Stormwater Infrastructure Management-December 2015

Stormwater Infrastructure ManagementStorm Drainage Infrastructure Reinvestment ProgramWater Asset Management ConferenceDecember 3, 2015Arlington, VA

Department of Public Works and Environmental Services

Working for You!

A Fairfax County, VA, publicationDecember 2015

2Maintenance and Stormwater Management Division 2

Agenda

• History of County Stormwater Codes• Stormwater Program Vision• County Asset Management Responsibilities• Elements of STAMP (Stormwater Asset Management Program)

• Growing Process• Challenges


History of County Stormwater CodesNuisance flooding

Pro Rata Share

Erosion & Sediment Control1940s Clean

Water Act

Floodplain Protection1950s 1960s 1970s1980s

2000s

1990s

2010s

Ches Bay Act

Regional Stormwater

Management WSPOD

GASB

NPDES-MS4

permittingDam

Standards

Stormwater Tax

Stormwater Management

OrdinanceTMDLs


Stormwater Program Vision

Implement a comprehensive sustainable asset management program for the

effective operation, maintenance and reinvestment of storm conveyance and

stormwater management components in our community.


Because things like these…

…result in these

Why we do this


Fairfax County• 399 sq. miles• 1.1 million population• 30 watersheds to

Potomac and Occoquan Rivers

• Phase I MS4 community – Since 1997– TMDLs


County Storm System• Residential areas• Through drainage

on commercial, industrial and institutional sites

• Integrated with the road drainage system, VDOT responsibility

• No driveway culverts or floodplain crossings


County Asset Management Responsibilities

60,000 storm drainage structures 1,300 miles of storm pipe 90 miles of man-made channels 1,600 publically maintained

stormwater management facilities Inspections of 4,400 privately

maintained stormwater management facilities

20 State regulated dams No CSOs


Elements of County STAMP

Inventory

Condition

Assessment

Risk Analysis

& Prioritiz

ation

Reinvestment

Initial Acquisition

Retire


Inventory

Inventory• Easements• As-built drawings (length, size, slope, inverts, material, location, etc.)• Walking survey• GPS• CCTV• Repair activity

• Reports - GASB-34 - MS4• Maps for condition assessment• Repair history

GIS


Inventory – Attributes

Size

Material & Shape

Location

Sample size: 605 miles

0

50

100

150

200

250

300

350

1920-95 1930-85 1940-75 1950-65 1960-55 1970-45 1980-35 1990-25 2000-15 2010-5

Miles of Storm System Constructed by Decade: Approximate Age of System

Decade Constructed - Approximate Age (years)

Mile

s of S

tormS

yste

mCon

stru

cted

Age


Condition Assessment

Condition Assessment

• Complaint investigation• Walking survey• Pole camera• CCTV in-house• CCTV contracted• Repair activity

• Defect scoring - Structural - O & M•Reports - MS4 inspections - Video inspections• O&M work orders • Renewal projects


Condition AssessmentWalking Survey Pole Camera CCTV Camera

Missing Pipe*


Risk Analysis & Prioritization

Risk Analysis &

Prioritization

• Likelihood of Failure - Condition assessment - remaining life, material• Consequence of Failure - location - capacity/slope - roads - utility conflicts - original design/ construction flaws

• Prioritized assets for reinvestment


Likelihood of Failure - ConditionStructural

Score

2% >5000

12% >4000

38% >3000

25% >2000

23% >1000

O & M Score

12% >5000

15% >4000

17% >3000

49% >2000

7% >1000


Consequence of Failure - Risk

Who and What will be affected by failure and by how much

Example Factors Distance to buildings Distance to roads Crossing utilities Pipe capacity


Ranking/Prioritizing

Rank Quick Score Project Cost Year

1 5Z4Z Scott St 190,000 2016

2 5B42 Lake Dr 20,000 2016

3 5A3A Valley Ave 28,000 2016

4 5444 Meadow Ct 18,000 2016

5 533A King Rd 29,000 2016

6 5232 Farm Ln 22,000 2016

$250k budget


1 5Z4Z Scott St 190,000 2016

2 5B42 Lake Dr 20,000 2016

3 5A3A Valley Ave 28,000 2016

4 5444 Meadow Ct 18,000 2016

5 533A King Rd 29,000 2016

6 5232 Farm Ln 22,000 2016


1

2

3

4 5444 Meadow Ct 18,000 2016

5 533A King Rd 29,000 2016

6 5232 Farm Ln 22,000 2016


5A3F West Ct 130,000 2017

534D Duvawn St 89,000 2017

5324 Rose Ln 25,000 2017

5444 Meadow Ct 18,000 2016

533A King Rd 29,000 2016

5232 Farm Ln 22,000 2016


1 5A3F West Ct 130,000 2017

2 5444 Meadow Ct 18,000 2016

3 534D Duvawn St 89,000 2017

4 533A King Rd 29,000 2016

5 5324 Rose Ln 25,000 2017

6 5232 Farm Ln 22,000 2016

$275k budget

Likelihood of Failure × Consequence of Failure Risk


Reinvestment

Reinvestment• Prioritization• Historical costs• O & M cost• Economic cost• Social cost• Environmental cost

• Prioritized assets for reinvestment - repair - renew - replace• Reinvestment cost


Project Initiation

Review Data Site Recon Identify Solutions

Easement verification

As-built plans Video inspection

report Complaint

history Repair history Institutional

knowledge/ experience Utility conflicts

Structure proximity to asset (construction conflicts)

Equipment accessibility

Revegetation opportunities

Disruption to property owner & businesses

Reinvest- Repair . Point repair . Eliminate third party intrusion . Reset EW/ES- Renew . CIPPL . Slip line . Test & Seal

- Replace Evaluate costs

Select appropriate alternative

Secure funding Design Work order for repair (in-house) Contract - capital project - cleaning/ flushing

Implement


Reinvestment OptionsSlip Lining

Open Channels

Pipe Replacement Point Repair Repair Renew Replace


Growing Process

Inventory

Condition

Assessment

Risk Analysis

& Prioritiz

ation

Reinvestmen

t

Inventory Condition

AssessmentRemaining

Life / Predict Failure

Life Cycle & Replacemen

t CostsLevel of ServiceRisk

Optimize O&M

Investment

Optimize Capital

Investment

Funding Strategy

Comprehensive Program

Define Failure

WeightingEvaluation

Optimize Investment


How do we know we succeeded?

• Estimate 3.5% of system is in some stage of failure

• Ratio of proactive vs reactive improvements- Target as high a number as possible {(1% * 1300 mi)/(0.1 mi) = 130}

Fiscal Year

Proa

ctive

vs R

eacti

ve R

atio

'13 '14 '15 '16 '17 '18 '19 '20 '21 '22 '23 '24 '250.0

20.0

40.0

60.0

80.0

100.0

1.9 1.3 1.8 2.3 3.0 4.0 4.9 5.7 7.3 9.0

15.7

32.3

99.0


Challenges• Contract procurement – innovative solutions take time

• Staff training and technology – a good investment

• Emergency response – unpredictable, takes us off task, delays schedules

• Flexibility is an asset– Be willing to change direction, accommodate citizen/political expectations– Build a scalable program to accommodate fluctuating funding/budgets

• Realize the differences in rehabilitation methods– Environmental impacts – styrene– Contract line items – influenced by lateral connections and liner thickness– Bypass/flow control – may or may not be necessary – The shorter storm pipe segments impact mobilization and set-up costs as

compared to wastewater systems


Wastewater & Storm System Structural DifferencesFeature Wastewater System Storm System

Construction Quality High Rely on contractor &

third party. inspections

Pipe section lengths 10', 12', 20’, fewer joints 4', 6' & 8’, many joints

Lateral connections Essential Not permitted, unauthorized

Lift holes None, slings or pipe hooks. Requires seals: leaks cause sink holes, root intrusion cause fractures

System depth Typically deeper, beneath storm Shallower, above sanitary

Acceptance Tests

Mandatory, health and water quality, leaks not tolerated Not required, visual inspection

Chemical breakdown

Constant flows, chemical and gaseous exposure, corrosive attack on walls

Episodic flows with storm events, usually free of contaminants


Wastewater & Storm System Structural DifferencesFeature Wastewater System Storm System

Third party intrusions

Susceptible, not included in underground location programs for

digging

Higher susceptibility due to shallower nature, not included in underground

location programs for digging

Infiltration type

Groundwater more likely due to deeper system; Stormwater from

defects or deterioration

Saturating water due to shallower system, less soil overburden, sink holes develop

quicker

Infiltration leaks

Reduces capacity, increases treatment costs

Carries soil from pipe envelope, causing voids/sink holes,

increased standards for joint seals

Abrasive flow Turbulence associated with pumping and elevation and directional changes

Debris may scour pipe walls; debris particles are larger,

harder and more dense

Pressure flow Yes Not usually, more so in coastal areas.

Gravity flow Yes Yes

Destination Treatment plant Stream system (Waters of the U.S.)


Feature Wastewater System Storm System

Capacity Overflows are regulatory violations Overland relief is incorporated into design

Joints Watertight, subject to acceptance tests, minimizes root intrusion

Lack of joint seals result in seepage, root intrusion, causing sink holes

Line Maintenance and Monitoring

Fat, oil & grease accumulation requires frequent cleaning,

FOG & cleaning damage pipe wallsHeavy debris and deposition blocks system

resulting in flooding., debris is larger and dense

Surface Impacts Force mains are typically shallower than gravity sewers.

Shallower pipe systems are susceptible to third party intrusions

Flow pattern Constant with diurnal swingsEpisodic, usually free of contaminants.

Contaminants do not contribute to deterioration

Vermin Roaches, spiders, snakes, etc. Nocturnal mammals, crickets, frogs, critters

Closed and Open Characteristics Closed system, may have lift stations

Open channel to pipe, then to open channel. Susceptible to submerged outlets into

impoundments and floodplains.

Security Intrusion alarms typically installed on critical assets; SCADA, telemetry.

Difficult to keep secure and free of vandalism, critters and human entry

Wastewater & Storm System O & M Differences


Wastewater and Storm System Rehab Differences

Feature Wastewater System Storm System

Lateral connections Many None allowed

Pump & Bypass flows

Requires pump operations during installation; may

need pipe decommissioning and sanitizing step prior to

disassembly

Installation can be scheduled during 'dry' days, eliminating need for pump and bypass

Styrene Flow is 'treated' in POTWNot permitted in discharge to stream, requires new liner to be flushed and pumped into

sanitary sewer

28Maintenance and Stormwater Management Division

Contact:

Valerie Tucker, PE, Storm Drainage Section ChiefAmy Linderman, Storm Drainage Section Engineer

Maintenance and Stormwater Management DivisionDepartment of Public Works and Environmental Services

County of Fairfax, VirginiaFor more information or to request this document in an alternate format,

call 703-877-2800, TTY [email protected]

[email protected]/dpwes

28

For More Information

QUESTIONS ???

mailto:[email protected]

mailto:[email protected]

Stormwater Infrastructure Management-December 2015

News & Politics

Transcript of Stormwater Infrastructure Management-December 2015