Attachment_1_Dewatering_Operations_Generic_Permit.PDF

Generic Permit for Discharge of Ground Water from

Dewatering Operations

February 2015

Water from Dewatering Operations

Rule 62-621.300(2), F.A.C.

• Generic Permit for Discharge of Ground Water from Dewatering

Operations

– DEP Document 62-621.300(2)(a)

• Notice of Intent to use the Generic Permit for Discharge of

Ground Water from Dewatering Operations

– DEP Document 62-621.300(2)(b)

• Notice of Termination Generic Permit for Discharge of Ground

Water from Dewatering Operations

– DEP Document 62-621.300(2)(f)

Water from Dewatering Operations

• Effective date February 10, 2015

• Includes site- specific control measures (Best Management

Practices) which are more effective at minimizing or eliminating pollutant discharges from dewatering operations to surface waters of the State

• User friendly Notice of Intent

Form (NOI) to standardize application requirements.

• Notice of Termination

Rule 62-621.300(2), F.A.C.

Dewatering Operations- Temporarily lowering the water table by draining or pumping of ground water from activities such as:

• excavations,

• building foundations,

• vaults,

• trenches and

• aquifer performance tests for exploratory purposes.

Applicability and Coverage

• Discharge of ground water from dewatering operations through a point source to surface waters of the state.

• Coverage under the dewatering generic permit shall not be effective until the applicant receives written notification from the Department.

• Discharges are limited to a term not to exceed 5 years from the effective date of coverage.

(Continued)

• Dewatering operations covered under the revised Generic Permit for Stormwater

Discharges from Construction Activities (CGP), will not be required to obtain separate coverage under the dewatering generic permit.

− Permitting requirements under the revised

CGP are the same permitting requirements as the dewatering generic permit.

• Sites currently permitted under the Generic Permit for the Discharge of Produced Ground Water from any Non-Contaminated Site Activity will have the option to:

- Continue to meet requirements of the produced ground water generic permit, or

- Elect to obtain coverage under the new dewatering generic permit

• New dewatering activities and renewals

- Coverage under the terms of the dewatering generic permit.

Fees

• Application fee as specified in the NOI

− $100.00.

• No annual fee in accordance with 62-4.052, F.A.C.

• Transfer of ownership fee accordance with

62-4.050, F.A.C.

− $50.00

Dewatering Generic Permit

GENERIC PERMIT FOR

DISCHARGE OF GROUND

WATER FROM DEWATERING

OPERATIONS

DEP Document

62-621.300(2)(a)

Dewatering Generic Permit

• Authorization to Discharge

─ The generic permit authorizes discharge of ground water from a dewatering operation through a point source to surface waters of the State.

• Definitions

• General Provisions

─ Limited to a term not to exceed 5 years from effective date of coverage.

─ Coverage is effective upon notification from the Department.

─ Submittal of a NOT within:

14 days completion of discharge or, upon expiration of coverage

Effluent Limitations

Parameter Units Discharge Limitation

Monitoring Frequency

Sample Type

Flow Gallons per day Report

1/week when discharging

Actual or Estimated

Best Management Practices

• Developed prior to the submittal of the NOI and implemented upon commencement of the discharge.

• Site specific to minimize or eliminate pollutant discharges to surface waters of the State.

• Require periodic inspections and maintenance to maintain treatment efficiency and recordkeeping.

• Most common types of sediment control technologies

– Sediment Traps and Basins

– Weir and Dewatering Tanks

– Filters

– Chemical Treatment

• Sediment Traps and Sediment Basins

– Temporary earthen basins formed by the excavation and/or construction of an embankment to detain runoff containing sediment and allow sediments to settle out before discharging.

– Sediment traps are usually smaller than sediment basins.

– Effective for the removal of large and medium sized particles and metals that settle out with the sediment.

– Design flow rates are 25 to 500 gpm.

Sediment Traps

• Sediment Basin

• Weir Tanks

– Use a series of over-flow and under-flow weirs to maximize the residence time in the tank and achieve efficient settling and removal of sediments including gravel, sand, silt and metals (with the removed sediment).

– Design flow rates are 60 to 100 gpm.

• Weir Tank

• Dewatering Tanks

– Equipped with a fabric filter.

– Water enters the tank through the top, passes through the filter, and is discharged through the bottom of the tank.

– Remove trash, gravel, sand, and silt, visible oil and grease, and metals.

– Design flow rates vary.

• Dewatering Tanks

• Gravity Bag

– Effective for the removal of sediments (gravel, sand, and silt). Metals are removed with the sediment.

– Have an initial higher design flow rates (300 gpm) when compared to other filters.

– Design flow rates are 300 to 800 gpm.

• Gravity Bag

• Sand Media Filters

– Water is treated by passing it through canisters filled with sand media.

– Effective for the removal of trash, gravel, sand, and silt and metals, as well as the reduction of BOD and turbidity.

– Often used as a secondary or higher level of treatment after a significant amount of sediment and other pollutants have been removed using other methods.

– Design flow rates are 80 to 1000 gpm.

(Filters Continued)

• Sand Media Filters

• Pressurized Bag

– Unit composed of single filter bags made from polyester felt material.

– Water filters through the unit and is discharged through a header.

– Effective for the removal of sediment (sand, silt, and some clays) and metals, as well as the reduction of BOD and turbidity.

– 50 to 1000 gpm.

• Pressurized Bag

• Cartridge Filters

– Provide a high degree of pollutant removal by utilizing a number of individual cartridges as part of a larger filtering unit.

– Often used as a secondary or higher polishing level of treatment after a significant amount of sediment and other pollutants are removed.

– Units come with various cartridge configurations (for use in series with bag filters) or with a larger single cartridge filtration unit (with multiple filters within).

– Design flow rates are 50 to 1000 gpm.

(Filters Continued)

• Cartridge Filters

• Chemical Treatment

– Includes the addition of carefully selected chemicals such as polymers (e.g., polyacrylamide, PAM), alum, or other flocculants to aid in the reduction of turbidity by the removal of smaller particulates such as clay and fine silt.

– Chemical treatment should be considered where turbid discharges to surfaces waters cannot be avoided using other available BMPs and turbidity needs to be reduced to levels less than the water quality standard of 29 nephelometric turbidity units

(NTUs) above background.

(Chemical Treatment Continued)

• Chemical Treatment - Factors to Consider

– The right chemical used at the right dosage.

• Will not cause or contribute to WQS violations.

– Flocculant mixed rapidly into the water to ensure proper dispersion and floc formation.

– Withdrawal system designed to minimize outflow velocities and to prevent floc discharge.

• If possible, discharge directed through a physical filter such as a vegetated swale to catch any unintended floc discharge.

• Chemical Treatment - Factors to Consider

– pH adjusting chemical shall be added, if needed.

– Systems can be designed as flow-through continuous or batch-treatment systems.

– Chemicals approved for potable water use

– Primary sediment basins may be required if the water to be treated has a high percentage of suspended solids.

• Continuous Treatment Systems

– Consist of the collection system, a chemical mixing system, sediment collection device, and interconnecting conveyances.

– May include pump(s)

– Primary settling in a sediment basins prior to treatment is recommended if the water to be treated has a high percentage of suspended solids.

– The size of the continuous treatment system has to allow for continuous mixing for the length of time required to complete the reaction at the flow rate expected through the system.

• Batch Treatment Systems

– Consists of the collection system, a sediment basin or sediment trap, pumps, a chemical feed system, treatment cells, and interconnecting piping.

– May be designed using ponds or portable trailer mounted tanks.

– Multiple treatment cells (at a minimum two) to allow clarification of treated water while other cells are filled or emptied.

– The combination of the sediment basin or other holding area and treatment capacity should be large enough to treat the volume of water anticipated

• Chemical Treatment System

• Sites that use cationic treatment chemicals are not eligible for coverage under the dewatering generic permit unless concurrence from the applicable local DEP office is obtained in advance of the submittal of the NOI.

– Site specific BMPs shall include appropriate controls and implementation procedures designed to ensure that the use of cationic treatment chemicals at the site will not cause or contribute to a violation of water quality standards.

Additional Information

State of Florida

Erosion and Sediment

Control Designer and

Reviewer Manual http://www.stormwater.ucf.edu/publications/2013RevisedDesignerManual.pdf http://www.stormwater.ucf.edu/publications/2013RevisedDesignerManual.pdf

Inspection and Maintenance

• Visual inspections of earthen embankments and discharge flumes or swales to prevent washout, scouring, and embankment blowouts. Areas subject to erosion shall be grassed or covered with some type of erosion control material.

• Sediments accumulated in sediment traps and basins shall be removed as necessary to maintain treatment efficiency.

• Sediments removed during the maintenance of a dewatering device shall be handled in accordance with the BMPs developed for the site.

• Periodic cleaning of tanks and associated piping and equipment shall be performed based on visual inspection or reduced flow.

Inspection and Maintenance

• Gravity filter bags shall be inspected for proper performance at a reasonable frequency based on amount of use. The bag shall be replaced when it no longer filters sediments or passes water at a reasonable rate.

• Filters shall be operated and maintained in accordance with manufacturer’s recommendation especially with respect to:

– cleaning,

– backwashing, and

– replacing overused filter media to ensure an acceptable level of efficiency.

• The permittee shall maintain records of weekly inspections and maintenance activities required to maintain treatment efficiency.

Recordkeeping Requirements

• Records of all data, including reports and documents, used to complete the NOI requesting coverage under the permit for at least 3 years from the date the Notice of Intent was filed.

• Records of flow monitoring as required in Part III.B.1., records of chemicals used for treatment, if any, and records of inspections and maintenance activities identified in Part IV.B.6. of the generic permit for at least 3 years from the date the record was created.

• Copy of the permit.

• Copy of coverage issued by the Department.

Other Conditions

• The discharge shall not cause a violation to surface water quality standards.

• Report any characteristic in the effluent that could indicate the presence of a pollutant(s) not previously identified or anticipated, and the occurrence, or new knowledge of, any spills, leaks or contamination in the vicinity of the project that could impact the water quality of the effluent.

• If contamination in the vicinity of the site that causes or contributes to violations of water quality standards is encountered, the permittee shall cease dewatering operations and contact the Department.

• Other Specific Conditions as outlined in Part VI. of the permit.

General Conditions

• Included those general conditions applicable to dewatering operations such as;

– Notification Requirements.

– Bypass Provisions

– Upset Provisions

Notice of Intent

NOTICE OF INTENT TO

USE THE GENERIC PERMIT

FOR DISCHARGE OF

GROUND WATER FROM

DEWATERING

OPERATIONS

DEP Document

62-621.300(2)(b)

Part I Instructions

• If dewatering operations are to be performed as part of construction activities, the applicant may elect to obtain coverage under the Generic

Permit for Stormwater Discharges from

Construction Activities, 2015 revision.

• NOI has to be completed and submitted at least

14 days prior to commencement of discharge.

• Permit application fee $100.00 (all sites)

Dewatering Site

Part II Dewatering Information

Contaminated

Contamination within 500 feet

Site Remediated

Parameters of concern above Surface Water

Criteria

Yes

Yes

Site is not eligible

Eligible

No

Yes No

No

• Tools applicant can use to determine cleanup restoration status.

– Contamination Locator Map (CLM)

• http://webapps.dep.state.fl.us/DepClnup/welcome.do

• http://ca.dep.state.fl.us/mapdirect/?focus=contamlocator

– Institutional Controls Registry (ICR) Web Viewer

• http://www.dep.state.fl.us/waste/categories/brownfields/pages/ICR.htm

• http://ca.dep.state.fl.us/mapdirect/?focus=icr

• Applicant may use other sources to determine whether contamination is present.

Part II.A. Dewatering Information http://webapps.dep.state.fl.us/DepClnup/welcome.do http://ca.dep.state.fl.us/mapdirect/?focus=contamlocator http://www.dep.state.fl.us/waste/categories/brownfields/pages/ICR.htm http://ca.dep.state.fl.us/mapdirect/?focus=icr

Contamination Locator Map http://ca.dep.state.fl.us/mapdirect/?focus=contamlocator http://ca.dep.state.fl.us/mapdirect/?focus=contamlocator

Institutional Controls Registry

Institutional Control Registry

Data

Institutional Control Registry

Data

Part II. D. Dewatering Information BMPs

• Site specific BMPs developed, (prior to the submittal of the NOI), or addressed in an existing BMP plan, in accordance to the requirements of the dewatering generic permit.

• NOI specifies that the BMPs must be implemented upon commencement of discharge.

Part II.D Dewatering Information (BMP Continued)

• Chemical Treatment

– The use of chemicals such as polymers, alum and other flocculants are authorized by the dewatering generic permit.

– Polymers (e.g. polyacrylamide) and alum can be used to reduce turbidity and other pollutants.

– Polyacrylamide (PAM) is typically used in conjunction with other BMPs to increase their performance.

• Note about Chemical Treatment

– Sites that use cationic treatment chemicals are not eligible unless concurrence from local DEP office is obtained in advance of the submittal of the NOI.

• The site specific BMPs shall include appropriate controls and implementation procedures designed to ensure that the use of cationic treatment chemicals will not cause or contribute to a violation of water quality standards.

• Cationic Treatment Chemical

– Polymers, flocculants, or other chemicals that contain an overall positive charge.

– Common examples of cationic treatment chemicals are

• chitosan,

• cationic polyacrylamide (C-PAM) and

• PolyDADMAC

– (POLYDIALLYLDIMETHYLAMMONIUM

CHLORIDE).

• Suggestions when reviewing request to use cationic treatment chemicals

– Check if treatment chemicals have been approved by FDEP for potable water use.

– Ask if laboratory data test were conducted to demonstrate that turbidity reduction necessary to meet the receiving water criteria will be achieved.

Parts III-V. Additional Information

• Receiving Surface Water Body Identification

• Coverage Status

• Site Name

• Permittee Information

• Site Location Information

– If records are kept off-site, the physical address of site where records will be kept.

• Owner /Operator Statement

Termination of Coverage

NOTICE OF

TERMINATION GENERIC

PERMIT FOR

DISCHARGE OF

GROUND WATER FROM

DEWATERING

OPERATIONS

DEP Document

62-621.300(2)(f)

Additional Items

• Template Notice of Coverage letter

• Create new permit type in PA exclusively for the dewatering generic permit. (IWDE)

• Instructions on entering permit information into

PA

Questions

• Questions

• Contact Information

Abel Agosto

850-245-8603 abel.agosto@dep.state.fl.us

2/11/2015 66 mailto:abel.agosto@dep.state.fl.us