Following a site visit by Timaru District Council engineers to complete annual inspections of stormwater outfall conditions along the Waihi River, Morphum Environmental was requested to support further investigation and design improvements to three targeted assets.

Alongside the Waihi River and the Geraldine Sculpture Trail , identified outfalls have impacted the safety of the path, leading to periodic closures of certain sections.

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Morphum began by reviewing information from the initial site visit, asset details and Timaru District Council’s Geraldine Stormwater Model to ascertain asset condition flow rates and pipe capacities. At this stage Morphum discovered that all three outfalls were capable of conveying the 100-year ARI rainfall return event.

Our team then undertook site visits to gather measurements and reduced levels and understand more about the surrounding landscape. Following the site visit and desktop study, one of the targeted outfalls was deemed to be in adequate condition and requiring no improvements, pointing the team to focus on the remaining two.

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With Morphum’s collaborative approach guiding the way, our teams of engineers initiated the design approach through an options analysis to ensure a best practicable and constructible solution within the existing landscape. Preferred options were developed and discussed with Timaru District Council, and following endorsement of the approach, detailed designs were developed and reviewed against the Canterbury Regional Council Land and Water Regional Plan. Detail design drawings were completed together with reporting to document the design process and final recommended solution.

The Waihi River Outfall Improvements was delivered to Timaru District Council in April 2025, meeting rapid timeframes. This project was the most recent in a long list of outfall improvements projects, where we have refined our approach over the past 20 years.

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