harris county-green infrastructure initiatives
TRANSCRIPT
8/9/2019 Harris County-Green Infrastructure Initiatives
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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
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Depressed Median
Green Roads – One idea
Green Roads – One idea
Swale on shoulder or Median
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Currently under design.
Depressed Median
Birnamwood Drive
Road extension in Northern Harris County-nearSpring Creek. Close to a popular County Park.
Birnamwood Drive
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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…
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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
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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
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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
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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
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Questions