Sewer Authority Mid-Coastside

(1)

COMMITMENT &INTEGRITY DRIVE RESULTS

Sewer Authority Mid-Coastside

Wet Weather Flow Alternatives

July 27, 2020 Presented by: Tony Valdivia, P.E.

(2)

Introductions & Acknowledgements



Woodard & Curran Team

 Project Manager: Jim Graydon, P.E.

 Technical Manager: Tony Valdivia, P.E.

 Project Engineer: Athena Pervissian, P.E.



Woodard & Curran would like to acknowledge the contributions of all previous engineering consultants and SAM staff.

 SRT Consultants  Carollo Engineers

 Whitley Burchett (West Yost Associates)

 Wastewater Management Services, LLC

(3)

Project Objective



Evaluate four potential projects for handling projected wet weather flows in the SAM Intertie Pipeline System (IPS)

3 No Project (Status Quo) 200,000 Gallons of Storage 400,000 Gallons of Storage Portola Pump Station Improvements

(4)

Basic Evaluation Criteria



Capital and Operating Costs (Life Cycle Cost)



Mitigation of Future Risk (spills; fines; reputation)

COST

(5)

Project Flow Criteria



SAM policy regarding design storm capacity in the IPS: 10-year, 6-hour storm

(6)

Project Objectives/Limitations: Non-Pump Station



Rely on prior studies (by others) to define project and technical details



Develop capital costs based on recent bids (storage projects)



Develop O&M costs based on current SAM practices



No independent validation of design storm flows or project capacity No Project (Status Quo) 200,000 Gallons of Storage 400,000 Gallons of Storage

(7)

Project Approach: Portola Pump Station



Develop project technical details and costs to support direct comparison to the other three alternatives:

 Mechanical and electrical systems evaluation

 New equipment selection and operational analysis

 Reasonable allowances for items beyond technical scope (e.g. structures)  Full capital and operating costs estimate

Portola Pump Station Improvements

(8)

Project Approach: Limitations



No analysis of treatment plant impacts



No detailed analysis of permitting requirements



No structural evaluation, though impacts may be significant Portola Pump Station

(9)

Portola Pump Station Improvements

Previous studies evaluated improving

the Portola Pump Station, but only assuming a costly parallel Granada Force Main.

Granada Force Main

(10)

Granada Force Main Improvements

Much of the Granada Force Main has now been repaired or replaced. Has the Pump Station Improvement

(11)

System Curve by SRT Consultants, 2019

System Hydraulics

Approx. 2020 Capacity w/ Two New 60 Hp Pumps 3,000 gpm Improvement Project Capacity 5,000 gpm* 67% Increase in Flow 91% Increase in Head

(12)

System Hydraulics

At 5,000 gpm, force main velocity is over 10 feet per second. This is very fast for raw wastewater and may result in long-term damage.

Design standard velocities are typically 2 to 7 feet per second under all operating conditions.

Head loss in pipes increases exponentially with rising velocity. Pump and motor size increase with head loss.

(13)

System Hydraulics

The Granada Force Main is too small for 5,000 gpm. A larger or parallel force main is still required.

(14)

Pump Selection @ 5,000 gpm

Alternative 1 SAM-Owned 60 Hp Pumps New Wet Weather Pumps 5,000 gpm 5,000 gpm Standby 1,500 gpm 1,500 gpm Alternative 3 1,667 gpm 1,667 gpm 1,667 gpm 1,667 gpm Standby 250 Hp Alternative 2 2,500 gpm Standby 2,500 gpm 2,500 gpm 1,500 gpm 250 Hp 350 Hp

(15)

Four Pumps is the Limit

(16)

The Smaller (60 Hp) Pumps are Important

60 Hp pumps more efficiently convey low flows when driven by variable frequency drives (VFDs).

Wet weather pumps are sized for very high flows and head. They

cannot get close to ADWF.

Average Dry Weather Flow (ADWF): 350 gpm

(17)

Pump Selection @ 5,000 gpm

Alternative 1 SAM-Owned 60 Hp Pumps New Wet Weather Pumps Alternative 2 Alternative 3 5,000 gpm 5,000 gpm Standby 2,500 gpm Standby 2,500 gpm 2,500 gpm 1,667 gpm 1,667 gpm 1,667 gpm 1,667 gpm Standby 1,500 gpm 1,500 gpm 1,500 gpm 250 Hp 250 Hp 350 Hp No Small Pumps

(18)

Pump Selection @ 5,000 gpm

Alternative 1 SAM-Owned 60 Hp Pumps New Wet Weather Pumps Alternative 2 Alternative 3 5,000 gpm 5,000 gpm Standby 2,500 gpm Standby 2,500 gpm 2,500 gpm 1,667 gpm 1,667 gpm 1,667 gpm 1,667 gpm Standby 1,500 gpm 1,500 gpm 1,500 gpm 250 Hp 250 Hp 350 Hp

(19)

Pump Station Electrical Improvements



New Standby Generator (outside enclosure)



New Main Distribution and Switchboard



New VFDs (all pumps)



New MCC (ancillary loads)



New HVAC (heat loads)



New Room Configuration



New Utility Service



New Conductors

The increase in station

horsepower is significant and is anticipated to require an overhaul of most electrical gear.

(20)

Additional Assumptions



New surge tank (higher velocities = high surge potential)



Structural retrofit to current code is likely



Retrofit of force main air valves (surge capacity)

(21)

Portola Pump Station Costs



Construction Cost:

$3.4 Million*

 Excludes 25% soft costs  Assumes existing force main



Annual Operating Costs:

$110,000

 Includes labor, power,

maintenance/parts



20-Year Net Present Value: $4.9 Million

(22)

Portola Pump Station Risk

•

Risk of damage to existing force main

•

Redundancy in pumping provides firm capacity equal to design flows

•

Multi-year schedule for implementation (schedule risk)

•

Permitting will be complicated (CEQA, Coastal Commission) and

(23)

No Project Alternative Costs



Initial Cost: $300,000 (Settlement payment)



Annual Cost: $192,000

 $97,000 Portola Pump Station (existing)

 $95,000 labor, equipment rental/maintenance for high flow

management (unverified)



20-Year Net Present Value:

(24)

No Project Alternative Risk

•

Labor and maintenance intensive approach

•

Failure to complete a capacity improvement project per the Settlement is likely to place SAM under additional scrutiny and increased risk of larger fines or legal action in the event of a future spill.

(25)

200,000 Gallons of Storage Costs



Construction Cost: $1.4 Million

 Excludes 5% soft costs, “shovel ready”



Settlement Credit: ($300,000)



Net Construction Cost: $1.1 Million



Annual Operating Costs: $97,000 (Portola Pump Station)

(26)

200,000 Gallons of Storage Risk

•

Passive overflow not dependent on mechanical systems

•

SAM experience indicates low cost to maintain (high availability)

(27)

400,000 Gallons of Storage Costs



Construction Cost: $2.9 Million

 Excludes 25% Soft Costs



Settlement Credit: ($300,000)



Net Construction Cost: $2.6 Million



Annual Operating Costs: $97,000 (Portola Pump Station)

(28)

400,000 Gallons of Storage Risk

•

Passive overflow not dependent on mechanical systems

•

SAM experience indicates low cost to maintain (high availability)

(29)

Summary of Alternatives

Pump Station Improvements No Project 200,000 Gallons Storage1 400,000 Gallons Storage1 Construction/Initial Cost $3.4 Million $300,000 $1.1 Million (Net) $2.6 Million (Net)

Net Present Value $4.9 Million $2.9 Million $2.4 Million (Net) $3.9 Million (Net)

Risk Assessment MODERATE HIGH MODERATE LOW

(30)

Recommended Project



400,000 Gallons of Storage is the Recommended Project

No Project (Status Quo) 200,000 Gallons of Storage 400,000 Gallons of Storage Portola Pump Station Improvements

(31)

Additional Considerations



Storage can be phased for capital expenditure planning

 Two 200,000-gallon projects will cost marginally more than a single

400,000-gallon project due economy of scale



It is the Granada Force Main limitations that drive the recommendation away from the Pump Station Improvements

 With a parallel force main, the Portola Pump Station alternative would be much

more compelling, and the risk of a force main break would also be largely mitigated

(32)

COMMITMENT &INTEGRITY DRIVE RESULTS