Finlay Jude Associates Ltd
Principal Mechanical Engineer

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Job Title: Principal Mechanical Engineer
FJA are recruiting on behalf of a leading service provider in the wastewater industry for an experienced Principal Mechanical Engineer to strengthen their team.
This role is based in Rickmansworth, with hybrid working available.
Benefits
- A competitive salary
- Hybrid Working (Jobs needs dependent)
- Car/car allowance (Jobs needs dependent)
- 25 days holiday + Bank Holidays (with an additional 5 days available to buy)
- Contribution Pension scheme
- Life Assurance
- Health Insurance
- Private Medical Insurance
- And many more benefits including – cycle to work scheme, discounts and savings Hub, Kids Pass etc
Principal Mechanical Engineer Responsibilities
- Report to Design Managers, Technical Discipline Lead, Regional Discipline Lead, and Engineering Manager.
- Develop complex, cost-effective design layouts that meet specifications and can be efficiently constructed and commissioned.
- Prepare, review, and verify all design deliverables, including specifications, schedules, drawings, and calculations.
- Collaborate with multiple disciplines to create comprehensive site and plant 3D models.
- Ensure all design-stage outputs are delivered on time and within budget.
- Coordinate design deliverables across technical disciplines to maintain consistency and alignment.
- Provide estimates and technical input to the Proposals team as required.
- Foster strong working relationships with construction teams and supply chain partners to improve buildability and design efficiency.
- Adhere to departmental procedures and processes while supporting their ongoing improvement.
- Assist in creating, reviewing, and updating departmental procedures and best practices.
- Maintain accurate documentation and records throughout all phases of the contract.
- Promote customer satisfaction by adopting a customer-focused approach in all activities.
- Lead Operability and Maintenance workshops with clients to ensure design solutions meet operational and maintenance requirements.
- Maintain a personal development plan and pursue continuous professional growth.
- Mentor, supervise, and support the development of team members.
- Ensure designs incorporate environmental considerations.
- Ensure all designs fully comply with CDM 2015 Regulations and relevant health and safety requirements.
Reasons to use Rodeo
I’m in my final year doing Economics and I don’t know whether to apply for grad schemes now or do a masters first. What do you think?
Honest answer — it depends on where you want to end up. A lot of top grad schemes (Big 4, civil service, banking) don’t need a masters. Let’s look at the ones you’d be competitive for now, and we can decide if a masters actually adds anything.
Also worth knowing: most autumn 2026 applications are open now. Timing matters more than you think.
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Graduate Consultant — 2026 Scheme
Why you're a good match
StrongYour economics background and your summer at a regional bank line up with what PwC looks for on the consulting scheme. Applications close in four weeks.
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Why you're a good match
You’ve got the grades and the economics background, and your bank internship is exactly the experience this scheme looks for. Apply soon — deadlines close within the month.
Experience fit
Your summer at the bank plus your econometrics coursework map directly to the day-one responsibilities on this scheme — client modelling, market briefings, and deal support.
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Principal Mechanical Engineer Requirements
- Extensive experience and in-depth knowledge of core engineering principles, including structural design, materials science, hydraulics, and environmental engineering.
- Strong understanding of water and wastewater treatment processes.
- Proven ability to lead, manage, and mentor design teams in the delivery of water and sewage treatment plant projects.
- Chartered membership (or actively working toward chartered status) with a relevant professional body, such as CIWEM.
- Degree in engineering or a closely related discipline.
- Skilled in rationalising design concepts and developing cost-effective plant layouts.
- Broad technical expertise spanning mechanical, process, and electrical engineering, combined with project management experience in water treatment.
- Comprehensive knowledge of roles, responsibilities, and compliance under CDM 2015 regulations.
- Familiarity with industry standards and regulatory frameworks (e.g., BS, WIMES, BSRIA), as well as HSE requirements and water quality regulations.
- Highly analytical and adaptable, with the ability to interpret and synthesize large volumes of complex technical data.
- Proficient in relevant engineering software and digital tools.
- Full UK driving licence.


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If you are looking for a fantastic Principal Mechanical Engineer opportunity and want to work for a leading national contractor with opportunities to progress, then click on the ‘apply now’ button.
Due to the high volume of applications, we receive we are not always able to reply to all applications. If you haven’t heard back from us within 2 weeks, then please accept that your application has been unsuccessful for the role we currently have advertised.
Please note that no terminology in this advert is intended to discriminate on the grounds of a person’s gender, marital status, race, religion, colour, age, disability or sexual orientation. Every candidate will be assessed only in accordance with their merits, qualifications and abilities to perform the duties of the job. Finlay Jude Associates Ltd acts as an employment agency for permanent recruitment and employment business for the supply of temporary workers.
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