Project for the Expansion and Construction of the Sewer System in the Village of Macieira

Municipality of Sernancelhe

Introduction

This technical project consists of the development of a domestic wastewater drainage network for Rua Pinheiro Manso, located in Maceira, in the municipality of Leiria. The intervention focuses on creating an efficient sanitation infrastructure for a specific residential area, ensuring the correct collection and storage of domestic effluents in accordance with health and environmental protection regulations.

Context and Need

The project’s necessity stems from the need to provide a public drainage system for a 280-meter stretch that currently serves 17 houses. The design was structured for a population of 60 inhabitants, considering a zero growth rate over a 40-year project horizon. The central objective is to replace the lack of sanitation with a viable and economical solution that ensures gravity flow, self-cleaning of the collectors, and protection against groundwater contamination, given the location of the water table in the region.

Summary of the Project Completed

The implemented technical solution is based on a gravity drainage system culminating in a watertight storage system, composed of the following main elements:

• Sewer Network: Installation of double-walled corrugated polypropylene (PP) piping, class SN8. This material was selected for its high circumferential rigidity, impact resistance, and ease of handling.
• Accessory Structures: Installation of precast concrete culverts with a maximum spacing of 60 meters, ensuring accessibility for maintenance. Specific sizing of these boxes was carried out to prevent flotation (Archimedes’ principle) due to the hydrostatic pressure of the water table.
• Domestic Connections: Execution of 17 connection branches in corrugated PP SN8, ensuring the conduction of water from residences to the public network through forks or direct connection to the boxes.
• Storage System: Construction of a watertight septic tank with a capacity of 120,000 liters. This equipment allows for the safe storage of effluents for periods of approximately 25 days, with bi-weekly cleaning recommended.
• Additional Works: Replacement of bituminous pavements after milling and trenching, in addition to rigorous shoring procedures for the safety of excavations with depths greater than 1.20 m.

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