“Gilbane Gold”“Gilbane Gold”

PHIL/ENGR 482

ETHICS & ENGINEERING

Gilbane Gold Case Study

Taxonomy of Obligations

To whom does an engineer have obligations?To self?To others?

Family and friends Employer and fellow employees Fellow professionals Clients/Consumers/3rd Parties Public; including future generations

To the environment?

Gilbane Gold Background

Allowable Lead and Arsenic Concentration in Wastewater

A person working a regular 40-h work week whois able to sort 1 ping-pong ball per second wouldtake 139 years to sort through a billion balls.

Note:

Assumptions:

250,000 gal/day wastewater before expansion Old test methods indicated 5 ppb lead, ok. New test indicates 7.5+ ppb lead Legal limit is 7.5 ppb lead

Planned expansion will cause 500% increase in wastewater (and lead) volume

Impact of proposed expansion...

Wastewater Current: 250,000 gal/day Future: 1,250,000 gal/day

Lead Current: 250,000 g/day @ 7.5 ppb = 5.7 lb/day Future: 1,250,000 g/day @ 7.5 ppb = 28.5 lb/day

A problem…?

When trying a new and more accurate test method, we discover that the plant is discharging wastewater concentrations at or above the legal limit of 7.5 ppb lead…

Regulations do not require the new test method be used...

0.25 MgpdWastewater

@7.5ppb lead

7.5 ppb Wastewater treatment plant

Sludge + treated effluent

A bigger problem…?

A proposed production increase will increase the amount of wastewater 500%...1.25 Mgpd

Wastewater@7.5ppb lead

7.5 ppb Wastewater treatment plant

Sludge + treated effluent

A potential solution?“The solution to polution is dilution…”

It is proposed to dilute effluent to achieve an acceptable concentration, say 5.75 ppb...1.25 Mgpd

Wastewater@7.5ppb lead

6 ppb Wastewater treatment plant

Sludge + treated effluent

0.4 MgpdClean H2O

Annual cost of 0.4 Mgpd water...

Fresh water purchase (@ $0.25/1,000 gal) = $35,000

Incremental sewage charges (@ $0.75/1,000 gal) = $105,000

Total annual cost = $140,000

Potential solution 2?Ion Exchange

Potential solution 3?Artificial Wetland

Summary of three possible solutions

Method Est. Annual Cost

Dilution $140,000

Ion exchange $270,000

Artificial wetland $150,000