Harris County MUD 449 Wastewater Treatment Plant Expansion

Facilities requiring expansion were also common wall construction, and the EHRA team converted the facilities into aerobic digesters and sludge thickeners.

Northpark Drive Mobility Project

EHRA completed preliminary engineering, phase one environmental site assessment and schematic development for the widening of Northpark Dr. between US 59 and Woodland Hills Dr. EHRA also provided program management, drainage analysis and design, traffic engineering, environmental documentation and schematic design for the roadway, as well as grade separation at the Loop 494/UPRR railroad crossing.

EHRA conducted traffic operations and access management studies for the Northpark Dr. corridor. This corridor is approximately 2.2 miles long and has major signalized and unsignalized intersections and driveways that access various subdivisions and industrial developments. These studies laid the groundwork for the widening of Northpark Dr. from a four-lane boulevard cross-section to a six-lane boulevard complete street. The new street design includes low impact development drainage, conventional drainage, a grade separation at the UPRR crossing with mechanically stabilized earth retaining walls, two at-grade crossings for bi-directional frontage access, reconstruction of two concrete bridges over a diversion channel, intersection improvements, a roadway-adjacent multiuse path and traffic signal improvements.

Drainage analysis and design included hydrologic and hydraulic studies of both existing and proposed conditions to demonstrate that proposed project components would not adversely affect the 100-year floodplain in the area. The roadway and traffic designs contained horizontal and vertical alignments, cross-sections, plan and profile, sidewalk and bicycle accommodations, intersection layouts, traffic control plans and signing and pavement markings.

As the program management firm, EHRA coordinated with TxDOT, UPRR, the City of Houston Council District E, COH Planning and Development Department, COH Public Works and Engineering Department, Montgomery County, Harris County, HCFCD and area residents throughout the project.

Cutten Green Park Northwest Harris County MUD No.6

This project was the second phase of parks implementation outlined in the District's Parks Master Plan, which was completed by EHRA in 2007. Utilizing the site of a recently demolished former wastewater treatment plant provided an opportunity to create a passive park space for District residents.

Meridiana

The purpose of this project was to convert the existing at-grade crossing of Brazoria County Road 56 (CR 56) and State Highway 288 (SH 288) into a diamond interchange that includes a new overpass bridge and providing access to the newly developed Meridiana Development. Coordination with TXDOT, area landowners, utility companies, and Brazoria County was integral in obtaining approval and acceptance of the project. The main design challenge for this project was to accommodate double intersections on the west side of SH 288 to tie into existing access roads with two-way traffic and a new southbound on-ramp within a close proximity. EHRA coordinated with TxDOT throughout the project from preliminary concepts for the intersection and bridge through final design and construction. Each component of this project was designed in accordance with TxDOT standards and criteria.

Water Crest Development

EHRA assisted with the district creation of Montgomery County Municipal Utility District No. 126 to accommodate a ±329 acre master planned community located in northern Montgomery County in the City of Conroe, south of League Line Road, west of Longmire Road, and adjacent to Lake Conroe.

19 May 2023

Project InFocus: Tower Oaks Subdivision Drainage Improvements

Adam Earle, PE, PMP, ENV SP Practice Area Leader – Public Infrastructure

EHRA was contracted by Harris County to perform planning and design for the drainage improvements for the Tower Oaks Plaza Subdivision, located in northwest Harris County. This investigation identified drainage solutions intended to reduce the risk of structural flooding and improve resiliency in the subdivision.

Cypress Creek is the major source of flooding for the subdivision. EHRA utilized a two-dimensional analysis to determine the threshold of service that could be provided locally before Cypress Creek inundated the subdivision. The analysis revealed that the 10% annual exceedance probability event was the maximum achievable level of service for the internal drainage system. The internal drainage analysis concluded that the roadside ditch conveyance system was adequate for a two-year level of service in most locations, but the outfalls were not. EHRA then analyzed both the internal drainage system and the Tributary to Cypress Creek (K161-00-00) to determine what improvements needed to be made to achieve a ten-year level of service.

EHRA recommended the following drainage improvements:

Dual storm sewer and roadside ditch improvements along both sides of the Oak Plaza Drive. Storm sewer size varies from 18” to 5’x3’ RCB.
Upsizing outfall from 36” to 42” into K161-00-00
Ditch regrading along both sides of the road along King Circle and incorporation of a 6’x6’ RCB storm sewer trunkline
Adding 43 acre-feet of detention volume to mitigate additional flows entering Cypress Creek
Construction of overflow swale from the northeast corner of the subdivision to proposed detention basin
Use of freeboard within K161-00-00

Due to the location of the detention pond within a park and buyout area, there was extensive coordination with Precinct 3, Harris County and Harris County Flood Control to optimize detention storage while allowing for existing and proposed infrastructure within the park. During its design, EHRA put careful thought and consideration into maximizing the size and configuration of the detention pond, while minimizing the impact to the park. EHRA provided an estimate of how many trees would be impacted and went back and forth with the Precinct in collaboration to find a solution which would benefit the neighborhood with respect to drainage detention while maintaining tree coverage. In addition to these drainage improvements, EHRA recommended additional voluntary buyouts be pursued for structures within the effective 100-year floodplain for Cypress Creek.

EHRA also paid mindful attention to both schedule and cost throughout the duration of this project. When data showed two 36” Kinder Morgan pipelines crossing the project, EHRA designed a siphon for the storm sewer to take it under the gas lines and maintain 3’ of clearance. This resulted in a $3 Million cost saving and allowed the project to remain on schedule.

In 2023, EHRA completed the final construction plans for the Tower Oaks Plaza subdivision and has moved into the construction phase of this project. The construction is scheduled to start in June 2023 and be completed within 12 months.

PUBLIC WORKS Project In Focus