Turbidity_Monitoring_Criteria.pdf

TURBIDITY

MONITORING

CRITERIA

Turbidity Monitoring Criteria

1. Sarasota County shall be notified 48 hours prior to commencing the dredging operation. At that time, the County’s Project Manager will arrange an on-site inspection to insure that all preliminary procedures (i.e., installation of best management practices and turbidity monitoring stations, etc.) have been adhered to.

2. Two rows of turbidity curtains shall be used during the entire dredging operation. For activities within upland cut canals, curtains shall extend across the mouth of the canal. For activities within coastal streams and bays, curtains shall surround the project limits. In all instances, curtains shall be staked in place, shall reach the submerged bottom at all times, and shall be flush against the shoreline for a minimum of ten feet.

The type of turbidity curtain (Type 1, 2, or 3) to be utilized shall be determined by project location and normal water flow. For projects located in coastal streams and bays, navigational markers identifying the turbidity curtains are also required.

3. Turbidity monitoring stations shall be established at specific locations and maintained throughout the duration of the project. The following locations are examples, actual station locations are to be established as needed for each project to provide more accurate monitoring.

Monitoring Site 1: In Phillippi Creek, 50 feet to the north of the project area.

Monitoring Site 2: In Phillippi Creek, 50 feet to the south of the project area.

Background Site(s): A minimum of 100 feet outside the limits of the project area, within

Phillippi Creek.

A minimum of 3 background sites will be established around projects that extend into a body of water that is influenced by the tides. All monitoring stations will be marked with a temporary buoy. Once established, turbidity monitoring stations cannot be relocated without specific written permission from Sarasota County’s Project Manager.

It is expected that the party responsible for monitoring will be an experienced professional affiliated with the selected general contractor.

4. Monitoring for turbidity as measured in Nephelometric Turbidity Units (NTU) shall be conducted for the duration of the project. Sampling will commence at the initiation of dredging activities and continue until the project is completed. Daily sampling will occur one hour prior to construction start-up, at four-hour intervals throughout the day, and one hour after construction ceases for the day.

Samples will be collected from mid-depth above the submerged bottom. Sampling will be restricted to the axis of the visible plume. If no plume is visible, samples will be collected at the intersection of the mixing zone boundary and a line parallel with the water current and extending from the source of turbidity.

5. Monitoring station data shall be submitted on a daily basis to Sarasota County’s Project Manager. Monitoring data submitted by spoken word on the phone shall also be submitted in writing within five calendar days.

6. All samples will be analyzed by using a turbidity meter. Collected samples must be analyzed immediately. The following information must be recorded for each sample taken and submitted in a Monitoring Report:

a. Site number;

b. Recorded turbidity measurements (NTU);

c. Dates and time of day when the sample was collected;

d. Total depth and sample depth;

e. Antecedent weather conditions, including wind direction and velocity; and

f. Tidal stage and/or flow direction.

7. In addition to the above-mentioned information, each Monitoring Report must include the following:

a. A statement of methodology including types of sampling equipment and analytical instrumentation, preservation, and handling;

b. FDEP Exemption Number;

c. A map indicating numbered locations of all sampling sites;

d. Copies of the Quality Assurance/Quality Control log; and

e. The printed name, address, and telephone number of the lab and/or person(s) conducting the monitoring.

8. The owner shall comply with the following Quality Assurance/Quality Control requirements for each sample collected:

a. All turbidity analysis shall be performed on instruments approved by this office;

b. The instrument must be recalibrated after a maximum of ten analyses and/or after every time the instrument has been turned on;

c. A duplicate analysis must be performed for all single samples analyzed. A minimum of one duplicate analysis must be performed for every ten samples analyzed;

d. Calibrations must be performed against a fixed standard and a prepared standard and must follow a zero adjustment against a blank;

e. All calibration procedures must be recorded in a permanent log book and copies must be submitted with the data; and

f. Date and time of collection, date and time of analyses, warm-up time, and the printed name of the analyst must be included in the log.

9. Should monitoring reveal that the reading at any monitoring station exceeds the background station reading by 29 NTU, then all dredging activities associated with the project shall cease immediately. Corrective measures must immediately be taken to rectify this problem (i.e., ensure that turbidity curtains are installed properly and are functioning correctly). Any such occurrence shall be reported immediately to the County Project Manager.

10. Turbidity curtains shall not be removed until authorization has been given by the county’s

Project Manager.