Floodplain Management Program Notes
Bill DeGroot, P.E., Chief, Floodplain Management Program
Planning for the future
One of the first and best policy decisions of the District was to delineate and
regulate 100-year floodplains based on projected future development of the watershed. I
was reminded of this fact again recently when the 2000 census numbers were released and we
found that Colorado had added a million people over the last ten years, with most of them
landing in the Districts area.
Even though this makes all the sense in the world we still have lots of developers and
their engineers insisting that they should only have to address the historic discharges.
We constantly have to educate these folks that urbanization dramatically changes the
watershed hydrologic regime, and those changes have to be accounted for in order to
provide for the health, safety and welfare of our citizens and their customers. The surest
way of doing that is to use future conditions hydrology.
Our preferred approach continues to be to stay out of the floodplain, thereby
preserving its natural and beneficial values while minimizing the risk to new development.
David Mallorys cover story details examples of several successful developments where
the developer has set aside open space along major drainageways, to the benefit of all
Another approach, which we have been putting into many of our recent master plans for
developing areas, is regional detention. The advantages of regional detention are that you
can own it, maintain it, and know that it will be there when needed. The major
disadvantage is getting the funding to get it built by the time it is needed. More on this
The year in review
We continue to be just about maxed out on development referrals, and it is a constant
struggle to assure that new development doesnt increase the flood hazard potential
within the District.
Our maintenance eligibility program continues to expand under David Mallorys
direction. He currently has over 200 separate projects somewhere in the process between
design review and final acceptance of construction. Unfortunately, most projects, no
matter how simple, require two, three or even four submittals.
Kevin Stewart continues to assure that we have the best possible flood detection
system, and he continues to be in demand as an expert in this field (see his list of
professional activities on page 20 and his column in this issue). If you check out our web
site at www.udfcd.org you will also see Kevins
One real challenge has been to implement portions of our master plans, particularly
regional detention facilities, as development occurs. We have had some successes over the
last couple of years that I would like to highlight.
The E-470 Public Highway Authority has helped build the first phase of detention ponds
where their highway construction crossed East Toll Gate Creek and Tributary T to First
Creek. They also constructed their crossing of Second Creek such that it is compatible
with the plans for future implementation of a detention pond at that location. Finally,
their plans for their final construction phase include borrow areas on Third Creek and
Buffalo Run Tributary which will be converted to detention ponds. Weve had some
battles along the way but we do appreciate and acknowledge the Authoritys efforts.
We have negotiated an intergovernmental agreement (IGA) with Aurora, Denver, Gateway
Regional Metro District and Town Center Metro District (Oakwood Homes) for implementation
of the regional detention facilities called for in the upper First Creek master plan,
including cost sharing for two of the facilities, Green Valley Ranch Golf Course Pond and
Blue Grama Pond. The IGA calls for Town Center to construct the Green Valley Ranch pond in
conjunction with golf course construction and to be reimbursed by the other parties. Even
though the IGA is still in the signing process, Town Center went ahead and built the Green
Valley Ranch pond. I appreciate their willingness to do that.
Perhaps the most gratifying project, however, was the construction of what we call
Parkfield II Pond by American Realty Trust (ART) on the Rocky Mountain Arsenal (RMA). We
have been trying for six years to negotiate intergovernmental agreements between Denver,
the RMA, Commerce City, Adams County and the District for the implementation of the
Irondale Gulch master plan.
Finally, everything came together in 2000 for this one facility. The US Fish and
Wildlife Service (USFWS), ART and Denver signed the agreement and construction began. The
key elements of the agreement are that the USFWS, acting on behalf of the RMA, allowed the
facility to be built on the RMA; the project creates 6.9 acres of new wetlands, ART funded
the project and built it; and Denver agreed to accept maintenance responsibility for the
facility. Our involvement was to approve the facility for District maintenance
eligibility. We expect Denver to request our maintenance assistance out of the Denver
allocation of District maintenance funds.
With that success under our belts, we have begun preparation of an environmental
assessment (EA) of the remaining master planned facilities proposed on the RMA. Our hope
is to have an EA approved later this year, which will then allow us to implement these
facilities over time as needed. ERO Resources/Sellards and Grigg is the consultant.
Finally, we completed an interim implementation plan for Third Creek. We know that
implementation of the master plan will be a long time coming. In the meantime development
of the upper watershed is underway, and the lower Third Creek facilities are very limited
in their capacity. This plan will help us buy some time before the full master plan
facilities will be required. HDR Engineering prepared the plan.
I continued to represent the National Association of Flood and Stormwater Management
Agencies (NAFSMA) as an advisor to FEMAs Technical Mapping Advisory Council. The
councils authorization expired in November. Its final report is being printed, and,
along with FEMAs proposed map modernization plan, offers great hope for future maps.
However, until FEMA receives some significant funding source ($750 million over seven
years), most of these recommendations will languish.
Our Cooperating Technical Communities (CTC) activities were fairly limited this year.
In March we felt we had reached an agreement with FEMA to assume the review of requests
for Letters of Map Change (LOMCs). In fact we even selected a consultant to assist us with
that effort. However, at the last moment FEMAs lawyers found something they
didnt like, and we have been unable to finish the deal.
We received a small grant from FEMA from funds allocated to CTCs. We used the funds to
combine AutoCAD files from our Willow Creek Flood Hazard Area Delineation (FHAD) study and
Douglas County GIS roadmap files using FEMAs Digital Flood Insurance Rate Map
(DFIRM) specifications. We used that experience to develop guidelines for our consultants
to use on future FHADs to assure maximum compatibility with future DFIRMs. Our consultant
was Merrick and Company.
A pet peeve
One of my pet peeves is developer engineers who look at a FIRM and if no floodplain is
shown, declare their project to be free of flood hazards. Never mind the size of the
channel on their site or the size of the tributary watershed. Never mind the fact that the
Flood Insurance Study that created the FIRM is 20 years old and that the drainageway
wasnt studied then because it was way out in the boonies. And never mind that the
District delineated the floodplain several years before. If its not on the FIRM,
there is no hazard.
Lakewood City Engineer Jay Hutchinson has asked FEMA to put the following note on
Lakewoods FIRM and they have agreed to do so: "Local community floodplain
management requirements may apply in areas other than specific zones shown on this Flood
Insurance Rate Map. Contact the local community for specific requirements." Maybe it
Master planning efforts
Somehow I ended up managing two difficult master planning projects, even though the
District has a separate Master Planning Program. Im certainly going to be more
careful in the future so that that doesnt happen again.
We have completed the Phase A portion of the master plan revision process for the lower
portion of the First Creek watershed. We expect Commerce City and Adams County to select
an alternative for preliminary design by the end of February, and the new master plan to
be done by the fall. We have also been re-delineating the First Creek floodplain and
delineating some tributary floodplains for the first time. Our consultant is Turner,
Collie & Braden.
We have also completed the Phase A for the South Boulder Creek master planning effort.
This is the Districts third attempt to prepare a plan that has a chance to be
implemented. We should know by April if we have been able to devise an alternative
acceptable to Boulder, Boulder County and the University of Colorado. Our consultant
is Taggart Engineering Associates.
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