiency.

Considerations Related to    11.4%                   10.3                     7.5          HC1 best met criteria related to
Biosolids Option                                                                           reliability due to year round
                                                                                           availability and low dependence on
                                                                                           private sector contracts

Operating Considerations     10.3%                    7.1                     8.9          HC2 best met criteria since it is the
                                                                                           simplest operation (digestion and
                                                                                           dewatering only)

Construction Considerations 7.6%                      5.2                     5.6          HC2 best met criteria related to
                                                                                           construction since only a truck
                                                                                           loading facility is required, HC!
                                                                                           requires a relatively long
                                                                                           implementation schedule

Community Consideration      11.3%                   10.3                     7.7          HC1 best met criteria related to the
                                                                                           community since it has the lowest
                                                                                           odour potential and traffic

Natural Environment          18.9%                   15.7                    15.1          HC1 best met criteria related to the
Considerations                                                                             natural environment since it has low
                                                                                           pollutant emissions and low
                                                                                           supplemental fuel use.

Public Health Considerations 18.9%                   15.1                    12.6          HC1 best met criteria related to
                                                                                           public perception of risk, emergency
                                                                                           situation risk and odour potential.

Financial Considerations     8.8%                     7.4                     5.1          HC1 has lowest operating and life
                                                                                           cycle costs.

Total                        100.0%                   82                         73

20 Year Life Cycle Cost                              $96                     $142
($ million)

Score (No Costs)                                      75                         68

Value Indicator                                      0.78                    0.48
Score/20 Year Cost) (points per
$million)


Biosolids and Residuals Master Plan                                                                                       9
City of Toronto
KMK 2523 040707 R
July 13, 2004
                                                                                 EVALUATION OF
                                                                         WASTEWATER TREATMENT
                                                                       PLANT BIOSOLIDS STRATEGY
                                                                                   ALTERNATIVES

5.3       SENSITIVITY ANALYSIS
The results of the sensitivity analysis are depicted in Figure 5.1 and indicate that
regardless of which set of weights is applied, Alternative HC1 has the highest scores.

                                            Sensitivity Analysis

                              85                                   Base Score
                                                                   Technical Emphasis
                              80                                   Environment Emphasis

                              75
                Total Score




                              70

                              65

                              60

                              55

                              50
                                      HC1                                HC2
                                                  Alternative


Figure 5.1         Sensitivity Analysis Results for HCTP

6.        NORTH TORONTO TREATMENT PLANT

6.1       ALTERNATIVES EVALUATED
A previous memo to the BRMPAC indicated that only one plant strategy had been
identified for North Toronto TP, and that no further evaluation was required, as follows:

     ♦   NT1: Management at the Ashbridges Bay TP via Coxwell trunk sewer. Biosolids
         management to be determined by the results of the Ashbridges Bay TP evaluation.

7.        NEXT STEPS
The final strategies will be the subject of further consultation with both the BRMPAC and
the public before being recommended for inclusion in the Biosolids and Residuals Master
Plan.




Biosolids and Residuals Master Plan                                                       10
City of Toronto
KMK 2523 040707 R
July 13, 2004

								
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