rb-ar 0 21 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 predicted annual volume (ac-ft)...

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  • 1

    Brandes, Deborah@Waterboards

    From: Megan Otto Sent: Tuesday, April 15, 2014 11:37 AM To: Purdy, Renee@Waterboards; Ridgeway, Ivar@Waterboards; Nguyen,

    Thanhloan@Waterboards; Lai, Ching-piau@Waterboards; Christmann, Rebecca@Waterboards

    Cc: Ken Susilo; Brandon Steets; hubertus.cox@lacity.org; hamid.tadayon@lacity.org; victor.e.harris@us.mwhglobal.com; elaine.jeng@redondo.org; rduboux@malibucity.org; Jennifer Brown; srobinson@jlha.net; tmoon@dpw.lacounty.gov

    Subject: Santa Monica Bay Watersheds - RAA Approach Presentation Attachments: DRAFT SMB RAA Approach - RB Meeting_040914.pdf

    Good morning, 

    Thank you again for your time and feedback on the proposed RAA approach for the Santa Monica Bay Watersheds. I  have attached the slides that were presented at the April 9th meeting. 

    Best regards,  Megan 

    Megan M. Otto, P.E.  Project Engineer   Water and Natural Resources  ------------------------------------------------------  3415 S. Sepulveda Blvd., Suite 500  Los Angeles, CA 90034  Phone: 310.957.6100  Direct: 310.957.6112  www.geosyntec.com  

    This electronic mail message contains information that (a) is or may be LEGALLY PRIVILEGED, CONFIDENTIAL, PROPRIETARY IN  NATURE, OR OTHERWISE PROTECTED BY LAW FROM DISCLOSURE, and (b) is intended only for the use of the Addressee(s) named  herein. If you are not the intended recipient, an addressee, or the person responsible for delivering this to an addressee, you are  hereby notified that reading, using, copying, or distributing any part of this message is strictly prohibited. If you have received this  electronic mail message in error, please contact us immediately and take the steps necessary to delete the message completely from  your computer system. 

     Please consider the environment before printing this e‐mail

    RB-AR 3965

  • D R A F T

    SANTA MONICA BAY WATERSHEDS

    Reasonable Assurance Analysis (RAA) Approach for Enhanced Watershed Management Programs (EWMPs)

    Los Angeles Regional Water Quality Control Board April 9, 2014

    1

    RB-AR 3966

  • D R A F T

    Outline • Objectives • WMGs & Study Area Overview • Reasonable Assurance Analysis (RAA) Approach

    • Dry Weather Approach • SBPAT Overview & Calibration • Target Load Reduction Approach • Structural BMPs • Non-Structural BMPs • Demonstrating

    “Reasonable Assurance” • Summary

    2

    RB-AR 3967

  • D R A F T

    Objectives • To present our draft RAA approach for RWQCB consideration • To receive initial feedback and input from RWQCB • To confirm acceptance of approach

    3

    RB-AR 3968

  • D R A F T

    Watershed Management Groups • North Santa Monica Bay Coastal Watersheds WMG

    (Jurisdictional Groups 1 and 4) • Santa Monica Bay WMG (Jurisdictional Groups

    2 and 3) • Beach Cities WMG (Jurisdictional Groups 5 and 6) • Peninsula WMG (Jurisdictional Group 7)

    4

    RB-AR 3969

  • D R A F T

    Study Area Overview

    5(modeled in RAA)

    RB-AR 3970

  • D R A F T

    North Santa Monica Bay Coastal Watersheds WMG WMG Agencies • City of Malibu • Los Angeles County Flood Control District (LACFCD) • County of Los Angeles

    6

    Reference Watershed

    RB-AR 3971

  • D R A F T

    NSMBCW WBPCs

    7

    Category Water Body Pollutant

    1

    SMB Trash/Debris DDTs/PCBs

    SMB Beaches Dry Weather Bacteria, Wet Weather Bacteria

    Malibu Creek and Lagoon Indicator Bacteria Nutrients

    Malibu Creek Trash

    2 Topanga Canyon Creek Lead Malibu Creek Sulfates & Selenium Malibu Lagoon pH

    3 None None

    WBPCs established consistent with RB Guidelines for RAA

    RB-AR 3972

  • D R A F T

    Santa Monica Bay WMG WMG Agencies • City of Los Angeles • City of Santa Monica • City of El Segundo • LACFCD • County of Los Angeles

    8

    RB-AR 3973

  • D R A F T

    SMB WBPCs

    9

    Category Water Body Pollutant

    1 SMB Beaches Dry Weather Bacteria, Wet Weather Bacteria SMB PCBs/DDTs SMB Offshore/ Nearshore Debris

    2 Santa Monica Canyon Channel Lead Indicator Bacteria

    3 None None

    WBPCs established consistent with RB Guidelines for RAA

    RB-AR 3974

  • D R A F T

    Beach Cities WMG WMG Agencies • City of Redondo Beach • City of Manhattan Beach • City of Hermosa Beach • City of Torrance • LACFCD

    10

    RB-AR 3975

  • D R A F T

    Beach Cities WBPCs

    11

    Category Water Body Pollutant

    1

    SMB Beaches Dry Weather Bacteria, Wet Weather Bacteria

    SMB Trash/Debris DDTs/PCBs

    Dominguez Channel (including Torrance Lateral)

    Toxicity Total Copper, Total Lead, Total Zinc

    2 Dominguez Channel (including Torrance Lateral)

    Indicator Bacteria

    3 Dominguez Channel (including Torrance Lateral)

    Cyanide pH Selenium Mercury

    WBPCs established consistent with RB Guidelines for RAA

    RB-AR 3976

  • D R A F T

    Peninsula WMG

    12

    WMG Agencies • City of Palos Verdes Estates • City of Rolling Hills Estates • City of Rancho Palos Verdes • County of Los Angeles • LACFCD

    RB-AR 3977

  • D R A F T

    Peninsula WBPCs Santa Monica Bay Dominguez Channel

    • Indicator bacteria • DDT/PCBs • Marine debris

    • Toxics • Metals • Indicator bacteria • Cyanide • pH

    13

    Category Water Body Pollutant

    1

    SMB Beaches Dry Weather Bacteria, Wet Weather Bacteria

    SMB Trash/Debris DDTs/PCBs

    Machado Lake

    Trash DDTs/PCBs Chlordane Dieldrin Odor, Eutrophic Conditions, Algae, Nitrogen, Phosphorus, Ammonia, Chlorophyll a, Dissolved Oxygen

    Inner Harbor, Outer Harbor, Cabrillo Marina, Fish Harbor

    Copper, Lead, Mercury, Zinc PAHs DDTs/PCBs Chlordane

    2

    Wilmington Drain Copper, Lead Coliform Bacteria

    Machado Lake ChemA (fish tissue) Palos Verdes Shoreline Park Pesticides SMB Sediment Toxicity

    3 None None

    WBPCs established consistent with RB Guidelines for RAA

    RB-AR 3978

  • D R A F T

    14

    Dry Weather Approach for Bacteria

    Evaluation questions for every shoreline Compliance Monitoring Location (CML)

    RB-AR 3979

  • D R A F T

    Dry Weather Approach for Other Pollutants • Dry weather flows may be from non-MS4 NPDES permitted

    or conditionally exempt sources • To address remaining non-exempt flows, WMAs may adopt

    new residential/commercial over-irrigation controls such as: • Smart controller rebates • Water waste ordinance • Outreach/education • Site inspection/audits • Wet weather BMP that will also capture/treat dry weather flows

    • RAA will be narrative (i.e., no modeling) and will assume that proposed non-structural BMPs will eliminate any existing non-exempt NSW flows • Therefore 100% reduction of baseline load, and RA

    demonstrated 15

    RB-AR 3980

  • D R A F T

    Wet Weather Modeling Process

    Calibration •Hydrology •Water quality

    Targets •Select average,

    critical years •Set “existing”

    baseline loads to be consistent with TMDL analysis

    •Set “allowed” loads (bacteria: use open space LU; other pollutants: use WQS)

    •Baseline – Allowed = Target Load Reduction

    WQ Benefit •SBPAT to model BMP

    load reductions (LID/onsite, distributed, regional)

    •Non-modeled nonstructural: quantify using static “mass balance” calcs or assume bulk reduction (5-10%)

    Compliance •Compared expected

    load reductions with TLRs Reasonable Assurance of Compliance

    •Report output ranges based on stochastic analysis

    •Address interim and final limits/ milestones

    16

    Targets set consistent with RB RAA Guidelines

    RB-AR 3981

  • D R A F T

    SBPAT Overview

    17

    Model selection consistent with RB RAA Guidelines

    RB-AR 3982

  • D R A F T

    1) Randomly select number of storms, Ns, for given year from storm distribution

    2) Randomly select Storm Sifrom period of record – look up depth of rainfall, BMP hydraulic performance

    Catchment definitionSmallest unit = unique land use-distribute BMP combination

    Mean and st dev of # storms per year;  List of discrete storm characteristics from continuous simulation

    3) Estimate pollutant concentration in Storm Si from each land use area by randomly sampling from LU EMC distributions

    7) Sum bypass and treated flows to yield load, volume and concentration in Storm Si 8) Repeat steps 1-7 Ns times; sum to yield annual pollutant load 9) Repeat for many storms (20,000 is typical) to produce distribution of storm concentrations and annual loads

    6) Estimate BMP effluent concentration by randomly sampling from distributions 5) Apply percent capture and volume loss 4) Calculate total runoff volume and pollutant load for each land use; sum to yield watershed average concentration for storm Si

    18

    Monte Ca

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