Appendix B - Stormwater Management Plan

Other adjacent properties at 21 and 23 Tait Street.

It is likely that 21 and 23 Tait Street have existing overland flow issues from upstream properties at 16 and
possibly 18 Eagle Drive. The improvements obtained by having a flow path through 14 Eagle Drive and raising
verge of Eagle drive to take road flows will also reduce overland flow at these properties.

In addition it is proposed to add a landscaped bund beside 21 Tait Street to ensure that overland flow through
park has 300mm freeboard to QUDM requirements. The property at 21 Tait Street has a floor level close to park
level and verbal advice indicates there is existing flooding from park flow path which heads in a north west
direction (refer to contours on plan 1702-02A and 1702-02A).

As previously noted there will be an increase of flow to 14 Eagle Drive due to subdivision road construction which
is un-avoidable and as per Council drainage catchments and natural extension of Eagle Drive. This also means
there will be increased flow through Park at 15 Tait Street, even though subdivisions upstream will limit flow to
pre-developed amounts by detention. To protect 21 Eagle drive from Park overland flow, a landscaped bund will
be added to protect the property and provide 300mm freeboard as per plan 1702-02A. Once flow enters Tait
Street the water continues to existing sag and west into Road reserve/channel, where adjacent houses are well
above road levels. The Tait Street stormwater system was designed to Council master stormwater plans so the
proposed flow to this location was previously planned for.

Point 5.1.4: Properties at 31, 29, 27 and 25 Tait Street.

29 Tait Street: Existing Catchment =            0.3Ha,
                                                180m length of grass/treed area at 3.4%, tc = 18 minutes,
                                                fi = 0, C10 = 0.70, C5 = 0.67, C100 = 0.84.

                                                Q5        = FCIA = 1/360 x 0.67 x 121 x 0.3 = 0.068cumecs

                                                Q100      = FCIA = 1/360 x 0.84 x 195 x 0.3 = 0.137cumecs


29 Tait Street: Developed Catchment =           0.06Ha,
                                                Urban lot area at 3.4%, tc = 6 minutes,
                                                fi = 0.4, C10 = 0.78, C5 = 0.74, C100 = 0.94.

                                                Q5        = FCIA = 1/360 x 0.74 x 190 x 0.06
                                                          = 0.023cumecs - 0.010cumecs roofwater = 0.013cumecs

                                                Q100      = FCIA = 1/360 x 0.94 x 303 x 0.06
                                                          = 0.047cumecs - 0.010cumecs roofwater = 0.037cumecs


House        Pre-development          Post-development flow         Pre-development flow        Post-development flow
number      flow Q5 in cumecs             Q5 in cumecs                Q100 in cumecs              Q100 in cumecs

  29               0.068                       0.013                        0.137                      0.037

So mostly due to new road catchment and roofwater drainage a significant reduction in flow occurs as a result of
development without any detention. Detention for overall flow increases from subdivision will be dealt with at 14
Eagle Drive basin.

A similar order of flow reduction will apply for lots 23, 25, 27, 29, 31, 33 Tait Street.



                                                                                                                 pg. 10