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Category: Civil Engineering

LandTechNews/BlogCivil Engineering

CAD: A Design Tool for Civil Engineering and Land Surveying

Virtually every industry has been affected by computer technology, with civil engineering and land surveying being no exception. Land surveying field measurement procedures have been greatly enhanced from total stations with electronic distance measuring (EDM) and angle measurement, hand held data collection, and global positioning systems (GPS).

The use of computers has also revolutionized civil engineering and land surveying tasks in the office. Over time, the use of computers has evolved from more simple drawing tasks (computer-aided drafting, or CAD) to more sophisticated design tasks (computer-aided drafting and design, or CADD), and we typically use the term “CAD” to mean both computer-aided drafting and design software.

But, more specifically, what is CAD software? CAD is a computer software technology used for the preparation of drafting and design documentation in a two-dimensional (2D) and/or three-dimensional (3D) coordinate systems.

For example, property boundary plats are drawn in 2D space, and topographic survey maps or civil engineering plans with ground surface elevations are drawn in 3D space.

Below are images illustrating basic 2D and 3D coordinate systems.

354px-Cartesian-coordinate-system_svg
2D Coordinate System
3D Coordinate System
3D Coordinate System

 

 

 

 

 

 

 

 

LandTech uses CAD software licensed and distributed by Carlson. Carlson software has modules specifically tailored for civil engineering and land surveying, making our design and drafting process more efficient than using a CAD platform alone. Below is a screen capture of a CAD drawing in Carlson software.

CAD Screen Capture
CAD Screen Capture

 

We would love to talk with you about how we can help you with your project. For more information, visit our website http://landtechco.com/contact_us

Jay Lewis Civil Engineering, Land Surveying, Miscellaneous 0 Comments

Preparing a Constuction Cost Estimate

LandTech often includes preparation of a construction cost estimate in connection with our professional engineering design services. Preparing an “accurate” construction cost estimate can be an elusive undertaking.

We refer to this task as an “opinion of probable construction cost”, in accordance with language used by the Engineers Joint Contract Documents Committee (EJCDC; http://www.ejcdc.org/). According to EJCDC documents:

…..because [the] Engineer has no control over the cost of labor, materials, equipment, or services furnished by others, or over contractors’ methods of determining prices, or over competitive bidding or market conditions, [the] Engineer cannot and does not guarantee that proposals, bids, or actual Construction Cost will not vary from opinions of probable Construction Cost prepared by [the] Engineer. If [the] Owner requires greater assurance as to probable Construction Cost, [the] Owner must employ an independent cost estimator…

An opinion of probable construction cost estimate can be performed at different stages of design; i.e., concept design, preliminary design, final design, etc.  The earlier in the design process the estimation is performed, the less accurate it will be since more specific information will be available for estimation as the design plans are completed.

When preparing an engineer’s opinion of probable construction cost, LandTech typically use construction cost data available from the Tennessee Department of Transportation (TDOT) or RSMeans.

Average unit price information can be found for TDOT projects on their website here http://www.tdot.state.tn.us/construction/Average_Bid_Prices.htm. When using TDOT data it is important to remember how the size of a project might affect unit prices (i.e., economies of scale). For example, the unit prices for asphalt pavement may be smaller for a ten mile roadway project as compared with a small parking lot project.

RSMeans is a construction cost estimation database published by Reed Construction Data, which has been providing construction cost data for over 70 years. Updated construction cost data manuals are published annually. RS Means staff collects cost data for materials, labor, and equipment; and includes provisions for construction overhead and profit, and city cost indexes.

Please contact LandTech if you need assistance with developing an opinion of probable construction cost for your project or if you need advice with any other aspect of the land development process, including civil engineering or land surveying services. http://landtechco.com/home

Jay Lewis Civil Engineering, Land Development 0 Comments

Sewage Disposal Systems in Tennessee

An important element of land development projects is wastewater disposal. For projects in areas without public sanitary sewer systems, a subsurface sewage disposal system typically will be required.

The Regulations to Govern Subsurface Sewage Disposal Systems can be found on the Tennessee Department of Environment & Conservation (TDEC) website, here: http://www.tn.gov/environment/water/septic-disposal_regulations.shtml

There is a misconception that the only option for a subsurface sewage disposal system is a standard septic tank with a conventional disposal (drain) field). But the Tennessee SDS regulations also include sewage disposal alternatives such as advanced treatment systems, low pressure pipe systems, and subsurface drip disposal (SDD) systems, to name a few. In many instances these alternative systems provide options to increase development density.

If you have any questions about the sanitary sewer system for your project, contact LandTech at http://landtechco.com/home

Jay Lewis Civil Engineering, East Tennessee Region, Land Development, TN 0 Comments

LandTech Adds TDEC Level II Erosion Control Certifications

Two of LandTech’s personnel were recently notified of their successful completion of the Sediment Control Level II course presented by the Tennessee Water Resources Center in Knoxville during June. Jay Lewis and Mike Lewis each now hold a Tennessee Department of Environment and Conservation (TDEC) Level II Certification.

The Level II certification demonstrates a higher working knowledge of erosion prevention and sediment control practices. Additionally, a Level II certification is required for preparation of a Stormwater Pollution Prevention Plan (SWPPP) for sites discharging into impaired or exceptional Tennessee waters, per the requirements of the State Construction General Permit. A Level II certification is also required for individuals who perform “Site Assessment Inspections for quality assurance of installation, functionality and performance of erosion and sediment control practices at construction sites discharging into Impaired or Exceptional Tennessee Waters.” http://www.tn.gov/environment/permits/conststrm.shtml

If you have any questions about your project, please contact us. http://landtechco.com/contact_us

 

 

Jay Lewis Civil Engineering, Land Development, LandTech News, TN 0 Comments

LandTech Adds TDEC Level 1 Erosion and Sediment Control Certifications

LandTech’s Knoxville staff now includes three people (Mike Lewis, Preston Smith, and Jay Lewis) with Level 1 certifications for Erosion Prevention and Sediment Control.  The Tennessee Department of Environment and Conservation (TDEC) requires a Level 1 certification for anyone responsible for inspection of construction sites under the State’s General Construction Permit (i.e., General NPDES Permit for Discharges of Stormwater Associated with Construction Activities).

The Level 1 certification is achieved by attending a 1-day workshop on the fundamentals of erosion prevention and sediment control passing an exam. According to the Tennessee Erosion Prevention and Sediment Control Training Program (http://tnepsc.org/indexNew.asp) :

“The Level I Fundamentals workshop is a 1-day foundation-building course for individuals involved in land-disturbing activities and is intended for contractors, developers, inspection and enforcement personnel from all levels of government, plan preparers, reviewers, designers and engineers. The Fundamentals course aims to build a solid working knowledge of erosion and sedimentation processes and practices. Topics include: Revised (May 2011) Construction General Permit and related SWPPP requirements; function, installation, limitations, inspection and maintenance of Best Management Practices (BMPs); roles of local officials and state government agencies involved in the permitting process; and basic hydrologic and erosion processes.”

If you would like a free initial consultation about your project, or we can answer any questions for you, please don’t hesitate to contact us at http://landtechco.com/contact_us

Jay Lewis Civil Engineering, Land Development, LandTech News 0 Comments

Knoxville Stormwater Construction Permits

Civil Engineers in Knoxville and other regions of East Tennessee are well aware that stormwater management has become an increasingly important permitting component of land development projects. The Tennessee Department of Environment & Conservation (TDEC) is the State Agency regulating stormwater discharges from construction sites.

So, who is required to get a permit? According to the TDEC website (http://www.tn.gov/environment/permits/conststrm.shtml#who):

Operators of construction sites involving clearing, grading or excavation that result in an area of disturbance of one or more acres, and activities that result in the disturbance of less than one acre if it is part of a larger common plan of development or sale.

What is required to be submitted?

Applicants must submit the following information:

» A completed and signed Notice of Intent (NOI) for Construction Activity – Stormwater Discharges (see link below). The NOI must include a map on 8 ½ inch by 11 inch paper with boundaries 1-2 miles outside the site property with the site and construction area outlined and the receiving water or receiving storm sewer highlighted and identified. It is preferable for this map to be the appropriate portion of a USGS 7.5-minute quadrangle map.

» A site-specific SWPPP (Stormwater Pollution Prevention Plan) must be developed and submitted with the NOI. The SWPPP must be developed, implemented, and updated according to Part 3 of the CGP (Construction General Permit).

Completed Notices of Intent must be sent to the appropriate Environmental Field Office.

The City of Knoxville has been designated by TDEC as a “Qualified Local Program” (QLP). According to TDEC, the “main intent [of a QLP] is to eliminate the duplicative efforts of the current permitting process” by reducing the requirement to make submittals to local and state agencies.

The City of Knoxville has two good resources for additional information on stormwater permitting:

1. Land Development Manual, Chapter 5 – Permitting Requirements:   http://www.cityofknoxville.org/engineering/ldmanual/LDMCH05.pdf

2. BMP Manual, Chapter 6 – Stormwater Pollution Prevention Plan: http://www.cityofknoxville.org/engineering/bmp_manual/BMPCH6.pdf

If you have questions about stormwater permitting for your project, contact LandTech using our website: http://landtechco.com/home

Jay Lewis Civil Engineering, East Tennessee Region, Knox County, Knoxville, Land Development, TN 0 Comments

Civil Engineering Land Development Design – Water and Sewer Systems

The life blood of a land development project is the availability of water and capability for sanitary waste disposal.  The availability of public water and sanitary sewer services greatly affects how civil engineers and land surveyors would propose to develop a parcel.

For example, in the City of Knoxville Zoning Regulations, the property area regulations for properties zoned R-1 (Section 2.1.1.E.5):

http://library.municode.com/HTML/11098/level4/APXBZORE_ARTIVSPDIRE_S2BADI_2.1REDI.html#APXBZORE_ARTIVSPDIRE_S2BADI_2.1REDI_2.1.1LODEREDI

a. For each house, and building accessory thereto, served by a sanitary sewer system, there shall be a lot area of not less than seven thousand five hundred (7,500) square feet.

c. For those dwellings and buildings accessory thereto not served by a sanitary sewer system there shall be a minimum lot area of twenty thousand (20,000) square feet per dwelling unit; however, a greater area may be required based on recommendations by the health department because of inadequate percolation.

Therefore, a one (1) acre parcel with sanitary sewer systems could be subdivided into approximately five (5) lots, but only two (2) lots without sewer service……less revenue producing parcels.

A review of the property is crucial prior to development, including a determination of water and sanitary sewer availability and zoning regulations.

If you have questions about developing your property, please contact LandTech using our website at: http://landtechco.com/home

Jay Lewis Civil Engineering, East Tennessee Region, Knox County, Knoxville, Land Development, TN 0 Comments

Stormwater Management Design in the City of Knoxville

Due to increasing regulatory requirements, stormwater management is often a primary element of the civil engineering design process for land development projects. Important aspects of stormwater management requirements in the City of Knoxville are outlined in two primary sources:

1. The City of Knoxville Best Management Practices (BMP) Manual, found on the City’s website: http://www.cityofknoxville.org/engineering/bmp_manual/knoxvilleBMP.pdf

According to the BMP Manual:

The purpose of this manual is to establish minimum standards for the design and implementation of measures to prevent and control erosion, sediment, and other forms of stormwater pollution. The BMP Manual is intended primarily to assist developers, engineers, contractors, inspectors, and property owners in the selection and use of Best Management Practices (BMPs) for the design of new facilities.

2. The Knoxville Municipal Code, Part II, Chapter 22.5: http://library.municode.com/HTML/11098/level2/PTIICOOR_CH22.5ST.html#TOPTITLE

The stormwater management site development criteria includes stormwater detention pond requirements outlined in Section 22.5-23, and first flush water quality requirements outlined in Section 22.5-36.

http://library.municode.com/HTML/11098/level3/PTIICOOR_CH22.5ST_ARTIISIDECR.html#TOPTITLE

We’d be happy to discuss any questions you have about stormwater management for your project. For more information on LandTech and contact information, please visit our website here: http://landtechco.com/home

Jay Lewis Civil Engineering, East Tennessee Region, Knoxville, Land Development, TN 0 Comments

Civil Engineers face changes to Stream and Wetland Regulations?

Impacts to streams and wetlands can be a serious regulatory challenge to civil engineers and other land development professionals, not only in Knoxville, but around the country. There have been recent court cases challenging EPA’s authority, with the result being a potential clarification of the term “waters of the United States”.

The EPA took a giant step toward finally defining which bodies of water are subject to regulation under the Clean Water Act last week, when it filed a draft rule with the White House regulatory czar designed to settle the confusion created in recent years by a series of court decisions.

The legal battles have centered on the definition and scope of a seemingly innocuous phrase — what exactly are “waters of the United States”?

Judges and regulators have wrestled over how to interpret the term in the absence of legislative action to clarify it. Now, the EPA is not only proposing a regulatory solution — which is not yet publicly available — but is also conducting a scientific review to accumulate evidence to back up the penultimate rule.

See more at: http://cdn.rollcall.com/news/epa_seeks_definition_of_bodies_of_water_for_clean_water_act-227853-1.html?popular=true&pos=oplyh&cdn_load=true&zkPrintable=1&nopagination=1

If you have any questions about local stream and wetland regulations, contact LandTech’s civil engineering staff for a discussion about your project. You can find our contact information on our website here: http://landtechco.com/home

Jay Lewis Civil Engineering, Knox County, Knoxville, Land Development, TN 0 Comments

Civil engineering grading design

In many instances, the biggest variable cost for developing a site is grading. Grading is the construction process of altering existing ground surface elevations for producing roadways, parking lots, building pads and other site development features.

There are numerous economic factors civil engineers consider during the grading design process, including:

  1. Rock excavation can be very expensive, and areas of cut (lowering existing ground surface elevations) should be minimized in areas with rock.
  2. Grading volumes should be balanced between the amount of cut and fill (increasing existing ground surface elevations). Too much cut and soil will need to be hauled from the site; too much fill and soil will need to be hauled to the site. With high diesel fuel prices, the hauling expense may not be economically feasible for a development project.
  3. Areas with unsuitable soils (soils with insufficient strength or other undesirable properties to support the planned use) will have to be excavated, removed and replaced, driving up the construction cost for site development.

The LandTech civil engineering grading design process places an emphasis on minimizing rock excavation, minimizing cut and fill volumes, balancing cut and fill volumes, and if possible avoiding areas of the site with unsuitable soil.

We would be happy to discuss any grading design question you have about your site development project in the Knoxville or East Tennessee region.

For more information, visit our website: http://landtechco.com/home

Jay Lewis Civil Engineering, Land Development 0 Comments