Reference Document MCU22/0102 Cubo Consulting Letter Final

Engineering Buildable Solutions




Our Ref : 23122_LO_01/DB
Contact: Doug Black
21/12/2023
                                                                                  REFERENCE DOCUMENT
                                                                                       MCU22/0201
Kings Group (QLD) Pty Ltd                                                            NOOSA COUNCIL
PO Box 11,                                                                             27 NOV 2024
COOROY QLD, 4563

Attention: Joanne Hill




Dear Joanne,

PROPOSED CARWASH DEVELOPMENT, 34 ELM ST, COOROY QLD, 4563

Summary

This letter presents the results of a DRAINS drainage model including onsite detention for
the proposed development at the above address, and is intended as supporting information
for the Holistic Stormwater & Waste Water Management Plan, by TMC Building Design
Group, job number 20-032 CIV-Rev B, dated 11th May 2023.

The model found that the inclusion of 10.75m3 of onsite detention volume in the proposed
drainage arrangement will result in peak flow rates from the proposed development not
exceeding pre-development peak flow rates, for all events up to and including the 1% AEP
event with a 20% increase in rainfall intensity by 2100 for climate change.

The model was based on the drawings by CMG Consulting Engineers, 46143 rev C, issued
20/12/23.

Background

TMC have prepared a Water Management Plan for the proposed carwash development at
34 Elm St, Cooroy, stating that an effective reduction in impervious area draining from the
site will result in a reduction in peak flow rates from the site.

Noosa Council have requested more detail, specifically:

“A revised conservative assessment is required which demonstrates how peak flows will be
mitigated from the development to pre-existing levels, based on the rainwater tanks being
full.”

Existing Site Conditions

The existing site is currently unoccupied, with the previous motel having been demolished.
The site is surrounded on three side by roads with a bowling club on the eastern boundary.
The site falls generally to the southeast.


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