Harris County Flood Control District
MBCO Engineering (MBCO) was selected by the Harris County Flood Control District (HCFCD) to provide survey and design services for the critical maintenance packages of K112-00, K112-01, K116-00, K117-00, K120-00, K127-00, K131-00, K131-01, K133-00 that were drastically affected by both the Tax Day Floods and Hurricane Harvey rainfall events. MBCO prepared design packages that resolved the repairs of classic rotational failures, typical erosion failures, displaced riprap and fallen trees caused by the high level of storm water eroding and scouring the channel banks.
The project is comprised of 9 individual sites, all of which reside in the Cypress Creek watershed in Harris County Precinct 4. All the channels experienced typical erosion failures and outfall pipe failures and channels K112-00-00-X005, K127-00-00-X012 and K133-00-00-X024 experienced classic rotational failures where the soils were unstable and when the toe was washed away and the unstable soils traveled along the failure plane to the bottom of the channel. These locations were evaluated by the geotechnical engineering firm for identification of where the failure plane was located; to be repaired using a rock mattress or a rock trench with the placement of imported fill in 6” lifts. K116-00-00-X003 and K117-00-00-X001 are both natural channels; the designs were mandated to keep the natural channels and repair the side slopes while preserving the top of bank.
To help maintain schedule on this project, MBCO used laser scanning technology to pick up failures that were too dangerous to climb and survey with conventional equipment. This allowed us to pick up the terrain and failures in a fraction of the time, saving both time and budget. When it became evident that the cost of materials necessary to make the repairs and prevent channel toe erosion was going to exceed the Agency’s budget, MBCO was able to, working with the program manager, redesign a detail and integrate it into the design. This solution was more cost effective and MBCO was able to complete the re-design within the time constraints of the project. Similarly, when deep scour holes were identified in the channel flowline, the design team was able to think outside the box and design a solution to repair these areas while saving the district the excess material and time which would have been required if the original design standard was utilized.
MBCO provided the topographic survey services to include slope failures, utility locations, storm sewer systems, and using a hydrone to map the channel floor. Boundary verification included the research of easements and locating boundary corners along the project route. MBCO monitored the job progression along each channel and was able to deliver on schedule separate deliverable packages of control maps, project baselines, topography, DTM’s, and boundary verification to the standards of Harris County Flood Control.
MBCO designed innovative drainage design solutions comprised of strategically buried riprap, slope drop structures, planned outfall structure replacement and riprap maintenance and treatments for outfalls. MBCO provided utility coordination services to minimize required utility relocations and ultimately expedite construction progress. MBCO prepared final design plans to include plan and profile sheets, site specific designed cross sections and details. MBCO provided traditional construction phase services as well as quantity cross verification.