Method for constructing a synthetic infiltration collection system
The present invention is method for constructing a synthetic infiltration collection system for installation at seaside locations. This system filters undesirable elements from seawater including detritus, suspended solids, garbage, debris, volatile organics, toxic and harmful algal blooms and other biologics. The resulting filtered seawater is then pumped to a desalination plant for de-salting. This system comprises a subterranean reservoir installed at a sheltered location, such as behind a set of dunes. A borehole is created by slant drilling, the borehole breaking through the surf line and into the open ocean. A pipe is laid in the bore hole, the pipe extending from the reservoir out to the open ocean. The pipe ends in an intake, which is overlapped by gravel packets which act as filtration media. The intake receives water filtered through the gravel packets, which is transported through the pipe to the reservoir.
This patent application claims the benefit of U.S. provisional patent application Ser. No. 60/737,252, filed on Nov. 15, 2005.
2. TECHNICAL FIELDThis invention relates to the field of desalination of seawater and more specifically, to a method for constructing a filtered seawater collection system which removes suspended solids, debris and biological material prior to subjecting the seawater to desalination.
3. BACKGROUNDSeawater desalination is becoming an attractive source of drinking water in coastal states as the costs for desalination decline. A prime consideration for seawater desalination is a source of feed water that is reliable and consistent to sustain operations and produce potable water effectively and efficiently. The amount and quality of feed water entering a desalination plant is greatly dependent upon the placement of the feed water intake. Up to the present time, feed water intakes have been of two basic types, namely: 1) directly from the sea; and 2) indirectly from the sea. Each of these types of intakes has significant benefits and significant drawbacks which will be further explained below.
Open ocean intakes, or direct intakes, can be as simple as dredged channels through a nearshore region to draw in seawater. More sophisticated direct intakes involve the construction of pipelines from shore to beyond the nearshore, out to waters deeper than 35 meters. Deeper water is desirable in that the intake is less affected by wave and tidal action, but added pumping costs and pipeline costs limit the depth to which direct intakes can be practically placed. Direct intakes are fairly long lived in that they can have a service life of 30-50 years. They also provide an unlimited supply of seawater to a desalination plant as the seawater is pumped directly to the plant. However a first drawback of direct intakes is that they are hampered by impingement and entertainment of planktonic organisms that require additional filtration and pretreatment once the seawater arrives at the plant, thereby driving up fresh water production costs. Other common problems associated with direct intakes include biological fouling of intake pipes, trash and other debris in intakes, hydrocarbon products in feed water and recirculation of discharge to intakes. Additionally, uncertain construction permitting outcomes related to direct intakes in light of modified regulatory practices derived from Section 316(b) of the Clean Water Act plague desalination plant developers.
Indirect seawater intakes include vertical beach wells, Ranney wells, and infiltration galleries. Common among these indirect seawater intakes is that they are all dependent upon the nearshore geology in which they are placed, to provide a filtered seawater product.
Vertical beach wells are placed near a shoreline, typically very close to the nearshore in order to capture seawater filtering through the local nearshore geology. The beach well is a subterranean reservoir that is sunk approximate to sea level coupled to a pipe that is rammed outward from the bottom of the reservoir into the nearshore geological formation, the pipe having a plurality of through-holes for allowing the flow of seawater into the pipe. The distance that the pipe can be driven into the surrounding geology limits the ultimate length of pipe. As water flows into the reservoir, it fills the reservoir until the level of water in the reservoir is the same as at sea level. The water is then pumped from the reservoir to the desalination plant to be de-salted. Beach wells are advantageous because they avoid issues related to volatile organic spills and lessen potentially harmful algal blooms. Hence, the water quality provided by beach wells is excellent. However a drawback exists in that the water supply produced by a beach well is totally dependent on hydrogeologic conditions at the site. Furthermore, in comparison to the unlimited seawater supply from direct intakes, beach wells typically provide water volumes in the range of only 400-4000 cubic meters per day.
A Ranney well employs a plurality of radially arranged collector wells located horizontally beneath a beach. The collector wells channel filtered seawater to a central sunken reservoir from which the seawater is pumped to a desalination plant for de-salting. Ranney wells typically have higher infiltration rates than vertical beach wells, in that they can produce filtered seawater volumes in a range of 8,000-20,000 cubic meters per day. However, like beach wells, they are limited by the nearshore geology. Also, Ranney wells can be hampered by silt buildup and may also influence onshore groundwater resources, so careful evaluation of site characteristics must be employed before a Ranney well can be installed.
Indirect seawater intakes also suffer from a shorter life span, usually 15-20 years, when compared with the 30-50 year life span of direct intakes. Further, the limitation in production capacity limits the use of indirect seawater intakes to only small desalination plants. Also, due to the fact that indirect seawater intakes must be placed near the nearshore, they are vulnerable to storm damage or damage from beach erosion.
Present seawater intakes for use with desalination plants require choices and compromises between high volume, long life direct intakes and the low volume, shorter life, but higher water quality provided by indirect intakes. Therefore a need exists for a seawater infiltration system that incorporates the high volume and long life of a direct intake while providing the high water quality of an indirect intake without being limited by surrounding nearshore geology. A need also exists for a method for constructing such a seawater filtration system.
The foregoing reflects the state of the art of which the inventor is aware, and is tendered with a view toward discharging the inventor's acknowledged duty of candor, which may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing discussion does not teach or render obvious, singly or when considered in combination, the inventor's claimed invention.
SUMMARY OF THE INVENTIONThe synthetic infiltration collection system, which is constructed by the inventive method, provides high quality water without being dependent upon local nearshore geological formations. The system also provides water volumes much higher than systems that depend upon indirect intakes that are dependent on nearshore geology. The system's ability to eliminate dependency upon local nearshore geology allows it to be placed in coastal areas of the world where the nearshore geology renders indirect intakes an impossibility. This dependency on local geology is eliminated primarily because the inventive method for constructing the system employs directional drilling techniques to place the intake pipe of the system. Directional drilling allows for drilling through the nearshore geology in any coastal location, so that the intake pipe can be placed in the open ocean.
The inventive method is comprised of placing a subterranean reservoir in communication with the first end of an intake pipe. The reservoir is buried at a level approximate to sea level so that the inflow of water from the intake pipe occurs until the water in the reservoir reaches sea level. Directional drilling methods are used to create a bore for the placement of an intake pipe. Directional drilling can be used to place a single intake pipe. Alternatively, directional drilling can be used to place a very large pipe, such as a pipe having a 30″ or greater bore diameter. The large pipe in this case acts as a bore lining so that a plurality of intake pipes can be placed inside of the large pipe and connected to the reservoir. This allows for the filtration of much higher volumes of seawater from the multiple intakes. Also, as desalination needs grow with population growth, this configuration would allow for more intake pipes to be added.
The intake pipe extends from the reservoir out past the nearshore and into the open ocean where it is preferably anchored to the sea floor. The opposite end of the pipe terminates at an intake area where the pipe is perforated with a plurality of openings. In one embodiment, geological materials, preferably gravel, are filled into porous containers resembling bed mattresses and enclosed therein. The containers are then lowered precisely upon the intake so that the porous containers cover the intake openings. The containers then act as a portable geology causing only filtered seawater to enter the pipe. Undesirable suspended elements such as detritus, suspended solids, other suspended biologics, debris and hydrocarbons are either greatly reduced or eliminated altogether by the system. The placement of the intake in the open ocean also allows for the system to produce volumes of water above that of prior art indirect intake designs.
It is an object of this invention to provide an inventive method for constructing a system for filtering seawater that can bypass any nearshore geology.
Another object of the invention is to provide an inventive system and method for filtering seawater, which produces a higher volumetric flow of filtered seawater than existing indirect intake systems.
Still another object of the invention is to provide an inventive method for constructing a system for filtering seawater, which allows desalination plants to be located in areas having undesirable nearshore geology.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention, without placing limitations thereon.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be more fully understood by reference to the following drawings, which are for illustrative purposes only:
Referring to
The pipe 20 is inserted through a bore 32 (dotted line on either side of intake pipe 20) drilled through the nearshore geology 22 between the bottom of the reservoir 12 and through the surf line 30. The bore 32 is placed through the use of directional drilling techniques. Directional drilling can produce a bore 32 several hundred yards long or even up to a half-mile or more. This allows the reservoir 12 to be placed in a location that is safe from coastal forces such as beach erosion, wind, storm surges and the like. Here, as shown, the reservoir is placed behind a first set of dunes 14 which provides adequate shelter. This contrasts with indirect intake methods of the prior art where the reservoir is exposed to coastal forces due to its placement in or near the nearshore geology as a result of the limited ability to extend the intake pipes into the nearshore geology through pipe ramming methods.
The bore 32 created by directional drilling can be made to have a diameter of 30″ or greater. As shown in
Referring still to
The pipe 20 extends past the surf line 30 and out into the open sea 24 a sufficient distance from shore 40 and at a depth to avoid tidal effects. Generally, the pipe 20 is not restricted by water depth. The pipe 20 can be mounted 41 to the sea floor 42 as shown in
Referring also to
An example of a filtration media 54 which enables this invention is a sequence of 27% filter sand (typically NSF/ANSI Standard A8071), flint 10.8% (#20 NSF/ANSI Standard A8072), flint 10.8% (¼ to ⅛, NSF/ANSI Standard A8073), flint 10.8% (½ to ¼ NSF/ANSI Standard A8074), anthracite 14.8% (#1, 0.6 to 0.8 mm, NSF/ANSI Standard A8029), and garnet 24.3% (#30 to #40, NSF/ANSI Standard A8037). Site specific factors can augment this recipe depending on the characteristics of nearshore oceanography and water quality.
Finally, although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. This invention may be altered and rearranged in numerous ways by one skilled in the art without departing from the coverage of any patent claims which are supported by this specification.
Claims
1. A method for constructing a system for filtering seawater, the method comprising:
- (a) placing an underground subterranean reservoir near a seashore;
- (b) connecting a first end of a pipe to said reservoir;
- (c) extending said pipe underground from said reservoir past a shoreline until a second end of said pipe is positioned in open seawater, said second end including a seawater intake; and
- (d) positioning a geologic filtration media in communication with said intake to cause filtration of seawater through said filtration media prior to said seawater entering said intake.
2. A method for constructing a system for filtering seawater, the method comprising:
- (a) placing an underground subterranean reservoir near a seashore;
- (b) placing a first end of a pipe in communication with said reservoir;
- (c) extending said pipe underground from said reservoir past a shoreline into open seawater;
- (d) mounting a second end of said pipe upon a sea floor, said second end functioning as an intake to draw seawater into said pipe and reservoir;
- (e) selecting a geologic filtration media based upon characteristics of near shore oceanography and water quality criteria;
- (f) placing said geologic filtration media into a porous container; and positioning at least one porous container containing geologic filtration media about said second end to cause filtration of seawater through said filtration media prior to said seawater entering said intake.
3. A method for constructing a system for filtering seawater, the method comprising:
- (a) positioning a pipe intake in raw seawater;
- (b) placing a geologic filtration media into a plurality of porous containers; and
- (c) positioning said plurality of porous containers around said pipe intake to create a geological unit in filtering communication with said intake, wherein raw seawater is filtered through said geological unit prior to said filtered seawater entering said intake.
4. The method as recited in claim 3, further comprising the step of selecting said geologic filtration media based upon characteristics of near shore oceanography and water quality criteria.
5. The method as recited in claim 3, further comprising the step of sterilizing said intake with an oxidizing agent.
6. The method as recited in claim 5, wherein said oxidizing agent is ozone.
7. The method as recited in claim 1, further comprising the step of directionally drilling a bore for placing said pipe.
8. The method as recited in claim 7, further comprising the step of placing a bore lining within said bore.
9. The method as recited in claim 8, further comprising the steps of extending a plurality of pipes having intakes through said bore and connecting said pipes to said reservoir.
10. The method as recited in claim 7, further comprising the step of extending said directionally drilled bore a length to allow said reservoir to be placed at a location sheltered from damaging coastal forces.
11. The method as recited in claim 1, further comprising the step of anchoring said pipe upon a sea floor.
Type: Application
Filed: Nov 13, 2006
Publication Date: May 17, 2007
Inventors: Anthony Jones (San Diego, CA), Robert Campbell (Rancho Murieta, CA)
Application Number: 11/599,498
International Classification: E21B 7/12 (20060101);