The Imagine Panaji Smart City Development (IPSCDL) announced that they had successfully laid a 700mm diameter HDPE (high density polyethylene) sewage pipe 6m below the bed of St Inez creek using the horizontal directional drilling (HDD) method.
According to the IPSCDL, the pipe spans from the fire department ground at St Inez to the sewage treatment plant (STP) at Tonca. They explained that the HDD method entails drilling a precise underground path, which allows the pipe to be drawn without extensive on-ground excavation. This technique minimizes surface disruption and is considered ideal for navigating obstacles such as roads, waterways, and existing utility lines.
The IPSCDL further stated that the existing sewage line, located at a depth of about 4.5m, required drilling at a depth of 6m to prevent damage and additional complexity to the project. They emphasized that this measure was taken to ensure the safety and integrity of the existing infrastructure.
Explaining the challenges faced during the process, they noted that boring under the St Inez Creek presented difficulties due to the soft, collapsing soil. Special techniques were employed to maintain bore hole stability below the bed level of the creek.
The IPSCDL reported that the team had completed the remaining process, wherein bentonite slurry was used to stabilize the bore hole.
