Siem Reap on the Path to Becoming a Healthier and Cleaner Tourist City

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“The new sewerage system will be extremely helpful for my family and community, as well as for the tourists, as we are a tourist city,” said Mr. Oeng Bun Ey, a resident of Siem Reap City who was recently connected to the $25.5 million World Bank-funded and CDIA-assisted wastewater collection network development project in Cambodia.  

“In the past, the combined system [for drainage and wastewater] could not accommodate the influx of water during heavy rainfall, so rain and sewage would flood our streets, making our environment unsanitary,” Mr. Oeng added.  

Sanitation Challenges in Siem Reap 

Siem Reap in Cambodia is the gateway to the UNESCO World Heritage Site of Angkor. Its urban population of over 120,000, which can swell to more than 200,000 during the tourist season, requires adequate sanitation infrastructure and services to promote public health and a cleaner environment, which are crucial for tourism, the city’s economic lifeblood. 

Before 2005, the city’s wastewater infrastructure consisted of an old combined system, which served only a small portion of the town center. The majority of the city used onsite sanitation facilities, out of which, only 9% of the fecal waste was collected and properly treated, leading to pollution and public health hazards. The recurring floods in Siem Reap further damaged the system and caused pollution from the overflow.  


In 2007, the city started developing a dedicated wastewater system to address its sanitation issues. Funding from the Asian Development Bank (ADB) has facilitated the construction of an interceptor main trunk, a pumping station, and a wastewater treatment plant (WWTP). The French and Korean governments later helped expand the catchment area and the WWTP’s capacity.  

While a trunk sewer network was in place along some of the main roads of Siem Reap, secondary and tertiary networks were unavailable to allow for household connections, leading to a low sewer connection and inflows to the WWTP. Some sections of the sewer also failed, resulting in even less wastewater inflow into the WWTP. In 2018, ADB funded the rehabilitation of 3.7 km of interceptor main trunk along Sivutha Boulevard.  

Complementing the ADB investment, the Government of Cambodia requested support from the World Bank (WB) to develop secondary and tertiary sewer lines under the Siem Reap Wastewater Collection Network Development Project to increase the number of household connections and convey sewage to the WWTP. The $25.5 million investment will also help separate the collection of wastewater from the surface runoff, leading to a reduction in fecal contamination in the event of flooding.  

To facilitate the WB’s support, the Ministry of Public Works and Transport (MPWT) sought CDIA’s assistance in 2018 to undertake a project preparation study, including a wastewater development plan, a feasibility study report for a sewerage system, engineering designs for a portion of the investment, and the associated due diligence outputs necessary for project loan appraisal. 

“CDIA’s support has improved project readiness,” said Phyrum Kov, Project Officer from WB. “For us, that was very important. It was one of our readiness filters to show to our Board that the project was ready for implementation. We were able to fast-track project preparation because of CDIA,” he added.  

Project Status 

CDIA’s monitoring team conducted a tracer study (to track the progress of its interventions) in October 2023, from which they found out that most subprojects identified in the CDIA study were taken forward to implementation.  

A total of 16.8 km of sewer lines have already been installed, out of the 22 km of secondary and tertiary lines planned in the east trunk sewer, west trunk sewer, and interceptor sewer combined catchment areas.  

According to the CDIA study, the west trunk sewer had a total network length of 40 km. It was later reduced to 22 km as half of the catchment area was excluded from the WB loan and incorporated into the $200 million central government project in Siem Reap covering roads, sewerage, and drainage. Savings from the scope reduction were reallocated by WB to the east trunk sewer catchment area.  

Based on CDIA’s recommendation, the less intrusive pipe jacking was used to lay the underground pipes, particularly in highly populated areas.  

Mrs. Diet Sy Ne, a boutique restaurant owner in Sangkat Sala Kamruek, Siem Reap City, expressed how the project has considered the welfare of business establishments like hers in the construction sites.  

“We are happy with the method used because the workers did not have to excavate a substantial portion of the road, which, otherwise, would have disrupted our business and made it inconvenient for our customers to come to our shop,” she said.  

“We look forward to using the new system to have a much better environment, free from flood and pollution especially during the rainy season, and with improved road conditions that will hopefully bring in more customers,” she added. 

Meanwhile, rehabilitation works in three pumping stations at Wat Chork, Sala Kanseang, and Chunlouk are ongoing, as well as the rehabilitation of the sewage treatment plant, including wastewater inlet and drying beds, improvement of dry sludge storage zone, and road rehabilitation.  

Although the work is not yet fully completed, stakeholders in Siem Reap have expressed their appreciation of CDIA’s support in preparing the project for funding by the World Bank. 

“CDIA’s expansion of support to include preliminary engineering design, safeguards due diligence, and preparation of bidding documents are key to the success of its intervention in Siem Reap,” said Mr. Lun Heng, Project Manager from MPWT. 

“Broadening the CDIA support has resulted in early loan approval by the World Bank and it significantly reduced the time gap between project preparation and actual project implementation,” he added. 




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