CRZ clearance deferred for SWD project in Kosasthalaiyar Basin

CHENNAI: Directing the Greater Chennai Corporation to obtain expert opinion from IIT Madras or national institute for estimation of design return period, rainfall intensity and duration in view of extreme events due to climate change, the expert appraisal committee for projects related to coastal regulation zone has deferred clearance for carrying out integrated stormwater drain project in Kosasthalaiyar Basin.

While deferring the allocation made by the civic body, the committee also directed to design the drainage system and pumping stations considering outflow flood water into the estuaries for varied tidal conditions to avoid flooding.

The proposal was earlier considered for clearance by the committee in June, but clearance was deferred noting that the civic body had not submitted detailed project report and detail about proposed storm water drain plan in relation to intensity and duration of precipitation, topography, likely areas of flooding, management of extreme flooding, sub-canal distribution, pumping requirement during varying tidal conditions in estuaries and canals, assurance that the proposed drain will not be used for carrying sewage or industrial effluent in future among other details.

Based on this, the civic body made a detailed presentation and EIA report along with extract of DPR containing details, which are sought by the committee.

However, the committee deferred the clearance seeking expert opinion and directing the design of pumping system by considering outflow flood water into the estuaries for varied tidal conditions.

The Chennai Corporation has already commenced construction of drains in Kosasthalaiyar Basin at Rs 2,500 crore with the funding assistance from Asian Development Bank (ADB). Under the project, the civic body would construct the integrated stormwater drain network with a total length of 763 kilometers in the Kosasthalaiyar river basin.

While the construction of drains in interior parts does not need CRZ clearance, construction at coastal regulation zone area requires clearance. It may be noted that the state coastal zone management authority (TNSCZMA) cleared the project already.