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Summary

OCID:: ocds-kuma6s-162929
Published by:: Awdurdod Parc Cenedlaethol Eryri
Authority ID:: AA22451
Publication date:: 16 June 2026
Deadline date:: -
Notice type:: Contract Award Notice
Has documents:: No
Has SPD:: No
Has Carbon Reduction Plan:: No

Abstract

Reservoirs Act 1975: Llyn Mair Reservoir, County of Gwynedd, Eryri National Park Reservoir Safety Improvement Works (MIOS) Tender Expression of Interest Stillwater Associates has been employed by Eryri National Park to oversee the implementation of reservoir safety improvement works on Llyn Mair Reservoir. The site is located close to the village of Maentwrog, NGR SH 653 412. The proposed works are the construction of a new siphon pipe to allow the reservoir level to be drawn down in case of emergencies. This is to be achieved by repurposing one of the four existing spillways (Spillway ‘C’) to contain the new HDPE siphon and then subsequently backfilling with mass concrete or aggregate depending on the location. The upstream leg of the siphon is to be installed using qualified divers with some partial demolition work undertaken to the chamber. Additionally, Spillway ‘D’ is to be abandoned in situ by forming a wall across the existing channel. The works are required to address statutory recommendations made in the interests of reservoir safety. Eryri National Park has committed to having the works completed by 31st July 2026 and it is imperative that the successful contractor delivers the works accordingly.

Full notice text

CONTRACT AWARD NOTICE – NATIONAL

Notice Type: WORKS

1 Authority Details

1.1 Authority Name and Address

Official Name: Awdurdod Parc Cenedlaethol Eryri
Postal Address: Penrhyndeudraeth,
Town: Gwynedd	Postal Code: LL48 6LF	Country: UK
For the attention of: Edward Jones	Telephone: +44 1766770274
E-Mail:	Fax:
Internet Address (URL): http://www.eryri.llyw.cymru

2 Contract Details

2.1 Title

Reservoir Safety Improvement Works

2.2 Description of the contract

Reservoirs Act 1975: Llyn Mair Reservoir, County of Gwynedd, Eryri National Park

Reservoir Safety Improvement Works (MIOS)

Tender Expression of Interest

Stillwater Associates has been employed by Eryri National Park to oversee the implementation of reservoir safety improvement works on Llyn Mair Reservoir. The site is located close to the village of Maentwrog, NGR SH 653 412.

The proposed works are the construction of a new siphon pipe to allow the reservoir level to be drawn down in case of emergencies. This is to be achieved by repurposing one of the four existing spillways (Spillway ‘C’) to contain the new HDPE siphon and then subsequently backfilling with mass concrete or aggregate depending on the location. The upstream leg of the siphon is to be installed using qualified divers with some partial demolition work undertaken to the chamber. Additionally, Spillway ‘D’ is to be abandoned in situ by forming a wall across the existing channel.

The works are required to address statutory recommendations made in the interests of reservoir safety. Eryri National Park has committed to having the works completed by 31st July 2026 and it is imperative that the successful contractor delivers the works accordingly.

2.3 Notice Coding and Classification

a) Commodity Codes

	Code		Description
	45000000		Construction work
	45200000		Works for complete or part construction and civil engineering work
	45240000		Construction work for water projects
	45247200		Construction work for dams and similar fixed structures
	45247210		Dam construction work
	45247270		Reservoir construction works
	71000000		Architectural, construction, engineering and inspection services
	71300000		Engineering services
	71500000		Construction-related services

b) Delivery Location/Area

	Code		Location
	1012		Gwynedd

2.4 Estimated Total Value

3 Procedure

3.1 Type of Procedure

Dual stage

4 Award of Contract

4.1 Successful Bidders

4.1.1 Name and Address of successful supplier, contractor or service provider

Contract No:

Official Name: William Hughes (Civil Engineering) Limited
Postal Address: W H Offices, Bodffordd,
Town: Llangefni	Postal Code: LL777DZ	Country: UK
For the attention of:	Telephone:
E-Mail:	Fax:
Internet Address (URL): http://www.williamhughes.com

5 Other Information

5.1 Reference number attributed to the notice by the contracting authority

N/a

5.2 Date of Contract Award

16-06-2026

5.3 Number of tenders received

5.4 Other Information

(WA Ref:166464)

5.5 Additional Documentation

N/a

5.6 Publication date of this notice:

16-06-2026

SF 53

Coding

Commodity categories

ID	Title	Parent category
71000000	Architectural, construction, engineering and inspection services	Construction and Real Estate
45000000	Construction work	Construction and Real Estate
45247200	Construction work for dams and similar fixed structures	Construction work for dams, canals, irrigation channels and aqueducts
45240000	Construction work for water projects	Works for complete or part construction and civil engineering work
71500000	Construction-related services	Architectural, construction, engineering and inspection services
45247210	Dam construction work	Construction work for dams, canals, irrigation channels and aqueducts
71300000	Engineering services	Architectural, construction, engineering and inspection services
45247270	Reservoir construction works	Construction work for dams, canals, irrigation channels and aqueducts
45200000	Works for complete or part construction and civil engineering work	Construction work

Delivery locations

ID	Description
1012	Gwynedd

Alert region restrictions

The buyer has restricted the alert for this notice to suppliers based in the following regions.

ID	Description
There are no alert restrictions for this notice.

Document family

Notice details
MAR598554: Reservoir Safety Improvement Works / Expression of Interest Publication date: 16 March 2026 Deadline date: 10 April 2026 00:00 Notice type: Contract Notice Authority name: Awdurdod Parc Cenedlaethol Eryri
JUN627234: Reservoir Safety Improvement Works Publication date: 16 June 2026 Notice type: Contract Award Notice Authority name: Awdurdod Parc Cenedlaethol Eryri

About the buyer

Main contact:: N/a
Admin contact:: N/a
Technical contact:: N/a
Other contact:: N/a

Further information

Date	Details
No further information has been uploaded.

Reservoir Safety Improvement Works

Contents

Summary

Abstract

Full notice text

CONTRACT AWARD NOTICE – NATIONAL

1 Authority Details

1.1

Authority Name and Address

2 Contract Details

2.1

Title

2.2

Description of the contract

2.3

Notice Coding and Classification

2.4

Estimated Total Value

3 Procedure

3.1

Type of Procedure

4 Award of Contract

4.1

Successful Bidders

4.1.1

Name and Address of successful supplier, contractor or service provider

5 Other Information

5.1

Reference number attributed to the notice by the contracting authority

5.2

Date of Contract Award

5.3

Number of tenders received

5.4

Other Information

5.5

Additional Documentation

5.6

Publication date of this notice: