1.1 Audit findings
1.1.1 The site for the pumping station is at the lowest point of the Inner Harbour
In 2010, the Civic and Municipal Affairs Bureau (hereinafter referred to as IACM) proposed the “Construction of Rainwater Pumping Station and Box-Culvert in the Northern Area of the Inner Harbour” (hereinafter referred to as Inner Harbour North Pumping Station). The surrounding area of the site selected for the construction of the Station is at the lowest elevation point in Macao, and the rainwater from the north of the Inner Harbour would tend to flow into this area due to the water flow characteristics, and thus, requires a high drainage capacity.
1.1.2 The construction of the Inner Harbour North Pumping Station
The scope of the construction mainly included the replacement of drainage pipes in the downstream district, the construction of a box-culvert and rainwater pumping station, as well as the closure of coastal rainwater outlets. As to the aforementioned works, IACM adopted a 1 in 10-year rainfall intensity recurrence interval for the drainage system, which is the common standard used in general situations according to the “Regulations on Water Supply and Drainage in Macao”. However, the Regulation stipulated that according to the result from the comparative analysis of the investment necessary for protection against flooding and the damage caused by excessive rainfall, the recurrence interval can be increased to 20 or 25 years.
1.1.3 Decision by DSSOPT to take complementary measures for the Inner Harbour North Pumping Station
After the works of the Inner Harbor North Pumping Station, Land, Public Works and Transport Bureau (hereinafter referred to as “DSSOPT”) started to plan for the construction of the “Inner Harbour Rainwater Pumping Station and Drainage Project” (hereinafter referred to as Inner Harbour South Pumping Station). Since the Inner Harbour North Pumping Station did not reach the drainage standard, DSSOPT determined that in the construction of the Inner Harbour South Pumping Station, a new bypass drainage pipe shall be built to divert rainwater from the north to the south of the Inner Harbour and expand the pumping capacity, as complementary measures.
1.1.4 The flooding incident occurred after the completion of the Inner Harbour North Pumping Station and its cause analyzed by IAM
Despite the construction of the Inner Harbour North Pumping Station was completed at the end of May 2021, a rainstorm on 1 June 2021 in Macao caused serious flooding in the northern area of the Inner Harbour. Hence, the Municipal Affairs Bureau (hereinafter referred to as “IAM”) analyzed the cause and reached the conclusion that the water levels set for starting and stopping the pump were not properly adjusted, the capacity of the old drainage pipes was insufficient and there was accumulation of rainwater coming from other areas.
1.1.5 The actual drainage capacity of the Inner Harbour North Pumping Station
As to the flooding on 1 June, in addition to the reasons pointed out by IAM, the Audit Commission also found potential insufficiencies in regard of the drainage capacity of the new system. After conducting a data analysis of the rainfall, the water level and the operation of the Inner Harbour North Pumping Station registered on that day, it was found that when the rain was not heavy and the box-culvert was not full in the early hours of the rainstorm, the rate at which the replaced drainage pipes discharged rainwater into the box-culvert was lower than the rate at which rainwater flowed to those drainage pipes.
1.1.6 The process of determining the recurrence interval for the drainage system of the Inner Harbour North Pumping Station
The Audit Commission reviewed the process of determining the rainfall intensity recurrence interval for the drainage system of the Inner Harbour North Pumping Station, and found that IACM had neither consulted DSSOPT, nor conducted the relevant studies on the selection of the drainage standard, but only submitted the construction plan to DSSOPT for approval. When IACM commissioned a company to design the drainage system, it only required that the design need to be in accordance with the current legislation of Macao. Moreover, the construction was initially expected to be completed in 2014, but it was delayed for around seven years due to the location of the Station. In this regard, about the report and justification summitted to the superior regarding the delay of the works, the Municipal Affairs Bureau (hereinafter referred to as IAM) stated that because of the lapse of time and personnel turnovers, it was unable to provide the relevant documents.
On the other hand, in accordance with the current legislation, DSSOPT has the responsibility to monitor the compliance with the norms in regard of the rainfall intensity recurrence intervals for drainage systems. However, despite being aware, through two reports in 2012 and 2017, that it was recommended the adoption of a 1 in 20-year rainfall intensity recurrence interval for the drainage system in the Inner Harbour area, DSSOPT besides not having sent these reports to IACM for their knowledge, it did not give any opinion in regard of the adoption of a 1 in 10-year rainfall intensity recurrence interval, when assessing the construction plan for the Inner Harbour North Pumping Station, even it got the approval of the Chief Executive to adopt the abovementioned recommendation of a 1 in 20-year rainfall intensity recurrence interval in March 2017.
1.2 Audit opinions
The essence of large-scale infrastructure is to satisfy the long-term needs of the community after it is put into operation. However, during the construction of the Inner Harbour North Pumping Station, IACM and DSSOPT also failed to fulfill their duties properly and lacked effective communication.
On the one hand, with regard to the construction of the Inner Harbour North Pumping Station, IACM only considered the minimum requirements set out in the current legislation, rather than concerned the current and long-term needs of city development. It should be noted that since the location of the Station is at the lowest point of the Inner Harbour, the drainage system in this area is subject to the greatest pressure. Therefore, the rainfall intensity recurrence interval should have been longer in order to withstand the rainwater from other areas. On the other hand, as a specialized technical department, DSSOPT was aware that a 1 in 20-year rainfall intensity recurrence interval should be adopted in the Inner Harbour, and this recommendation was not only suggested by consultancy companies after research, but also was approved by the Chief Executive. However, DSSOPT did not make any comment in regard of the adoption of a 1 in 10-year rainfall intensity recurrence interval when assessing the project, reflecting that it did not perform its duty properly to ensure the technical control of the project.
As for inter-departmental communication, IACM did not consult DSSOPT about the drainage standard that would address the long-term needs in the future, nor did DSSOPT convey the recommendation on the adoption of a 1 in 20-year rainfall intensity recurrence interval for the drainage system to IACM. It should be pointed out that timely and effective communication between departments is conducive to achieve the established goals. In addition, IAM was unable to provide the document in which it reported to the superior regarding the delays of the works due to the selection of site, revealing that the file management system of IAM needs to be improved.
It can be learnt from this audit that the Inner Harbour North Pumping Station was not built for the purpose of meeting demands in the long term, failing to maximize the effect of public funds invested. If departments do not plan the construction of infrastructure carefully at the beginning, and not choose the most suitable plan for long-term needs, the defects in the infrastructure will exist for a long time and will be difficult to fully repair since the infrastructure will not be easily demolished. It should be highlighted that the complementary measures taken at the Inner Harbour South Pumping Station can only alleviate the problems in the short-term, but cannot change the fact that the standard set up for the drainage system of the Inner Harbour North Pumping Station is insufficient, failing to satisfy the needs of city developments in the future.
1.3 Audit suggestions
In order to find the long-term solution to the flooding problem in Macao, the relevant departments should:
Actively perform their own responsibilities, effectively manage the entire construction process of the flood prevention infrastructure in Macao, carefully evaluate the most suitable design and construction plan and adopt it.
Strengthen the communication and coordination mechanism with a view to performing collaborative governance.
To ensure the quality of management, IAM should:
Improve the document management mechanism in order to record and keep documents and materials in an effective way.