Appendix B - Engineering Letter

Callaghan & Toth Consulting Engineers Pty Ltd
ABN No. 45140292324

8/41 Sunshine Beach Road Noosa Junction
P.O Box 2305 Noosa Heads 4567 Callaghan & Toth

www. »hanandtoth.com.au te eee ee ee
Ph: 07 5474 908] Fax: 07 $474 Civil, Environmental & Hydraulic Engineers

Ph: 07 5474 9081 Fax: 07 54749041
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10" May 2016

Mark Lewis
Coordinator Engineering
(By email)

Dear Sir,

RE: PROPOSED 17 LOT SUBDIVISION LOT 6 RP149498 EAGLE DRIVE, TEWANTIN
STORMWATER DETENTION BASIN AND BIO BASIN LOCATION

Mark on behalf of the Owner we would like to summarize the investigations to date to provide a list
to Council of the benefits to local residents resulting from the placement of an external detention
basin/bio basin with new park on the existing flood prone house lot at No.14 Eagle Drive.

The Current Flooding Problems to Local Residents are listed below:

1. Currently there is no major flood dedicated overland flow path for the runoff from the
4.72ha catchment to the east of No.14 Eagle Drive (note: of the 4.72ha, our clients land
represents 1.04ha). The problem is also compounded by the fact that existing gully pits and
pipe drainage at the sag at No.14 Eagle Drive only has the capacity to take a one in one
year storm runoff. Therefore runoff overtops the kerb regularly and floods No.14 Eagle
Drive and in large storms the runoff also floods through No.16 Eagle Drive.

Both of those occurrences have been verified on site by the owner of No.16 and Agent for
No.14.

The Owner of No.16 said that in large storms the runoff floods No.14 and has entered the
house, it also backups and floods down his (No.16) driveway and floods his shed in the
south west corner.

The real estate agent handling the rental of No.14 said that carpet has been replaced as a
result of flooding, sand bags have been used in other events to stop water entering the
house, and that a mound has had to be built in the front yard to divert flooding from the
road away from the front door and down the side of the house.

A further problem is that this house is also built only 2.7m away from the boundary adjacent
where it floods through the land. In this location there is not enough room for a Council 3m
easement or to lay pipes without impact on the house footings. ;

2. Itcan be seen at the Eagle Driveway that Council has recently replaced and lowered the
grates to the gully pits in this location in an attempt to alleviate a problem.

3. The existing undersized stormwater pipe from the sag gully pits at No.14 does not go down
the side of the house in the lowest point in the street, instead it goes down the north side of
No.12.

This pipe has no easement and the house is built right next to the pipe approximately 0.8m
to 1.1m off the side boundary. These facts mean this pipe cannot be replaced by a larger
pipe to reduce flooding.

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