Customising Wick Trenches to Extreme Victorian Conditions

1. Customising Wick Trenchesto Extreme Victorian Conditions Callum Morrison Benalla Rural City Council

2. PAGE 57 Customising Wick Trenchesto Extreme Victorian Conditions Callum Morrison Benalla Rural City Council

5. 1. The Flat Country Rain TestOn Dispersive Clay Path 1. Path 2. Path 3. Recent Dispersive Clays that lose structure and are almost water proof Dry Deep Clays with More Absorption Capacity

6. Newly installed wick trenches not yet in use !

7. 2. Proposed Mounding in Flat Country to Test Rain Management On Dispersive Clay Path 1. Path 2. Path 3. Natural Ground Level Recent Dispersive Clays that lose structure and are almost water proof Dry Deep Clays with More Absorption Capacity

8. 3a. Proposed Mounded Wick with Rain Diversion to Sand Infiltration Path 1. Path 2. Path 3. Natural Ground Level Slight Rise Extreme rain or extreme use peak. Washed Sand infiltration Column or Auger Holes mostly for Stormwater Recent Dispersive Clays that lose structure and are almost water proof Dry Deep Clays with More Absorption Capacity

9. What is the point of water and Nutrient balance calculations if the vegetation in summer is likely to die or cost too much in precious town water to sustain?

10. 3b. Proposed Optional Manual Diversion from Summer Water Tank Overflow Trapping for Water Conservation Saving on Town Water and Surge Storm Flows Mounded 100mm Retention Basin To Recharge Wick & Deep (Between Trenches or across boundary between Trenches) ~ 40,000 litres with auto overflow Natural Ground Level Recent Dispersive Clays that lose structure and are almost water proof Dry Deep Clays with More Absorption Capacity

11. 4. Proposed Double Wick Mounded Trenches (Reduces length and space required) Site topsoil reused to cover mound and excavated clays used to form up sides of mound so minimal removal costs. Tilting down the side extensions to the trench would be even more effective than a bund to stop back flow into trench and save soil. Only really centre has steep mounding so reduces imported topsoil necessity. On sides run off not as critical and must not pool. Natural Ground Level 100mm clay Fill So original top Soil can be lifted. 100mm Clay Fill Does the geofabric have to extend under the mound causing potential sealing and blockage? Is down the trench sides and over the top of arching adequate? Dry Deep Clays with More Absorption Capacity

12. These are practical and common sense additions to the conventional wick trench model however they will need to be properly tested and electronically monitored on a few test installations first to fine tune the performance and minimise costs. This will also assist with how to approach repair of old systems.

13. 5. Blocked old trench systems(Side walls blocked and addition of pump needed to obtain elevation and expansion) Dry Deep Clays with More Absorption Capacity

14. 6. Proposed refurbishment of old trench systems using top dress mounding and wick techniques plus sand pick up and dispersal auger holes or narrow washed sand trench. Original Natural Ground Level Dry Deep Clays with More Absorption Capacity

15. Please advise if there is EPA support for this proposal. Benalla Rural City Council has just been presented with a Land Capability Assessment for an ecological Convention Centre with peak flows of 3000 litres a day and 300 mitres of Wick trench in some very difficult clay soils on public land with big buffer distances. This could be an ideal test site for trying some of these variations in very uniformly bad soils that should provide good comparisons and low risk test conditions.