[Ord. No. 5.000 § I, 9-9-1991; Ord. No. 2017-2935 § 1, 10-24-2017]
Storm drainage facilities for the City of Greenwood shall be
designed in accordance with the criteria set forth in this Chapter.
These criteria are presented as a minimum standard, and the designer
may use more complex methodologies or more stringent standards with
approval from the City Engineer. All design procedure must conform
to accepted engineering practice. Storm drainage facilities shall
be designed and certified by a Missouri Registered Professional Engineer.
[Ord. No. 5.000 § I, 9-9-1991]
All permanent facilities such as pipelines and culverts shall
be sized for projected flows generated by the ultimate development
of the drainage basin as currently zoned or as City approved land
use plans indicate. At a minimum, ultimate land use shall be considered
residential. Where proposed drainage facilities must accept flow from
upstream facilities, the flow must reflect ultimate development regardless
of the capacity of the existing upstream system.
[Ord. No. 5.000 § I, 9-9-1991]
Existing drainage facilities may be incorporated into expanded
facilities. The City must approve the structural integrity of existing
facilities to be used. The designer must show that the capacity of
the existing facility is sufficient for the ultimate development flows,
if the facility is considered a permanent installation.
[Ord. No. 5.000 § I, 9-9-1991; Ord. No. 2017-2935 § 1, 10-24-2017]
The developer of the new facility or development must provide
easement descriptions for maintenance of existing facilities should
such easements not be in place. Easements must be described and certified
by a Missouri Registered Land Surveyor. The City of Greenwood will
obtain easements based on descriptions provided.
[Ord. No. 5.000 § I, 9-9-1991; Ord. No. 2002-07-02-04 § 1, 7-2-2002; Ord. No. 2017-2935 § 1, 10-24-2017]
When the proposed facility or development discharges to an existing
downstream drainage system, the designer shall determine the capacity
of the downstream drainage system, including the path of the discharge
to the drainage system, to handle both existing flows and any increase
in flow created by the proposed facility or development. If the existing
downstream drainage system is adequate to handle existing flows, but
is not adequate for proposed additional flows, the designer may be
required to provide on-site flow detention facilities to reduce runoff
rates to the existing capacity. The City may also require detention
if the downstream drainage system is inadequate for existing flows.
The City may waive detention drainage facility requirements if the
developer increases the capacity of existing downstream drainage system
to meet ultimate development flows. If requested by the City, the
designer shall be required to compensate the City for all costs incurred
to conduct an independent study (prepared at the request of the City
and selected by the City) to determine if the impact, as determined
by the designer, is correct.
[Ord. No. 5.000 § I, 9-9-1991]
The designer shall determine the boundaries of any one percent
(1%) probable flood zone lying within his/her design area. Calculations
for flow quantity and depth shall be submitted to the City for review.
If the designer determines that a part of his/her area is included
in a FIRM flood zone erroneously, he/she may prepare information for
the City to submit to FEMA for a map amendment.
