An engineer can figure out what needs to be done and how much it might cost. Or, if there is a concrete retaining wall or bulkhead that needs extensive repair the County government may require a building permit for the work and it may also require engineering work to ensure that the job is designed and done correctly. Choosing an engineer is like all the other choices of professional services. Referrals from knowledgeable sources are best. However, engineers are licensed professionals who belong to varying organizations and groups.
Different engineers have different areas of expertise and background.
When you meet with an engineer ask about those things. Be sure to choose someone who is respected in the community and who has a good working relationship with the County Building Department and County Public Works Department. Engineering fees are expensive and they vary quite a bit. Be sure to ask about the cost of services and get a clear picture of exactly what is included in the price you are quoted. Your agreement with the engineer should be in writing.