Groundwater Master Plan Update: Emergency Groundwater Supply Analysis & Water Quality Discussion

Transcription

1 Groundwater Master Plan Update: Emergency Groundwater Supply Analysis & Water Quality Discussion BPU Study Session October 4, 2012

2 Presentation Outline Groundwater Quality Discussion Basin Overview Groundwater Contamination Test Boring Program Screening Criteria Emergency Groundwater Supply Analysis Overview of Planning Criteria Existing Water System and Operational Zones Need for Emergency GW Supplies Recommended Projects and Priorities Potential Policy Decisions

3 Restructured Agreement Requirements Sections 1.13 and 1.15 of the Restructured Agreement contain specific requirements for local supply and recycled water Summarized from Restructured Agreement: 1.13 Recycled Water and Local Supply Project Requirements Within 10 years from the date of the Agreement, the Water Contractors shall use best efforts to develop at least 7,500 AFY of recycled water or local supply projects, with approximately 50% coming from recycled water projects Local Production Capacity Goals Highly desirable for each Water Contractor to develop and maintain local water production capacity capable of meeting approximately 40% of the Water Contractor s average day maximum month demand.

4 Basin Overview: Groundwater Basins

5 Basin Overview: Geology Legend:

6 Basin Overview: Geologic Cross Sections

7 Basin Overview: Groundwater Flow Groundwater flow direction generally follows topography

8 Basin Overview: Groundwater Basin groundwater flow Contaminated releases can find their way into the groundwater aquifers

9 Basin Overview Site Specific Geologic Conditions Vary By Location Gravels Sands Silts Clays North Village Test Well Clay Doyle Park Test Well Rodgers Creek Fault Zone Martha Way Test Well Gravels Sands Silts Clays Bedrock 185 ft bgs 1,000 ft bgs 1,000 ft bgs 1,000 ft bgs

10 Groundwater Contamination: Common Contaminants Naturally Occurring Iron Manganese Arsenic Man-made Floaters: Petroleum Hydrocarbons Sinkers: Chlorinated Solvents

11 Groundwater Contaminants: Generic Spill Site

12 Groundwater Contamination: McMinn Superfund Site

13 Groundwater Contamination: Freeway Well Closure Toxic Release Site Status

14 Groundwater Contamination: Montgomery Village

15 Groundwater Contamination California Leaking Underground Fuel Tank (LUFT) Historical Case Analyses Lawrence Livermore National Laboratory November 16, 1995 The resulting estimated total volume of groundwater that may have been impacted above a concentration of 1 ppb benzene is approximately 7,060 acre-feet. The estimated total basin storage capacity in California is 1.3 billion acre-feet (CDWR, 1975). The proportion of the estimated total basin storage capacity that may be affected by LUFT benzene plumes can be calculated to be %.... (1) average site benzene concentrations have a high probability of decreasing even if no treatment is attempted, (2) benzene plume lengths rarely extend beyond 250 feet...

16 Screening Sites: Selection Criteria List All Parcels Parcels which meet hydrogeologic criteria (geology, aquifer region, etc ) Parcels which meet engineering criteria (proximity to pipelines, pump stations etc ) Parcels > 1,000 feet from documented toxic releases Parcels large enough to perform work Parcels with work area > 50 feet from sewer line Parcels with access to water Parcels with access to trunkline for sewer discharge

17 Screening Sites: General Well Construction Steel Conductor Casing Steel Well Casing Borehole Wall Annular Seal 100 Sanitary Seal Sand w/ some Clay Clay Gravel Pack Continuous Wire Wrap Screen Gravel and Sand (or fractured bedrock) Bull Nose Cap Hole Plug Gravel Fill

18 Screening Sites: Exploration Area Over 85% of Santa Rosa is more than 1,000 feet from a documented toxic release site

19 Screening Sites: Extensive Testing Pump Testing Title 22 Testing

20 Questions and Answers Discussion

21 Emergency Planning Framework City Plans Emergency Operations Plan Utilities Department Water System Emergency Response Plan How much Emergency Groundwater Supply is required? Urban Water Shortage Contingency Plan County Plans SCWA Emergency Response Plan

22 Emergency GW Planning Criteria EMERGENCY SCENARIOS Full Loss of Agency Supply Partial Loss of Agency Supply OUTAGE DURATIONS Short-term (2 days) Long-term (14 days) DEMAND CONDITIONS Existing & Buildout Conditions Buildout Demand based on uniform growth in City Health & Safety = 50% Average Day Demand FACILITY STATUS All Tanks Half Full Pump Stations Operational Pipelines Operational Existing City Wells Operational New Wells Produce 700 gpm (equivalent to 1 mgd) LEVEL OF SERVICE Service to all pressure zones to extent possible Provide supply to key pump stations or other key locations within City for distribution to customers

23 Existing Water System Storage Reservoirs 8 Agency Reservoirs 61.5 MG total capacity 50% of 61.5 MG=30.75 MG 40% available to City = 12.3 MG 25 City Reservoirs 28.3 MG total capacity 50% of 28.3 MG=14.2 MG Pressure Zones 31 Hillside Pressure Zones 2 Aqueduct Pressure Zones (Central City and Oakmont)

24 Operational Zones Master Zones Pressure Zones S-1 R1, R2, R3, R5 S-4 R4, R16, R17 S-6 R6, R7, R8 S-9 R9, R10, R11 S-12 R12, R13, R14, R15 Central City Oakmont Aqueduct Zone Each Master Zone has a key pump station that can provide water to other Pressure Zones within that Master Zone A8

25 S-1

26 S-1 S-4

27 S-1 S-4 S-6

28 S-1 S-4 S-6 S-9

29 S-1 S-4 S-6 S-9 S-12

30 S-1 S-4 S-6 Oakmont Aqueduct S-9 S-12

31 Methodology Calculate Health & Safety Demand (50% of Average Day Demand) for each scenario for each Master Zone Determine available City and/or Agency storage in each Master Zone Identify existing well capacity in each Master Zone Calculate emergency supply shortage under each scenario Determine the number of new wells required within each Master Zone Living document, to be reviewed every 5 years

32 Scenario Existing Demand Condition day Outage-----No Supply from Agency Master Zone Demand (MG) Supply (MG) Deficit (MG) Deficit (mgd) Number of Wells Reqd Master Zone S Master Zone S Master Zone S (9.3) (0.7) 1 Master Zone S ** 0** 0** Master Zone S (0.9) (0.1) 1 Central City--Aqueduct * (18.7) (1.3) 2 Oakmont--Aqueduct A (2.8) (0.2) 1 Totals (2.3) Total New Wells 700 gpm each 5 to 6 * Includes GW from Farmers Lane 1 & 2, Carley and Peters Spring Wells. ** Could require 1 well, depends on specific field operational conditions

33 Scenario Buildout Demand Condition day Outage-----No Supply from Agency Master Zone Demand (MG) Supply (MG) Deficit (MG) Deficit (mgd) Number of Wells Reqd Master Zone S (8.6) (0.6) 1 Master Zone S * Master Zone S (33.0) (2.4) 3 Master Zone S * 0*** 0*** 0*** Master Zone S (7.2) (0.5) 1 Central City--Aqueduct ** (90.0) (6.4) 7 Oakmont--Aqueduct A (4.7) (0.3) 1 Totals (10.2) Total New Wells 700 gpm each 13 to 14 * Increased supply due to higher % of available production capacity from Farmers Lane 1 & 2 dedicated to meet increased hillside demand at buildout ** Decreased supply because less GW available from Farmers Lane 1 & 2 for Central City *** Could require 1 well, depends on specific field operational conditions

34 Master Zone S-1 Leete Well is out of service, if fixed, can only serve ~45 homes due to location; low priority fix Two proposed test boring locations identified, could provide emergency supply to both S-1 and Central City Number of New Emergency Wells Required for S-1 Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

35 Master Zone S-4 No problems or issues in this zone due to availability of Farmers Lane Wells 1 and 2 to provide emergency supply Number of New Emergency Wells Required for S-4 Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

36 Master Zone S-6 ~1 well short of supply, will need up to 3 wells Need to identify potential additional well sites Madrone Test Well data looks promising. Identify new emergency well location in vicinity of Madrone Need to construct pump around/jumper project identified by Operations staff to provide system operational flexibility Number of New Emergency Wells Required for S-6 Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

37 Master Zone S-9 Feasibility-wise, no major issues due to the ability of City emergency wells; however, need construction of several operational projects. A new test boring site and emergency well in Bennett Valley would allow increased system operational flexibility to deliver water to Central City. Number of New Emergency Wells Required for S-9 Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA 0 Possibly 1 0 Possibly 1 Partial Supply from SCWA Rodgers Creek Fault Rupture 0 Possibly 1 0 Possibly 1

38 Master Zone S-12 Zone is ~1 well short of supply Critical need to further explore use/transition of private well acquisition and/or explore potential test boring sites Emergency well could also be used to supply Oakmont Aqueduct Zone needs Number of New Emergency Wells Required for S-12 Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

39 Central City-Aqueduct In an emergency Operations staff would open isolation valves from R6R1 to allow Farmers Lane and Carley/Peters Wells to also supply Central City Critical need for 2 wells now; 7 wells needed for buildout Some test wells already drilled in northern portion of service area Need to identify potential test well sites in southern portion of service area Need to move forward to identify location of potential emergency well(s) in the vicinity of Martha and Slater test sites Number of New Emergency Wells Required for Central City Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

40 Oakmont-Aqueduct No wells in this Zone Critical need for 1 well now Need to aggressively move forward with identifying potential test well sites and/or transition or acquire private wells to meet shortages today Number of New Emergency Wells Required for Oakmont Existing Demand Conditions Buildout Demand Conditions 2 day outage 14 day outage 2 day outage 14 day outage No Supply from SCWA Partial Supply from SCWA Rodgers Creek Fault Rupture

41 Summary of Required Emergency Groundwater Wells Master Zone Existing Demands 2-day outage 14-day outage Buildout Demands 2-day outage 14-day outage S * S S S-9 0 ~1 0 ~1 S ** 0 1** Central City Aqueduct * Oakmont Aqueduct 1 1** 1 1** Total Number of New 700 gpm 3 4 to 5 8 ~11*** * S-1 well could also be used to serve Central City--Aqueduct ** S-12 well could also be used to serve Oakmont Aqueduct *** Number of required wells reduced to account for 2 wells which can be used to serve multiple zones.

42 Summary of Required Emergency Supply Master Zone Existing Demands 14-day outage gpm 14-day outage mgd Buildout Demands 14-day outage gpm 14-day outage mgd S S S , S-9 ~0* ~0* ~0* ~0* S Central City Aqueduct , Oakmont Aqueduct Add l Emergency GW Supply Required ~1,600 ~2.4 ~7,150 ~10.2 Notes: Original City target of 8.7 mgd of emergency groundwater production capacity Current emergency supply capacity accounted for: Farmers 1&2, Carley, Peters Spring = ~4.3 mgd * Depending on specific operational conditions, S-9 could be short of supply (but would be balanced by an equal reduction in required supply in Central City)

43 Recommended Projects & Priorities Critically Needed Projects (Short-term Program, 2-3 years) Design/Construct 3 new emergency wells Identification & construction of 2 emergency wells in Central City (1 well near S-1 and 1 well in central/southern portion of service zone) Identification & construction of 1 emergency well in Oakmont Aqueduct Zone Design and construction of pump around/jumper in S-6 and S-9 by Operations Division Identify next test well site in S-6, and possibly in S-9 Evaluate possible new emergency well(s) in vicinity of Martha and Slater test sites Mid-term Needs (5-7 years) Revisit/revise project prioritization list every 5 years to reflect actual areas of specific development and/or other potential changed conditions Construct 1 emergency well in S-6, and possibly in S-9 Construct 2 additional emergency wells in Central City Longer-term Needs (10-15 years) Construct 1 to 2 additional emergency wells in Central City Construct 1 to 2 additional emergency wells in S-6

44 Potential Policy Direction for Use of Groundwater Use groundwater for emergency use only Develop an additional 10.2 mgd to meet anticipated buildout demands (total of 14.5 mgd) Move forward to phase in Emergency Wells over next ~15-year period, focusing on addressing critical need areas first

45 Other Policy Direction to be Considered Adopt GW Master Plan and implement recommendations to inform City s participation in the GW Management Plan Prepare an Annual GW Status Report to track local GW conditions Consider Aquifer Storage & Recovery, if feasible We will be providing a general overview of ASR at the Oct 18 BPU Study Session

46 Questions and Answers Discussion