Over the past month the Roads and Drainage subcommittee has been inspecting roads and drains in the Village and updating the list of issues identified in the Council 2017 drainage strategy.
The next step is to organise a meeting with Council to discuss what needs to be done to fix drainage issues and what the priorities should be.
The subcommittee has prepared an interim report on its observations and initial recommendations.
This report is reproduced below. It can also be downloaded from the bottom of this post.
CROSS ROAD FLOODING & DRAINAGE IN NORTH ARM COVE 2020
Information and Background.
Observations and Initial Recommendations from your NACCIA Roads, Drainage and Signage Sub Committee. Resulting from a Survey Conducted by Seamus Devlin and Gary Sylvaney during October and November 2020.
There have been three recent Reports on drainage problems in North Arm Cove. The first for Great Lakes Council in 2014, an update for Mid Coast Council in 2017 and a third by the then Residents Association, NACRA in 2018. The Consultant Reports to Council were conducted by a company called BMT and identified what and where drainage and flooding existed and suggested actions by Council to greatly reduce the causes and effects. The 2017 Report can be viewed on the Mid Coast Council website and is titled “North Arm Cove Stormwater Management Strategy. May 2017” (A good place to look if you experience flooding and would like to see if your problem is identified already). The third, a Resident Report by NACRA Committee Len Yearsley and the writer examined progress by Council in correcting issues identified in the Council Reports and suggested further improvements.
Whilst the 2018 Report found progress had been made and other major works were then currently under way, much was still needed to be done to improve drainage on our steeply sloping terrain due in large measure to the lack of kerb and guttering in the Cove and inadequate table drain maintenance and poor/old pit design. It should be noted, Council has completed extensive and costly upgrades to Water St., The Esplanade and some remedial work in Merriwa Blvd. In recent years and just prior to the October rain event had cleared most table drains.
Five Key Points to Consider.
During the time spent inspecting drains and driveway crossings, five factors became very apparent in reference to the up-slope side of each road’s contribution to Cross Road Flooding of down-slope properties:
1. Keep the table drains that run along the upslope sides of the roads clear of vegetation debris. Residents or owners can assist their across road neighbours by keeping a watch for debris and vegetation build up between Council mechanical scrape cleaning.
2. Keep under driveway pipes clear. At water entry, exit and for the entire internal length. It should be noted here that Council is not responsible for clearing under driveway pipes. The resident /owner is responsible for all driveway maintenance.
3. If a driveway is not sealed, ensure any top dressing washing down and into a table drain by erosion of the driveway is cleared from the drain as soon as possible. Depending on the sideways slope, the provision of one or two side drains running the length of the driveway may reduce water flow onto the driveway and so reduce wash away and erosion of the driveway surface. The side drain(s) to then direct water flow to the road table drain.
4. Ensure all under driveway pipes meet Council minimum pipe internal diameter size specifications. These specify that no down slope under driveway pipe can be of less internal diameter than those upslope of it. Pipes located in cleared areas a minimum internal diameter of 375mm or in areas where trees overhang drains, a minimum of 450mm internal diameter. The latter describing our village we believe. It is clear therefore many driveway pipes do not meet these standards and are a significant contributor to cross road flooding.
5. A further action can be taken by down slope property owners to reduce the volume of water flowing onto their driveways. It has been common practice in our village that when constructing a driveway either sealed or with loose gravel and kerb and guttering not present, the top end is finished level with the road surface. In fact, your driveway should finish higher than the road surface to stop road surface water flowing down the drive to your house. A Council Plan and approval is required to be followed when constructing a driveway and specifies the shape, width and a height difference of that part of your drive connecting with the road surface and kerb and gutter either existing or planned. Council requirements for a residential driveway are detailed in “Standard Drawing Residential Driveway Plan, Sections and Details No.SD0100”. Available on Mid Coast Council’s Website under PLAN & BUILD- DRIVEWAYS. If no kerb and guttering exist yet, the plan requires a sealed driveway to stop at least 1 meter short of the road edge. To reduce water flow until kerb and guttering is constructed, build this temporary surface up to be higher than the road surface by about 100mm. When kerb and guttering is installed by Council, at a future time, the driveway top section will then be completed to specifications leaving your driveway top end section higher than the road surface. Not by a large amount but enough to make a very significant reduction in Cross Road Flow volumes entering your property. Your Council will construct this final top section without cost to the property owner.
Identified Temporary Solution
We believe, if you are having stormwater problems, some temporary solutions are also available. At least one property owner has utilised flexible plastic garden edging available from Gardening / Hardware suppliers to build a temporary kerb barrier and then direct the water where required. I know Bunnings sell a product for about $25 for a 10 metre x 75mm roll and $52 for a 10 metre x 150mm roll. I have used the latter product myself to redirect surface flows entering my property. A note of caution that it is illegal to deliberately direct your stormwater flows onto a neighbour’s property. Cooperation is the key word here, discuss your common flooding problem and agree solutions that assist both properties.
Updating Issues Identified in Council’s Stormwater Strategy
A central part of your Sub Committees efforts this year is the updating of the list of Drainage problems identified in the 2017 Council Report. Hence the time spent on inspecting our roads and drains. This is now complete and will be provided to Council and reviewed. After this review the updated list of Council works required will be available on the wonderful website. “northarmcove.nsw.au”
Council are of course working to effect long term solutions but incomes are limited and budgets must therefore set expenditure limits for each financial period and region of our municipality. Your Residents Association is working with Council to ensure significant reductions in North Arm Coves Stormwater and Drainage problems are resolved, as soon as practicable. In the meantime, if you have concerns about anything relating to the above please contact your Association via email or drop a note into the NACCAI Post Box at the Community Centre. We will then contact you to see what assistance is or can be made available.
Seamus Devlin
Gary Sylvaney
