TECHNICAL NOTE 01: Overland Flow Path adjacent to Chapel · Please refer to attached sketch ‘5162001-WS+P-SK-41 Chapel Overland flow path’ for further details of overland flow

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Introduction:

This technical note has been prepared in response to the Department of Planning and Environment query raised by Campbelltown Council in relation to the overland flow path north of the proposed chapel.

DPE comment: “Campbelltown Council comment regarding the overland flow path of stormwater behind chapel. Despite comment provided by the Stormwater engineer, we have not included a drawing detailing the measures to mitigate the overland flow on Road 1 north (and upstream) of the Chapel.”

Response:

The proposed stormwater network consists of a swale (adjacent to Road 1) as well as a pit and pipe system within Road 1 kerb and gutter adjacent to and (north) of the proposed chapel. The swales located north of the road will capture any overland flow sheeting down the hill before reaching the road. This flow will then be conveyed through the pit and pipe system located under the road kerb and gutter.

The stormwater system has been designed based on a minor and major system in line with

Campbelltown Council’s Development Control Plan. The minor system, designed to a 10-year ARI, will

contain all flows within the proposed system therefore resulting in no overland flow near the chapel.

The major system, designed to a 100-year ARI, is designed to safely convey major storm flows when

the capacity of the minor system is exceeded. The proposed stormwater system north of the chapel

safely conveys overflows within the road network without any potential impact to buildings or public

safety in the 100-year ARI. Any surcharge from pits near the proposed chapel will be conveyed within

the road network away from the chapel. Please refer to attached sketch ‘5162001-WS+P-SK-41 Chapel

Overland flow path’ for further details of overland flow paths. Table 1 below also identifies overland

flows encountered between each pit near the chapel in the 100yr ARI event. It is evident that the

overflows are minor in nature with maximum depths of 89mm.

Table 1: Overland Flows (100 year ARI)

TECHNICAL NOTE – 01: Overland Flow Path adjacent to Chapel Project name: Macarthur Memorial Park Issued to: Dept of Planning & Environment

Project no: 5162001 Prepared by: Niall Quinn

Reviewed by: Michael Cahalane

Client: CMCT Date issued: 18/10/2018

Document No: 5162001-WS+P-CS-TN-0001 Revision: 1

Overland Flow Route Max Flow (l/s) Max Depth (mm)

Pit 1/1 to Pit 1/4 22 77

Pit 1/4 to Pit 1/5 6 39

Pit 1/5 to 7/1 1 21

Pit 2/9 to Pit 3/9 0 0

Pitt 3/9 to Pit 4/9 10 89

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PROPOSED CHAPEL

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COMMENCEMENT OF& LEVELS BEFOREVERIFY ALL DIMENSIONSDRAWINGS, CHECK &DO NOT SCALE FROM

ANY WORK.

AMENDMENTREVISION DATE

PROJECT

CLIENT

JOB No.

DATE

SCALE

TITLE

DRAWING No. ISSUE

AMENDMENTREVISION DATE

MACARTHUR MEMORIAL

PARK

5162001

N.Q. M.C.

ISSUE FOR INFORMATION

PREPARED BY

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1 FOR INFORMATION 18/10/18