North Carolina Piedmont Nutrient Load Reducing Measures Technical - - PowerPoint PPT Presentation

▶
north carolina piedmont nutrient load
SMART_READER_LITE
LIVE PREVIEW

North Carolina Piedmont Nutrient Load Reducing Measures Technical - - PowerPoint PPT Presentation

Jan 24, 2023 173 likes •546 views

North Carolina Piedmont Nutrient Load Reducing Measures Technical Report Project Update Victor DAmato Jonathan Smith Andrew Anderson and Natalie Carmen Project Approach - Schedule Activity May June July August September Task 1 Selection of

slide-1
SLIDE 1

North Carolina Piedmont Nutrient Load Reducing Measures Technical Report Project Update

Victor D’Amato Jonathan Smith Andrew Anderson and Natalie Carmen

slide-2
SLIDE 2

Project Approach - Schedule

Activity May June July August September Task 1 Selection of Measures

  • Kick off and NSAB meeting

Task 2 Data Sources

  • Data protocol
  • Data collection
  • Data assessment
  • Data summary

Task 3 Technical Report

  • Method/tool development
  • Draft report
  • NSAB presentation
  • Final report
slide-3
SLIDE 3

Project Approach – Tasks

  • Task 1. Selection of Measures
  • May 13th NSAB meeting: kick off/presentation attended by Vic, Jonathan
  • Will begin putting together data protocol (Task 2) in preparation
  • Prepared to discuss key questions to be addressed prior to data collection
  • Coordination with PTRC/DWQ
  • Task 2. Data Sources
  • Data protocol technical memo (by May 20th) – criteria for accepting data

– NC Piedmont applicability – Data QA/QC and other characteristics

  • Data collection – collect data sources/references
  • Data assessment – assess sources versus acceptance criteria
  • Data summary (by June 14th) – summarize assessment and recommend data

sources to use

slide-4
SLIDE 4

Project Approach – Tasks

  • Task 3. Technical Report
  • Method/tool development – data processing and

analysis

  • Draft report (by August 9th)
  • NSAB presentation (September 6th)

– Summarize draft report, comments received and proposed revisions and other actions to be taken

  • Final report (by September 20th)
slide-5
SLIDE 5

Today’s Presentation

  • For each measure:
  • Orientation to and

summary of content in draft report

  • Major issues

identified

  • Remaining work to

finalize report

  • Question/answer
  • Executive Summary
  • Background and Introduction
  • Project Parties and Roles
  • Project Overview
  • Data Sources and Assessment
  • (Load Reducing Measure)
  • (Load Reducing Measure)
  • Background
  • Baseline Load Characterization
  • Potential Management Practices
  • Management Practice Performance

Summary and Validation

  • Other Recommendations
  • Program Implementation

Recommendations

  • References
slide-6
SLIDE 6

Remedy Malfunctioning Septic System – Background

  • “Malfunctions” and load delivery characteristics vary spatially and

temporally

  • New malfunctions occurs as old malfunctions are remedied
  • Malfunction types
  • Illicit septic tank effluent discharge
  • Illicit graywater (e.g., from laundry) discharge
  • Demonstrated drainfield malfunction
  • Remedy types
  • Repair to properly functioning septic system
  • Repair with properly functioning TS-II (nitrogen-reducing) onsite system
  • Connection to permitted major NPDES system
  • Replacement with a discharging TS-II system
  • Credits awarded based on rates of different types of malfunctions and

remedies implemented

slide-7
SLIDE 7

Remedy Malfunctioning Septic System – Program Elements

  • New “survey program” for jurisdictions to establish

malfunction rates and accounting for malfunctions and remedies

  • 20% of systems inspected per year
  • Normalize seasonal differences
  • Apply malfunction rate improvement to all systems in jurisdiction
  • Remedies resulting from malfunctions identified via

traditional methods (complaints, required inspections, home transfers)

  • Systems (functioning and malfunctioning) otherwise

eliminated by connection to sewer

  • Averaging across multiple systems captures expected range

in malfunction intensity and remedy performance

slide-8
SLIDE 8

Remedy Malfunctioning Septic System – Malfunction Types

  • Illicit septic tank effluent discharge
  • TN load of 11 lb/yr-person (assumes no reduction in septic tank)
  • TP load of 1.8 lb/yr-person
  • Illicit graywater (e.g., from laundry) discharge
  • TN load of 0.70 lb/yr-person
  • TP load of 0.98 lb/yr-person
  • Based on published data post detergent phosphate reduction
  • Demonstrated drainfield malfunction
  • TN load of 1.1 lb/yr-person
  • TP load of 0.036 lb/yr-person
  • Based on combination of Piedmont water quality data and malfunction

accounting methodologies used in other watershed studies

slide-9
SLIDE 9

Remedy Malfunctioning Septic System – Remedy Types

  • Repair to properly functioning septic system
  • TN load of 0.55 lb/yr-person (95% reduction of STE load)
  • Zero TP load (100% reduction)
  • Based on combination of Piedmont water quality data, Chesapeake and others
  • Currently conducting additional literature review and review of Piedmont water

quality data to estimate functioning and malfunctioning system loads

  • Repair with properly functioning advanced (TS-II) onsite system
  • TN load of 0.22 lb/yr-person (60% + 95% = 98% reduction of STE load)
  • Zero TP load (100% reduction in soil)
  • Connection to permitted NPDES system
  • Assume all load transferred to point source sector, but awaiting DWQ input
  • Replacement with TS-II equivalent discharging system
  • TN load of 4.4 lb/yr-person
  • TP load of 1.8 lb/yr-person
slide-10
SLIDE 10

Remedy Malfunctioning Septic System – Credit Summary

TN load reduction credits TP load reduction credits

Remedy (R) M alfunctioning System (M) Properly functioning septic system (R1) (lb/cap/year) Properly functioning TS-II system (R2) (lb/cap/year) Connection to major NPDES system (R3)* (lb/cap/year) Connection to a TS- II Discharging System (R4) (lb/cap/year) Direct STE discharge (M1) 10.45 10.78 11.0 6.6 Direct graywater/laundry discharge (M2) 0.15 0.48 0.70

  • Demonstrated drainfield

malfunction (M3) 0.55 0.88 1.1

  • Remedy (R)

M alfunctioning System (M) Properly functioning septic system (R1) (lb/cap/year) Properly functioning TS-II system (R2) (lb/cap/year) Connection to major NPDES system (R3) (lb/cap/year)* Connection to a TS- II Discharging System (R4) (lb/cap/year) Direct STE discharge (M1) 1.8 1.8 1.8

  • Direct graywater/laundry

discharge (M2) 0.98 0.98 0.98

  • Demonstrated drainfield

malfunction (M3) 0.036 0.036 0.036

slide-11
SLIDE 11

Remedy Discharging Sand Filter – Background

  • Describes several different types of systems with varying characteristics
  • Only a portion have actually been identified and permitted
  • Accounting can be done on a system-by-system basis but there are

benefits for jurisdictions to combine program with that for septic systems

  • Discharging system types
  • Gravity-dosed single pass sand filters with regular discharges
  • Gravity-dosed single pass sand filters with no or infrequent discharges
  • Recirculating filters and TS-II equivalent treatment systems
  • Malfunctioning (surface failing) systems
  • Remedy types
  • Upgrade to recirculating filters or TS-II treatment systems
  • Connection to major NPDES system
  • Replacement with properly functioning septic system
  • Replacement with properly functioning TS-II onsite system
slide-12
SLIDE 12

Remedy Discharging Sand Filter – System Types

  • Gravity-dosed single pass sand filters with regular discharges
  • TN load of 7.4 lb/yr-person (33% load reduction)
  • TP load of 1.8 lb/yr-person (no load reduction)
  • Based on Durham/DWQ data and some published data
  • Gravity-dosed single pass sand filters with no or infrequent discharges
  • TN load of 7.4 lb/yr-person (33% load reduction)
  • TP load of 0.9 lb/yr-person (50% load reduction)
  • Recirculating filters and TS-II treatment systems
  • TN load of 4.4 lb/yr-person (60% load reduction)
  • TP load of 1.8 lb/yr-person (no load reduction)
  • Malfunctioning systems
  • TN load of 7.4 lb/yr-person (33% load reduction)
  • TP load of 1.8 lb/yr-person (no load reduction)
slide-13
SLIDE 13

Remedy Malfunctioning Septic System – Remedy Types

  • Upgrade to recirculating filters and TS-II

treatment systems

  • TN load of 4.4 lb/yr-person (60% load

reduction)

  • TP load of 1.8 lb/yr-person (no load

reduction)

  • Connection to major NPDES system
  • Assume all load transferred to point source

sector, but awaiting DWQ input

  • Repair to properly functioning septic

system

  • TN load of 0.55 lb/yr-person
  • Zero TP load
  • Repair with properly functioning advanced

(TS-II) onsite system

  • TN load of 0.22 lb/yr-person
  • Zero TP load
slide-14
SLIDE 14

Remedy Malfunctioning Septic System – Credit Summary

TN load reduction credits

Alternative (A) Discharging System (D) Upgrade to TS-II treatment system (A1) (lb/cap/year) Connection to major NPDES system (A2)* (lb/cap/year) Replacement with properly functioning septic system (A3) (lb/cap/year) Replacement with properly functioning TS-II

  • nsite system (A4)

(lb/cap/year) Single-pass filter with regular discharges (D1) 3.0 7.4 6.9 7.2 Single-pass filter with no or infrequent discharges (D2) 3.0 7.4 6.9 7.2 TS-II or equivalent treatment system (D3)

  • 4.4

3.9 4.2 Malfunctioning discharging systems (D4) 3.0 7.4 6.9 7.2

slide-15
SLIDE 15

Remedy Malfunctioning Septic System – Credit Summary

TP load reduction credits

Alternative (A) Discharging System (D) Upgrade to TS-II discharging treatment system (A1) (lb/cap/year) Connection to major NPDES system (A2)* (lb/cap/year) Replacement with properly functioning septic system (A3) (lb/cap/year) Replacement with properly functioning TS-II

  • nsite system (A4)

(lb/cap/year) Single-pass filter with regular discharges (D1)

  • 1.8

1.8 1.8 Single-pass filter with no or infrequent discharges (D2)

  • 0.9

0.9 0.9 TS-II or equivalent treatment system (D3)

  • 1.8

1.8 1.8 Malfunctioning discharging systems (D4)

  • 1.8

1.8 1.8

slide-16
SLIDE 16

Stormwater Measures – Improved Street Sweeping

Chesapeake Bay Expert Panel Recommendation Summary

  • Credit approved in March 2011
  • Primarily based on Law, 2008
  • Two credit methods:
  • Mass loading approach
  • Qualifying street lanes approach
  • *CBP reconvening in August 2013 to update protocol
  • Updated performance
  • Expanded credit for less frequent sweeping
slide-17
SLIDE 17

Stormwater Measures – Improved Street Sweeping

Street Sweeping Pollutant Removal Performance Background

  • First studies in 70’s -80’s
  • Technology of the time limited to mechanical broom
  • Initial research indicated no impact (NURP, 83)
  • Poor pick-up performance of small particulates
  • Improvements to sweeper design in last 30 years have resulted

in significantly increased performance

  • Many studies on pick-up performance, few on impact of

sweeping to downstream WQ

slide-18
SLIDE 18

Stormwater Measures – Improved Street Sweeping

Credit Protocol: Direct Measurement

  • Maintain records of collected “sweepings” mass
  • Conduct analysis of N and P content of collected materials
  • Alternative: Apply standard rates

Lbs of TN = 0.0025 pounds of dry weight sweeping solids Lbs of TP = 0.001 pounds of dry weight sweeping solids

  • Concerns:
  • Little research supporting impact of street sweeping on

downstream water quality

  • Nitrogen processing prior to discharge
slide-19
SLIDE 19

Stormwater Measures – Improved Street Sweeping

Credit Protocol: Miles swept method

  • Estimate annual Nutrient load to road surface
  • Apply removal performance per frequency and type of sweeper

technology

Frequency TP TN Monthly 4% 4% Biweekly 5% 6% Weekly 5% 6%

slide-20
SLIDE 20

Stormwater Measures – Improved Street Sweeping

Credit Protocol: Miles swept method

  • Concerns
  • Road dirt load and constituents highly variable
  • Age/type of roadway surface
  • Traffic load/type
  • vegetation/seasonal effects
  • Climate
  • Sweeping obstructions
slide-21
SLIDE 21

Stormwater Measures – Improved Street Sweeping

Credit Protocol: Miles swept method

  • Sweeping program criteria
  • No parking or other obstructions
  • Sweeper type: regen/vac
  • Primary and secondary roads only
slide-22
SLIDE 22

Stormwater Measures – Stream Restoration/Enhancements

  • Stream Restoration Credit Protocols
  • Prevented sediment
  • In-stream nutrient processing
  • Floodplain reconnection
  • Regenerative Stormwater Conveyance (RSC)
slide-23
SLIDE 23

Stormwater Measures – Stream Restoration/Enhancements

“Prevented Sediment” Protocol

  • Evaluates the reduction in nutrients delivered to receiving waters associated

with the reduction in streambank erosion and relies on computation of three factors:

  • Pre-project annual sediment load
  • Nutrient content (N and P) of streambank soil
  • Net efficiency (%) of restoration in reducing bank erosion
slide-24
SLIDE 24

Stormwater Measures – Stream Restoration/Enhancements

Prevented Sediment: Pre-Project Annual Sediment Load

  • Option 1: Estimate sediment loss rate based on pre-project monitoring of

streambank erosion rates via cross-section surveys and bank pins.

  • Requires pre-project monitoring
  • Monitoring stations must be representative of reach
slide-25
SLIDE 25

Stormwater Measures – Stream Restoration/Enhancements

Prevented Sediment: Pre-Project Annual Sediment Load

  • Option 2: Estimate sediment loss rate based on the application of the Bank

Assessment for Non-Point Source Consequences of Sediment (BANCS, Rosgen 2001, Doll, 2004) method. The BANCS method relies on two common bank erodibility estimation tools which have seen widespread application in North Carolina

  • Bank Erosion Hazard Index (BEHI)
  • Near Bank Stress (NBS)
  • Concerns:
  • Variation among practitioners
  • Erosion rate curves specific to region
slide-26
SLIDE 26

Stormwater Measures – Stream Restoration/Enhancements

Prevented Sediment: Nutrient content of eroded sediments

  • Option 1: Conduct monitoring of streambank sediment

characteristics within the reach of interest

  • Concerns
  • Sediment monitoring protocol
  • Distribution of sampling locations
slide-27
SLIDE 27

Stormwater Measures – Stream Restoration/Enhancements

Prevented Sediment: Nutrient Content of eroded sediments

  • Option 2: Use default nutrient concentration values

representative of urban streams within the region

  • Concerns
  • Variability between reaches
  • Representative values not published for NC

Source Phosphorus Nitrogen Content (lb/tn) 0.46 1.26

slide-28
SLIDE 28

Stormwater Measures – Stream Restoration/Enhancements

Prevented Sediment: Net efficiency

  • Incorporates the efficiency of the restoration to reduce

streambank erosion

  • Concerns
  • Efficiency may range widely between projects
  • Should also consider delivery of nutrients to

downstream resources Limited data was discovered supporting the selection of a restoration efficiency in NC Net Efficiency= 50%

slide-29
SLIDE 29

Stormwater Measures – Stream Restoration/Enhancements In-stream Nutrient Processing Protocol

  • Applies to projects or components of projects in which in-stream

design features promote nutrient processing specifically de-nitrification within the “Hyporheic” zone

  • Protocol:
  • Determine appropriate reach length for credit
  • Identify “hyporheic box”
  • Apply unit denitrification rate
slide-30
SLIDE 30

Stormwater Measures – Stream Restoration/Enhancements In-stream Nutrient Processing Protocol

  • Concerns
  • Hyporheic box/exchange
  • Bed material/bedrock can limit vertical extent of box
  • Slope
  • Substrate
  • Very limited on headwater streams
  • Denitrification rate
  • No published values for NC
  • Net reduction depends on bulk density of bed material
slide-31
SLIDE 31

Stormwater Measures – Stream Restoration/Enhancements

Floodplain Reconnection

  • Applies to projects in which stream restoration results in

frequent overbank flooding and provides temporary storage and treatment of overflows

.

slide-32
SLIDE 32

Stormwater Measures – Stream Restoration/Enhancements

Floodplain Reconnection Protocol

  • Estimate net storage volume of floodplain reconnection
  • Estimate N and P load/concentration delivered to the

floodplain*

  • Estimate N and P removal performance to floodplain

reconnection

  • Compute Net N and P reduction

*Since this credit applies to N and P contained in stormwater runoff, the load estimation should account for the performance of any upland BMPs.

slide-33
SLIDE 33

Stormwater Measures – Stream Restoration/Enhancements

Floodplain Reconnection

  • Estimate of net volume of floodplain reconnection
  • Survey or computation of floodplain treatment storage

volume

  • Computation of fraction of annual runoff which will be

“captured” by floodplain storage

  • Requires detailed hydrologic and hydraulic analysis
slide-34
SLIDE 34

Stormwater Measures – Stream Restoration/Enhancements

Floodplain Reconnection

  • Estimate of N and P Load delivered to the floodplain
  • Determine total N & P load delivered to watershed
  • < 40 acres JFLSLAT
  • > 40 acres
  • Falls: WARMF model
  • Jordan: Jordan Lake Model Compute net load

delivered to floodplain by multiplying total load by fraction of runoff treated

slide-35
SLIDE 35

Stormwater Measures – Stream Restoration/Enhancements

Floodplain Reconnection

  • Estimate N and P removal performance of floodplain

reconnection

  • Compute load reduction by applying stormwater

wetland effluent values (JFLSLAT) to reconnection volume

slide-36
SLIDE 36

Stormwater Measures – Stream Restoration/Enhancements Regenerative Stormwater Conveyance

  • Dry Channel RSC Protocol
  • Compute treated volume (filtered, infiltrated, retained)
  • Compute N & P load per JFLSLAT
  • Apply effluent values for treated volume per Dr. Hunts
  • ngoing research (use Sand Filter in interim)
  • Concerns
  • Unproven BMP in NC