I-DEV0393: Deviation from the Monitoring Plan regarding alternative sludge final use and indirect monitoring; and Chemical Oxygen Demand monitoring frequency

1) This section of the deviation regards the parameter “sludge generated by the wastewater treatment” in the revised Monitoring Plan (approved on 19/12/2009), and comprises two issues:

i) Alternative final use:

The revised Monitoring Plan states that the sludge generated in the tridecanter, at both facilities, would be dried by natural gas/oil boiler’s combustion gases and burned in special boilers.

However, the design and construction of the sludge boilers took more time than the estimated at the time of writing the PDD due to technical inexperience within Argentina about drying and combusting this type of sludge. For this reason, a Request for Deviation for the first verification period was submitted on 16 September 2008. The request asked the EB to approve an alternative final use of the sludge until the operation start dates of the boilers at each facility that was estimated sometime during March 2009 at that time.

The alternative final use of the sludge during that period was as pigs’ food due to its important protein content. Thus, the dried sludge was collected in containers and delivered to pigs farms in the surroundings of La China and Cahuané facilities.

The EB approved this request for deviation until March 2009 (http://cdm.unfccc.int/Projects/deviations/71865). However, the operation start dates of the sludge boilers were delayed beyond March 2009 due to construction problems mainly related to the delay in the delivery of the boilers’ tubes and water pumps. Letters from the boiler provider explaining the reasons of the delays are available. In addition, after the boilers’ installation a period of operation adjustment was required at each facility. Hence, the boilers only started to operate as per the required normal operating regime (burning the total amount of sludge generated by the wastewater treatment) on May 21st and August 13th 2009 at Cahuané and La China facilities respectively. Until these dates, the alternative final use of the sludge remained the same as stated above i.e. the sludge was dried and delivered almost every working day to pig farms in the surroundings of the project facilities to feed their pigs. Letters from farmers confirming they received the sludge and used it daily to feed their pigs were obtained. Then, during this period, there was not anaerobic accumulation or anaerobic final disposal of sludge. All the sludge transported to the pig farms was weighed in the weighbridge before leaving the facilities in accordance with the revised Monitoring Plan.

Therefore, this request is submitted to seek the Executive Board’s approval for an extension of the period of the deviation of the final use of the sludge until the actual operation start dates of the boilers: May 21st and August 13th 2009 at Cahuané and La China facilities respectively.

ii) Indirect measure of sludge:

This issue concerning the measurement of the sludge produced covers the period since the boilers started to operate (May 21st and August 13th 2009 at Cahuané and La China facilities respectively) until 31/12/2009.

The revised Monitoring Plan states that the sludge would be measured directly by weighing.

Until the boilers started to operate, all the sludge produced was transported by trucks to the pig farms. The trucks were weighed in bridge scales before they left the facilities.

The bridge scales stopped being used when the sludge boilers were installed because the boilers feed system consist of conveyor belts that continuously transport the sludge from the dryers to the boilers.

Since May 21st and August 13th 2009 at Cahuané and La China facilities respectively until 31/12/2009 indirect measurement was performed. The sludge was indirectly measured (by its volume and density) according to the applicable methodology (AMS III.I, version 4). However this is not in compliance with the revised monitoring plan.

The conveyor belt discharges the sludge from the dryer in a hopper, and then it is fed to the boiler by a screw feeder. Thus, the hopper accumulates the sludge from the dryer before it is sent to the boiler. The amount of sludge combusted in the boiler is obtained by monitoring the number of batches of sludge sent to the boiler through the hopper and multiplying it by the capacity of the hopper. This is represented in the equation below:

Sludge (kg/day) = Quantity of hoppers filled/day * Hopper volume (m3) * Sludge density (kg/m3)

The hopper volume and sludge density determinations are available at Ref. 1.

Since the first working day of January 2010 until the belt scales started to operate (April 6th and 16th 2010 at Cahuané and La China facilities respectively) and despite the operational difficulties, the Project Developer re-started weighing the sludge in the bridge scales in order to be fully in line with the Revised Monitoring Plan.

From April 6th and 16th 2010 at Cahuané and La China facilities respectively until now, direct measurements in belt scale are performed. Purchase and installation records of the belt scales are available. It is important to note that all the sludge produced during this period was burnt in the boilers, avoiding anaerobic decay (caused by anaerobic disposal) and consequently without affecting emission reductions.

Due to the above reasons, this request is submitted seek the Executive Board’s approval for the deviation from the revised Monitoring Plan regarding the indirect measurement of the amount of sludge produced during the period 21 May and 13 August 2009 (at Cahuané and La China facilities respectively) until the 31/12/2009.

2) This section of the deviation regards the monitoring frequency of the “Chemical Oxygen Demand of the wastewater at the exit of the tridecanter (CODww,tridecanter)” and “Chemical Oxygen Demand of the total wastewater at the equalizer tank (CODww,total)” parameters.

The revised Monitoring Plan states that the CODww,tridecanter and CODww,total will be determined every two working days.

However, the necessity to monitor the CODww,tridecanter was the cause for revising the Monitoring Plan and was not identified until October 2008. Therefore, until the 06/10/2008 there is no CODww,tridecanter monitoring data available. For this reason, a Request for Deviation for the first verification period (25/04/2008-31/08/2008) was submitted on 22/03/2010 asking the EB to approve a conservative estimation of the CODww,tridecanter as the maximum CODww,tridecanter monitored value for the period 01/10/08 until 31/12/09. The EB accepted this request for deviation (http://cdm.unfccc.int/Projects/deviations/99460).

Therefore, the present request for deviation is submitted to kindly ask the EB for an extension of the period of the approved deviation until the 06/10/2008.

Furthermore, during the following months some other CODww,tridecanter and CODww,total determinations were not performed with the frequency stated in the Revised Monitoring Plan. Particulary:

i) During October 2008 and December 2008 until May 2009, the CODww,tridecanter at Cahuané was measured weekly instead of every two working days. The missed values were conservatively estimated as the maximum monitored value for the period October 2008 – December 2009 in accordance with the Deviation I-DEV0310 accepted for the first monitored period;

ii) In October 2008 there were three CODww,total determinations missed at Cahuané. These values were conservatively estimated as the minimum monitored value for the period October 2008 – December 2009 in accordance with the deviation I-DEV0310 accepted for the first monitored period;

iii) In December 2008 there were two CODww,total and two CODww,tridecanter determinations missed at La China. These values were conservatively estimated as the minimum and maximum monitored values for the period Oct08-Dec09, respectively, in accordance with the deviation I-DEV0310 accepted for the first monitored period.

Therefore, this request is submitted to kindly ask the EB to extend the conservative criteria of the accepted deviation I-DEV0310 for the monitored values mentioned above.

The proposed deviation from the monitoring plan is in accordance with the approved monitoring methodology applicable to the project activity (AMS-III.I version 4).

The deviation regarding the sludge has no impact on the calculation of the emission reductions since the sludge is not disposed to decay anaerobically in a landfill without methane recovery. Thus, neither the alternative final use of the sludge nor the indirect measurement affects the project emissions according to the applicable methodology (AMS III.I, version 4).

The deviation regarding the CODww,tridecanter and CODww,total has the following impact in the ERs. According to the registered PDD, the ERs are calculated as follows:

ERy = BEy - PEy

PEy = PEy,ww,treatment + PEy,power = Qww,y * CODww,y * Bo * MCFaerobic * GWPCH4 + ECy * EFy

BEy = SUM (Qww,y,m * CODy,ww,m) * Bo * MCFlagoon * GWPCH4

ERy = SUM (Qww,y,m * CODww,y,m) * Bo * GWPCH4 * (MCFlagoon - MCFaerobic) + ECy * EFy

Being CODww,y,m,

CODww,y,m = [Qww,total,y,m * CODww,total,y,m - Qww,tridecanter,y,m * CODww,tridecanter,y,m] / [Qww,total,y,m]

Therefore, the higher the CODww,tridecanter,y,m and the lower the CODww,total,y,m, the lower is the CODww,y,m and the ERs calculated.

Consequently, in order to be conservative the highest CODww,tridecanter and lowest CODww,total values directly monitored during the period were selected to conservatively estimate the CODww,tridecanter and CODww,total data missed. These values were compared with the average and maximum of the monthly values to demonstrate the conservativeness of this approach.

The results included in the attached spreadsheet (ref 2) were:

1. La China facility:

CODww,tridecanter
a. Average of monthly averages CODww,tridecanter,m value: 14,781 mg/l
b. Maximum of monthly averages CODww,tridecanter,m value: 19,572 mg/l
c. Maximum CODww,tridecanter monitored value: 27,136 mg/l
i. Maximum CODww,tridecanter monitored value is 84% higher than the average of monthly averages value;
ii. Maximum CODww,tridecanter monitored value is 39% higher than the maximum of monthly averages
value.

CODww,total
d. Average of monthly averages CODww,total,m value: 5,214 mg/l
e. Minimum of monthly averages CODww,total,m value: 4,549 mg/l
f. Minimum CODww,total monitored value: 3,252 mg/l
i. Minimum CODww,total monitored value is 38% lower than the average of monthly averages value;
ii. Minimum CODww,total monitored value is 29% lower than the minimum of monthly averages value.


2. Cahuané facility:

CODww,tridecanter
a. Average of monthly averages CODww,tridecanter,m value: 11,597 mg/l
b. Maximum of monthly averages CODww,tridecanter,m value: 15,567 mg/l
c. Maximum CODww,tridecanter monitored value: 20,940 mg/l
i. Maximum CODww,tridecanter monitored value is 81% higher than the average of monthly averages value;
ii. Maximum CODww,tridecanter monitored value is 35% higher than the maximum of monthly averages
value.

CODww,total
d. Average of monthly averages CODww,total,m value: 7,191 mg/l
e. Minimum of monthly averages CODww,total,m value: 5,504 mg/l
f. Minimum CODww,total monitored value: 3,587 mg/l
i. Minimum CODww,total monitored value is 50% lower than the average of monthly averages value;
ii. Minimum CODww,total monitored value is 35% lower than the minimum of monthly averages value.

In conclusion, applying the above conservative criteria, the ERs calculated for the second monitoring period are 2% lower than the ERs that would be obtained applying the average of the monthly averages CODww,tridecanter,m and CODww,total,m, and 1% lower than the ERs that would be obtained applying the maximum and minimum of the monthly averages CODww,tridecanter,m and CODww,total,m, respectively.

Therefore, the present deviation implies a conservative reduction on the estimates of the emissions reductions.