Harris County-Green Infrastructure Initiatives

8/9/2019 Harris County-Green Infrastructure Initiatives

http://slidepdf.com/reader/full/harris-county-green-infrastructure-initiatives 1/16

John Blount, P.E., LEED AP

Director, Harris County-

Architecture & Engineering Division

Harris County-Green Infrastructure

Initiatives

Agenda

Introduction

Storm Water Program Overview

Green Infrastructure Initiatives

Rules for Low Impact Development

Green Roads Future Projects



Introduction Largest metro area in U.S with NO zoning.

Development based on the“Municipal Utility District”model.

High annual rainfall ~52 in.

~2500 miles of waterwaysand flood control channels.

2009- Bid $121 million inRoadway projects.

Storm Water Program Overview

1980’s- County and Flood Control District beganrequiring detention basins for storm water to reduceflooding.

1990’s to 2000’s – Development required to addressstorm water quality:

First through Construction phase.

Later by Permanent SWQ BMPs. We share our Phase I MS4 permit with the City of

Houston, TxDOT, and the Harris County Flood Control District.



Storm Water Program

Overview During Dry Weather:

The water in our bayous/channels is mostly WWTPeffluent (generally speaking, non-tidal areas).

This effluent is being called “Storm Water” by many,particularly when the effluent leaves the weir (outfall)of the WWTP.

When it Rains:

It pours!

WWTPs & systems may overflow, but most of water inbayous is Storm Water runoff.



Bacteria TMDLs We have Very High bacteria levels in streams.

Working with stakeholders for Implementation Planthrough the HGAC’s – Bacteria ImplementationGroup (BIG).

The BIG has targeted WWTPs

as a top pollutant source.

Bacteria TMDLs TCEQ placing bacteria

limits in WWTP newpermits & renewals,beginning this year.

-Likely not restrictive

enough for our regiondue to bacteriaregrowth in ourstreams.



Storm Water BMPs

Most developers implement a combineddetention/water quality basin to meet County requirements.

Some dry, some wet, a variety of designs.

SWQ for Road Projects Treating SWQ for road projects can be difficult, due

to their linear nature.

HC chose to not exempt road projects from our SWQregulations, so we do treat our own road projects thesame –Urban forestry, floatable collection, WQbasins, etc.



Advantages of GICounty benefits:

Reduced land for project.

Reduced capital cost.

Improved water quality.

Public perception.

Items to Evaluate

Financial Analysis – Is it cost effective (per project)?

Design Criteria – what is acceptable?

Hydrologic Modeling –which model to use?

TCEQ MUD-reimbursements – some GI/LID itemsare not reimbursable to the Developer.



Buy in for LID Working with stakeholders on Summer LID

workshops to develop criteria for LID.

June-Roads

July-Urban Re-developments

August-Site / Subdivisions

Invitation only.

City/County staff

and consultants.

County Rules for LID

The post development hydrograph indicates the peak flows are belowthe pre-development hydrographs for the 10 and 100yr storm events.

For SWQ, we also include storm events up to the 5yr event.

A conceptual design meeting is held.



Leading the South

LEED for County Buildings.

Major supporter of the Houston Land/Water Sustainability Forum.

Donated “Green Road” project for HLWF -LID contest andsupported contest with judging and support.

County employees participated in Contest from Green Road category.

Driving future workshops to implement LID design criteria for future regulations.

Working with EPA on Green Infrastructure alternatives.

Typical Roadway

Raised Median



Depressed Median

Green Roads – One idea

Green Roads – One idea

Swale on shoulder or Median



Currently under design.

Depressed Median

Birnamwood Drive

Road extension in Northern Harris County-nearSpring Creek. Close to a popular County Park.

Birnamwood Drive



I n d

e p e n d e n c e

I n d e p e n d e n c e P a r k w

P a r k

a y a w

y

2 lane asphalt Road

Independence Parkway The Road to TX Independence.

Used as a design category for the HLWSF LID Competition.

County Staff participated in contest, examples on following slides.

Green Road Design Challenge

From This…



To This…4 lane PERVIOUS asphalt Parkway

Existing

Tidal Road

Proposed

I n d e p e n d e n c e P a r k w a y

The existing road is borderedon the east by ditches of varying depth from 2’ to 3’.The easement just east of the ditches are overgrownwith mature trees, weeds,native grasses and seasonalwildflowers.

•Rain gardens and grass swales asbioretention elements for storm water

management•Green walls designed of hog wireand metal poles•Lighting is provided by solar panelsmounted on green wall•Dry stacked retaining walls allow theditch to be widened.

Design Concepts



Proposed Monument Pull-off

Existing Monument

The monument pull-off was designed toencourage passers-by topause and experienceHarris County’s history.

A tranquil mini-park area

is achieved with acircular permeablepavers patternsurrounding themonument anddecorative stone polesbordering the rear. Eachsides of the monument isflanked with rain

The existing marker is inneed of enhancement toprovide recognitiondeserving of suchhistorical landmark.

Design Concepts

Design Concepts

The “green wall” designed of metal poles and hog wire. Vines are used to provide coverage along the hog wirecreating a green wall. This application creates a similar coverage of bushes without the required trimming toachieve a manicured look.Butting the green wall are short columns with a profile inspired by the San Jacinto Monument. The columns aretopped with solar powered light poles. The existing Precinct 2 banners were relocated to the light poles. A HarrisCounty emblem is flanked by round pipes that are attached to the inside of the short columns.

Independence Parkway Easement Elevation



We envision an

opportunity for a bikepath that is a part of theState Park routes toIndependence Parkwayat strategic points.

Bike Trail Elevation

Design Concepts

Grass Crete & Porous Asphalt



HEC-HMS software is used in our office andtherefore was utilized to create this hydrological

data. The post development hydrographindicates the peak flows are below the pre-

development hydrographs for the 5yr,10 yr

and 100 yr storm events.

The same parameters and calculation method(SCS Method) from the published output file todevelop the Comparative Existing Model wasutilized and reflects a flow reduction.

5-Year Storm

Modeling

10-Year Storm 100-Year Storm

LID ROADWAY CONSTRUCTION COST

Excavation, demolition $180,000.00New fill material $637,000.00Grass paver section at median $160,000.00Pervious Pavers $250,000.00Concrete drives and tie ins $ 70,000.00Underground storm. $260,000.00Limestone retaining walls $291,000.00Porous asphalt paving $425,000.00Demolition and removal of temp. drives $ 20,000.00Ditch re-grading $ 80,000.00Misc. items (swp3, striping, permitting, bonding, etc.) $160,000.00Finish grading with grass, sod, and plantings $115,000.00Contingency $250,000.00Total Estimate $2,998,000.00

TYPICAL PRECINCT 2 ROADWAY CONSTRUCTION COST

1 Mile Roadway with side ditches $5,000,000.00*

Design Concepts



Questions

[email protected]

Documents

Harris County-Green Infrastructure Initiatives