Wet Utilities Construction in Land Development
Underground construction of wet utilities:
The wet utility phase of construction in land development revolves around the proper preparation and installation of the on-site sanitary sewer system, storm drains and the potable and non-potable water systems. This includes the fire suppression main and fire line infrastructure. All of this has to be done with a certain degree of precision, particularly in solving slope, grade and compaction challenges for line placement. Who wants sewer lines where waste flow is impeded by dips or humps that cause blockage or backflow? To avoid these nasty problems, alignment of structures and routing of pipes must strictly comply with the technical specifications on the construction plans. An additional key consideration is accurate and proper feeding of the on-site infrastructure into the main supply network.
Sanitary sewer mains:
Placement of the sewer main is first. Installation of sewer pipeline, sewer lift stations and vertical chambers for access manholes. Sanitary sewer is a piping or tunnel system, and when properly designed and constructed, will primarily use gravity as the propulsive force for movement of blackwater and greywater from project homesites to the offsite infrastructure - then on to the treatment facility.
In low lying areas, lift stations may be necessary to sump, pump and route sewage to varying elevations. Lateral lines from homesites, access chamber floors, and line joints must be carefully constructed to avoid unintentional trapping and accumulation of solid waste. Technical requirements must be adhered to, then installation inspected for quality workmanship along the way.
Sometimes, combined sewer systems are used. This is where runoff and storm drainage is collected and distributed by the sewer system, along with wastewater. There can be challenges when both sewage and storm water are collected and distributed in a combined system. These systems can cause stress at the regional treatment facilities since waste water, when mixed with storm water, is significantly diluted. This in turn slows the primary, secondary and tertiary treatment process at the plant, since bacterial degradation is the fundamental basis of sewage treatment. The more wastewater is diluted, the longer it takes for microbial breakdown. Additionally, heavy storm runoff can place capacity stresses on treatment plants at random times.
Storm Drainage infrastructure:
Like all piping and channel construction, proper grading with particular attention to topography and slope characteristics is required for storm drainage. Once again gravity is a key force of directional flow.
Here we prep and install storm water piping, storm drain lines, point and channel drains and the supporting storm drain structures. Also, pump stations as required, to supplement elevation and gravitational flow limits. Prefabricated or pour-in-place structures are used for box installations.
All this storm water has to go somewhere and unless a combined sewer system is in place, detention ponds, retention ponds and/or reservoirs are constructed. Detention ponds collect and distribute runoff, retention ponds and reservoirs collect and intentionally store water.
For more detail on drainage see this article:
Why is Drainage Required in Land Development? https://www.landdevelopmentrealities.com/home/2020/8/3/v09ipvf9g9osk15z75xgdv5wskbiit-fktfy-jb8nf-dbfhh-c2xey-67bef-jyhwg-zbf58
Water systems:
Project infrastructure for potable and non-potable water requires a consistent and calcuable source. Projects will typically be fed by a public or private water system main, or a community or private well. No matter which, we need to build it out according to specs.
Public systems start with regional collection of the necessary raw water volume - which is vast. It is collected, purified and treated (as required) and then stored at distribution points for mainline feeding service.
For more, see Water Sources in Land Development: https://www.landdevelopmentrealities.com/home/2020/6/24/qdyxy52s8mtw0ltmilzcyu0sc492it
As land developers, our task is to install the on-site water pipe, fittings, valves and related infrastructure like fire hydrants; then make sure it properly ties into the off-site regional supply network. Also, to stub out the terminal points as required by public works, so that the growth criteria for future tie-ins is met for other projects.
If I could pick a single utility that is critical in every way, it is an approved water supply for the project. This is a particularly important consideration in acquisition where 4 primary questions must be asked (and preferably clearly answered):
What is the water source?
Is water for the project realistically available from the source?
Does the utility have the capacity to serve the project?
Can I get a certificate of water availability?
….easy questions to ask, but not always easy to answer…
If the water system depends on a well, water rights from the state are typically necessary. This very complex issue is discussed in the following article:
Understanding Water Rights:
https://www.landdevelopmentrealities.com/home/2019/1/20/water-rights
Underground infrastructure materials:
Traditional piping and infrastructure materials include concrete, corrugated galvanized, ductile iron, steel, and even clay. Lower cost and highly effective materials include thermorplastic high density polyethylene (HDPE) and polyvinyl chloride (PVC), which are strong and durable and can be molded into various pre-engineered shapes. The approved construction plans, material cost and product availability dictate which construction material solutions are best for the application.
Wet Utilities Construction In Land Development:
Precision installation and adherence to the construction plan is key for a quality wet utility installation. I make sure the contractors are well expereinced for the task and have a solid sequential on-site plan in place. When problems come up during construction the team also needs to be resourceful and move quickly to resolve them. A proper installation results in expected sewer and drainage flows at the volumes, collection and distribution rates required. Waterlines are servicing at the proper pressure, flow rates and neatly tie into the regional system. Good luck and stay focused!
Contact me at: ldr@landdevelopmentrealities.com
Blog photos courtesy of Unsplash.com - Eliobed Suarez and Jake Nackos - Thank you. Also, PE Devlopment Trust, and Dnzplan LLC.
