St Mary’s Colac – Response to Colac Otway Shires Stormwater Strategy

My name is Jan Healey.  I am speaking on behalf of the Parish of St Mary’s, the owners of the land on which Trinity College is located and of the vacant area north of the Trinity carpark and bounded by Hart and Hearn Streets.

As part of mitigation works outlined in the Stormwater Strategy it is proposed that a retarding basin be constructed on part of the vacant land.  This is marked as just north of the Trinity carpark on the map designated Location 2 in Appendix F of the Strategy.

Council staff met with St Mary’s Parish and Trinity College representatives (Principal Tim O’Farrell, Business Manager David Testa, Parish Priest Fr Michael O’Toole, Helen Paatsch from the Parish Finance Committee and myself from the Parish Leadership Team) on Friday February 1.   We discussed the implications of the Stormwater Strategy for the Parish plans to develop housing on their land adjoining Trinity and any possible effects on Trinity. This was useful meeting and we thank the three Council staff who made themselves available.

We acknowledge the changes that have been incorporated into the Strategy as a result of that meeting

The proposed structure is now referred to as a “constructed wetland” rather than as a retarding basin both on the map in Appendix F and in section 7.2.1 where the proposed mitigation works are described.

The third paragraph of section 7.2.1 now states and I quote:

“As part of the works identified at Location 2 a constructed wetland with flood storage provision is proposed as there is undeveloped land within the Trinity College (Parish) property (the property is owned by the Parish) which could possibly be acquired or used for stormwater management as part of future development of the balance of the land.  The existing conditions flood modelling results highlight that a large portion of the undeveloped area in the north-eastern corner of the property is subject to flooding approximately 200-400 mm deep for the 100 year ARI event.  Any future development in the area should consider the extent of flooding for existing conditions (the implementation of a Special Building Overlay (SBO) would ensure this was the case) to appropriately set floor levels for any development and ensure that it does not obstruct overland flows.  This could result in a more expensive development design and construction (eg structural footings).  As such the construction of a wetland with flood storage within a portion of the property presents an opportunity to appropriately retard catchment flows that would reduce the constraints on any future development within that part of the property.  An opportunity exists to negotiate the construction and funding of the asset as part of the future development of the land, subject to detailed design.”

In the meeting with Council staff several points were raised –

The Parish will need to consider all the general planning requirements, not only the Stormwater Strategy, when it is deciding how best to develop the land.  If it is developed as residential land then the planning scheme requires that storm water is managed on site.  This then takes us to the Storm Water strategy requirement for a structured wetland as being a solution for the storm water management.  The final sentence in the paragraph quoted from section 7.2.1 then becomes the critical statement from our point of view –

An opportunity exists to negotiate the construction and funding of the asset as part of the future development of the land, subject to detailed design.”

This negotiation will be critical to the development of an outcome that best meets the needs of all parties

While Trinity acknowledges that a constructed wetland could be a location for educational activities for its students it is also aware of the potential for increased dangers with habitat suitable for snakes so close to the school.  The ongoing maintenance of the wetland site will need to be addressed.  It was acknowledged in the meeting with Council staff that this maintenance would become a Council responsibility.

The Parish is at the very initial stages of planning for residential development of the site.  In the notes for this meeting (discussion on the Trinity submission, s/7 on pages 27 and 28) it acknowledges that the exact location and shape of the constructed wetland could be modified. The design for the wetland needs to be considered as an integral component of the overall design for the development of the entire block.  The cost of the wetland (acknowledged as being partly funded by council because of the benefit to the wider catchment) will have a major impact on the overall residential development of the block and how this can be staged so that costs are manageable.  This is a major consideration for the Parish.


However, this level of detail is beyond the scope of this Strategy.  We welcome the changes that have been made in response to our discussions and submission, in particular the addition of the final sentence.  This negotiation will be the key.


Thank you for your time.