Pise Weir, located on Bhatsai River downstream of Bhatsa dam, is a Concrete masonry structure. It creates bondage for extraction of 300 mgd of water for MCBM. The prevalent pumping capacity was 140 mgd at the time of execution allowing for no additional storage.To enable additional pumping by 140 mgd, the existing storage capacity was to be enhanced. An increase in storage of equal quantity of water for emergency use in the good season was also required.
To increase the storage upstream of the weir (160 m long) by 140 mgd to act as bondage for pumping additional 140 mgd from Bhatsai river at Pise Weir, an inflatable and deflatable gate of 2m height was installed over the crest of the wier. It was pivoted on a mild steel gate and raised and lowered by rubber pillows.
In the inflated position, an excess of 2m of water could be stored. It provided the required storage in the regular season; however at the time of flood, the gates would deflate, taking the shape of weir ogee thereby allowing the flood to pass by and re-inflate after that. There was no obstruction to the flow in terms of pillars or piers.