Spanaway Lake Management Plan

Transcription

1 Spanaway Lake Management Plan Background Spanaway Lake is a valuable Pierce County resource. The lake is threatened by a variety of water quality problems including excess algae and weed growth and elevated fecal coliform concentrations. Pierce County Surface Water Management (SWM) has made protection of Spanaway Lake a top priority. In 2011, SWM initiated the Raise the Grade program to improve water quality in Spanaway Lake and two other key Pierce County water bodies. SWM is now installing bioretention facilities to treat stormwater in Spanaway Park and retrofitting stormwater drywells around the lake. SWM has published newsletters to educate lakeshore residents about phosphorus and bacteria sources such as septic systems, pets, fertilizer use, and stormwater runoff. In 2013, the County received a state budget allocation for the Lake Spanaway Management Plan. Pierce County (COUNTY) asked Brown and Caldwell and their team (CONSULTANT) to support development of the Lake Spanaway Management Plan (Plan). The COUNTY will lead the stakeholder involvement and assist with monitoring activities while the CONSULTANT will lead the technical evaluations and plan development activities. In addition, the COUNTY s contract laboratory will analyze the samples collected for this project. The CONSULTANT s scope of work is described below. Scope of Work The COUNTY will develop the Spanaway Lake Management Plan in two phases: watershed characterization (Phase 1) and Plan development (Phase 2). The scope and budget for Phase 2 may be refined based on the key findings of Phase 1. The project management task encompasses both phases. The tasks in this Scope of Work are described below. Phase 1: Watershed Characterization The watershed characterization phase will consist of the tasks described below. Task 1. Develop stakeholder strategy. COUNTY staff will lead the stakeholder involvement activities with support from the CONSULTANT. The CONSULTANT will: Review the COUNTY s lakes management program Review and comment on the COUNTY s initial identification of key constituencies and potential champions for lake management initiatives Help the COUNTY assess community values, expectations, and willingness to support lake management, based on existing data Review and provide input on the COUNTY s stakeholder involvement strategy ed comments/suggestions on the stakeholder involvement strategy The COUNTY staff will develop the stakeholder strategy and lead its implementation 1

2 Task 2. The CONSULTANT will participate in one meeting and two conference calls on the stakeholder strategy Review existing data and prepare initial Watershed Characterization The CONSULTANT will meet with the COUNTY to confirm the project objectives and identify the data needed to meet those objectives. We will also identify existing data that the COUNTY or other agencies may have relevant to the lake s water budget, nutrient budget, and potential sources of phosphorus and fecal coliform bacteria. The CONSULTANT and the COUNTY will then tour the watershed. The COUNTY will provide any relevant data that it has and the CONSULTANT will supplement this with data from other sources. The CONSULTANT will prepare a summary of existing water quality and hydrologic data while keeping in mind the overall goals and objectives of the Plan. The CONSULTANT will also prepare GIS maps of relevant watershed data (e.g., land use, storm drainage system, soils data, and zoning and parcel information). The CONSULTANT will review and compile existing data to identify potential sources of nutrients or bacteria, such as: Stormwater (runoff and dry wells) Septic systems Waterfowl Aerial deposition Internal loading Tributary inflows (dry weather and wet weather) Lake outflows Future land use Historical status of the lake (water quality data, visual observations, etc.) Groundwater inflows and water quality Inventory of domestic wells and other groundwater monitoring stations Geologic maps and well logs The CONSULTANT will then prepare summary materials (e.g., PowerPoint slides, maps) of watershed conditions based on the available data. The CONSULTANT will meet with the COUNTY to discuss the findings, identify key data gaps that may need to be filled to help meet the goals and objectives of the Plan, and discuss our monitoring strategy. GIS maps of salient watershed characteristics to support initial watershed characterization. Three CONSULTANT staff will participate in a 6-hour data meeting and watershed tour. The COUNTY will provide GIS data, water quality data, flow monitoring data, and other relevant data in its possession, and assist with collection of relevant data from other agencies such as the Tacoma-Pierce County Health Department (TPCHD). Four CONSULTANT staff will participate in a four-hour meeting with COUNTY staff to discuss data gaps and monitoring strategy. 2

3 Task 3. Focused data collection The CONSULTANT will meet with the COUNTY (and others if deemed appropriate by the COUNTY project manager) to discuss strategies for filling the key data gaps identified in Task 2. Addressing gaps related to stakeholder strategy could include surveys or questionnaires, online outreach, and meetings. For data gaps related to lake and watershed conditions, we will discuss potential monitoring approaches and the availability of SWM/TPCHD staff, as well as local volunteers, to assist with monitoring and to maximize efficiency of resources. This may include assessing residential wells and on-site systems and the collection of data from other potential monitoring sites. Monitoring could include water sampling in Spanaway Lake, Coffey Creek, Spanaway Creek, and/or nearby wells; installation of groundwater monitoring wells or other monitoring stations, deployment of datasondes to provide temperature/dissolved oxygen profiles for characterizing the severity, duration and extent of hypolimnetic oxygen depletion within the water column; lake sediment sampling, and/or other activities. Given the limited budget and schedule for this project, the monitoring program will prescribe cost-effective methods that focus on the key data gaps and take full advantage of available COUNTY and Tacoma-Pierce County Health Department (TPCHD) staff and equipment. Samples collected for this project will be analyzed by the COUNTY s contract laboratory. The CONSULTANT will prepare a preliminary draft quality assurance project plan (QAPP) to guide the monitoring activities. The COUNTY will provide one set of consolidated review comments. The CONSULTANT will revise the QAPP, which the COUNTY will then submit to the Washington State Department of Ecology (Ecology). The CONSULTANT will then work with the COUNTY to respond to Ecology comments that are within the scope of this project and then revise the QAPP. After the QAPP has been approved by Ecology, the CONSULTANT will help the COUNTY implement the monitoring program. This task could also include public surveys, interviews with long-time county staff or retired staff or other activities to fill data gaps related to stakeholder support for lake management activities. Preliminary, draft and revised QAPP Three CONSULTANT staff will participate in two conference calls for this task. Each conference call will last 2 hours. The QAPP will be approximately pages. The COUNTY will provide one set of consolidated comments on the preliminary draft QAPP. Ecology comments on the QAPP will not require major revisions. The monitoring cost estimate for this Work Order is based on a number of assumptions. The initial monitoring budget is based on the assumptions listed below. o CONSULTANT will spend up to 2 days collecting lake bed sediment samples. Samples will be collected using a mini-ponar or van Veen sampler. Five composite samples will be analyzed for TP, TKN, ammonia-n, % solids, TOC, and particle size distribution. o COUNTY staff will perform water quality monitoring in the lake, Coffey Creek, and Spanaway Creek, and groundwater wells. o CONSULTANT will accompany COUNTY staff on the first round of monitoring to provide guidance as appropriate. 3

4 o COUNTY staff will collect lake profiles monthly except during June through October when monitoring will be done twice per month. Profiling will be done in the deepest portion of the lake and at up to four other locations. o COUNTY staff will collect lake water samples from the epilimnion and hypolimnion in the deepest part of the lake. The samples will be collected concurrently with the lake profiles. All lake samples will be analyzed in the lab for TP, SRP, TKN, ammonia-n, nitrate+nitrite-n, TSS, iron, alkalinity, chlorophyll a, and fecal coliform. In six of the rounds, the epilimnion lake samples will also be analyzed for phytoplankton. Two rounds will also be analyzed for zooplankton. o The COUNTY has access to a boat, flow monitoring equipment, and surface water sampling equipment. o CONSULTANT will purchase a multi-parameter datasonde (temperature, ph, DO, conductivity) for profiling, a Secchi disk for transparency measurements, and a Kemmerer sampler for sampling below the lake surface. o COUNTY staff will contact property owners to seek permission to sample existing shallow wells around the lake. o CONSULTANT will install up to 9 shallow (20 ft) monitoring wells using a geoprobe. The wells will be located within County rights-of-way. Well installation will cost approximately $15,000 (3 days for geoprobe o COUNTY will survey the wells (to establish benchmarks for water elevation measurements); therefore, CONSULTANT cost estimate does not include survying costs. o COUNTY will collect groundwater samples and measure water levels quarterly at up to 10 locations. o COUNTY staff will perform monthly surface water sampling at two locations (Coffey Creek just upstream of the lake and Spanaway Creek just downstream of the lake). In addition, COUNTY staff will collect surface water samples from four locations during three wet weather events. o Surface water samples will be analyzed in the lab for TP, SRP, TKN, ammonia-n, nitrate+nitrite-n, TSS, and fecal coliform. o COUNTY staff will install recording flow gages near the surface inlet and outlet to the lake and collect instantaneous flow measurements to establish stage-discharge relationships at the gage sites. o TPCHD and PCS staff will assist with monitoring as possible. o All laboratory analyses will be performed by the COUNTY s contract laboratory and billed directly to the COUNTY. Therefore, the CONSULTANT cost estimate does not include analytical costs. The monitoring cost assumptions will need to be revisited after the initial characterization has been completed. The monitoring program will be adjusted to align with the available budget. If public surveys are deemed necessary, the COUNTY will develop the questionnaire(s) (with input from the CONSULTANT as appropriate) and distribute them as appropriate to stakeholders. 4

5 Task 4. Refine Watershed Characterization. The CONSULTANT will use the Task 3 results to develop water and nutrient budgets and estimate the lake response. Based on our current understanding of the available budget and data, the CONSULTANT will develop a Vollenweider model (or similar model) to predict current and future inlake phosphorus concentrations based on the results of the phosphorus budgets. The Vollenweider model is commonly used to predict in-lake phosphorus concentrations as a function of annual phosphorus loading, mean lake depth, and hydraulic residence time. The team may also develop a similar model, such as the Nurnberg model, of in-lake phosphorus concentrations if seasonality and the effects of internal load are deemed important. The modeling efforts will provide information on the estimated effects of watershed management strategies on the concentration of phosphorus within Spanaway Lake. We will participate in a conference call to brief the COUNTY on the water and nutrient budgets. The Task 3 results will also be used to refine our understanding of the phosphorus and bacteria sources affecting Spanaway Lake. The CONSULTANT will identify the most likely sources (e.g., septic systems, landscaped areas, pets, wildlife and the transport pathways (e.g., Coffee Creek, groundwater discharge from dry wells and septic systems, runoff from shoreline areas). The CONSULTANT will participate in a meeting to brief the COUNTY on the source identification results. The CONSULTANT will prepare a brief memorandum summarizing the lake and watershed characterization. The memo will summarize the water quality and flow data collected during Task 3 and describe our understanding of the lake water and phosphorus budgets. The water budget will estimate groundwater as well as surface water flows into and out of the lake. The memorandum will also summarize our understanding of potential nutrient and bacteria sources, and include logs for the monitoring wells installed for this study. The memorandum will be formatted to serve as an appendix in the Plan that is developed in Phase 2. We will meet with the COUNTY to discuss the lake and watershed characterization and revisit the scope and budget for Phase 2. The CONSULTANT will also prepare a brief summary of the lake and watershed characterization suitable for the Spanaway Lake newsletter. In addition, the CONSULTANT will participate in a stakeholder meeting to discuss the key findings and next steps. Draft characterization memorandum (15 to 20 pages) Brief summary for newsletter Presentation for stakeholder meeting Three CONSULTANT staff will participate in one meeting and one conference call for this task. The meeting will last three hours and the conference call will last 1.5 hours. Two CONSULTANT staff will participate in a two-hour stakeholder meeting. Comments on the draft characterization memo will be addressed during preparation of the Plan (Phase 2, Task 6). Phase 2. Management Plan Development In Phase 2, the CONSULTANT will use the watershed characterization results to evaluate management options for Spanaway Lake (Task 5) and prepare the Plan document (Task 6). Phase 2 may need to be refined based on the Phase 1 results. Therefore, descriptions for Tasks 5 and 6 should be regarded as preliminary. 5

6 Task 5. Develop and Evaluate Management Measures The CONSULTANT will meet with the COUNTY to discuss the water quality goals for the lake in light of the previous tasks. Immediately after the meeting we will revisit the watershed to identify opportunities to implement watershed management practices to reduce watershed phosphorus and bacteria loading to the lake. We will then develop a preliminary list of potential short-term and longterm management measures to improve water quality of the lake. If the Phase 1 results indicate that watershed measures alone may not protect the existing uses of the lake, at least in the short term, the CONSULTANT will identify potentially appropriate in-lake management measures, such as alum treatments to inactivate internal recycling of phosphorus that may fuel late-summer algal blooms. The CONSULTANT will hold a workshop with COUNTY staff to discuss the preliminary management measures and identify any measures that might not warrant additional consideration due to technical, cost, or other issues. We will participate in a stakeholder meeting to get input on the candidate list and the criteria for selecting the measures to be recommended in the Plan. This outreach may also provide an opportunity to inform stakeholders about lake management costs and time frames. The CONSULTANT will meet with the COUNTY to discuss stakeholder input and refine any of the management measures evaluation criteria. The CONSULTANT will then use the criteria to evaluate and rank the candidate lake management measures. The CONSULTANT will use the Vollenweider/Nurnberg models developed in Phase 1 to estimate and compare the water quality benefits of the most promising source control and in-lake measures. We will then meet with the COUNTY to discuss the results and select the most promising measures. The CONSULTANT will develop planning-level concepts and cost estimates for each measure. If sewering appears to be a potentially appropriate measure, the planning-level cost estimate will be based on typical costs and readily available data. The CONSULTANT will work with COUNTY staff to develop a long-term monitoring strategy to track progress and support adaptive management. Successful implementation of the lake management measures will require funding. To that end, CONSULTANT will use available information to identify potentially appropriate funding sources, such as formation of a lake improvement district. The CONSULTANT will participate in a conference call with COUNTY staff to discuss the pros and cons and refine the funding options. Hand-outs at workshop Brief summary of workshop Preliminary and prioritized list of management measures and associated planning-level costs Preliminary summary of potential funding sources Four CONSULTANT staff will participate in a one-day site visit. Four CONSULTANT staff will participate in a 6-hour workshop. Two CONSULTANT staff will participate in a two-hour stakeholder meeting. General planning-level concepts will be developed based on available data for up to six source control and/or in-lake treatment measures. Each will be one page long. No modeling survey, etc. 6

7 If the COUNTY decides that sewering is potentially appropriate, the CONSULTANT will develop general planning-level concepts based on estimated distance to existing COUNTY system and typical costs per lot. Task 6. Prepare Lake Management Plan The CONSULTANT will prepare an annotated outline of the Lake Management Plan based on the preceding tasks. We will hold a conference call with COUNTY staff to discuss and refine the Plan outline. The CONSULTANT will then prepare a preliminary draft of the Plan that identifies actions towards achieving the environmental and community goals for the lake. The Plan will be consistent with the COUNTY s lake management program framework and applicable state guidelines. The Plan will be a concise document that recommends appropriate source control and/or treatment measures, lays out the implementation strategy and identifies potential funding sources. The Plan will include an adaptive management monitoring program to track water quality trends and assess the effectiveness of the lake management measures. The CONSULTANT will meet with the COUNTY to discuss their comments on the preliminary draft Plan and identify any necessary revisions. The CONSULTANT will then prepare a public review draft and summary presentations for stakeholders, the Surface Water Management Advisory Board (SWAB), and the planning commission, as appropriate. The team will revise the Plan as needed based on their input. Preliminary, draft and final Lake Management Plan Presentation for stakeholders, the SWAB, and the planning commission COUNTY comments on the preliminary and draft plans will be consolidated and conflicting comments resolved for delivery to CONSULTANT Four CONSULTANT staff will participate in a one-hour conference call on the outline The Plan will be a concise document (~100 pages). The Plan will include a conceptual level adaptive monitoring program description. Two CONSULTANT staff will prepare a brief presentation on the Plan and give the presentation at a stakeholder meeting. Task 99. Project Management The CONSULTANT project manager will perform staff supervision, budget and schedule tracking, and QA/QC throughout both phases of the project. At the start of the project, the CONSULTANT will prepare a brief project management plan (PMP) for internal use. The CONSULTANT will submit invoices and progress reports monthly and maintain frequent communication with the COUNTY project manager. Monthly invoices and progress reports. The project will be completed in two years. Progress reports will be brief bullet lists of activities completed during the invoice period. 7