Site Development – How To
I have been operating heavy equipment off and on for almost 34 years but have been in the construction industry most of my life. I have been an independent professional operator since 2006.
On this page I’m going to talk about what goes into a typical site development, excavation service, and some of the how-to of the trade. Sometimes a home owner may want to save money and rent the equipment to do his own excavation and/or hire a novice. But as I’m going to point out there are other factors that come into play that only experience can foresee. Having the job done right the first time will save you money in the long run.
Most of my past customers have hired me on an hourly rate to do excavation and site development (which does not include side sewers, brush mowing, stump grinding or tree work). I’m happy to give a free detailed written estimate too. When customers get a written estimate to do a job over an hourly rate for excavation, what they often times don’t realize is that every time they make a change, a change order will be written up and an additional cost for the change will be added to the original estimate. Most contractors know this and make double the money to make the change. This is where there is an opportunity to make more profit, and many new to building a home or structure do not know this in the beginning.
Before You Buy a Development Property
Buying property to build on? It is important to investigate the ground quality of a plot before you purchase. Check records and ask around locally to make sure that it doesn’t have an unsavory history. For example, an infill site (old dump site) may be an expensive option because if it is, it may require piles. A proper survey with test bore holes – to assess the type and quality of the ground. This is a sensible precaution and should ensure that there are no surprises when the digging starts. On septic, does the property perk? Its best to get permission to dig perk holes and have a septic design company inspect them. If you are applying for a construction (building, demolition, or grading) permit or planning for future construction (land use permit) that involves ground disturbance (including staging areas) or tree or vegetation removal, advance inspection of your site may be needed from an inspector. Other factors that may need to be taken into consideration are steep slopes, wetlands, drainage patterns, large trees, existing structures, flood plains, street curb and butting property line improvements that might be affected by the proposed development. Design issues include, but are not limited to: location of existing and new slopes, structures such as retaining walls and their relation to proposed and existing construction. Local government often times take control of privately owned property by designating them as wet lands. It is important to have a biologist inspect the property before purchasing. I currently work with an awesome permit company that has a team to assist you with your per-purchase feasibility and post purchase permits. Call me for details at (253) 651-7494.
Ready To Break Ground?
Once you have all your permits approved along with civil and structural engineered blue prints, we are ready to break ground. First we call for a free locate to make sure there are no hidden underground utilities. Then depending on the plans and proposed site we may or may not need a survey company to stake out the project for the proper location and elevations of the proposed foundation. If it’s a commercial project then hiring and working with a survey company is a must. Their service can cost anywhere from $2500 to $10,000. Often times hiring a survey company is the first important step in construction layout because everything else is based on those survey stakes. They’re especially important when you have set-backs from wetlands, property lines and easements to worry about. In residential construction, outside of city limits or where there is lee-way on the property for set-backs we can often times lay out the site ourselves. One of the chanenges with laying out a site that is on a small plot is gauging how much dirt needs to be excavated to eliminate the need for export or import of additional material. Over the years I have gotten very good at looking at sites and predicting their outcome by using a laser lever and calculations.
Don’t Forget Utilities – and a toilet!
Now is a good time to call in for a temporary electrical panel box and having it inspected and have a water meter turned on or installed. Depending on the municipality sometimes the excavating contractor can do the water hook up. Also are you on sewer or septic? If it’s a sewer hookup, is it stubbed into the property or do we need to tap into the sewer main in the street? These are both services I provide depending on the municipality. I also have the equipment to repair the asphalt in street (right of way) after a sewer tap. Most of the time we are not allowed to back fill the trench in the street with the native soil. This needs to be exported and structural soil or crushed rock need to be put in its place, along with proper compaction and testing. Mother nature has its calls. One of the first things we need to get the job started is a portable toilet on the job site.
Don’t Throw Away Your Sod
The top layer of earth is called organic soil and is typically 10-18 inches deep. This layer may be from leaves and pine needles because it was a forest. Or this can be grass and sod. I have even seen this organic layer to be deeper in pastures where they had livestock in the past. When this layer is stripped, its often times put in a separate pile for later use. But if its sod it takes two to three years to compost. Sod that is piled up with a bulldozer or excavator is not easily spread later when back filling. If you bury it, it may settle and your yard will end up with a dip or low spot. My solution to this problem is to use my Harley Rake attachment on my bobcat. This chews up the sod into a fine powder like form compared to the lumpy sod. I can rake any rocks and debris off to the side and the soil is ready for seed. The advantages are you will not have to buy as much top soil, you will not have to export, and you won’t have low spots from it composting under your new lawn.
How To Manage Trees On Your Development Property
Sometimes the proposed building site will have tall trees, brush, and large stumps hidden in the brush. I often times recommend to leave as many healthy trees as possible, but still clear out enough for the driveway and the house itself. Keeping trees on your property can beautify it and raise its value. This is a job that some people try to tackle with a chainsaw and a pickup. On small lots sometimes the trees can be taller than the lot is wide. The only way to get these trees out is by climbing and taking the top out first. This is what I specialize in. Even if the trees don’t need to be climbed, it is important to know how to gauge a lean, cut notches, use wedges, and determine the hinge wood strength, because tree felling is a very important skill that comes with years of experience. It can be a lot of work though, especially on a lot with many trees and could take several days to weeks to complete yourself if you don’t have the proper equipment and training. Remember, that your time is worth something and it might be better spent managing another part of the project.
Another consideration is if you clear a wooded area for a home and the surrounding trees may be left venerable to the next wind storm. Often times these trees have been protected during storms from the trees that were just logged off. To help remedy this problem we can sometimes wind sail the existing trees to help them resist blowing over in a storm. To do this we clean out the inner canopy of the tree and sometimes remove branches. Another item often over looked in clearing land where your foundation will be dug and driveway installed, is the stump removal. Logging companies do not compact when they back fill the stump holes. This will create differential settlement. I don’t advise burying brush and/or stumps on your lot, as these tend to form an unsightly depression and/or leave holes in the ground as the material in them settles or rots. This can also create a hazard if someone steps in a hole and could catch fire underground.
Most of the time the county or municipality will require a silt fence and construction entrance. A silt fence, sometimes called a “filter fence,” is a temporary sediment control to protect water quality in streams, rivers, lakes and bays from sediment (loose soil) in storm water runoff. Silt fences are widely used, due to their low cost and simple design, although their effectiveness in controlling sediment is often rather limited, due to problems with design, installation and/or maintenance. A construction entrance is a temporary stone-stabilized pad located at points of vehicular ingress and egress on a construction site. Mud on vehicle tires is significantly reduced which avoids hazards caused by depositing mud on the public roadway. Sediment, which is otherwise contained on the construction site does not enter storm water run-off elsewhere. To provide a stable entrance and exit from a construction site and keep mud and sediment off public roads. You also may need to put drainpipes or culverts in at the roadside if they are required by either ordinance or common sense. They allow roadside water to flow under the driveway and prevent water from washing the dirt and stone away.
Excavated Dirt and Soil Compaction
Once the home or building is laid out and we put together a site plan for the excavation we are ready to start digging. Even though this is easy for a seasoned operator, this is one of the most important parts on any site development because if you put the excavated dirt in the driveway where the future pump truck and cement truck need to park, it may cost another day to move that dirt out of the way. It is very important for the excavating contractor to plan ahead for the future construction crews to have room to perform their services. In some cases the excavated dirt will have to be stored off site or hauled away. It is very important not to over dig the depth of native soil for the foundation. If an operator accidentally over digs and back fills, this area must be properly compacted to 95%. If it is not properly compacted differential settlement could be the end result a year or more down the road. Differential settlement causes foundations, concrete slabs, and interior dry wall to crack. Doors and windows may become out of square and unable to open or shut, your floors could sag and become uneven. Other problems that can occur when you excavate a site have to do with unseen existing underground utilities, such as gas and electrical lines, tree root systems and large rocks. When you excavate, it’s always an educated guess as to what might be discovered in the excavation site. Once the foundation hole is dug you will need to call for an inspection before any concrete is poured.
Storm Water Filtration
If a storm water filtration system or a dry well is part of the plan, it is important to see its location and plan if it should be installed before or after the foundation. Depending on the size and location some times it is better to install after the foundation dig because it may be an access route for heavy equipment. But if it’s large and will be in a hard to reach location after the foundation is poured sometimes it is better to install the filtration system first. Why do I need a filtration system or dry well? As more and more people move to cities and towns, the storm water runoff problem worsens, because the flattened, impervious surfaces and lack of natural vegetation in these environments prevent precipitation from soaking into the ground. While runoff is a problem of immense scale, this is why we use filtration systems to reduce storm water runoff on your own property.
Now after the foundation or basement has been poured and inspected it’s a good time for the excavation contractor to come back and back fill. This will be the sub grade of the final grade that will take place as we back fill around the structure for top soil or gravel and concrete. If you were to have a septic installed its better to have it done before the back fill takes place that way the excess material from the drain field and tanks can be spread or exported at this time. This is also when we finish bringing in the underground utilities such as the power, phone, cable tv, water and sewer to the structure. During this time we have to pay attention to grade elevations, slopes away from the structure, install curtain drains, footing drains, tight lines for the down pouts, as needed. To miss something at this point could cost thousands to fix after all the driveways and landscaping is completed. An inspector will want to sign off on the installed footing drains and tight lines before we back fill.
Drainage and Sumps
As you know here in Washington we get a lot of rain. Many homes and structures are built on hills sides or in wet areas at don’t drain well such as clay. A major concern with a basement is will it leak or will a crawl space have standing water even though we have footing drains. Think about where the water will be coming from: groundwater seeping up or surface water seeping down. For high water tables, an internal drain with a sump pump could be the answer. I personally had a home in Edgewood WA on top of a hill and still had water in the crawl space. To remedy this I dug a curtain drain on the interior of the footing and directed it to a sump pump. The sump pump then ran a sprinkler in the back yard when it came on. When in doubt I recommend planning ahead especially when it comes to basements. I have seen the exterior walls of daylight basements sealed only to have a water leak at the cement joint of an interior floor and wall in a half basement style home. This was because there was no footing drain along the interior footing.
We hand dug a footing drain in the crawl space that was accessed through the customer’s family room, and routed the perforated pipe to the exterior. We carried hundreds of five gallon buckets of dirt out and then installed perforated drain pipe and washed drain rock to create a footing drain. To protect the interior finish we used Amerdrain 500 against the foundation wall to keep it absolutely dry. I recommend using Amerdrain 500 on all basements, along with using paint on rubberized asphalt sealer to protect against future foundation cracks. Another method is to spray the outside of the foundation with a rubberized asphalt sealer. Before the spray dries cover with R-10 insulating panels. The kind I used was made of fiber glass formed to channel water straight down along the surface so moisture has very little chance of reaching the asphalt membrane. Properly installed footing drains is one of the most important aspects of keeping your basement and crawl spaces dry. Moisture can and will travel through unprotected concrete.
When installing a new gravel driveway over clay or moist soil. It is important to have a good base and properly compact it. If your driveway is installed in the summer time, you could end up with a mud hole in the winter due to Western Washington’s wet climate. Often times we will import structural soil and sometimes export the bad soil. To minimize the import and export of soils we can sometimes use a mat. Typar Landscape products offers a driveway fabric mat that can save time and money, installing a new driveway over soft soils. If you will be pouring a concrete driveway, it’s important to remove all the organic soil to minimize cracking. I recommend using structural fill and 4 inches of 5/8 minus crushed gravel properly compacted if you need to build up a base for concrete in these areas. If there is any chance a heavy truck will cross your drive way it’s best to thicken the boarders of the concrete slab by over excavating it deeper by two or three inches. Rebar or 6×6 wire mesh also helps prevent cracking in concrete slabs.
I wish you luck in your endeavor. I hope you book mark my company for your future excavation and tree service needs. Thanks Bob