Trinidad’s Integrated Coastal Watershed Management Plan Succeeds in Water Quality Improvements
Rebecca Crow | Project Manager
GHD @ WEFTEC 2015
Trinidad located in rural Northern California
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Set the stage of the project area: Project site ~250 miles north of San Francisco. Rural Northern California
GHD @ WEFTEC 2015
Trinidad Bay Area of Special Biological Significance
Area of Special Biological Significance
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In 2004, the City of Trinidad received a letter prohibiting discharge of polluted water to Trinidad Bay and the area surrounding Trinidad Head, which was declared an Area of Special Biological Significance (ASBS) by the State in 1974. Explain what an ASBS is….. The Trinidad is a Small City with a population of ~1,000 people Popular tourist sport – commercial fishing fleet, ocean access, state beach… The City did not have a lot of financial resources, however, did have lots of technical expertise in the area ICWMP Initiated to Address Protection of the Trinidad Bay Area of Special Biological Significance (ASBS) Trinidad Bay ASBS one of 34 ASBSs along the coast of California Bull Kelp Forest present in Trinidad Bay – important because…. ASBS areas have special protections to maintain high quality waters Set the geographic stage Located on bluff above bay Septics – Dense development lots of impervious surfaces Rains a lot (in/ yr) Bluff stability Cultural Resources
GHD @ WEFTEC 2015
Essential components for project implementation
Plan it
Follow it
Will to Act
Do it
Chi Wei Lin Former Mayer City of Trinidad
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Weave back in theme of putting it all together – Here’s how you put it together… Why People Don’t Take Action Fear Lack of Awareness and Disbelief Procrastination Overload Overanalysis Indecision… When it comes to creating Economic Prosperity in the face of challenges, action is what is needed
Plan it Integrated Coastal Watershed Management Plan
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Got $ to complete plan In 2006 the City obtained a grant to complete an Integrated Coastal Watershed Management Plan
GHD @ WEFTEC 2015
ICWMP Key management issues
• Water quality • Water supply • Stormwater management • Watershed management • Groundwater management • Ecosystems and habitat
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Management objectives for the Trinidad-Westhaven planning area were developed based on an analysis of existing environmental conditions, desired conditions, and regulatory requirements. As a result of the detailed wastewater, stormwater, and sediment analyses, a number of key management issues were identified Water quality: • Degraded water quality conditions exist at Trinidad State Beach and Luffenholtz Beach due to a high presence of “indicator bacteria” that pose a threat to human health. • Turbidity monitoring results on local streams indicated elevated levels of suspended sediment, particularly in those watersheds with higher densities of gravel and dirt roads. • On-site wastewater treatment systems (septic systems or OWTS) are used throughout the planning area, and may contribute to bacteria and nutrient pollution in local water bodies due to old age and lack of proper maintenance. Water supply: • Water diverted from Luffenholtz Creek by the City of Trinidad currently requires treatment for high levels of tannin and sediment during the rainy season. Water conservation and water quality improvement are essential to protecting supplies for new and existing water users. Stormwater management: • The City of Trinidad’s storm drain system is incomplete, with some streets lacking proper drainage structures. There are a number of areas within the City were stormwater flows directly over the bluff, increasing the potential for bluff erosion. In addition, Stormwater runoff entering the Trinidad Head ASBS has potential adverse effects on water quality and the kelp beds. Watershed management: •. A comprehensive long-term monitoring program is needed to document baseline conditions and identify trends for pollutants of concern. • Land use practices such as road-building, residential development, and forestry activities have impacts on watershed health and may be managed to some extent. Groundwater management: • Nonpoint source pollution affects groundwater as well as surface waters, which creates a problem as many residents pump drinking water from individual wells. General groundwater conditions in the planning area are not well documented. Ecosystems and habitat: • Trinidad Bay and its associated habitats comprise an important natural resource shared by the Trinidad-Westhaven community. Improving the quality of waters entering the Trinidad Head ASBS is the driving force behind this integrated watershed planning process. • The Trinidad-Westhaven planning area supports a number of special-status species, includingsalmonids. The ability of salmonid species to migrate upstream is currently restricted by man-made and natural barriers; however, the upper watersheds are being managed for the possibility of salmonid recovery. Salmon, steelhead and coho recovery is a long-term goal for ecosystem management throughout the Trinidad area as well as the greater North Coast region.
GHD @ WEFTEC 2015
ICWMP involved multiple stakeholders and participants
Yurok Tribe
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Truly a stakeholder driven process. The plan reflects the goals of the community as well as state and regulatory agencies. Local Gov’t Tribes Citizen watershed Groups State Agencies University Private Industry Non-Profits Consultants
• Water Quality Monitoring: On-going • On-Site Wastewater System Management: Policies
put in place • Road-Related Sediment Reduction Projects: Partially
completed • Public Outreach Projects: On-going • Water Conservation Projects: On-going • Stormwater Management Projects: Partially
complete • Collaborative Watershed Planning: On-going • General Plan Updates: Complete
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One of the outcomes of the ICWMP was a list of actions to implement the goals of the plan. List of action and status of those actions. Like to talk more in depth about 2 specific projects that cam out of the plan. Tee up two major project I will talk about – Stromwater Project and a watershed restoaration/ sedimetn reduction project
Do it ASBS Stormwater Improvement Project
GHD @ WEFTEC 2015
ASBS Stormwater project design
Overall objectives • Improve stormwater discharge from City area
to Trinidad Bay • Protect water quality of the Trinidad Bay ASBS Considerations • Small City with few resources • Existing septic leach fields interaction with
proposed stormwater infiltration • Existing bluff stability • Street parking important to residents • Cultural resources present
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Up until recently the City didn’t even have a City manager – City clerk, part time admin, part time police, 3 water operators. – Trying to accomplish big project with few resources. The ultimate goal of the multi-phased Trinidad ASBS Stormwater Improvement Project is to eliminate discharge of urban runoff from the City of Trinidad to the ASBS. The solution incorporates Low Impact Development (LID) stormwater treatment technologies with existing infrastructure, including a native plant rain garden, streetside parkable vegetated bioswales, and underground stormwater treatment chambers and infiltration pipes. Systems were designed to treat the 2-year design flow while accommodating a 50-year design storm volume. To develop this solution, data collection, modeling, and analysis prior to project design began in 2008, and mitigation and monitoring during construction was needed to overcome challenges related to site conditions. One challenge was that the City sits atop coastal bluffs which are naturally subject to erosion. To identify suitable locations for infiltration, soils and bedrock beneath the City were mapped and characterized, and a groundwater model was created to simulate the effects of infiltrating stormwater into the ground.
GHD @ WEFTEC 2015
Geotechnical evaluation overview
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Tee up why this was necessary – public concerned about effects to septic and bluff stability…. First step conduct geotechnical eval included: 8 soil Borings 9 Monitoring Wells (2 existing) 4 Transects Electrical Resistivity Seismic Reflection Work was needed to better understand subsurface conditions – address public concerns about interference with septic and bluff stability.
GHD @ WEFTEC 2015
Electrical resistivity results
Transect on Line 1 Edwards Street
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Technique to find bedrock - identify appropriate areas for percolation. Interesting tidbit from resistivity analysis – Black Line – highlighted in Blue shows interpreted bedrock interface Shows a possible buried sea stack – confirmed by MW testing, with shallowest well at 20 feet just east of deepest well at 70 feet.
GHD @ WEFTEC 2015
Isometric view of bedrock surface
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Putting it all together….. How did I use this info…. Comprised of Two Dominant Geologic Formations Unconfined Uplifted Marine Terrace Aquifer Acts primarily as one sand unit Ranges from 15 to 70 feet thick Saturated hydraulic conductivity ranges from 40 to 84 feet/ day Upper 5 to 10 feet has higher percentage of fine grains and lower hydraulic conductivity Confining Franciscan Bedrock Layer Groundwater Aquifer is confined by Mill Creek, Parker Creek, Pacific Ocean and Trinidad Bay, and exits the system through the creeks, springs/ seeps along the bluffs, or direct subsurface mingling with seawater Groundwater enters the system from upgradient groundwater sources, surface infiltration, and septic loading Data used to develop groundwater model. Groundwater Model MODFLOW-Surfact 3-D flow groundwater model was developed based upon physical properties collected during the geotechnical investigation Predictive groundwater model that describes groundwater movement and response to various changes in conditions – spatial and temporal Used during design to determine where infiltration can occur while considering existing septic systems, bluff stability, creeks and seeps
GHD @ WEFTEC 2015
Existing storm drainage system
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Talk about lack of infrastructure.. Move on quickly… Add pic of existing ocean outfall….
GHD @ WEFTEC 2015
Design of storm drain improvements
GHD @ WEFTEC 2015
Storm drainage system concept
Rain garden or bio-swale
Storm drain
Package sedimentation/
treatment chamber
Infiltration gallery
Urban runoff
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Talk old system – from DI to pipe to ocean…..
GHD @ WEFTEC 2015
Infiltration basins construction
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Preparing the site – Middle of rural residential street – lots of community outreach and homeowner interaction Digging out infiltration areas – notice lots of existing pipes to avoid – City over 150 years old. Installing treatment chamber Starting backfill around treatment chamber Installing infiltration chamber – notice connection for cleanout at the top
GHD @ WEFTEC 2015
Infiltration basins main street
BEFORE
AFTER
DURING
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Before – Main Street – access to School, Restaurants, City Hall, primary access to waterfront – state beach, boat launch, Public Peir During – Had to close street, worked closely with businesses and school on timing – limited road closure time After – public isn’t inconvenienced at all by improvements
GHD @ WEFTEC 2015
Bio-swales design
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Objective not to reduce parking – park able bio swales.
GHD @ WEFTEC 2015
Bio-swales construction
Do it #2 Luffenholtz Creek source water protection project
GHD @ WEFTEC 2015
Luffenholtz Creek source water protection
Objectives • Reduce sediments inputs to Luffenholtz Creek • Improve Water Quality in ASBS • Reduce treatment needed at City Water Treatment Plant Considerations • Project conducted on private property • Permits and Environmental Quality Act Compliance completed by
Private Green Diamond Resource Company • City responsible for 20-years of project maintenance • Project rock blasted from on-site Quarry
GHD @ WEFTEC 2015
Luffenholtz SWP construction
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Re-route logging roads (~1 mile) Decommission old logging roads Interesting note – CR-1000 built during WW II as alternate to coastal Highway to avoid car headlights begin seen by possible Japanese submarines
GHD @ WEFTEC 2015
Luffenholtz SWP construction
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Figure 13. View of restored channel and new bridge crossing to maintain road access New Bridges (2)
GHD @ WEFTEC 2015
Luffenholtz SWP construction
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View of restored creek crossing after the culvert was removed and the road was decommissioned.
Follow it Project Results and Next Steps
GHD @ WEFTEC 2015
Trinidad’s Integrated Coastal Watershed Management Plan Succeeds in Water Quality Improvements
• Implementation projects completed, monitoring showed reduced pollutant loadings to Trinidad Bay
• City still has a project champion planning for implementation of the next part of the stormwater improvement project
• Trinidad Watershed Council still active in informing the public about stormwater best management practices and the state of the watershed
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Project Outcomes 2014 Flow monitoring showed a 36.4% reduction in stormwater flows to the City’s stormwater discharge Project addressed some historic private property drainage issues Next Steps Completing Updated Preliminary design for Phase 2 of the project Looking for Funding through multiple state sources
