J-4_Exhibit_1_SWPPP_9_pages.pdf

Mission Beach Wastewater Treatment Facility Improvements Project

Construction Stormwater Pollution Prevention Plan

June 2013

IHS - Tulalip Tribes

Mission Beach Wastewater Treatment Facility Improvements Construction Stormwater Pollution Prevention Plan

Table of Contents Introduction

Existing Site Conditions

Adjacent Areas

Critical Areas

Soils

Erosion Problem Areas

Construction Stormwater Pollution Prevention BM Elements

Mark Clearing Limits

Establish Construction Access

Control Flow Rates

Install Sediment Controls

Stabilize Soils

Protect Slopes

Protect Drain Inlets

Stabilize Channels and Outlets

Control Pollutants

Control Dewatering

Maintain BMPs

Manage the Project

Financial/Ownership Responsibilities ............ Error! Bookmark not defined.

Wastewater Treatment Facilities Improvements Construction Stormwater Pollution Prevention Plan

Introduction

This Stormwater Pollution Prevention Plan (SWPPP) has been prepared for submittal to the Government as required per the specifications of IHS project Number PO-10-L17, Tulalip tribes Mission Beach Wastewater Treatment Plant Improvements. The project is located at the site of the existing Mission Beach Wastewater Treatment Plant (WWTP) and the current site of the influent lift station serving the plant, Lift Station No. 3. (Note that this SWPPP applies only to stormwater runoff and dewatering operations from the construction site and not to sewage discharges. Untreated sewage shall not be discharged from the site under any circumstances). It is the overall intent of the SWPPP to manage runoff and dewatering flows such that the water infiltrates into the soil rather than entering surface waters, and if any flows must enter surface waters that the turbidity and contaminants have been removed prior to discharge.

Construction activities will include demolition, excavation, trenching and minor grading. The purpose of this SWPPP is to describe the proposed construction activities and all Temporary and permanent Erosion and Sediment Control (TESC) measures, pollution prevention measures, inspection monitoring activities, and record keeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to:

1. Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity.

2. Prevent violations of surface water quality, ground water quality, or sediment management standards.

3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff/dewatering flows at the Permittee's outfalls and downstream of the outfalls.

Existing Site Conditions

The WWTP site is slightly less than 1 acre with 75% of the surface area paved.

Runoff from the WWTP site is collected in catch basins and conveyed west toward the tide flats of Tulalip Bay.

Adjacent Areas

No upstream areas contribute flow to the site.

Critical Areas

Wetlands are present in the Lift Station No. 3 area.

Soils

The NRCS Snohomish County Soil Survey identifies the predominant soil type on the site as Kitsap silt loam: very deep, moderately well drained, on 0 to 8 percent slopes; on terraces from lacustrine sediments. The soils have slow permeability and the hazard of water erosion is slight.

Erosion Problem Areas

There are currently no known erosion problem areas within the clearing limits of the site. However, erosion is a possibility during construction. The risk of erosion in this area may be mitigated through the use of proper BMPs as described below. Since rainfall on the site is likely to be the principal cause of erosion, the risk of erosion will be reduced by scheduling earthwork for the dry summer season.

If this project continues into the winter season, the following wet weather precautions will be practiced.

Prevention of tracking mud onto roads through the use of equipment sweeping onsite and if necessary, a wheel wash installed near the construction entrance.

Geotechnical fabric shall be installed under all construction entrances with rock surfaces.

Exposed portions of the site shall be adequately covered by straw or mulch material based upon the weather. Straw or approved equivalent material will always be available on site and ready to use. Exposed areas will be adequately covered when raining and at the end of the day if the next day is a “non-working” day. Weather forecasts shall be used to govern whether work will commence or stop for the day.

All site work generating exposed soil (with the exception of installation and maintenance of erosion control BMPs) shall cease during weather conditions when rain generates runoff and causes erosion.

If necessary, earthwork shall be phased to minimize areas of exposed soil.

The Contractor will devise a maintenance and inspection schedule with an identified erosion control specialist responsible for these items.

An erosion control specialist (Certified Erosion and Sedimentation Control Lead, CESCL is recommended but not required for this project) will be present or on-call throughout the project duration to insure the BMPs are working appropriately and are well maintained. The specialist will monitor the discharge after each storm event that generates runoff. They will also conduct site inspection reports on the installed BMPs. These reports will be available on site and provided to the Contracting Officer’s Representative (COR) on a monthly basis and/or when requested. The monitoring and sampling shall be done in a professional manner consistent with current sampling protocols and reporting requirements. Sampling points will be determined during the pre-construction meeting and shall be marked on the ground.

Vegetated buffers and forest areas shall be protected, especially through the use of silt fences or compost socks, and minimization of soil exposure.

If necessary, dirty water shall be filtered through an approved device such as a Baker tank, prior to releasing it to the infiltration facility.

Open drainage ditches shall have a method of slowing the surface flow of water through the use of stilling pools created with sand bags or quarry spalls.

Construction Stormwater Pollution Prevention BMP Elements

Mark Clearing Limits

The clearing limits will be established prior to beginning land disturbing activities by placing high visibility fence around the areas indicated on the plans.

Establish Construction Access

A riprap construction access with geotextile fabric under the rock will be installed at the entrance of the Lift Station No. 3 site. If necessary during wet weather, a wheel wash facility may be constructed to minimize the impact of construction on nearby streets. As an additional measure, street sweeping will be performed when required.

Control Flow Rates

All drainage from the site will be directed to an on-site infiltration structure or level spreader designed to infiltrate the runoff/dewatering flows into the soil.

Any flows that can not be infiltrated into the soil will be treated prior to discharge from the site. No sediment laden or contaminated runoff will enter surface waters under any circumstances.

Install Sediment Controls

Sediment controls include a silt fence or compost sock along the perimeter of the site, interceptor ditch, covering of soil stockpiles, and installation of straw or mulch when necessary. Erosion control BMPs shall be installed prior to land disturbing activities as noted on the plans.

Stabilize Soils

To protect soil stockpiles from erosive forces such as rain, plastic sheeting, jute mats or similar BMPs will be placed upon exposed and non-worked soil throughout construction. Per wet weather requirements, these BMPs will be placed within 2 days of stockpiling the soil from October 1st through April 30th or if raining.

Protect Slopes

Slopes are not anticipated to be damaged from concentrated flows. Stockpile slopes shall be protected as mentioned in the “Stabilize Soils” section.

Protect Drain Inlets

To prevent sediment from moving off the site, catch basin inlet protection shall be used for any catch basins downstream of work areas and on new catch basins as they are installed. Inlets will be inspected weekly at a minimum and daily during storm events as noted on the plans. Sediment shall not accumulate greater than six inches in depth within the inlet protection device.

NOTE: catchbasins within the WWTP yard drain back into the influent lift station No. 3 wet well and then through the wastewater treatment system. Catch basin inlet protection filters will be monitored and replaced frequently to eliminate any sediment from entering the treatment processes.

Stabilize Channels and Outlets

Where site runoff is to be conveyed in channels, or discharged to some other natural drainage point, efforts will be taken to prevent downstream erosion.

Control Pollutants

Good housekeeping practices and appropriate BMPs will be utilized to control pollutants on site. Any water used to clean equipment or pumped from the existing drainage facilities shall be filtered through an approved filtering device and tested prior to discharging to an undeveloped portion of the site.

Control Dewatering

Any water from dewatering operations that may occur throughout this project, will be conveyed to an approved filter such as a Baker tank and then released to an undisturbed area on site. All measures shall comply with Tulalip Tribe and Washington State Department of Ecology requirements.

Maintain BMPs

The BMPs shown on the plans will be maintained and repaired as needed.

Specific maintenance requirements are listed in the notes and/or details on the plans. Monitoring will be conducted by the designated erosion control specialist to insure BMPs are working effectively and are not damaging facilities or waterways downstream of the site.

Manage the Project

Erosion Control Specialist: The contractor shall provide the name of a an erosion control specialist that will verify that the actions noted in this Stormwater Pollution Prevention Plan and on the drawings will be implemented.

Phasing of Construction: The first order of work will include establishing clearing limits, installing appropriate BMPs for erosion control and clearing sediment. The remaining site will then be cleared and project development will commence. The site shall be protected as described in this Plan and on the drawings. Throughout the work, the contractor is responsible for maintaining all BMPs. Upon completion of the work, temporary BMPs shall be removed as necessary.

Seasonal Work Limitations: Work should be scheduled for the dry season however, it may be conducted during the wet weather season of October 1 through March 31st. Construction entrances consisting of a wheel wash facility and/or underlying geotextile fabric will be utilized to minimize the disturbance from transporting soils from the existing site. All stockpiles shall be covered with plastic sheeting, straw (or equal) to minimize any loss of soil during the wet weather. The Contractor will be responsible for consistently monitoring the outfall to ensure all applicable requirements are met and that water quality downstream is not being compromised throughout this process.

In addition, the contractor’s erosion control specialist will be responsible for ensuring that proper BMP maintenance is conducted throughout the season as well as ensuring the local requirements are met through testing and other appropriate methods.

Coordination with Utilities and Other Contractors: As stated on the plans and in the specifications, the contractor shall be responsible for coordinating any utility work with the appropriate agencies.

Inspection and Monitoring: Inspection and monitoring as well as compliance will occur in accordance with the Washington State Department of Ecology (DOE) Stormwater Management Manual for Western Washington. At any location where runoff will enter surface waters, a runoff sample will be obtained and tested for turbidity and pH by a state certified laboratory. If the contractor wishes to use their own turbidity meter, they must demonstrate calibration for the COR prior to use. An erosion control specialist will be present or on-call throughout the project duration to insure the BMPs are working appropriately and are well maintained. The specialist and the Contracting Officers Representative (COR) will choose appropriate monitoring sites and note them on the field copy of the plans. Sampling points will be determined during the pre-construction meeting and after observing movements of runoff as work progresses and shall be marked with a stake. They will monitor the discharge from this site after each storm event that generates runoff as well as once per month if flow is occurring. They will also conduct site inspection reports on the installed BMPs. The monitoring and sampling shall be done in a professional manner consistent with current DOE sampling protocols and reporting requirements. A turbidity value greater than 25 NTUs indicates erosion/sedimentation control measures are not adequate. A turbidity value greater than 250 NTUs indicates a significant problem and the contractor shall stop work and focus efforts on erosion/sedimentation control.

Reporting: All spills or discharge of pollutants shall be reported within 24-hours to the COR and the Tribe. Discharge samples shall be tested for turbidity during or immediately after significant precipitation events and the results reported to the COR. A turbidity level of 250 NTUs requires the contractor to contact the Washington State Department of Ecology following the instructions on the DOE website:

http://www.ecy.wa.gov/programs/wq/stormwater/construction/.

Site inspection reports will be available on site and provided to the COR on a monthly basis and/or when requested by the COR or the Tribe. An NPDES Construction Stormwater General Permit is not required for this project. A Notice of Intent is not required for this project, however the contractor shall follow the reporting requirements of the Tulalip Tribes in addition to those of

DOE.

Maintenance: No maintenance on heavy equipment is expected to occur on site throughout the project. Any spilled equipment fluids such as hydraulic fluid or oil shall be immediately absorbed, contaminated soil excavated, and the absorbent and/or soils disposed of at a disposal site equipped to accept such wastes.

Maintenance of the Construction SWPPP: This plan will be located on site at all times. The plan will be revised accordingly if significant changes have been made to the design, construction, operation, or maintenance of any BMPs.