Sufficiently Complex Connection Involving Pipeline Construction and/or System Reinforcement

Project Sequence

Project Elements

Initial Enquiry

Feasibility Study

Conceptual Design

Construction

Detail Design

Initial Enquiry

• Enquiry is sufficiently complex as detailed by the DN’s Statement of Principles and Methods for Determining Connections Charges – Licence Ref. 4B.

• Generally at this stage (depending on the specific enquirer’s request) NGN will normally issue the following:• A desktop assessment of the availability of supply.• A quotation for a Feasibility Study and associated timescales.• If possible a “ballpark estimate” of costs – This is usually based on

pipeline cost curves and other costs from previous projects.

Feasibility Study

• Detailed network analysis.• Establish design alternatives. • Establish pipeline route corridors.• Develop principles from desktop study

information to reach informed cost effective decisions based on engineering and environmental constraints.

• Formulate a cost estimate (usually base cost + 30%) to allow high level decisions).

Conceptual Design

• Investigate design alternatives further.• Reduce risk and increase cost estimate accuracy.• Develop/refine solutions and options.• Define the essential elements and options for

detailed design.• Formulate a cost estimate (usually base cost +

15%) to allow high level decisions.

Detailed Design

• Confirm pipeline route.• Initiate easement negotiations.• Confirm pipeline and/or reinforcement (e.g. offtake

upgrades) design parameters.• Detailed routing study to fine tune pipeline routes.• Detailed design drawings for pipeline, special crossings,

pressure reduction equipment etc..• Detailed project programme.• Materials identified and maybe ordered.

Possible Variations

• For a small simple connection a feasibility, conceptual and detailed design studies may be one or the same thing.

• Easement negotiations can be problematical.• Environmental surveys can be seasonal

dependant.

Points to Note

• DN transmission connections/enquiries are:• Small in number• Bespoke• Dealt with by one or two people and so receive

personal attention with continual dialogue• Flexible to meet customers needs• Have agreed timescales and milestones