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Working closely with the Government of Nepal to reduce flooding in Patan Durbar Square 

July 2019

Patan Durbar Square is a jewel of Kathmandu. In a city starving for public space, and where many heritage areas are still under reconstruction after the 2015 earthquake, it is a beautiful and bustling expanse of Malla-era palaces, temples, and monuments in the Lalitpur municipality. Together they form one of Kathmandu’s best tourist attractions that is also heavily used by locals for festivals, rituals, and socializing.  

The area was designated a UNESCO World Heritage Site (WHS) in 1979, with most monuments dating to the 16th and 17th centuries. As the city has been built and rebuilt over the centuries, untold layers of Kathmandu’s past lie beneath the traditional red brick plaza and monument buildings. 

In the current era of Kathmandu’s history, a new threat exists to this already fragile site: flooding. As the urban area expanded and densified, infrastructure has not kept up. 

While there is an existing sewer system servicing much of the catchment, it is under capacity and drainage is lacking; so in the monsoon, the sewers become overwhelmed and Patan Durbar Square, which sits in a small depression, fills up like a polluted bathtub. 

This not only affects community health and tourism, but architects also suspect that the pooled water is slowly eroding building foundations. 

The Kathmandu Valley Wastewater Management Project (KVWWMP) implemented by Kathmandu Upatyaka Khanepani Limited’s (KUKL) Project Implementation Directive (PID) includes a small package (about 2.8 kilometers [km]) for sewer rehabilitation works in the Lalitpur core area (SN-03) that would improve capacity to accommodate additional wastewater and stormwater runoff to reduce flooding in the core heritage area in the long term. 

The project is a high priority for the Lalitpur Mayor, who has committed to financing 20% of project costs through the municipal budget, but also entails risky work in an area with fragile buildings and narrow streets, and where the most feasible technical option would cross directly through the core heritage area and main walkway through the square seen in the photos. 

While it was known during project preparation that the SN-03 project would take place in a WHS, there has been a steep learning curve in how to design such a project, even a small one that wouldn’t fundamentally alter the heritage character of the area or pose a risk to core zone monuments. We needed to properly assess the risks both to the built environment and archaeology, but had little guidance in how to do so from past projects and low capacity in Nepal to carry out the right level of due diligence. 

With the detailed designs and initial environmental examination (IEE) nearly complete, ADB determined that a Heritage Impact Assessment (HIA) was also required to comply with ADB Safeguard Policy Statement. 

However, no clear guidance existed as to what the HIA should look like for a project like this and our government counterparts and the loan consultants had never prepared one before. 

Preparation of SN-03 has been delayed by about 9 months due to preparation of the HIA, design changes in the alignment to minimize risks, and consultations (including the Department of Archaeology and heritage experts), but is nearly ready to issue the invitation for bids. 

Despite the delay, both the Project Implementation Directorate (PID) and Nepal Resident Mission (NRM) teams have learned the value of a robust process to assess heritage impacts and integrate the findings and mitigation measures into a project to improve quality and reduce the risks. 

Lessons for preparing projects in a heritage area

Ensure that an HIA is built into the scope of work for the IEE or the environmental impact assessment (EIA) from the beginning. If a project will touch physical cultural resources such as a UNESCO World Heritage Site or even work in the buffer zone, include an HIA from the start as part of the due diligence (don’t expect that the IEE or EIA will suffice). The SN-03 subproject experienced a significant delay because an HIA wasn’t originally required. The safeguards team then didn’t have the required experience, and no one really knew the extent of what was needed for compliance with ADB’s Safeguard Policy Statement (SPS). 

We needed to properly assess the risks both to the built environment and archaeology, but had little guidance in how to do so from past projects.

Determine the HIA scope. While an HIA is by nature intended to assess the impacts of a project on a site’s “Outstanding Universal Value” (OUV), in an ADB project context it serves a broader purpose of SPS compliance for physical cultural resources. So, we viewed it more as a stand-alone heritage-specific IEE to make sure it is comprehensive. Importantly, the scope should cover the core zone and buffer zone (get maps from UNESCO or the heritage agency), architectural monuments, archaeology and potential chance finds, and intangible heritage (such as festivals and other cultural aspects). 

Get the right team and ensure safeguard awareness. This was a challenge in Nepal given a scarcity of field archaeologists and heritage experts. In the end, the HIA included inputs from a civil engineer, structural engineer, archaeologist, environmental specialist, and social specialist, among others. Design engineers/consultants should also be knowledgeable on safeguards to ensure design considerations to avoid impacts are examined early before finalizing the design and alignments. 

While every HIA will be scoped differently, at a minimum the process should include: 

  • a detailed inventory of all heritage assets in the core and buffer zones (both monuments and archaeology); 

  • assessing intangible heritage, including festival days, sites and pathways used for rituals, etc.; 

  • physical survey work, including subsurface surveys (e.g., using ground penetrating radar–for SN-03, PID is using three survey methods combined) to map archaeological risk zones, and surveys of vulnerable/unstable buildings that could be impacted by earthworks. We want to identify any potential risky areas in advance, to show where extra precautions need to be taken or where design modifications are needed; and 

  • a comprehensive consultation plan that includes heritage authorities, local authorities, local conservation/preservation organizations, and local residents. It was highly useful to document these consultations in detail to demonstrate agreements, approvals, and endorsements during the design phase, both for the PID and for SPS compliance. Leadership of the Lalitpur Mayor during consultations has also been critical. 

Develop specific, implementable mitigation measures. The HIA of course includes an assessment of the project’s impacts on heritage assets and corresponding mitigation measures. Because the impact assessment showed the highest risk would be on subsurface archaeology for example, the mitigation measures included a much more detailed chance finds procedure than usual – e.g., step-by-step actions for movable smaller artefacts and another set of procedures for immovable archaeology (like old building foundations). 

Ensure that the bidding documents and contracts include specifications and bill of BOQ (bill of quantities) items that will mitigate impacts on heritage. In addition to specifications for construction aspects like mandatory hand digging for excavation in sensitive areas and repaving to match the current traditional red bricks in the core zone (which are in poor condition and due to be replaced anyway), PID included costs for the contractor to hire a field archaeologist and provisional sums that include trial trenches, special procedures that would be followed in case of chance finds, and allowances for extra supervision by the Department of Archaeology for works in the core zone. The contractor also must factor festival times into their construction schedule. 

Provide hands-on training. While some construction laborers in Kathmandu have been trained for working in archaeological sites through a university post-disaster assessment project, it’s unlikely that local contractors will have undertaken a project that requires intensive safeguards for archaeology. To address this, the project has set aside budget for a comprehensive training program for the DSC and contractor teams as part of the mobilization phase, including site visits, awareness of potential chance finds, and training in handling chance finds. 

Closely involve safeguard colleagues. Being this the first time our division (South Asia Urban Development and Water Division [SAUW]) is undertaking a project in a WHS in Nepal, the team has coordinated closely with the Safeguards Division (SDSS) to review early versions of the HIA and fielded a mission including meetings with key agencies and site visits. 

Share findings and data to enrich understanding. The surveys done for the HIA will contain a wealth of information that might be of great interest to academics studying Patan Durbar Square’s archaeology, organizations interested in preservation, and heritage authorities alike. These will also have the potential to bring greater understanding to Kathmandu’s past. Rather than leave the survey work as a one-off exercise for the HIA, ADB will work with government to share this data once available. 


A learning opportunity 

By its nature, there will always be uncertainties and risks from any construction project in a WHS, but the do-nothing approach in this situation was a risk in itself to Patan Durbar Square’s precious monuments and thriving culture. 


Through properly assessing the impacts and working hard to develop practical solutions, we can help ensure that important projects happen, but are implemented in such a way that protects heritage assets and maybe even brings a greater awareness and understanding of those assets, providing a learning opportunity for other heritage areas in Nepal.  

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Amy Faust 
Amy is an urban planner and ADB consultant based in Kathmandu. Her work has focused on urban infrastructure and climate resilience in Latin America, Africa, and South Asia. 
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