Services
Geodetic and Control Surveying
Horizontal and Vertical Control Surveys
The most fundamental aspect of a successful survey and all subsequent activities based on that survey is accurate, reliable and precise survey control. Mohler and Pendleton Surveying (MAPS) works with the client to ensure all parties understand and agree on the requirements for horizontal and vertical datum during the planning phase to reduce the likelihood of datum mismatch that can be extremely costly for any project.
MAPS establishes control by using a combination of Continuously Operating Reference Stations and passive control monuments closest to the site. Local project control monuments are selected based on the project and cost/benefit analysis, ranging from concrete monuments with Aluminum disks, to rebar and cap with vertical benchmarks on stable infrastructure.
Primary horizontal and vertical control is brought to the site using Dual Frequency Static GPS techniques (some vertical control will be digitally leveled based on project requirements).
Local horizontal site control is established using a combination of static GPS and conventional angular and distance techniques using multiple set observations which are processed for analysis in StarNET Least Squares Review and Adjustment Software. Average RMS precision 0.02’+/-
Local Vertical control is established using digital differential leveling techniques and processed for analysis in StarNET Least Squares Review and Adjustment Software. Average RMS precision less than 0.01’+/-.
Example (PDF)
Flood Elevation Certificates
With the Recent roll out of the new DFIRM or Digital Flood Insurance Rate Maps (the first revision in almost 30 years), more detailed hydrological and tidal information has placed an extremely large percentage of existing property and structures previously outside of Flood Hazard zones into newly defined hazard areas. This in turn has impacted many individuals and businesses by the increase or new requirements to carry Flood Insurance which can carry extremely expensive premiums.
Property determined to be in a “Base Flood Elevation Determined” can benefit from on-the-ground vertical Elevation Certificate surveys to determine the relationship of structures to the base flood elevation, which can translate into reduced premiums and often change the flood status of a property.
MAPS provides on the ground Elevation surveys using Digital differential leveling from a minimum of two existing passive control monuments and checks the vertical accuracy of those monuments using Static GPS techniques to ensure that the local area has not been subjected to subsidence that would not normally be discovered by on-the-ground surveying.
Example (PDF)
Deformation and Subsidence Monitoring
Infrastructure can be subject to movement based on a variety of issues ranging from degradation, erosion, flooding or new construction. High accuracy deformation and subsidence surveying allows the surveyor to compare the horizontal and vertical position of established monitor control points over time to allow the quality control engineer to evaluate if there is a trend in movement and decide the appropriate course of action. New monitor points are controlled from high accuracy offsite horizontal and vertical control (Hyperlinked to Horizontal and Vertical Control Surveys) to ensure the level of accuracy and precision based on project requirements.
Example (PDF)
Cadastral Surveying
Boundary and ALTA Survey
MAPS provides Cadastral Boundary surveying in the District of Columbia, Maryland, Virginia and West Virginia. Our surveyors stay abreast of State Law and Standards of Practice to ensure every survey is of the highest quality and reliability. All research of the subject and adjacent property, field work, office processing and boundary resolution is performed by the licensed land surveyor who certifies the survey.
MAPS has provided ALTA Surveys to Private Commercial and Government and Public entities since our inception in 2006. MAPS understands the requirements set forth by the ALTA Land Surveying Standards of 2011 and specializes in providing “Housing and Urban Development” HUD ALTA Surveys and HUD Surveyor’s Certificates in compliance with HUD-92457A-M requirements.
Example of Boundry (PDF)
Example of ALTA (PDF)
Easements and Legal Descriptions
Large Design and Right-of-Way surveys often require a client to acquire portions of land either by Fee or by Easement from the existing property owners. MAPS understands the general requirements for creation of plats and legal description for inclusion to deeds of records; but also recognizes that requirements for submission are unique to the local municipal regulations. MAPS works with the client and the municipalities to ensure plats are created in a format ready to go straight from review to record.
Example (PDF)
DC Registered Survey
Greg Pendleton is a Registered Surveyor with the Office of the Surveyor in the District of Columbia and can provide surveying services in an official capacity for the D.C. Regulatory Authority as well as record surveys with the documents of the DC Surveyor.
- Survey to Mark Corners
- D.C. Wall Check
Topographic and Utility Base mapping
Topographic Feature Mapping
MAPS provides Topographic Mapping Services in support of Architectural and Engineering design. MAPS employs state of the art robotic total stations and digital data collectors using field to finish collection software to draw a digital 3 dimensional model of the site in the field. At MAPS we also use the same surveyor who collects the data to process the data, cleanup the drafting and generate the DTM providing consistency from inception to delivery.
- Aerial Drone Photogrammetry and Inspection
Example (PDF)
Class A thru D Utility Mapping
MAPS realizes that to our A/E clients, infrastructure below the ground is as much, if not more important that what is above the ground. New design requires both avoidance and connection, which without the proper information can be extremely expensive. At MAPS we are able to offer in-house utility mapping of Class B thru D and subcontracted Class A location as required by the client.
Class D: Utility location based only on plans of record. This should only be used in planning stages and never for design.
Class C: Utility location based on plans and rectified with visible utility structures. This level provides a strong level of confidence in the general area of the utility, without exact horizontal location. Storm and Sanitary are normally located in 3D by field measurement with this level of location.
Class B: Utility location based on passive and active induction of the utilities. This provides accurate horizontal location of inducible utilities such as water, electric, gas and telecommunication.
Class A: Non-destructive pressurized air and soil vacuum is used to expose the utility which can then be given a direct 3 dimensional location. After the utility is located, the vacuumed dirt is reinserted leaving no permanent damage to the site.
Aerial Photogrammetry and LIDAR (Light Detection and Ranging)
There are many factors that make Aerial Photogrammetry and LIDAR a strong alternative to conventional surveying for many of our client’s needs. MAPS will work with our clients to determine accuracy requirements, possible areas of obscurity and the time of year (leaf off or leaf on) to see if aerial surveying is the best alternative. MAPS will then coordinate with our aerial vendor to determine altitude of flight, establish aerial control points for triangulation and take the aerial product to the field to edit those features that cannot be accurately determined in flight (e.g. water valves, types of manholes, etc.) and ground truth the aerial survey to ensure the survey meets or exceed the horizontal and vertical requirements established by the National Standards of Spatial Data Accuracy.
Aerial Drone Photogrammetry and Inspection
MAPS hold an FAA Part 107 Commercial Remote License to fly aerial drones in the United States. MAPS employ a DJI Phantom 4 Professional Quad Copter with automated flight, redundant safety features and 4K CCD for still and video photography and photogrammetry. Using surveyed ground control points and PIX4D software, MAPS is able to create high resolution orthophotography as well as create digital terrain models.
Right-of-Way Surveys
MAPS has performed a variety of Right-of-Way surveys for both transportation and proposed utility corridor work. Right-of-way surveys require a unique combination of services including pre-design boundary, topographic and utility base mapping and culminating into post-design fee and easement platting and legal descriptions for property acquisition.
GIS/LIS (Global Information Systems / Land Information Systems)
High Accuracy Asset Collection and Feature Attribution
Using a combination of GPS and Conventional Robotic Total Stations along with Mobile GIS Data Collection, MAPS can populate a GIS using the clients existing data-model so that the feature class and data structure maintain the consistency of the existing data model while providing metadata of the method and accuracy of collection.
Accurate Integration of Cadastral Data
MAPS can provide computation and boundary resolution as required by a licensed surveyor to populate a cadastral database or Land Information System with high accuracy boundary information.
Existing Feature Verification and Rectification
MAPS can update existing GIS data to reflect a more accurate location of data or updated attribute information and return it to the existing GIS maintaining the consistency of the existing data model while providing metadata of the method and accuracy of collection.
BIM (Building Infrastructure Management)
2 Dimension High Accuracy Building Modeling
Using Conventional and Reflectorless Surveying technology wirelessly linked to laptop based AutoCAD on a rolling mobileplatform, MAPS is able to create real-time high accuracy floor plans for architectural design, lease calculation and integration to BIM platforms such as Revit.
Example (PDF)
Laser Scanning and 3 Dimensional Modeling
When there is a requirement for complex 3D modeling or the need to create base mapping where conventional location is difficult or hazardous, MAPS can provide terrestrial LIDAR or Laser Scanning Services. Depending on the range requirements, MAPS can employ either phase based scanning for confined areas or time of flight based scanning for larger more conventional projects. Feature data can be extracted to provide the client with CAD data required by scope or a full point cloud deliverable with rectified imagery.