Response to Information Request · OPW11/0177

                                                      TATE PROFESSIONAL ENGINEERS PTY LTD
                                                                                ABN 28 086 262 035

    Rational Method

     For a 1 year ARI storm in Noosa:

    51,   = 128mm / hr

    60ho = 72m/hr

    From Table 4.05.3(a) of QUDM:

    C,o = 0.76
    FY = 0.80

    5Qr = 0.76 x 0.80 x 128mm If hr x 1686m2

          = 0.036m3 / sec


    Swale Capacity - Mannings

    For Swale 2 flowing full:

    A     =0.3x1.0=0.3m2
    P     = 2 x 0.3 + 1.0 = 1.6m
    R     = A/P = 0.188m
    n     = 0.04 (medium grass)
    s     = 0.005
    V     = R213 S12/n=0.188213x0.0051 /2/0.04
                       = 0.58m / sec

    Q     = V.A = 0.58m / sec x 0.3m2
                   = 0.174m3 / sec >>5Q,

    This proposed Swale 2 is adequate to convey 1 year ARI flows and hence 3 month ARI flows.




    3.    Demonstrate that there will not be an increase in runoff in events that exceed the
          design capacity of the swales. Appropriate detention must be demonstrated where
          required.

    All rainwater incident on the proposed development, up to 100 year ARI events is to be infiltrated
    on site via Rapid Infiltration Pits as demonstrated in the application. As such there will be no
    runoff from the site for events up to 100 year ARI and no increase in runoff from the site for
    events up to 100 year ARI, satisfying the requirements of QUDM and Condition 49.




    4.  Revise surface treatment proposed for swales so that it is low maintenance and likely
        to maintain its modeled configuration during the long term and consistent with the
    -- -requirements of -the approvedmanagement plans---

    Drawings have been revised to remove reference to turf in swales (despite its successful use on
    previous adjacent stages). We defer to the landscape architect for details of Swale planting.




S3000/11/L5/Response to Information Request - Sunshine Coast Regional Council
SH/cw