Page 80 - Black Bay Vision Plan

IV. WATER QUALITY ELEMENTS (WQ)
WQ – 1 WATER QUALITY BAND – PLANTING MEDIUM
A. MAINTENANCE SPECIFICATIONS
i. Inspect for standing water. Use the bi-annual health evaluation of the plants as an indicator of
possible hydraulic problems. If ponding persists for more than 4 hours after a storm event, the
following steps will be taken to improve hydraulic functioning; cleaning out the underdrain with a
rooter, or replacing the planting medium and pea gravel surrounding the perforated underdrain
in that area. Properly dispose of any waste using appropriate disposal methods. Management
of vegetation will help in maintaining adequate hydraulic functioning and will limit habitat for
disease-carrying animals.
ii. Fill all Animal burrows. If the problem persists, vector control specialists should be consulted
regarding removal steps. This consulting is necessary as the threat of rabies in some areas
may necessitate the animals being destroyed rather than relocated. If the BMP performance is
affected, abatement will begin. Otherwise, abatement will be performed annually in September.
iii. During each inspection and maintenance visit to the site, trash and debris shall be removed
to reduce the potential for inlet structures and other components from becoming clogged and
inoperable during storm events.
iv. Sediment, debris, and trash, which impede the hydraulic functioning of the WQ band and
prevent vegetative growth, shall be removed and properly disposed. If accumulation of debris or
sediment is determined to be the cause of decline in the infiltration rate, prompt action (i.e., within
ten working days) shall be taken to restore the WQ band to design performance standards.
Actions will include using additional fill and vegetation and/or removing accumulated sediment to
correct channeling or ponding. The removed medium can be safely landfilled, if testing shows it
to be non-toxic. Vegetation will be re-established after sediment removal. Full replacement of the
planting media is recommended every 6 years.
v. Where revegetation has been ineffective, or where other factors have created erosive conditions
(i.e., pedestrian traffic, concentrated flow, etc.), corrective steps shall be taken to prevent loss
of soil and any subsequent danger to the performance of the WQ band. The corrective actions;
include erosion control blankets, riprap, or reduced flow through the area. Designers or
contractors will be consulted to address erosion problems if the solution is not evident.
vi. Organophosphate insecticides and petrochemical fertilizers will not be allowed. Weeds will be
removed through mechanical means. Herbicide will not be used because these chemicals may
impact water quality.
VISION PLAN 80
WQ – 2 WATER QUALITY BAND – SAND FILTRATION
A. MAINTENANCE SPECIFICATIONS
i. Inspect for standing water after all large storm events (>0.5 inches of precipitation) to verify that
they are working as intended. Typically, sand filters begin to experience clogging problems within
5 years. In order to coincide replacement of material with replacement of the planted sections
of the WQB, replacement of the unplanted section is recommended every 6 years. Corrective
maintenance of the filtration chamber includes removal and replacement of the top layers of sand,
gravel, and/or filter fabric that has become clogged. The removed media can be safely landfilled,
if testing shows it to be non-toxic.
ii. During each inspection and maintenance visit to the site, trash and debris removal will be
conducted to reduce the potential for inlet structures and other components from becoming
clogged and inoperable during storm events.
iii. Sand filter systems may also require periodic removal of vegetative growth.
WQ – 3 CURB OUTLET FILTERS
A. MAINTENANCE SPECIFICATIONS
i. Inspect the outlet filters on a monthly basis during wet weather and every 3 months during dry
weather. Remove any trash and debris to reduce the potential for inlet structures and other
components from becoming clogged and inoperable during storm events.
ii. To clean the filter: remove the curb grate, if present; unbolt the frame from the inside face of the
outlet (both sides); pull the frame out; and remove the filter fabric (like a pillow case). Filter fabric
can be rinsed with water and reused until replacement is required. Rinse water can be discharged
to the WQ band.
iii. Replacement is required when filter fabric becomes saturated with hydrocarbons and changes
from a light grayish coloration to a dull greenish brown color. The replaced filter fabric must be
properly disposed of according to applicable local, county, and federal waste control programs.
A secondary set of filter fabric should be kept on-hand should any emergency arise requiring
immediate replacement.
iv. Re-install the frame back into place and bolt in place. Re-install the curb grate, if present. Replace
grates if visual inspection indicates that they are bent or damaged, creating an impedance to flow
or a hazard to pedestrian traffic.