Att 2 -Rev SPEC 02670_VertWell.doc

CNF Water Well Improvements

SECTION 02670

VERTICAL WATER WELL

DRILLING

PART 1 - GENERAL

1.01

SCOPE: This work shall consist of furnishing all labor, equipment, and materials to provide a new vertical water well. Work includes the drilling, casing, grouting, disinfecting, water quality testing, development, yield test, installation of the annular seal and water quality sampling and testing. Work also includes the destruction of existing abandoned vertical water wells and associated pump equipment, enclosures, control panels and concrete slabs.

1.02

ABBREVIATIONS AND DEFINITIONS::

A.

Abbreviations:

AQ.........Actual Quantity

HR.........Hour

L.F..... ...Linear Foot

LSQ.......Lump Sum Quantity

PVC.......Polyvinylchloride

B.

Definitions:

Actual Quantity - These quantities are determined from measurements of completed work.

Lump Sum Quantity - The quantities denote one complete unit of work as required or described in the contract, including necessary materials, equipment, and labor to complete the job. They will not be measured.

C.

Location of Work - The exact location of the well will be staked on the ground by the Government. The Government will assume all responsibility for locating the well site. It is understood that the drilling contractor does not represent, warrant, or guarantee the quality, quantity, or kind of water, if any, which may be encountered.

D.

Personnel and drilling equipment - All work shall be performed under the direct supervision of an experienced well driller. The contractor shall supply capable and experienced support personnel and cable tool or rotary (air or mud, standard or reverse circulation) drilling equipment. All work under this contract shall be performed in a skillful and workmanlike manner.

E.

Licenses and permits - The contractor shall be responsible for obtaining applicable permits. The Contractor shall have a valid California C57 license and shall supply all required information to the State and County subsequent to completion of the work.

F.

Notification - The Contractor shall notify the Contracting Officer's Representative 72 hours in advance of arrival at the site.

G.

Engineer - The technical Engineering representative designated by the Contracting

Officer.

H.

Timing of Drilling - Drilling and drilling related activities at the site will be limited to between the hours of 6 am and 6 pm of each day during the life of the contract.

I.

Protection of Waterways - All waterways, drainage courses, intermittent streams and the like, near the project area shall be protected by the Contractor in accordance with requirements of the California Department of Fish and Game and the California Regional Water Quality Control Board. All water encountered or used during construction of these projects shall be discharged in conformance with these requirements.

1.03

CODES AND STANDARDS: The Contractor shall comply with all Federal, State, or Local laws, ordinances, rules and regulations relating to the performance of the work. In the event that a conflict between these rules and regulations exists, the more stringent requirements shall govern.

A.

The Department of Water Resources, Bulletin 74, California Well Standards, will be used as the standard for completing all work performed under this contract.

B.

American Welding Society.

C.

National Sanitation Foundation (NSF).

D.

American Society of Testing Materials (ASTM).

E.

National Electric Code (NEC).

F.

American Water Works Association (AWWA).

G.

California Code of Regulations (CCR).

1.04

MEASUREMENT AND PAYMENT

A.

MEASUREMENT

Measurement and payment for contract work will be made under those pay items as listed in the Schedule of Items.

1.

The quantity of well drilling to be measured will be the actual number linear feet and size of drilled hole. Hauling water for drilling related use, containing drilling muds and final grading work at the wellhead is included in this item.

2.

The quantity of the steel conductor casing for the annular seal will be measured by the actual linear feet installed and accepted within the well. The conductor casing will start at a point at least 50 feet below the original ground surface and will extend to a minimum of 24 inches above the ground surface with a minimum 10 inch ID.

3.

The quantity of solid well casing to be measured will be the actual number of linear feet of casing furnished, installed and accepted in the well. The solid casing will be measured from 24 inches above ground surface down to the perforated casing. The solid well casing extends inside the conductor casing down to the perforated casing with a minimum 6 inch ID.

4.

The quantity of perforated water well casing or well screen to be measured will be the actual number of linear feet of perforated casing or well screen furnished, accepted and installed in the well. The perforated casing shall have a minimum 6 inch ID.

5.

The quantity of gravel pack will be measured as a lump sum quantity and will be as recommended by Contractor and licensed geologist and include all materials, equipment and labor.

6.

The quantity for well development will be measured as a lump sum quantity and will be determined to be complete by the Contracting Officer.

7.

The pump draw down and yield test will be measured as a lump sum quantity and will be performed as an 8 hour test as described herein.

8.

The annular seal grout to be measured will be the actual linear feet of approved approved annular seal grout furnished and installed in the well. ( In no case shall the depth be less then 50 linear feet).

9.

The destroyed wells will be measured as a lump sum quantity for each abandoned well and will include the destruction of all above ground appurtenances including pump panel, pump, valves, piping, surface concrete, top portion of well casings and well enclosures.

10.

Should the well fail to conform to these specifications through faulty workmanship or procedural failure by the Contractor and the Contractor is unable to correct the condition or negotiate a mutually acceptable cost reduction with the Contracting Officer for specification deviations, the well shall be considered an abandoned well through the fault of the Contractor and no payment will be made for any portion of the work. The Contractor shall be responsible for abandonment of the well at no cost to the Government.

11.

Should the Contracting Officer determine that the failure of the well to conform to these specifications is through no fault or responsibility of the Contractor or the Contractor's equipment, the work will be paid for at the unit prices in the Schedule of Items for the work performed. Additional well(s) drilled, at the direction of the Contracting Officer, in the same general location of the well previously drilled and abandon under this contract, shall be considered new wells and will be negotiated for at the contract rates. The Government shall be responsible for abandoning wells abandoned through no fault of the Contractor.

12.

Water quality sampling shall conducted in accordance with California Administrative Code, Title 22 and San Diego County Environmental Health Department for a public drinking water system classified as a transient non-commuity water system. All samples shall be taken to a California Certified Lab. .

B.

PAYMENT

The quantities as measured above will be paid for at the contract unit price as shown on the Schedule of Items. Such payments shall be considered full compensation for completion of the work and providing a fully operational and sanitary vertical water well.

PART 2 - PRODUCTS

2.01

CASING

A.

The Contractor shall provide submittals for the casing to be used, including product information and testing qualifications to the Contracting Officer within ten (10) working days prior to the start of approved drilling.

1.

ANNULAR SEAL CASING: The annular seal casing shall be a new, single wall, steel water well casing with a minimum thickness of a quarter (1/4) inch and fabricated from high-tensile strength, corrosion-resistant steel with the minimum material properties set forth in ASTM A53.

2.

PRODUCTION CASING: The production well casing shall be a new, undamaged, polyvinyl chloride (PVC) water well casing. PVC casing shall be pressure class 200 and meet ASTM F480 "Standard Specifications for Thermoplastic Water Well Casing Pipe and Couplings Made in Standard Dimension Ratios" including the later revisions thereof.

3.

PERFORATED CASING: Perforated well casing shall be of the same material as the solid well casing or may be an approved manufactured perforated casing or well screen. The Contracting Officer shall specify where perforated water well casing or well screen shall be installed. The casing shall be perforated to give the maximum yield and to minimize the intrusion of post development sediment into the well (for natural development screen should be sized so that 60% of the formation passes the screen during development; for a filter pack 90% of the filter pack material is retained). The casing must be perforated before it is installed. The slot width will be determined by Contractor and approved by Contracting Officer and be based on filter pack gradation or formation grain size distribution.

2.02

GROUT/ANNULAR-SEAL

A.

The grout shall be Sand cement, consisting of a mixture of Portland Cement (ASTM designation C-150 Type II), sand and clean water in the ratio of two parts of sand and one part of Portland cement by weight to not more than 5 gallons of clean water per sack (94 lbs) of cement, weighing approximately 118 pound per cubic foot. The well annular seal shall consist of a monolithic grout seal filling the annular space between the bore hole and the conductor casing to a minimum depth of 50 feet below the ground surface and extend to grade.

The use of special cements; bentonite to reduce shrinkage, or other admixtures to reduce permeability increase fluidity, control time of set, and the composition of the resultant slurry; must be approved by the Government.

2.03

DRILLING FLUIDS

A.

Drilling fluids shall consist of fresh, nonpolluted potable water, high grade clays commonly used in this area or biodegradable foams and approved commercial agent applied and used as prescribed by the manufacturer. All fluids shall be approved by the Contracting Officer prior to use and shall be applied and used as prescribed by the manufacturer. Toxic and/or dangerous substances shall not be added to the drilling fluid. Material Safety Data Sheets (MSDS) shall be provided for all proposed fluids (except water) and additives used at least 10 days prior to commencement of drilling.

2.04

WATER

A.

Contractor shall be responsible for providing an adequate supply of potable water for all drilling activities. Due to the low production of the existing water well at the station, the Contractor will not be allowed to use water from the water storage tank at the Camp Ole Fire Station. Water may be available at Cameron Fire Station on Kitchen Creek Road.

2.05

DISINFECTANT

A.

The disinfectant to be used for final sanitizing shall be calcium hypochlorite, sodium hypochlorite, or other approved disinfectant that is certified by the National Sanitation Foundation (NSF). The desired residual concentration is 50 ppm chlorine residual.

2.06

TEST PUMP

A.

The test pump shall be like new and will have a capacity of 50 gpm with maximum pumping level of 500 feet below the ground and shall be equipped for variable discharge so that various drawdown rates including the rate of 3 gpm can be determined.

2.07

SANITARY WELL SEAL

A.

Sanitary well seal tappings shall be a solid face type with adequate sized ports for the pipe column and two additional threaded ports for electrical conduit connections. Split face seals shall not be allowed.

PART 3 - EXECUTION

3.01

WELL DRILLING

A.

The Contractor shall drill the well at the location designated by the Contracting Officer. Access to the well site is the responsibility of the Contractor. The project area must be returned to its original condition. The Contractor shall drill the well and install the materials previously described so that the finished well conforms to the general design within these specifications and AS SHOWN ON THE DRAWINGS.

B.

The Contractor will contain all drilling fluids and cuttings in an excavated drilling sump or portable sumps supplied by the Contractor, when drilling muds or other drilling additives are used. The Contractor must indicate before drilling begins whether or not drilling additives are likely to be used and what they will be. The Contractor must submit MSDS for each additive at least 10 days prior to commencement of drilling. No additives will be allowed when drilling has proceeded without a drilling sump. Construction of the sumps will be provided by the Contractor.

C.

The Contracting Officer will review and approve the method of disposal of water discharged prior to well drilling and completion. Drilling fluids, cuttings, and discharged water will not be allowed to enter the roadways, drainages adjacent to the site or cause damage, including erosion, to adjacent property. The Contractor shall use all reasonable measures to prevent the entrance of foreign material into the well. The Contractor shall be responsible for any objectionable material that may fall into the well and any effect that it may have on water quality and quantity until the Contracting Officer accepts the well. During periods of temporary shutdown, the well bore and casing shall be covered in a manner approved by the Contracting Officer and the well and sumps shall be protected to prevent accidental entry by the public. The Contractor shall be responsible for maintaining safety procedures in accordance with Occupational Safety & Health Administration (OSHA) requirements.

D.

The bore size of the well shall accommodate both the production casing, conductor casing, sanitary seal and the gravel pack ( if needed) to the depth indicated on the Schedule of Items or determined by the Contracting Officer.

E.

The bore size of the first fifty feet of the well shall be four (4) inches larger than the outside diameter of the production casing. The well shall not exceed 400 feet in depth unless the Contracting Officer approves deeper drilling. At any time during the drilling operation the Contracting Officer may determine the production of water as adequate and halt the operation.

F.

Once the maximum depth is reached, provided the Contracting Officer does not abandon the well or stop the drilling, the Contractor shall install casing as specified by the Contracting Officer’s Representative. Unless the Contracting Officer approves otherwise, drilling, casing and surface sealing shall be completed in a reasonably continuous operation.

3.02

WELL LOG

A.

During the drilling operation the Contractor shall have a licensed geologist oberve and record a detailed and technically accurately written log. Elevations demacating changes in material type shall be recorded to within a reasonable level of accuracy as can be done with the drilling method and equipment. The materials shall be field classified as to the type of geologic formations encountered and shall minimally include grain-size (where applicable), color, moisture, and a qualitative assessment of the density as can be determined from the drilling. In rock formations an attempt at rock type should be made based on cuttings and drilling characteristics and depth(s) at which water is encountered shall be noted. Entries shall be dated and signed. The Contractor shall take particular care to locate and log all water-bearing strata and to determine the actual depth and type of water-bearing strata encountered. Other entries shall include static water levels and the times at which they were taken and casing information, including the lengths installed, the locations and lengths of slotted casing. The log shall be made available to the Contracting Officer during the drilling operations. Upon completion of the work, a copy of the log shall be filed with the State and a copy furnished to the Contracting Officer.

B.

A sufficient quantity of material shall be extracted from each water-bearing strata as is needed to perform a grain-size analysis for the purposes of determining filter pack gradation and/or well slot/screen size. Materials shall be delivered to an acceptable lab and the sieve analysis shall be used to produce a chart with the grain-sized distribution curves for each sample. The vertical axis shall identify the percent of meterial retained on each sieve while the horizontal axis will present the sieve size and grain size (thousandth of an inch). Copies of these charts shall be presented to the Contracting Officer prior to ordering filter material and/or well screen or perforated casing.

3.03

WELL CASING INSTALLATION

A.

All well casing shall be handled and placed with sufficient care to avoid damage to casing sections and joints. All sections shall be swabbed with a 50 parts per million (ppm) disinfectant solution as they are lowered into the well. All sections of the well casing shall be joined by sound, water-tight solvent welds or mechanical joints (threaded or otherwise coupled). Casings shall be equipped with centering guides to ensure the uniform radial thickness of the annular seal and/or gravel pack. The length of well casing to be installed will be determined by the depth of the drilled well. The well casing shall extend the entire depth of the well, or to a depth of 10 feet below the top of the bedrock interface, whichever is encountered first. The bottom of the well casing shall be capped if agreed upon by Contractor and Contracting Officer. A length of perforated well casing shall be installed at locations as approved by the Contracting Officer. If the drilled hole is primarily comprised of unconsolidated materials, a gravel pack of two (2) inches thick minimum around the casing shall be provided such that it will produce a maximum yield from the water bearing zone. The gravel pack shall be designed from the sieve analysis results corresponding to the strata being screened and will be submitted to the Contracting Officer for approval prior to installation. If multiple strata are being screened, it may be possible to design a single gravel pack based on the finest material being screened. The multiplier for the 70% retention shall be between 4 and 10 and will be based on the characteristics of the material. The gravel pack shall consist of clean material with well-rounded grains of 90% - 95% quartz. It shall have a uniformity coefficient of 2.5 or less. The gravel pack shall extend a minimum of 20 feet above the top of the upper most well screen and through all screened sections to either a depth of 10 feet below the screened section, the bottom of the blank section or the top of the bedrock, whichever is applicable; unless otherwise agreed to or as directed by the Contracting Officer.

B.

At the completion of all drilling operation, the conductor casing shall be evenly cut to at least twenty four (24) inches above grade. The cut surface shall have all burrs and/or slag removed and the Contractor shall provide a temporary cap to ensure the sanitation of the well until pump installation.

3.04

PLUMBNESS AND ALIGNMENT

A.

After the well casing has been lowered into position and before the gravel packing and cementing operations begin, the Contractor shall, at no cost to the Government, test the well for plumbness and alignment. The finished hole shall be straight and true with not more than 3 inches horizontal variation per 100 feet of depth. The alignment must be satisfactory for the successful installation and operation of the permanent pumping equipment. Should the allowable variation be exceeded, the well casing shall be removed from the well and the plumbness and alignment of the well shall be corrected by the Contractor at their own expense.

B.

The Contracting Officer may waive this requirement if, in his/her judgement, the Contractor has exercised all possible care in constructing the well and the defect is due to circumstances beyond his control.

3.05

ANNULAR SEAL

A.

In order to prevent the entrance of contaminated water, all annular space between the outer-most casing and the natural earth formation from a point at least 50 feet below the ground surface to the ground surface shall be completely filled with cement grout. The conductor casing, used to maintain annular space, shall remain in place during grouting to become a permanent part of the sanitary seal. Grouting shall be introduced via tremie or grout pipe from the lowest level of the annular space to be grouted. The grout shall slowly fill the annular space toward the surface in one continuous operation, filling the minimum, 2 inch annular space between the wall of the drilled hole and the outside of the casing. Grout shall not be allowed to free fall through water and shall be placed in such a manner that shall prevent the possibility of voids. Grouting shall be done in the presence of the Contracting Officer and an Inspector from the County. The Contractor shall notify the Contracting Officer at least 48 hours before a seal is to be installed.

3.06

WELL DEVELOPMENT

A.

Upon completion of drilling, casing, and sealing, the well shall be developed by surging, air lifting, or air jetting. Development shall continue for 4 hours or until the well is cleaned of all native silts and clays and drilling fluid residues deposited on the borehole face and in adjacent portions of the aquifer during the drilling process and water runs clear, whichever is greater. The objective of the development process is to assure the maximum specific capacity of the well. The Contractor shall provide the Contracting Officer with an estimate of the well capacity once development is completed.

B.

The Contractor shall notify the Contracting Officer 48 hours before the well is developed. Development shall continue until the Engineer in consultation with the Contractor determines that further development is unnecessary.

3.07

YIELD AND DRAWDOWN TEST

A.

After recovery (a minimum of 24 hours) of well development is complete, the Contractor shall perform a pump test to determine the yield, static water level and drawdown of the well. The Contractor shall notify the Contracting Officer at least 48 hours in advance of pump testing the well. Test pump shall be as described in part 2.06 of this section. A minimum test of 8 hours shall be conducted at the maximum pump rate which the well will sustain. After the 8 hour pumping test the Contracting Officer will have the option of discontinuing the yield and drawdown test if in his/her opinion an adequate water supply has been found. Additional pumping may be required at the discretion of the Contracting Officer to assist in the development of the well. If the yield is unsatisfactory to the Contracting Officer, drilling will resume.

B.

The Contractor shall furnish and install all necessary pumping equipment and discharge piping for the pumping unit, which shall be of sufficient size and length to conduct the water being pumped a minimum distance of 100 feet from the well. Discharge measurements shall be made using a digital flow meter accurate to at least 1% of full scale.

C.

The Contractor shall keep a written record of the pumping rates and shall provide the Contracting Officer with a copy. Measurements shall be made using a pressure transducer and data logger with an accuracy of at least 0.15 feet. The discharge rate for this constant rate test shall be set to a discharge rate that will not draw the water down to the pump during the test, but will stress the aquifer. Water level measurements in the pumping well will be made prior to the start of pumping. The record shall include the static and operating water levels corresponding to each pumping rate at the minimum following intervals:

First 10 minutes

- every 1/2 minute

First 20 minutes

- every 1 minutes

First 40 minutes

- every 2 minutes

First 60 minutes

- every 5 minutes

First 100 minutes

- every 10 minutes

For the remainder of the test

- every 20 minutes

D. After the pump has been shut off, monitoring of the recovery will begin. During the recovery portion of the test, water level readings will be taken at intervals identical to those during the pumping portion of the test. Readings will continue at this interval until the water level has recovered to its pre-test level, or a period of time equivalent to the period of pumping, whichever occurs first.

E. After the completion of the final test, the Contractor shall remove by bailing, sand dumping, or other method any sand, stones, or other foreign material that may have become deposited in the well.

3.08

DISINFECTION

A.

The Contractor shall clean and disinfect the well upon completion of well development.

1.

CLEANING: All foreign substances shall be removed and if required, swabbed with alkalies to remove oil and grease.

2.

DISINFECTION: Disinfect the well with chlorine solution of sufficient strength to provide a 50 mg/L (ppm, parts per million) chlorine residual in all parts of the well. The chlorine solution shall be poured directly into the well and the pump drop pipe shall be washed with the chlorine solution as it is lowered into the well. The disinfectant shall then be thoroughly agitated to mix the solution throughout the well until the discharge water smells of chlorine. Repeat this procedure several times at one hour intervals. After agitating, wash the walls of the casing above water level thoroughly with water bailed from the well. The well shall be allowed to stand without pumping for 12 hours. At this time, the chlorine residual should be monitored and if necessary, increased to 50 ppm. Repeat if necessary. After the chlorine residual of 50 ppm has been maintained for a full 12 hours without any significant drop, pump the water to waste, while de-chlorinating the discharge, until the presence of chlorine is no longer detectable by a chlorine residual test kit designed for this purpose.

3.09

WATER QUALITY SAMPLING

A.

The Contractor shall sample the well water 24 hours following disinfection so that the analysis will not be affected by the chlorine. Depending on the state classification of the well, the constituents to be tested for are listed in Chapter 15, "Domestic Water Quality and Monitoring", of Title 22, of the California Regulatory Code. Minimally, the following sampling and testing shall be performed on a representative water well sample: a bacteriological sample, a General Mineral and General Physical (iron, manganese, bicarbonate alkalinity, carbonate alkalinity, hydroxide, total hardness, calcium magnesium, sodium, TDS or specific conductance, turbidity, pH, color, odor and foaming agents (MBAS). Further, an inorganic analysis should be performed, including aluminum, antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, dluoride, mercury, nickel, nitrate, nitrite, perchlorate, selenium, thallium. The water analysis shall be performed by a state certified laboratory. A copy of the laboratory analysis shall be submitted to the Contracting Officer.

B.

Approval of the water analysis by the enforcing agency must be obtained before the well is put into use for potable consumption.

3.10

WELL DESTRUCTION

A.

If well is to be destroyed, the well shall be filled and sealed in accordance with California Well Standards, California Department of Water Resources, latest Bulletin, and in such a manner as to avoid accidents and to prevent it from acting as a vertical conduit for transmitting contaminated surface or subsurface waters into water bearing formations. Used drilling muds and materials containing organic material shall not be used to fill destroyed wells.

3.11

DESTRUCTION OF ABANDONED WELL: The abandoned water well shall be destroyed in accordance with California Well Standards, California Department of Water Resources, Bulletin 74.

A. The well shall be cleaned, as needed, so that all equipment and any obstructions to filling and sealing, debris, oil from oil-lubricated pumps, or pollutants and contaminants that could interfere with the well destruction are removed for disposal.

B. It shall be filled and sealed in such a manner as to avoid accidents and to prevent it from acting as a vertical conduit for transmitting contaminated surface or subsurface waters into the water bearing formations. Used drilling muds and materials containing organic material shall not be used. A well destruction permit should be obtained from the County of San Diego.

C. A suitable sealant impervious material (including neat cement, sand-cement grout, concrete, and bentonite clay) shall be added to the well from the bottom of the well up to the top of the upper most casing and in a continuous manner. No free fall of filler materials shall be permitted.

D. If applicable, in the gravel-packed zone, the casing shall be perforated or otherwise punctured along the entire gravel depth and the material shall be forced out under pressure into the gravel envelope.

E. Well sealing shall be completed to the top of the concrete pad within the existing structure. After a minimum of 24 hours following the addition of sealing materials, clean native backfill materials shall be used to cover the top portion of the seal.

3.12

CLEANUP

A.

Upon completion of all work on the well and removal of the drilling equipment, the well site shall be left in a clean and neat condition, free of all trash and debris in accordance with Section 01711, Cleanup and Disposal. Forest Service trash containers may not be used for disposal of project trash and debris.

B.

Drilling fluids spilled during drilling shall be cleaned up and placed in the drilling sump. No toxic or hazardous materials may be placed in the drilling sump. The Contractor will be responsible for the final disposal of drilling fluids and cuttings contained within the drilling sump off of National Forest land and of the closing of any drilling sumps.

END OF SECTION

DIVISION 2

Section 02670-1