Louis Thompson Road Sewer Project

NOTICE: Important Board Meeting Information below 

The Sammamish Plateau Water and Sewer District is proposing a sewer line extension in the Louis Thompson area in coordination with the City of Sammamish stormwater installation.

 The District seeks to maximize efficiency by working with the City of Sammamish to perform utility work on Louis Thompson Road. The work is scheduled to begin in early 2024. The District is attempting to reduce possible future disruptions by combining the installation of a new sewer line during the period when the City of Sammamish will be exposing other underground utilities.

 The Project Area and Proposed Improvements are shown on the following map:

ULID S-23 Map newest5.24.23with sewer

Sewer service provides a reliable alternative to problems associated with septic drainfields, protects our groundwater quality, and may enhance your property values.

Project Information can be found at these links:

 King County On-Site Septic System (OSS) Information: https://kingcounty.gov/depts/health/environmental-health/piping/onsite-sewage-systems/maintenance.aspx

 Information on the City of Sammamish Louis Thompson Tightline project is available on the City’s website.


Board will be considering a Resolution that would declare their intention to form the proposed Louis Thompson Area Sewer Utility Local Improvement District (ULID).

  • Agenda for the June 5, 2023 meeting will be posted in the afternoon of June 2, 2023. The link to the meeting is included in the Agenda Page
  • The meeting starts at 3:30 PM, and attendance can be in person or virtually.

Owners of property in the proposed ULID area were sent a letter regarding the June 5, 2023 meeting. See a Sample Letter 


May 8, 2023 Public Meeting presentation

Thanks to all who attended our public meeting on Monday, May 8, to answer your questions regarding the sewer project, the ULID process, and timing. Your questions clearly expressed your views of this project and the need for more information.

Louis Thompson Rd. Sewer Public Meeting for website 5.8.23




1. What area is included in the Louis Thompson Road Sewer Project?

The project area is shown as shaded within the blue boundary on the map below.

ULID S-23 Boundary Map cleaner


2. What facilities would be built as part of the sewer project?

ULID S-23 Map with sewer cleaner

The facilities that would be built as part of the sewer project are shown in red.

3. We conducted a survey of property owners in the Louis Thompson Road area in June 2022. What were the survey results?

  • The survey indicated that there were some property owners interested in sewer, and others were not. There were also many property owners who did not respond to the survey at all.  The results of the survey are shown on the following map.

 Survey results rev

4. Why didn’t I receive a survey in June 2022?

  • The June 2022 survey asked about interest in getting sewer service, so it was not sent to owners of property that already had sewer service.

 5. I received a survey in June 2022, why am I not included now?

  • The area now proposed for the project does not include some properties along 210th Pl SE, and also those along Louis Thompson Road between Main Street and 210th Pl SE. Of the 14 properties that are not in the project now, 13 currently have sewer available, and the project scope was reduced to limit the overall project cost.


6. Why are you proposing to do the sewer project now?

  • The sewer project is being considered now to take advantage of the planned City of Sammamish project for improvements on Louis Thompson Road.
  • There are potential cost savings to the District by partnering with the City’s project.

7. What happens if the sewer is not installed now?

  • If the sewer project is not done now, it will likely cost more in the future. The District will have to reopen the roadway and work around the City’s completed project.
  • The current proposal is for a project that provides sewer service to a larger area. If this project is not done now, the sewer will likely be installed smaller individual projects at a higher cost per project.

 8. What is the proposed sewer project schedule?

  • The proposed sewer project would be built in 2 phases.
    1. Phase 1: Louis Thompson Road in conjunction with the City’s road improvements. Design in 2023. Construction expected in 2024.
    2. Phase 2: Side Streets Project: Roads and accesses off of Louis Thompson Road
       Design in 2023/2024. Construction expected in 2025.


9. What is a Utility Local Improvement District (ULID)?

  • A Utility Local Improvement District, or ULID, is a method of financing improvements that allows the District to assess costs against the properties that would be able to receive service from the improvements. The ULID is intended to respect the will of the majority of property owners.

10. What if I don’t want to participate in a ULID?

  • If a ULID is formed that includes your property, you are required to participate, unless you can show that the improvement will not provide service and a benefit to your property.

11.Can you tell me more about the ULID Process?

  • More information about the ULID process is provided later in this document. Please scroll down to the Utility Local Improvement District Basics.


12. How is the cost of the project split among the properties?

  • The estimated cost to the District to install sewer in the Louis Thompson Project Area is $5,584,000. This cost would be split evenly between the properties in the project area.
  • The cost share to the property owner is $65,000 per property. 
     This is considered the Local Facility Charge for the property.
  • 50% of the sewer project cost for each property can be spread out over 20 years through the ULID process. This would be the ULID Assessment

50% cost share

Mandatory for all property owners

Annual payment at 4% interest


$2,392 annually for 20 years


Two options for paying the remaining 50%

Option 1: Payment upon connection to Sewer

Pay the remaining balance of $32,500 
 upon connection to sewer

Option 2: Finance total amount

Total cost of $65,000 at 4% interest = 
  $4,784 annually for 20 years

Note: All costs are estimates.

13. How much is the sewer project going to cost?

  • The current District estimate for the sewer project is $5,584,000. 
     This includes the installation of approximately 6,825 lineal feet of sewer main, both in Louis Thompson Road, between 205th Ave NE and Main Street, and in the streets and access locations connecting to Louis Thompson Road.
  • This is an estimate based on early information, and not based on a final design or bids provided by a contractor.
  • If the cost of the sewer is divided equally between the 87 properties in the project area, the current estimate of the Local Facility Charge cost per property is $65,000 per lot.
  • The proposed ULID will assess 50% of the Local Facility Charge through the ULID, and the Remaining Local Facility Charge can be paid at the time the property is connected to the sewer system.
  • The ULID Assessment per property is estimated at $32,500 per lot, and the 
     Remaining Local Facility Charge also estimated at $32,500.
  • The annual assessment for each property would be $2,392 for 20 years.

14. What is the minimum I have to pay if I have no interest in connecting to sewer?

  • The minimum amount would be 50% of the Local Facility Charge through the ULID. This amount is estimated at $32,500 per lot. This assessment can be paid through annual payments at a rate of $2,392 per year for 20 years.

 15. When is the first payment due? 

  • Based on the current estimated schedule, the first annual payment would be in Spring 2026.

 16. Will I be able to qualify for financing?

  • The ULID assessment is associated with the property by the District through the ULID process. There is no qualification.

17. I have a limited income, and am concerned I will have trouble paying the annual assessment. Is there a way to have the payment deferred?

  • Property owners that meet certain age and income requirements may be able to request through King County to have the ULID assessment deferred. District staff is working with King County staff to obtain more information on this possibility. 
  • Related information from the King County Assessors department is linked here. 
  • Washington State Code Chapter 84.38 RCW has information on deferral of special assessments

18. What if the project cost changes during design or construction? 

  • The current costs are estimates based on very preliminary design information. 
    The Final Assessment charges (see ULID Basics information) will be based on a combination of project construction bids and actual construction costs.

19. Are there other costs to connect to the sewer system?

  • Yes, there are other District Connection Charges, and also costs paid to others. Go here to see the District's Comprehensive Sewer Costs. *Note* The charges in this attachment are those in effect at the time of this writing and are subject to change at any time without prior notice. These charges will be paid at the rate in effect at the time they are paid.

20. Why do we have to pay for the sewer project?

  • The District’s source of funding is primarily from existing customers. If the District does not collect from new and potentially new customers, the existing customers end up paying for the entire project through their sewer rates.

21. Why doesn’t the City pay for the sewer project?

  • The District owns and maintains the water and sewer infrastructure in this area, and is the responsible party for installing this capital improvement project.


22. Will I have to connect to the sewer once it is installed?

  • Maybe. There are three different entities that have a part in making the decision on sewer connection requirements; City of Sammamish, King County Health Department and Sammamish Plateau Water.
  • Some properties will be required to connect to the sewer based on connection agreements. Other properties may be required to connect if they pursue property improvements. A few of the possible situations are described in the following more specific questions.

23. Will I have to connect to the sewer if I am remodeling or rebuilding my house?

  • Yes, if you are building a new house you would be required to connect the new house to the sewer.
  • Many home improvements would also require connection to the sewer system. If the City of Sammamish or King County requires a Certificate of Water or Sewer Availability for your home project, you will most likely be required to connect. 

24. Will I have to connect to the sewer if my drainfield fails?

  • Yes, if your drainfield fails and sewer is available, the King County Health Department would most likely require connection to the sewer system.

25. Will I have to connect to the sewer if my drainfield needs to be improved?

  • Yes, if you need to improve your drainfield, such as adding additional lineal feet to your drainfield, you will most likely be required to connect to the sewer system.

 26. If the sewer is not installed, and my drainfield has problems, what can I do?

  • If the sewer that has been previously installed is within 200 feet of your property, you may be required to extend the sewer and connect to the sewer system.
  • Sewer installed for connection of just one property is most frequently done by the property owner through a Developer Extension Agreement process with the District. The property owner is responsible for all costs associated with these extensions.
  • If the sewer is more than 200 feet from your property, you may be allowed to apply to repair or replace the septic system on your property. The onsite-septic system work would be reviewed for approval by the King County Health Department.

27. Will I have to connect to the sewer if there is an agreement recorded on my property regarding sewer connection?

  • If an Agreement for Future Connection to the Sewer with the District is recorded on your property, you will be required to connect to the sewer. You will have 5 years after being notified that the sewer is available for service to complete the connection, including payment of District connection charges.
  • There may be other agreements on your property (not with the District) that require connection. The District is not aware or in control of these agreements, and cannot provide direction on how or when connection to the sewer will be required.


28. Why would I want to support the installation of sewer? What are the benefits of having the sewer installed?

  • Provides an option if your septic system should develop problems.
  • Provides reliability. The District is responsible for maintaining the sewer system. King County provides wastewater treatment services.
  • Removes the recommended maintenance of the septic system.
  • Provides flexibility for use of the property, once the septic system is decommissioned.
  • Allows for greater use of the property, including remodeling, rebuilding, Accessory Dwelling Units (ADU), etc.
  • Adds to the underlying value of the property.
  • An investment in your property and your neighborhood.

29. What is the cost saving of constructing the sewer now?

  • We estimate the cost of constructing the sewer in Louis Thompson Road after the City completes their Louis Thompson Tightline project would be over 40% higher than constructing it at the same time as the City project.

 30. Will the roads be paved with the project?

  • Louis Thompson Rd will be repaved with the City’s tightline project.
  • The District anticipates full or half-width repaving of the side streets depending on whether the water mains are replaced at the same time. Note that replacement of water main is funded separately through water rates.

31. What are some of the issues with onsite septic systems (OSS) in this area? 

  • King County has information on their website discussing good practices for caring for an on-site septic system.

King County OSS owner requirements

As a septic system owner, you need to have your septic system regularly inspected and maintained (which may include repairs and replacements as your septic system ages). If septic systems are not properly maintained, we no longer receive their benefits. Instead, they can have harmful impacts on groundwater and pollute lakes, streams, and beaches. They can even cause sewage to surface in your yard or back up into your house. To prevent this, a septic system owner also needs to operate their system properly, for example, by throwing all food waste into the compost or trash can, instead of tossing it down the drain.

  • Other factors may also impact how well a septic system performs or your ability to obtain a permit for a new or upgraded septic system including; steep slopes, Landslide Hazard Area, or soil types.
  • Septic issues or failures may not always be apparent from the surface or on your property. In well-draining soils and slopes it is also possible for septic systems to “fail down” where sewage does not receive adequate treatment from the soils. These failures could lead to odors downhill and pollution in streams and lakes downstream.


 Water and sewer districts are authorized by state statute to use the ULID method for projects to build and extend water and sewer systems to serve private property. The basic concept is that the properties which receive the benefit will pay the cost of the project. The District finances the initial costs and collects assessments from the property owners to eventually cover the project costs.


ULID Projects can be initiated either through a petition method or a resolution method. The Louis Thompson Basin Proposed ULID is being initiated by the resolution method.

Resolution Method:

  • District identifies:
    1. Boundaries of the proposed ULID
    2. Nature and extent of the project improvements
  • District Board of Commissioners schedules a ULID Formation Hearing.
  • Formation Hearing and Preliminary Assessment Notices are sent to all property owners.
  • If the Board receives formal written protests from property owners representing more than 40% of the area of the land within the ULID Boundary, the project must be cancelled.



The District Board will schedule a date, time and location for a public hearing regarding formation of the proposed ULID. Property Owners are notified of the public hearing through newspaper publication (Seattle Times) and by an individual notice mailed to each property owner. The individual notices include an estimate of the portion of the project cost which would be allocated to the individual property, if the ULID project proceeds.

Formation Hearing Content

At the Formation Hearing, the Board of Commissioners hears questions, objections, and testimony from property owners within the proposed ULID. The specific purpose of this hearing is to receive information relating to the project such as:

  • Boundaries of the ULID
  • Nature and extent of the proposed project improvements

All objections to the formation of the ULID must be in writing. Objectors must provide written comments to the District before, during or in the 10 days after the Formation Hearing. This is the 10-day appeal period.

Estimated project costs and methods of distributing the costs among the properties may also be a topic at the hearing. However, the formal consideration of the cost and distribution is specifically addressed in the Final Assessment Hearing, which occurs later in the process.

For the Louis Thompson Basin ULID, the Board is proposing that 50% of the estimated project costs be assessed against each property, with the remaining 50% of the project costs be collected at the time the property is connected to the sewer system.

Formation Hearing Appeal Period

If the District receives formal written objections to the formation of the ULID representing more than 40% of the area included in the proposed ULID, the ULID is considered cancelled and terminated.

Board Action Following Formation Hearing and Appeal Result

If the ULID is not cancelled by formal objection, the Board of Commissioners may decide to:

  • Form the ULID and order the project to proceed as initially presented.
  • Modify the ULID proposal by reducing the project scope, and then order the project to proceed.
  • Terminate the proposed ULID.


When a ULID is created, the Board of Commissioners also authorizes the preparation of surveys, designs, plans, specifications, any required environmental reviews, acquisition of any required property and permits. When the plans and specifications have been completed, the ULID project is advertised through the public works competitive bidding process.

When the project has been designed and bid, the District tabulates all known and estimated costs to complete the ULID project including: 

  • Surveying and Engineering
  • Construction
  • Easements or property acquisition
  • Legal
  • Administrative
  • Permitting 

Design and installation of the sewer included in the proposed Louis Thompson ULID would be completed in two phases. This is due to the schedule of the City’s road improvement project in Louis Thompson Road.

Phase 1 = Louis Thompson Road project: Design in 2023, construction in 2024

Phase 2 = Side streets project: Design in 2023/2024, construction in 2025 

District Board of Commissioners awards the contract to the lowest responsible bidder for the ULID Project, and construction proceeds as a District Capital Improvement Project.


Final Assessment Basis

The Final Assessment may be based on cost estimates from project bids or actual construction costs. For the proposed Louis Thompson ULID project, the Final Assessment will most likely be based on the actual construction costs for Phase 1 and the cost estimates from project bids for Phase 2.


The District Board will schedule a date, time and location for a public hearing regarding apportioning of the total estimated costs of the ULID. Property owners are notified of the public hearing through newspaper publication (Seattle Times) and by an individual notice mailed to each property owner. The individual notices include an exact amount of the portion of the project cost which would be allocated to the individual property, if the ULID project is constructed.

 Optional Final Assessment Additions

The District Board has indicated the project cost per property, the Total Local Facility Charge, would be split into two halves.

  • The ULID Assessment would include one half or 50% of the Total Local Facility Charge for each property. 
     The ULID Assessment would be collected through annual assessments over 20 years.
  • The Remaining Local Facility Charge would include the other 50% of the Total Local Facility Charge. This would normally be collected as part of District Connection Charges when the property connects to the sewer.
    1. Option to include the Remaining Local Facility Charge with the ULID Assessment: Each property owner may request the Remaining Local Facility Charge for their property be included in the ULID Assessment. This means the ULID Assessment for that property would be 100% of the Local Facility Charge.
    2. A written request prior to or during the Final Assessment Hearing is required to include the Remaining LFC with the ULID Assessment.
    3. The Board considers each request for inclusion to formally add the Remaining LFC to that property’s ULID assessment.

 Final Assessment Hearing Content

At the Final Assessment Hearing, the Board of Commissioners hears questions, objections, and testimony from property owners within the proposed ULID. The specific purpose of this Hearing is to receive information relating to the project such as:

  • Method used to distribute the cost to an individual property.
  • Specific amount of the project cost assessed to a specific individual property.
    1. Requests to include the Remaining Local Facility Charge in the ULID Assessment are included here.

All objections to the cost allocation to a specific property or requests to add optional Remaining Local Facility Charge in the ULID must be in writing, and provided to the District prior to or during the Final Assessment Hearing.

 Final Assessment Hearing Result

At the conclusion of the Formation Hearing the Board of Commissioners may decide to:

  • Confirm the Assessment Roll as initially presented at the Assessment Hearing
  • Adjust assessments for specific properties and confirm the modified Assessment Roll.
  • Not confirm an Assessment Roll for the ULID and terminate the ULID project.


After the Assessment Roll has been confirmed, the Assessment Roll is filed with King County for collection. The schedule for payments is as follows:

  • Initial Assessment Notice:
    1. Provides an opportunity to pay any portion of the assessment without interest.
    2. Payment must be made within 30 days of receiving the initial notice.
    3. No payment is required with the initial notice
  • 20 Annual Assessment Notices:
    1. 1st annual assessment is due 1 year after the Initial Assessment Notice.
    2. Payment required within 30 days of receipt of each annual notice.
  • Early Payment:
    1. Assessments may be paid off early.
    2. Assessments paid off mid-year will have accrued a full year’s interest.
    3. Many financial institutions require the assessment be paid as part of a new loan.


Jackson.Dove@spwater.org and/or Jay.Regenstreif@spwater.org