Stormwater Management Plan, Page 2
Planning and Capital Projects
Over a decade ago, Tulsa faced up to its need for $500
million in corrective flood projects. The city had been built,
over decades, without much of a drainage system, and the result was
disastrous. The task appeared overwhelming.
Since then, Tulsa has completed or has under construction more
than $200 million in capital plans and projects, including $80
million in federal funds.
The capital program includes structural, nonstructural and
multi-objective projects. By combining techniques, flood hazards
have been reduced for thousands of Tulsans.
More than $300 million in flood-reduction projects are still
needed. Tulsa's program is still under way, and will be for years,
to correct drainage problems that were created over many
decades.
Planning
The backbone of Tulsa's stormwater management system is its
master drainage planning. The planning process involves extensive
citizen participation, including hundreds of public meetings over
the past decade.
Master drainage plans. Tulsa has completed master drainage plans
for virtually all drainage basins. Each plan is a comprehensive,
watershed-wide study of a drainage basin that documents existing
floodplain information and recommends solutions for flooding and
drainage problems.
A typical master drainage plan is developed within the context of
the community, and so takes into account community values, existing
conditions, goals and objectives, and future plans. The result is a
plan for actions and projects, including costs and benefits.
City-wide master plan. In 1989, the city synthesized its various
master drainage plans into one city-wide document, The City of
Tulsa Flood and Stormwater Management Plan, 1990-2005. This
city-wide plan ranks and prioritizes hundreds of recommended
projects, to guide capital scheduling.
Capital projects
Priority-setting was challenging. Citizens in every watershed
faced severe flooding problems. In general, priorities are based on
hazard, cost, benefit, and feasibility.
Mingo Creek project. The 61-square-mile Mingo watershed drains the
eastern one-third of the city but has accounted for two-thirds of
Tulsa's flood damages in recent years. The U.S. Army Corps of
Engineers and the city worked together in the late 1970s to develop
a plan for Mingo flood control, which Congress authorized for
construction in 1986.
The Corps estimates that the completed $143 million project will
prevent $32 million in average annual flood damages. With an
average annual cost of about $16 million, the Mingo project has a
benefit-to-cost ratio of 2 to 1.
The local cooperation agreement signed by the city helped forge
new legislation, written into the Water Resources Development Act
of 1986, which also gives communities credit for past construction
projects. The federal government recognized that before 1986 Tulsa
had constructed some Mingo channels and detention basins that were
compatible with the Corps project. The federal government agreed to
give the city credit toward its local share plus reimbursement for
the federal share of prior expenditures that pertain to the
project. Tulsa has received $10 million in reimbursements and
expects to receive about $10 million more.
Acquisition and relocation. Over the past 15 years, Tulsa has
cleared more than 900 buildings from its floodplains. The largest
clearance came after the 1984 flood, when more than 300
single-family homes and 228 mobile homes pads were acquired and
cleared.
The City's floodplain program is gradually reducing its inventory
of thousands of floodprone buildings. The City is also updating its
post-flood mitigation plan to include acquisition and relocation
recommendations for before, during, and after a flood.
Small capital projects. Many flooding and drainage projects
throughout the city are localized but troublesome. They are
addressed through small capital projects, generally less than
$100,000 each. Every year, $700,000 is allocated from the utility
fee for small projects. Some are also funded through long-range
capital sources.
Floodproofing. In some instances flood damages to existing
structures can be averted by spot flood-proofing, such as elevation
of the existing structure on site, shields for windows and doors,
and ring levees. Oklahoma law does not allow the City to spend
public funds to floodproof individual structures, so currently the
City's role is limited to technical assistance to private property
owners.
Tulsa's Stormwater Management
Plan, Page 3
