BRAYS BAYOU + BRIDGEFall 2015 Concept Presentation

Presented by:

Julianne Crawford, Avi Gori, Kasia Nikiel

Project Description + Goals

➔ Design Brays Bayou channel modifications

➔ Reconstruct of Greenbriar Bridge between Braeswood & Main

➔ Consider of additional stormwater flow from 7200 Main

➔ Coordinate with 7200 Main development for other features

➔ Protect Meyerland area from future flooding

Brays Bayou between Fannin St. and Greenbriar St.

Greenbriar Bridge

Background Research + Modeling

Project Brays➔ Funded by US Army Corps and HCFCD➔ Comprehensive re-design of Brays Bayou

◆ Channel Modifications◆ Bridge Replacement/Renovation◆ New Detention Area

➔ Aimed at mitigating riverine flooding throughout Brays Bayou Watershed ➔ Status:

◆ Upper Reach: Completed◆ Middle Reach: In Progress◆ Lower Reach: In Progress

➔ Scheduled to be completed in 2021

Project Brays Proposed Improvements

100-year Floodplain (TSARP Model - 2004)

100-year Floodplain (Current Conditions - 2010)

100-year Floodplain (Post Project Brays - 2021)

100-year Floodplain (TSARP) at Site Location

100-year Floodplain (Post Project Brays) at Site Location

Bridge - Current Conditions

Concept Design

OPTION 1: Widen the Channel

HEC-RAS Geometry for Greenbriar Section

Main Street

Greenbriar Street

Fannin Street

Cross Section Comparison - Downstream (RS 56478)

Current 100-yr Level (44.07 ft)

PPB 100-yr Level (43.47 ft)

PPB Geometry

Current Geometry

OPTION 1: Widen the Channel -- BRIDGE

OPTION 2: Retaining Wall

HEC-RAS Geometry for Greenbriar Section

Main Street

Greenbriar Street

Fannin Street

Cross Section Comparison - Upstream (RS 59882)

Current 100-yr Level (45.70 ft)

PPB 100-yr Level (44.96 ft)

PPB Geometry

Current Geometry

OPTION 2: Retaining Walls -- BRIDGE

Existing Plan View of Bridge Deck

87.0’

Bridge Tie-Ins With Existing Roads

87.0’

5% Grade 4.35’

Proposal

Modified Scenario

➔ Retaining walls and some

widening on both banks

from Main to Greenbriar

➔ Retaining walls and

substantial widening on the

right bank from Greenbriar

to Fannin

Modified HEC-RAS Geometry Examples (Upstream - RS 58740 )

Modified Geometry

PPB Geometry

Modified HEC-RAS Geometry Examples (Downstream - RS 57958)

Modified Geometry

PPB Geometry

Modified Scenario Results - RS 59882

Modified Geometry

PPB Geometry

Modified 100-yr LevelPPB 100-yr Level

44.71 ft 44.96 ft

Modified Scenario Results - RS 56478

Modified Geometry

PPB Geometry

Modified 100-yr LevelPPB 100-yr Level

43.47 ft 43.37 ft

Proposed Bridge Cross-Section

Proposed Plan View of Widened Bridge Deck

Impact of Proposed Modifications

➔ Modifications along the Main to Fannin portion of the channel should not have

drastic adverse effects on downstream sections.

➔ According to the 100-year floodplains, both current and post project brays, the

areas downstream of our site already face a much lower inundation hazard

than the middle and upper reaches.

Moving Forward

Brays Bayou

➔ Finalize channel modifications for Main to Fannin segment

➔ Add additional cross sections to existing HEC-RAS geometry

➔ Perform unsteady state HEC-RAS analysis

➔ Incorporate additional flow from hotel if necessary

Proposed HEC-RAS Geometry Modification

Bridge

➔ Finalize aesthetic design with 7200 Main St. group

➔ Determine appropriate foundations

➔ Superstructure/Substructure design of the bridge

Meyerland

May 2015 Storm - Comparison of Flooding to Current 100-year Floodplain

May 2015 Storm - Damage Reports in Meyerland

100-year Floodplain (Post Project Brays) at Meyerland

Appendix

Channel Profile

Fannin Greenbriar Main

Direction of Flow

Construction

Green Space

➔ Finalize design for green space with hotel

➔ Ensure that all trails are integrated smoothly

Meyerland 100-yr Floodplain - Current Conditions v. Post Project Brays