June 1

Projects & Studies

Poor Farm & Kilmarnock Ditches

Poor Farm Ditch (HCFCD Unit D111-00-00) and Kilmarnock Ditch (HCFCD Unit D113-00-00) are man-made drainage channels that carry stormwater from surrounding neighborhoods in southwest Harris County to Brays Bayou. Collectively, the channels provide drainage to portions of the cities of West University Place, Southside Place, Houston and Bellaire. 

Prompted by concerns of frequent street and house flooding, as well as failing infrastructure in Poor Farm Ditch, the Harris County Flood Control District, in 2002, initiated a regional drainage study for the two channels to investigate alternative improvements that might be considered. 

During the execution of the study, a stakeholders group comprised of representatives from the cities of West University Place, Southside Place, Houston and Bellaire, as well as representatives from the Braeswood Place Homeowners Association, was organized to help the Flood Control District formulate alternatives and assess community preferences regarding possible solutions. The study findings were published in 2004 in a report entitled the “Poor Farm & Kilmarnock Regional Study” (2004 Study).

FEASIBILITY STUDY

The study was directed by Flood Control District staff and supported by Claunch & Miller Inc., engineering consultants, and focused on the hydraulic capacity of Poor Farm Ditch and Kilmarnock Ditch and the constraints associated with these two channels. Poor Farm Ditch provides drainage to approximately 1,330 acres of highly developed watershed, and Kilmarnock Ditch provides drainage to 884 acres of highly developed watershed. The analysis considered stormwater flow that would be generated by both 10 percent (10-year) and 1 percent (100-year) rainfall events. Because of the two channels’ close interface with Brays Bayou, and the ongoing federal flood damage reduction project  (“Project Brays”)  sponsored by the US Army Corps of Engineers and the Flood Control District, the study had to consider stormwater detention volume needed to mitigate the potential impacts on Brays Bayou resulting from identified improvements on these two tributary channels.

Key findings from the Poor Farm & Kilmarnock Regional Study included the following:

  • Kilmarnock Ditch has adequate capacity to convey runoff from a 1 percent (100-year) storm event. However, the channel crossings at the Beechnut Street/North Braeswood Boulevard bridge, and at the Brays Bayou outfall, are inadequate and need to be enlarged.
  • Poor Farm Ditch upstream of University Boulevard has adequate capacity to convey runoff from a 1 percent (100-year) storm event.
  • Poor Farm Ditch downstream of Bellaire Boulevard to the confluence with Brays Bayou has 57 percent excess capacity to convey runoff from a 1 percent (100-year)storm event.
  • The reach of Poor Farm Ditch between University and Bellaire boulevards is not adequate and would need to be enlarged by as much as 75 percent to convey runoff from a 1 percent (100-year) storm event.
  • The Bellaire Boulevard bridge needed to be widened because it was a constraint to stormwater conveyance.

The study concluded that, despite making the improvements to the reach of Poor Farm Ditch between University and Bellaire boulevards, the channel downstream of Bellaire Boulevard had more than adequate capacity to contain the increased flow within banks. No additional stormwater mitigation was necessary.

However, the study also concluded it would be necessary to mitigate the impacts of the proposed Poor Farm Ditch and Kilmarnock Ditch improvements on Brays Bayou by providing stormwater detention along Brays Bayou. It was estimated that 43 acre-feet of mitigation was necessary to mitigate impacts of the proposed Poor Farm Ditch improvements, and another 21 acre-feet for proposed Kilmarnock Ditch improvements.

SUBSEQUENT STUDIES

Following the Poor Farm & Kilmarnock Regional Study, the Flood Control District undertook additional, more detailed studies of Poor Farm Ditch. It was determined that proposed improvements on the channel reach between University and Bellaire boulevards would be limited by right-of-way, and something less than a 1 percent (100-year) channel design would be possible. A 2009 study concluded that the mitigation necessary for the proposed bridge and channel improvements on Poor Farm Ditch could be reduced to 13.56 acre-feet.

When that was combined with the requirement for 21 acre-feet needed to mitigate proposed Kilmarnock Ditch improvements, a total of 34.56 acre-feet would be required to mitigate impacts on Brays Bayou.

In 2010, the Flood Control District participated with the City of Houston in the construction of the Meyer Stormwater Detention Basin (HCFCD Unit D500-08-00), which resulted in District ownership of 39 acre-feet of stormwater storage. This storage was eligible to be used for storm drainage mitigation projects between Fondren Road and State Highway 288, which included the proposed improvements on Poor Farm Ditch and Kilmarnock Ditch. Specifically mentioned in the agreement is that 10.3 acre-feet of the District’s stormwater storage capacity in the Meyer Basin would be dedicated to the widening of the Bellaire Boulevard bridge. The above 10.3 for Bellaire bridge is part of the 13.6 acre-feet.

Subsequent versions of the Poor Farm Ditch Project Development Reports analyzing the design of the channel cross section on Poor Farm Ditch between University and Bellaire boulevards have been generated without reaching a consensus on how to proceed. 

COLLEGE STREET STORM SEWER PROJECT/BELLAIRE BRIDGE RESTRICTOR REMOVAL

In 2007, the City of West University Place initiated construction of the College Street storm sewer project to improve local storm drainage. Outfall for the storm drain was at the new Bellaire Boulevard bridge over Poor Farm Ditch. In 2010, a study conducted for the Flood Control District concluded that the impact from the storm drain on Poor Farm Ditch would be insignificant compared to the widening of the Bellaire Boulevard bridge. Hydraulic analysis of Poor Farm Ditch downstream of Bellaire Boulevard indicates the increased flow can be contained within banks. There is, however, an impact on Brays Bayou. For that reason, the Flood Control District required the City of West University Place to either restrict its outfall or provide 13.5 acre-feet of detention storage to offset the impacts on Brays Bayou.

Because the Flood Control District had additional capacity in the Meyer Basin beyond what was required for the Poor Farm and Kilmarnock projects, the District agreed to sell to the City of West University Place 4.4 acre-feet of stormwater storage capacity in 2012.

KILMARNOCK DITCH STUDY

In 2013, the Flood Control District elected to perform an internal review of the stormwater detention requirements associated with Kilmarnock Ditch. It was determined that, because no enlargements were proposed for the channel itself, the only mitigation needed would be associated with enlarging the channel crossings at the Beechnut Street/North Braeswood Boulevard bridge and at the Brays Bayou outfall. By conducting detailed modeling it was determined that flow overtops the current dual culvert crossings at the Brays Bayou outfall and enters Brays Bayou under existing conditions. For this reason it was determined the 21 acre-feet stormwater mitigation requirement identified in the initial Poor Farm & Kilmarnock Regional Study was excessive and could be used for other purposes. In early 2014, the District elected to sell an additional 9.1 acre-feet of capacity in the Meyer Basin to the City of West University Place.