2016 Event Summary

In 2016, an investigation was undertaken by NPTCBC in response to the flood event that occurred on 3^rd September 2016 at Varteg Road, Ystalyfera. Following a prolonged intense rainfall event eighteen properties along Varteg Road and one outbuilding on Ynysydarren Road suffered internal flooding.

It is encouraged the 2016 report is read in conjunction with the findings details in the following.

In 2016 NPTCBC concluded a key drainage system shown in figure 12 Connection A to B was severed during the construction of the nearby Asda Stores site, being one of the key contributing factors for the property flooding along Varteg Road. Water intended to convey through the culvert was being discharged into the ground at the location of the Asda site, by way of percolation and dispersal. As such, the existing drainage network was simply acting as an attenuation tank.

Investigations also identified a partial collapse on another culvert within privately owned land off Ynysydarren Road that had a significant effect on the flood extent. The water that surcharged from an adjacent inspection chamber within the highway flowed through the Varteg Estate to the low point at the Ynysydarren and Varteg Road junction.

A mitigation measure was introduced by the NPTCBC that involved the construction of a temporary pumping station on the line of the blocked Asda culvert. The system currently pumps surface water overland into the A4067 highway drainage system, and consequently its effectiveness at dealing with intense rainfall is limited.

Table 1 below displays the recommended action derived from the 2016 report.

No	Action By	Action	Action to date
1	Asda Land Owner/ Developer	Resolve the Issue with the lost drainage	Investigations remain. The Authority is developing a business case alongside correspondence with stakeholders in order to find an appropriate solution.
2	Property Owners	Consider flood risk to own properties	The Authority has implemented property resilience measures to properties at Varteg Road
3	DCWW - Dwr Cymru Welsh Water	Ensure efficient operation of public combined and surface water sewers	No issues detected upon investigation with integrity of sewer network. Surcharge water from ynysydarren culvert entered the network causing surcharge to sewer system
4	Land Owners	Remove any obstructions within a watercourse if found	As a LLFA the Authority has utilised its land drainage powers to enforce removal of impediments within private land.