Stormwater Management Plan

INSTALLATION                         MAINTENANCE                           2. REMOVE COLLECTED SEDIMENT AND     4. GRADE THE AREA AND SMOOTH IT OUT
                                                                           DISPOSE OF IN A SUITABLE MANNER      IN PREPARATION FOR STABILISATION.
1. REFER TO APPROVED PLANS FOR       1. INSPECT THE LEVEL SPREADER AFTER   THAT WILL NOT CAUSE AN EROSION OR
LOCATION, DIMENSIONS AND             EVERY RAINFALL EVENT UNTIL            POLLUTION HAZARD.                    5. STABILISE THE AREA AS SPECIFIED ON
CONSTRUCTION DETAILS. IF THERE ARE   VEGETATION IS ESTABLISHED.                                                 THE APPROVED PLAN.
QUESTIONS OR PROBLEMS WITH THE                                             3. REMOVE AND APPROPRIATELY
LOCATION, DIMENSIONS, OR METHOD OF   2. AFTER ESTABLISHMENT OF             DISPOSE OF ANY EXPOSED GEOTEXTILE.
INSTALLATION CONTACT THE ENGINEER    VEGETATION OVER THE LEVEL
OR RESPONSIBLE ON-SITE OFFICER FOR   SPREADER, INSPECTIONS SHOULD BE
ASSISTANCE.                          MADE ON A REGULAR BASIS AND AFTER
                                     RUNOFF-PRODUCING RAINFALL.
2. WHEREVER PRACTICAL, LOCATE THE
LEVEL SPREADER ON UNDISTURBED,       3. ENSURE THAT THERE IS NO SOIL
STABLE SOIL.                         EROSION AND THAT SEDIMENT
                                     DEPOSITION IS NOT CAUSING THE
3. ENSURE FLOW DISCHARGING FROM      CONCENTRATION OF FLOW.
THE LEVEL SPREADER WILL DISPERSE
ACROSS A PROPERLY STABILISED SLOPE   4. ENSURE THAT THERE IS NO SOIL
NOT EXCEEDING 10:1 (H:V) AND         EROSION OR CHANNEL DAMAGE
SUFFICIENTLY EVEN IN GRADE ACROSS    UPSTREAM OF THE LEVEL SPREADER,
THE SLOPE TO AVOID CONCENTRATING     OR SOIL EROSION OR VEGETATION
THE OUTFLOW.                         DAMAGE DOWNSTREAM OF THE LEVEL
                                     SPREADER.
4. THE OUTLET SILL OF THE SPREADER
SHOULD BE PROTECTED WITH EROSION     5. INVESTIGATE THE SOURCE OF ANY
CONTROL MATTING TO PREVENT           EXCESSIVE SEDIMENTATION.
EROSION DURING THE ESTABLISHMENT
OF VEGETATION. THE MATTING SHOULD    6. MAINTAIN GRASS IN A HEALTH
                                                                                         (a) Typical layout of level spreader
BE A MINIMUM OF 1200mm WIDE          CONDITION WITH NO LESS THAN 90%
EXTENDING AT LEAST 300mm UPSTREAM    COVER UNLESS CURRENT WEATHER
OF THE EDGE OF THE OUTLET CREST      CONDITIONS REQUIRE OTHERWISE.
AND BURIED AT LEAST 150mm IN A
VERTICAL TRENCH. THE DOWNSTREAM      7. GRASS HEIGHT SHOULD BE
EDGE SHOULD BE SECURELY HELD IN      MAINTAINED AT A MINIMUM 50mm BLADE
PLACE WITH CLOSELY SPACED            LENGTH WITHIN THE LEVEL SPREADER
HEAVY-DUTY WIRE STAPLES AT LEAST     AND DOWNSTREAM DISCHARGE AREA,
150mm LONG.                          AND A MAXIMUM BLADE LENGTH NO
                                     GREATER THAN ADJACENT GRASSES.
5. ENSURE THAT THE OUTLET SILL
(CREST) IS LEVEL FOR THE SPECIFIED   REMOVAL
LENGTH.
                                     1. TEMPORARY LEVEL SPREADERS
6. IMMEDIATELY AFTER CONSTRUCTION,   SHOULD BE DECOMMISSIONED ONLY                    (b) Typical profile of the the outlet weir
TURF, OR SEED AND MULCH WHERE        AFTER AN ALTERNATIVE STABLE OUTLET
APPROPRIATE, THE LEVEL SPREADER.     IS OPERATIONAL, OR WHEN THE INFLOW
                                     CHANNEL IS DECOMMISSIONED.