The sudden drop in groundwater levels will not affect the construction of a tunnel for the city’s first metro line, Thanh Nien newspaper reported, citing the HCMC Department of Construction.
Employees are at work at the construction site of HCMC's first metro line project. The city’s metro line No. 1 is unaffected by falling groundwater levels in the project area
The SMC4 contractor has stopped work on the tunnel on Le Loi Street for two weeks due to the fall in groundwater levels and the abnormal sinking of neighboring works.
In response to the announcement from the HCMC Management Authority for Urban Railways (MAUR) on the sudden drop in groundwater levels caused by the execution of the hotel and housing project at 129 Le Thanh Ton Street, Pham Huu Tao, deputy head of quality management for construction works, said on April 22 that the department had quickly dispatched experts to the related sites to evaluate the situation.
However, the project at 129 Le Thanh Ton Street has been put on hold while the project at 125-127 Le Thanh Ton Street is in the process of pumping up the groundwater.
At a meeting at the site, a Japanese expert from the unit in charge of constructing the tunnel section for the urban railway insisted that the dipping groundwater levels would not cause the metro line’s foundation to sink, according to Tao.
In accordance with the Japanese contractor’s construction standards, it is necessary to put on full alert neighboring buildings that have sunk by three centimeters.
The Japanese side was concerned by residents’ complaints and claims of adjacent buildings sinking, leading to the expedited progress of the metro line project, Tao said.
As such, the Japanese contractor needs a clear decision from the authorities as the contractor will be held accountable for failing to construct the metro line on schedule if the project at 125-127 Le Thanh Ton Street affects its construction progress, Tao added.
Nguyen Van Hiep, former deputy director of the municipal Department of Construction, said that the diaphragm walls of the Le Loi tunnel section, with its firm and deep foundation, will be unaffected by falling groundwater levels.
He said that even though it was not the address provided by MAUR, the department had carefully checked the project at 125-127 Le Thanh Ton Street and asked the owner of the project to present its construction method documents, measurements of neighboring buildings and groundwater lowering methods.
After reviewing the submitted documents to check whether the contractor has applied the technical requirements correctly and is capable of completing the project, the department will issue a final conclusion on the project’s influence on neighboring structures.
Metro line foundation at risk of sinking
A hotel and housing project under construction on Le Thanh Ton Street, District 1, HCMC has caused groundwater levels to fall, which may lead the construction site of the city’s first metro line to sink, Thanh Nien newspaper reported, citing the HCMC Management Authority for Urban Railways (MAUR).
Duong Huu Hoa, director of the Project Management Unit No. 1, under MAUR, on April 21 confirmed that the unit had written to the HCMC Department of Construction and the District 1 authority, reporting a sudden fall in groundwater levels, which is likely to cause the subsidence of the foundation and neighboring buildings on the Le Loi tunnel section of package 1a under the metro line No. 1 project linking Ben Thanh Market in District 1 with Suoi Tien Park in District 9.
MAUR voiced concern over the impact of the construction of the hotel and housing project at 129 Le Thanh Ton Street on the first metro line project. The authority explained that Linh Ha Company, the investor in the hotel and housing project, had pumped up the groundwater during its construction, resulting in the sinking. This action affected neighboring buildings and the progress of the city’s first metro line.
Under the plan to construct metro line No. 1, the SMC4 contractor will carry out the excavation and construction of the tunnel section on Le Loi Street. However, after groundwater levels dropped abnormally and the sinking of the foundation and neighboring buildings increased, MAUR asked the project’s consulting unit, NJPT, to check the levels regularly and advised the contractor to suspend the excavation of the affected area.
The contractor has stopped work on the project for two weeks, collaborating with the competent agencies to inspect and measure the levels of sinking and the groundwater.
Measurements taken on April 15 showed that the groundwater level outside the diaphragm walls of the Le Loi section had fallen consistently, while the foundation and buildings adjacent to 52 Le Loi Street were continuing to sink.
Given the urgent situation, MAUR proposed the Department of Construction and the District 1 Authority adopt preventive measures as soon as possible to ensure the safety of residents living near the project and that of the neighboring buildings and to guarantee the progress of the metro line.
Earlier, at the beginning of April, MAUR had sent an announcement to the department and the authority of District 1, but it has yet to receive any reply.
As the first metro line is slated for completion by end-2020, the contractor of package 1a will have to speed up its execution, MAUR Director Bui Xuan Cuong noted in a letter, adding that it is impossible to lengthen the construction period for the metro line No. 1 project.