HomeMy WebLinkAboutP_FLOWCONTROLBMP_EXHIBIT_B__250529_V1EXHIBIT B - MAINTENANCE INSTRUCTIONS FOR BASIC DISPERSION
YOUR PROPERTY CONTAINS AN ON -SITE BMP (BEST MANAGEMENT PRACTICE) CALLED "BASIC DISPERSION," WHICH WAS INSTALLED TO
MITIGATE THE STORMWATER QUANTITY AND QUALITY IMPACTS OF SOME OR ALL OF THE IMPERVIOUS SURFACES OR NON-NATIVE PERVIOUS
SURFACES ON YOUR PROPERTY.
BASIC DISPERSION IS A STRATEGY FOR UTILIZING ANY AVAILABLE CAPACITY OF ONSITE VEGETATED AREAS TO RETAIN, ABSORB, AND FILTER
THE RUNOFF FROM DEVELOPED SURFACES. THIS ON -SITE BMP HAS TWO PRIMARY COMPONENTS THAT MUST BE MAINTAINED:
(1) THE DEVICES THAT DISPERSE RUNOFF FROM THE DEVELOPED SURFACES AND
(2) THE VEGETATED AREA OVER WHICH RUNOFF IS DISPERSED.
DISPERSION DEVICES
THE DISPERSION DEVICES USED ON YOUR PROPERTY INCLUDE THE FOLLOWING AS INDICATED ON THE SITE PLAN:
❑ SPLASH BLOCKS, ❑ ROCK PADS, SGRAVEL FILLED TRENCHES,❑ SHEET FLOW.
MAINTENANCE RESTRICTIONS
THE SIZE, PLACEMENT, COMPOSITION, AND DOWNSTREAM FLOWPATHS OF THESE DEVICES AS DEPICTED BY THE SITE PLAN AND DESIGN
DETAILS MUST BE MAINTAINED AND MAY NOT BE CHANGED WITHOUT WRITTEN APPROVAL FROM THE CITY OF RENTON OR THROUGH A FUTURE
DEVELOPMENT PERMIT FROM THE CITY OF RENTON.
INSPECTION FREQUENCY AND MAINTENANCE GUIDELINES
THIS ON -SITE BMP HAS TWO PRIMARY COMPONENTS THAT MUST BE MAINTAINED PER APPENDIX A OF THE CITY OF
RENTON'S SURFACE WATER DESIGN MANUAL:
(1) THE DEVICES THAT DISPERSE RUNOFF FROM THE DEVELOPED SURFACES AND
(2) THE VEGETATED FLOWPATH AREA OVER WHICH RUNOFF IS DISPERSED.
MAINTENANCE OF DISPERSION DEVICES
• DISPERSION DEVICES MUST BE INSPECTED ANNUALLY AND AFTER MAJOR STORM EVENTS TO IDENTIFY AND REPAIR ANY PHYSICAL
DEFECTS.
• WHEN NATIVE SOIL IS EXPOSED OR EROSION CHANNELS ARE PRESENT, THE SOURCES OF THE EROSION OR CONCENTRATED FLOW
NEED TO BE IDENTIFIED AND MITIGATED.
• CONCENTRATED FLOW CAN BE MITIGATED BY LEVELING THE EDGE OF THE PERVIOUS AREA AND/OR REALIGNING OR REPLENISHING
THE ROCKS IN THE DISPERSION DEVICE, SUCH AS IN ROCK PADS AND GRAVEL FILLED TRENCHES.
MAINTENANCE OF VEGETATED FLOWPATHS
• THE VEGETATED AREA OVER WHICH RUNOFF IS DISPERSED MUST BE MAINTAINED IN GOOD CONDITION FREE OF BARE SPOTS AND
OBSTRUCTIONS THAT WOULD CONCENTRATE FLOWS.
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DEPAR MENT FLOW CONTROL BMP DETAILS
DATE: 2-10-2019