City of Waco

CHALLENGE

Outdated Criteria, Policies, and Ordinances
Waco’s Storm Drainage Design Manual was published in 1959 and was the forerunner for municipal storm water management. Municipalities from around the State and across the U.S. used information from the Manual to establish their own criteria. The City of Austin, considered by many to be a leader in urban storm water management, has utilized Waco’s Manual as the foundation for much of their drainage design criteria.

The Manual’s focus and intent is to provide design criteria to engineers to use to design the various components of an urban storm drain system – inlets, storm sewers, culverts, channels, etc. The Manual does not address: 1) the effects of urbanization on downstream waterways and properties; 2) the management and protection of floodplains; or 3) the quality of the storm water runoff from urbanized areas and the possible effects that it may have on the water quality of the receiving streams, rivers, and lakes.

Inaccurate Floodplain Maps
FEMA updated their Flood Insurance Rate Maps (FIRM) utilizing updated digital Lidar topographic information. These new maps, published in 2008, are referred to as Digital Flood Insurance Rate Maps, or DFIRMs. After close review, two important discoveries were made:

1. Mapping errors existed in the newly published DFIRMs.

2. Existing structures and properties which previously were not inundated by the 100-year (1% recurrence interval) floodplain now appeared to be within the floodplain. Property values, especially newer, high-end homes and high-profile retail developments were compromised.

These inaccurate floodplain maps caused some property owners to pay high premiums for flood insurance when it is not warranted while also hindering economic development.

Outdated Capital Improvement Plan
Waco’s Drainage Capital Improvement Program was last updated in 2002; however, none of those projects have been implemented today. The reason that the CIP was not implemented was two-fold: 1) lack of funding; and 2) lack of awareness and priority due to drought conditions.

SOLUTION

Walker Partners has been retained to prepare a new Storm Water Master Plan which will serve as a “road map” for future storm water management planning. The goals for the Master Plan include the following:

• Accurate establishment and mapping of the limits of the 100-year floodplains of the creeks and streams within the city limits – based upon urbanization as it exists today, as well as for future growth.

• Review and updating of storm water management regulations and design criteria in an effort to reduce the loss of human life caused by flooding; to reduce flood damage to property; and to reduce soil erosion.

• The assurance of adequacy and safety of existing drainage infrastructure including bridges, culverts, channels, and other facilities.

• New policies, regulations, and ordinances to minimize pollutants and soil sediment transport in storm water runoff from new and existing development.

• The exploration of regional approaches and “best management practices” to storm water management planning.

• Identification of local and regional flood mitigation projects to provide long-term, sustainable flood protection measures.

• Guidelines and recommendations for a storm water fee structure in order to maintain and manage the existing drainage infrastructure as well as for the planning and construction of new capital improvements.

VALUE

When the Storm Water Master Plan is complete, it will provide an unprecedented road map for urban storm water management for a rapidly-growing community in Texas along the IH-35 corridor. It will complement the recently completed Water and Wastewater Master Plans as well as will support the soon to be published, comprehensive City Plan. 

completion date: 2020

location: waco, Tx