PEAIP Tracking, Quantifying, and Reporting for Phase II MS4 Permit Compliance

Transcription

1 PEAIP Tracking, Quantifying, and Reporting for Phase II MS4 Permit Compliance Avery Blackwell, P.E Geosyntec Consultants, Santa Barbara, CA Cathleen Garnand County of Santa Barbara, Project Clean Water Program 1

2 2 Discussion Topics Requirements, Local Context, and Model Objectives LPR Model Overview and Lessons Learned LPR Model Benefits Questions

3 Phase II MS4 Permit Requirements Quantification of pollutant loads and pollutant load reductions achieved by the program as a whole (Section E.14.a.ii.a.6) Assess BMP and program effectiveness in terms of the following Outcome Levels: 4) Pollutant load reductions (Sections E.14.a.ii.b.4) Quantitatively assess BMP performance at reducing pollutant loads wherever feasible, using science-based estimates of pollutant load removal for BMPs where direct measurement of pollutant removal is overly challenging (Sections E.14.a.ii.d.2) 3

4 Central Coast Regional Board Requirements July 2014 June 2016 Quantify Pollutant Loads and Load Reductions (Yr 2) Evaluate and select flow and pollutant loading models; Prioritize load quantification by catchment; and Provide schedule for completing pollutant load quantification to inform submittal of Stormwater Program Modifications by Year 5 Map stormdrain system (Yr 2) Catchment delineation to support catchment scale stormwater volume and pollutant loading (Aug 2016) Structural BMP Inventory (Yr 3) Volume and Pollutant Loading, Catchment Ranking, without BMPs (Yr 3) Structural BMP Assessment, Volume and Pollutant Loading, Catchment Ranking with BMPs (Yr 5) 4

5 Santa Barbara County Context 5

6 6 Primary Model Objectives Perform minimum requirements from Permit and Central Coast Regional Board Customizable with County-specific datasets Ease of use Reflect Countyspecific water quality priorities Low cost No models existed that could fulfill all these objectives, therefore it was necessary to create a new model

7 7 Load, Prioritization, and Reduction Model (LPR Model)

8 8 LPR Model Components Quantify baseline annual average wet weather pollutant loads and runoff volumes; Prioritize MS4 catchments; Track BMP implementation details; Quantify non-structural and structural BMP pollutant load and runoff volume reductions; and Summarize, format, and graphically present all results for easy reporting.

9 Quantify Runoff Volumes and Pollutant Loads 9

10 Estimate Runoff Volume Runoff coefficients developed using: detailed land use (to estimate imperviousness) hydrologic soil group Average annual precipitation Drainage areas 1. catchments 2. MS4 Permit Area 3. Watershed 4. to BMPs 10

11 11 Estimate Runoff Volume Lesson Learned: Land use data should be verified

12 Calibration of Runoff Volumes Observed Flow Data Model-Predicted Runoff Volume Annual Precipitation Data 25,000 20,000 15,000 10,000 5,000 Atascadero Creek USGS Flow Gauge Observed Annual Runoff Volume (ac-ft) Statistical Comparison of Runoff Volumes Calibrated Runoff Volume Multiplier Modeled Runoff Coefficients 25,000 20,000 15,000 10,000 5,000 Land use and Soil GIS data Modeled Annual Runoff Volume (ac-ft)

13 Catchment and Land Use Loads MS4 Permit Area by Land Use 13

14 Watershed Loads Lesson Learned GIS analysis removed IGP parcels and Caltrans by MS4 & non-ms4 areas 14

15 Prioritize Catchments 15

16 16 Catchment Prioritization Pollutant of Concern Identification Pollutant of Concern Prioritization All pollutants Pollutants with available land use EMC data (Modelable pollutants) Modelable pollutants that have land use EMCs above Basin Plan objectives or related TMDL WLAs for MS4 dischargers (Pollutants of Concern [POCs]) Pollutant-specific catchment priority rankings are calculated for each Modelable pollutant POCs are assigned weighting factors based on watershed-specific 303(d) listings and TMDLs Final catchment priorities are made based on combined weighted POC-specific rankings Areas of highest priority to the Permittees

17 Pollutant of Concern Identification Residential Land Use MS4 Area Land UsesSingle-Family TSS TP DP NH3 NO3 TKN Diss Diss Fecal Tot Cu Tot Pb Tot Zn Cu Zn Col. #/100 mg/l mg/l mg/l mg/l mg/l mg/l ug/l ug/l ug/l ug/l ug/l ml ,600 Commercial ,510 Industrial ,700 Education ,800 Transportation ,680 Multi-Family Residential ,800 Agriculture ,800 Open Space BPO or typical WLA: 0.3* 8* 13** 14** 82** 120** 120** 400* Cells highlighted yellow have Land use EMCs that exceed BPO or typical WLAs * SMR Nutrient /Bacteria TMDL wet weather WLA for MS4 dischargers ** CTR default value (acute freshwater criteria, hardness -100 mg/l) 17

18 Pollutant of Concern Prioritization 18

19 19 Catchment Prioritization Maps Multipollutant Lesson Learned: 50% of the top ranked catchments are different if prioritized using County-specific water quality priorities instead of traditional surrogates TSS only

20 BMP Tracking and Reductions 20

21 Model Framework 21

22 Table 7. BMP Reductions (Additional BMPs may be added to the next empty row) *Note: units shown under pollutants represent concentration. Unit reductions are in units specified in Table 2 and percent reductions are in %. Volume TSS Tot P Diss P NH3 NO3 TKN Diss Fecal Tot Cu Tot Pb Diss Zn Tot Zn Cu Col. BMP Type Reduction Method* % Capture cu ft mg/l mg/l mg/l mg/l mg/l mg/l ug/l ug/l ug/l ug/l ug/l #/100 ml 85th Redevelopment (100% Infiltration) E 89% 100% ,890 85th Redevelopment (50% Infiltration) E 89% 50% ,890 85th Redevelopment (100% Treatment) E 89% 0% ,890 95th Redevelopment (100% Infiltration) E 100% 100% ,890 Brake Pad Copper Phase-out Legislation p 100% Other Non-structural BMPs (CBSM) P 100% 0.05 Other Non-structural BMPs (WAAP BMPs - Tanglewood & Orcutt only) P 100% * Percent Load Reduction (P) or Effluent Concentration (E) Lesson Learned: It was important to incorporate advanced logic to accurately estimate BMP reductions when multiple BMPs treat the same area BMP Reductions Pollut ant Pollut ant Pollut ant unit unit unit 22

23 BMP Reductions 23

24 LPR Model Benefits 24

25 25 Future LPR Model Uses Prioritize catchments (or land uses) for MS4 cleaning, street sweeping, outreach, structural BMP placement, etc. Prioritize BMPs e.g., compare relative cost-benefit of different BMP options Support grant applications and/or Stormwater Resource Plans Use maps as educational tools for public, PW managers, and/or elected officials Forecast long-term cost of compliance (TMDL WLAs, etc.) Identify/prioritize potential BMP retrofit opportunity sites Quantify water supply benefits of structural BMPs

26 26 Key Benefits of the LPR Model ability to model 12 water quality parameters for current or planned BMP implementation exceeds Permit requirements a simple to navigate interface and report ready figures provide a user-friendly experience a non-proprietary Excel model owned by the jurisdictions reduces long-term cost of Permit compliance and other modeling requirements capacity for streamlined updates and modification to GIS data and all prepopulated datasets provides maximum customization meaningful catchment prioritization and BMP reductions are based on locally important water quality concerns

27 27 For More Information Download: Approach Memo - discusses the modeling approach and the default model values Guidance Document - describes the model organization, how users can add new BMPs and extract model results for future annual reports, how to modify model defaults, and how model calculations are performed CASQA presentation Available for download next week

28 Avery Blackwell - ablackwell@geosyntec.com 28 Cathleen Garnand - cgarnan@cosbpw.net