I like to think of a catch basin as the “first line of defense” in cleaning up rain water and drainage pipes. It is common for homeowners to put their downspout water into a pipe that then travels out to the street or a back yard location. This often leads to clogged drainage pipes. Over time, leaves, sticks and sand particulate from roofing shingles will build up in the pipe to gradually reduce drainage efficiency. A catch basin helps to reduce this problem in two ways. First, the grating that covers the basin filters out the coarse debris that finds its way through the downspout, thus “catching” the biggest contributing factor to clogged drain pipes.

The second way of cleaning the water is the catch basin sump. Finer particles that pass the grating are “caught” in the sump portion of the basin. The sump is a small water reserve that is just below the exit pipe (invert out) of the basin. As suspended particles are first entering the basin, they must pass a swimming test. If they are able to enter the sump portion of the basin and “float with the current” to the exit pipe, they win. If they are too heavy or the water is too slow, they will sink to the bottom of the sump and be left there for later removal. The particles that generally “pass” the sump test are light organics and fine silt and clay sized. The particles that get trapped in the sump need to be cleaned out periodically. (So, check your sumps!!) Also, the deeper or wider the sump, the more difficult it will be for the particle to “swim” to the exit pipe.

Catch Basin Installation

That’s the theory. Let’s talk about installation. I’m going to show two methods that involve installing catch basins in concrete: the Single pour and the Double pour methods. I always like to place drainage products in concrete because of a number of reasons.
1) It adds strength to the drain, especially if it is made of plastic,
2) It anchors the drainage product to the ground and reduces “floating”,
3) I like the look of a concrete apron around the drain and feel that it helps direct the water to the drain,
4) And lastly, I like working with concrete.

Single Pour Method

The single pour method involves setting a catch basin in a form and making a single concrete pour to form the casing. For demonstration purposes, I’m using a NDS 900 Catch basin with a single outlet. The 900 series catch basin is a 9” x 9” basin with a built in 2 inch sump. When you order this basin, you need to know what pipe size you are using to evacuate the water because you will have to order a pipe adapter to insert into the outlet of the basin. (Note: all larger NDS catch basins will have this feature.)

Basin Install Hole

The next step requires setting the basin, connecting the pipe to the drain and building a wooden mold that will form the concrete casing. I was sloppy with this installation. I admit it. Normally, my work has symmetry. In this case, I never centered the basin properly within the mold. But, you will see soon that this can be made to look good. You can see that I used metal “pins” (or spikes) that were hammered into the ground which hold the wooden form into place. The pins have holes in them which allow me to hammer nails through them and into the wooden form. This is how the mold is held rigid against the earth. Also, the inside of the mold was lubricated with an oil to help in the release of the mold from the hardened concrete. Many products are available on the market to provide this release. However, an oil and kerosene mixture will work, as well as, plain ol’ Vaseline.

Pouring the concrete in the mold is the next step. I used a 50 pound sack of concrete purchased from a local home improvement store. After mixing to the proper consistency, I placed the concrete in the mold and used a metal rod to poke the wet mixture and ensure that air bubbles were not trapped. I want to point out here that I didn’t have concrete under the catch basin. I actually had a large stone. The purpose of the concrete was to provide a “shell” around the catch basin which could provide additional drainage surface for downspout water to collect prior to entering the basin.

Basin Install Pour

 I stripped the mold after I let the concrete set over night. I trimmed away all tramp rock, dirt and wood to leave behind a clean, crisp concrete cube. I want to point out here that I centered the drain under the downspout. And, because the downspout pipe was so close to the wall, I opted to rest the catch basin against the house. I could have put a curved spout on the downspout and brought the catch basin 3 inches away from the wall. In this case, I would have had a concrete section between the house and the catch basin. Perfect symmetry would have been achieved!!! (I should have done that.)

Basin Install Stripped

 Next, I made it look purdy! (Some people would prefer “pretty”.) I packed clean soil around the concrete. I put a bead of caulking between the wall and the concrete casing to keep water away from that spot. I added a little downspout extension to accurately direct the water. And, I mulched the area. Doesn’t it look nice? Even with the poor symmetry of the concrete, it looks charming. Even still, I learned from this experience and I will do a better job on the next installation.

Final Basin

 Double Pour Method

The double pour catch basin installation method utilizes two concrete pours to set the drain. The first pour is made around the drain to stabilize it, and the second pour, made after the first has hardened, is to complete construction of the larger drainage surface.

The double pour method is generally used when you are placing the drain within a large open area or within a larger form. For instance, if you are making a new concrete driveway, there will be forms defining the edges of the driveway. It would be unnecessary to build a perimeter form around your catch basin or driveway drain. You would merely set your drain in a location at an elevation that would facilitate the drainage of the driveway. And, after setting up the drain pipes and any structural steel, the whole driveway would be poured at the same time.

However, a catch basin will try to rise out of the wet concrete as would a boat on water. Lightweight objects will become buoyant and sway or float due during concrete placement if not locked down. A small amount of concrete poured at the base of the drain will provide the stability needed for the final pour. And prior to drying, the elevation and alignment can be “fine tuned” in preparation of the final pour.

In the example that follows, I used a 12” x 12” catch basin made by NDS. This product, NGB1200, is promoted as the Next Generation Basin. Its walls are constructed in a manner which allows you to adjust the depth of the sump area at the base of the basin. Walls are constructed either with an invert opening or with a solid wall. The following picture shows installing and trimming a solid wall section of the basin.

Install Closed End

 For this installation, I decided to have a shallow sump. When installing the open invert wall section, I trimmed the section to give only a 1” deep sump. A pipe adapter was required for me to attach my 4 “ S&D pipe. This NDS fitting (#1243) locked into the side of the open basin wall.

Install Open End

 This basin was to be placed at the base of a downspout adjacent to a driveway. The drain was to become a part of a new sidewalk next to the driveway and house. A hole was prepared to the proper depth. The existing driveway and house foundation formed borders that flanked the drain.

Install Hole

 Next, a small amount of concrete was placed in the hole. The catch basin was set in the hole and filled with stones to help keep it from floating. More concrete was poured around the basin to ensure that it would be locked into place once dried. While the concrete was still wet, the basin was adjusted to the proper elevation and symmetry with the driveway and house.

Install 1st Pour

 After the first pour had hardened, it was time to pour the sidewalk. The stones that were originally put in the catch basin to stabilize it were left in place during the 2nd pour. Once the sidewalk had been poured and was dry enough to walk on, the stones were removed and the catch basin was cleaned of stray concrete. As a final touch, a cast iron “Sun Grate” by Ironage Designs was then installed to complete the project.

Sungrate Installed

 Final Notes

Catch Basin sizes and styles vary with application and drainage requirements. Residential catch basin range in size from 6” diameter garden drains to 24” x 24” yard drains. A wide variety of grating options are available. Plastic, brass, cast iron and chrome grates are designed to meet the cost or aesthetic requirements of your drainage project.

Trenchdrain.biz is an authorized dealer for NDS drainage products and can offer advice in making catch basin selections. In addition, we carry Ironage decorative grating products that fit many of the NDS drainage products.

 Contact at 610-638-1221 or email Trenchdrain.biz

A driveway that slopes into a garage can direct storm water toward the house. Trench drain can be used to remedy this drainage problem by helping to redirect water away from the garage or living space. However, a big contributor to the water problem can also be downspout water. Driveways often have downspouts that drain roof water directly onto the pavement. If the driveway doesn’t slope away from the house or allow for adequate drainage, water pooling or flooding can occur. This article is about how simple catch basins can help to re-route downspout water.

Nobody likes a wet basement. The first line of defense in keeping your basement dry is to keep water away from your foundation. The most common source of water will be storm water which falls on your roofs and hardscapes. Take that water and re-direct it away from your foundation by using drainage pipe and catch basins. This is going to require that you first develop a drainage plan. For this plan, you need to determine which point sources of water you have and where you want to re-route them using drainage pipe. To minimize digging, use a single “artery” through which all the other downspouts and yard basins connect. In some cases, you may find it more efficient to use two different drainage sites (i.e. front yard site and back yard site). Devise a plan that minimizes digging and disturbing your shrubs and landscape.

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Taking your downspout directly into a drainage pipe is a common and economical method. This involves first digging a trench and laying drainage pipe to a lower drainage point. In some communities, the drainage pipe can run underground to the street where it exits from a hole drilled in the curb. Then hook your downspout directly into the pipe for immediate redirection of your roof water. ?????? ?????????

If you want to include surface water in your drainage plan, consider using a catch basin under your downspout. If situated properly, the catch basin can collect water that pools in your yard as well as water from your downspout. Catch basins can also be made to be an attractive addition to your garden down spout. In the examples shown below, the catch basins (9” x 9”) were set in concrete for stability. These basins were part of a larger “gray water” plan which directed all the downspout water to a 1300 gallon reservoir which could later be used for an irrigation system. The overflow from the holding tank travels through perforated pipe prior to draining into a ravine.

Basins have a variety of sizes and outlet configurations which should be a consideration when designing your system. Basin selection will be a function of the anticipated water volume, piping depth and water source layout. Catch basin grating selection is broad. You will have color, style, application and material options that will depend on the cost and aesthetics desired on the project. Plastic grating is, by far, the least expensive option and is available in a number of colors. Smaller basins can also be fit with brass or chrome grates, which are both attractive and costly. Cast iron grates are surprisingly affordable and available in a variety of styles for 12” x 12” basins and some small round drains. For help in material selection, call EarlyCut Supplies at 610-882-3630.

In this situation, the homeowner was getting water into his garage with every hard rain. Further investigation suggested that water was running through a seam at the asphalt-garage floor interface and filtering to the foundation which caused dampness at the base of his basement walls and an over active sump pump. In addition to having a driveway that gently sloped toward the house, his house was at the low end of the street, which made his site more prone to collecting street run-off. To make matters worse, he had downspouts from the roof on either side of the garage door that supplied more water to the affected area.

To remedy his problem, it was decided that a trench drain be installed abutting his garage floor to accept the water from his downspouts. The water was to be discharged toward his back yard, which sloped to a creek. The home owner selected a pre-sloped 4″ wide polymer concrete trench drain (Polycast 600) with cast iron grates and steel channel protectors. The drain channels of this system were pre-sloped (not neutral) so water would flow the moment it entered the drain.

The Installation

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Prior to any work, a sheet of plastic was hung to protect the garage door and siding from slurry and concrete splashes. A cut line was made in the asphalt 20 inches in front of the garage door using a concrete saw. The diamond blade on this saw had a 6″ cutting depth which made it able to cut through the 4 inches of asphalt and another 2 inches of the gravel below. This asphalt strip was then cut into smaller squares for easy handling during removal.

The sectioned asphalt and underlying gravel was removed manually. In this case, gravel and asphalt was put into the back of a pick-up truck and taken to a land fill for disposal. During this time, the downspouts were fitted with the 4″ PVC fittings necessary to divert the roof water into the trench and drainage pipe.

To assemble the channels, placement began at the lowest point (invert out) and progressed to the shallowest end. A level line was established just below the surface of the asphalt and 14″ from the edge of the garage floor. Installation hardware was attached to the first polymer channel section (4 foot length). The channel was then set in place, suspended 4 inches above the excavated surface, with the use of #4 rebar.

The top edge of the channel was adjusted to meet the level line. Vertical adjustments were done by sliding the installation chair on the rebar. Horizontal alignments were made with the adjusting bolts on the installation chair. Installation hardware was added to the end of the second channel and attached in an “end to end” manner with the first channel. Again, the second channel was suspended 4″ above the excavated surface and adjusted laterally and horizontally on the rebar supports to match the level line. This technique was repeated until the last channel section was put in place.

Once the channel was assembled, end caps (with knockouts) were installed, down spouts and piping was attached and grates were put in place. The grates were wrapped in plastic sheeting to protect them from concrete, as well as to help keep concrete out of the trench. Some people place a strip of plywood in the grate recess during concrete pouring. This is a good idea. It allows you to keep the grates clean and the trench free from concrete and not deal with the plastic sheet.

Concrete placement was done next. For this installation, the drain was centered in a 20″ wide excavated trench that was approximately 12″ deep. A minimum 4″ space was below the channel and 6″ on either side of the channel for concrete to fill. No reinforcing was used in the concrete (4000 psi mix). The concrete truck discharged the mix directly into the trench. Two men placed the concrete in the trench using hand tools. It would have been useful to have a pencil vibrator during the placement. Never-the-less, concrete pouring only took about one half hour.

Once the concrete was placed and the truck had left, the grates (with plastic sheeting) were removed and concrete finishing began. After removal of the trench cover, some clean-up of the channels was required using a wet rag. Trowels and edging tools were used in the finishing. Once the concrete began to set and finishing was complete, the grates were put in place and the lock bolts were tightened.

On the following day, some house-keeping was required to complete installation. Concrete forms were removed, dirt was placed in areas affected by the excavation, mulch was replaced, flower planters were put back construction rubbish was picked up and the asphalt driveway was power washed.

The job was located in the Pocono Mountains of Pennsylvania, earshot from the Pocono Raceway. The trench drain was to be installed in a new equipment storage facility. The floor of the facility was being pour at the same time as the drain in order to pitch the floor toward the drain.

Initially, the excavator roughed out a trench in which to install the drain. The site was already installed with gravel, but was not compacted.

(This will probably cause a problem in the future. The gravel base for trench drain and all concrete floor projects need to be compacted. This floor has an excellent chance of developing voids underneath the concrete in the future.)

The position of the drain was determined and a level line was set. Then, the trench was cleaned of debris to assure that the channels could be set without obstructions.

Next, the channels were set along side the trench in order that they would be installed. The highest number channel (deepest) was set at the discharge invert. The smallest channel number was set at the beginning of the drain flow path. For this particular installation, the channel protector and grates were both left in place. The grates were later protected with plastic sheeting prior to pouring concrete.

The discharge water was designed to exit the end of the drain through 4” PVC pipe. A hole was drilled through the foundation of the building for this pipe to exit. It was later tied into a drain pipe that took the water to a sewer.

Installation started with the deepest channel first, then proceeding upstream. The channels were connected to each other with an installation bracket and connected to ½” rebar (#4). This particular installation bracket is patented and used exclusively with the Polycast system. It makes installation easy. However, in this case, the installation would have been easier if the excavator hadn’t used so many large stones in the base. At times, large boulders have to be removed in order to hammer the rebar in the ground. No matter, the bracket was adjustable enough to line the channel up perfectly, even if the rebar stakes didn’t install perfectly.

Down with Love trailer

From the photo to your left, you can get a better idea on how the Polycast installation chair works. Bolts from the installation chair fit into the “dimples” of adjoining channels to hold the channel tight. The bolts can adjust in our out to help align the channels left or right. The chair can also be adjusted up or down on the rebar to keep the top of the drain (grate) on level.

Once the first few channels were put into place, the remainder of the installation went smoothly. The channels seemed to fall into the proper place when the installation chair was properly used. In the end, we had a 40 foot length of polymer concrete trench drain, suspended in air, and ready to be set in concrete.