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Mott MacDonald • Seattle, WA, US

Principal Project Manager - Water/ Wastewater

Salary:  £181,000 – £221,000 per annum
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Job Description

At Mott MacDonald, we trust our brilliant people to do brilliant things in engineering, management, and development services, supporting multisector project work in over 150 countries. As one of the largest employee-owned companies in the world, we pride ourselves on our ability to deliver exceptional outcomes through our network of 20,000+ talented consultants. With sustainability and innovation at the heart of all our sectors in North America, including, Buildings, Energy, Transportation, and Water.

We believe in empowering our people to excel, learn, and grow, offering diverse opportunities to contribute to career-defining work. Join us and be part of a collaborative environment where your ambitions are united with ours, and you can truly shape your story.

We are seeking a highly motivated and experienced Principal Engineer (Design Manager) to provide strategic and technical leadership on Combined Sewer Overflow (CSO) and wastewater conveyance programs across the Puget Sound region.

This is a high-impact role leading complex, multi‑disciplinary projects; supporting key pursuits and delivery strategy; and strengthening long-term partnerships with major utilities and public agencies.

You’ll collaborate across our North American network working with highly talented local team focused on resilient, sustainable wet‑weather solutions.

Role & Responsibilities:

  • Serve as Technical Principal/Design Manager for large CSO tunnels, gravity/pressure conveyance, pump stations, and related assets from planning through construction support.
  • Establish project governance (scope, schedule, budget, risk, change control) and ensure safety‑in‑design and quality management (QA/QC) throughout delivery.
  • Direct planning studies, alternatives analyses, feasibility assessments, and basis-of-design documentation.
  • Oversee hydraulic modeling, surge/transient analyses, and capacity planning; guide trenchless technology selection and constructability.
  • Lead preparation of drawings, specifications, technical reports, and cost estimates; support procurement and construction-phase engineering (RFIs, submittals, field support).
  • Act as Project Principal building and maintaining executive-level client relationships, supporting the development of account plans and program roadmaps.
  • Champion BIM and model-based coordination; promote data-driven decision-making, carbon-aware design, and sustainability/resilience best practices.
  • Mentor and develop multi-disciplinary teams; foster an inclusive, high‑performance culture; support recruitment and succession planning.
  • Coordinate with tunneling, geotechnical, structural, and environmental specialists across offices; occasional regional travel as needed.

Candidate Qualifications:

  • Bachelor’s degree in Civil, Environmental, or Water Resources Engineering (Master’s preferred).
  • Professional Engineer (PE), Washington
  • 15+ years in water/wastewater infrastructure with substantive experience delivering CSO and wastewater conveyance projects.
  • Demonstrated success leading large, multi‑disciplinary teams across planning, design, procurement, and construction support.
  • Proficiency in wastewater hydraulics, pump station design, trenchless methods and construction-phase engineering.
  • Competence with scheduling, budgeting, risk management, change control, and quality systems.
  • Strong written/oral communication; skilled in client-facing presentations and stakeholder engagement.

Preferred Qualifications

  • Prior work with Seattle-area agencies and counties, including Seattle Public Utilities (SPU), King County Wastewater Treatment Division (WTD), City of Tacoma Environmental Services, Pierce County Sewer Utility
  • Familiarity with Puget Sound regional standards, permitting, and delivery methods (progressive DB, CM/GC, DBB).
  • Experience addressing wet‑weather/consent decree drivers, system resilience, and environmental compliance.
  • Working knowledge of BIM and common hydraulic modeling tools; commitment to digital delivery and sustainability practices.

Our teams are comprised of bright and enthusiastic people who wish to make a difference to the world that we live in. If you share that vision and don’t have all the experience outlined in this posting, we still want to hear from you!

Let’s discuss how we can help you take the next step in your career and how you can participate in an exciting new chapter for Mott MacDonald in North America.

At Mott MacDonald, we provide a comprehensive benefit package that includes 401k, medical, dental and vision insurance, short-term/long-term disability, paid holidays, PTO, parental leave and company paid life insurance.

The expected salary for this position is $181,000 - $221,000

Individual pay is determined based on several factors such as work location, education, experience, and unique skills.

Equal opportunity is the law.

We seek to promote fair employment procedures and practices to ensure equal opportunities for all. We encourage individual expression in our workplace and are committed to creating an inclusive environment where everyone feels they have the opportunity to contribute.


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All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, age, protected veteran status, creed, marital status, sexual orientation, gender identity, citizenship status or disability status.

Hybrid working policy

At Mott MacDonald, we believe it makes business sense for you and your manager to choose how you can work most effectively to meet your client, team, and personal commitments. We offer a hybrid working policy that embraces your well-being, flexibility, and trust.

Company benefits

Accrued annual leave
Adoption leave – 26 weeks full pay
Annual bonus
Annual pay rises
Bank holiday swaps
Bike parking
Book swaps
Buddy scheme
Buy or sell annual leave
Carer’s leave – up to 5 days, two of which are paid
Compassionate leave
Critical Illness Insurance
Cycle to work scheme
Dental coverage
Employee assistance programme
Employee discounts
Enhanced maternity leave – 26 weeks full pay
Enhanced paternity leave – 2 weeks
Enhanced pension match/contribution – matched up to 7%
Enhanced sick pay
Ergonomic workstations
Eye Care Support – Eyecare vouchers
Faith rooms
Fully stocked snack cupboard
Further education support
Health assessment
In house training
Income protection
L&D budget
Learning platform
Life assurance
Life insurance – 4 x salary
Lunch and learns
Meditation space
Meditation space
Mentoring
Modern office
On-site shower
On-site yoga classes
Open to part time work for some roles
Open to part-time employees
Pregnancy loss leave
Pregnancy support
Private booths
Private GP service – Private Medical care for all UK staff
Professional subscriptions – We pay for your primary professional annual subscription
Referral bonus
Religious celebration leave
Returnship
Salary sacrifice
Share options
Shared parental leave – We match up to 24 weeks full pay
Study support
Tax-free childcare
Teambuilding days
Theme park discounts
Travel loan
Women’s health leave
Reservist leave – 10 days leave

Working at Mott MacDonald

Company employees:

18,000 worldwide

Gender diversity (m:f):

65:35

Hiring in countries

Australia

Bulgaria

Canada

Czechia

France

Germany

Hong Kong

India

Indonesia

Ireland

Italy

Japan

Malaysia

New Zealand

Serbia

Singapore

Spain

Thailand

United Arab Emirates

United Kingdom

United States

Office Locations

Awards & Accreditations

2nd – Career Progression

2nd – Career Progression

Flexa awards 2025
3rd – Family Friendly

3rd – Family Friendly

Flexa awards 2025
Work-Life Balance

Work-Life Balance

Flexa awards 2025
Flexible

Flexible

Flexa awards 2025
Culture

Culture

Flexa awards 2025

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